3DEC3 Dimensional Distinct Element Code

Users Guide

2003Itasca Consulting Group, Inc. Phone: (1) 612-371-4711Mill Place Fax: (1) 6123714717111 Third Avenue South, Suite 450 E-Mail: software@itascacg.comMinneapolis, Minnesota 55401 USA Web: www.itascacg.com

First Edition December 1998

First Revision May 1999

Second Revision September 1999

Second Edition January 2003

Terms - 1

Terms and Conditions for Licensing 3DEC

YOU SHOULD READ THE FOLLOWING TERMS AND CONDITIONS CAREFULLYBEFORE USING THE 3DEC PROGRAM. INSTALLATION OF THE 3DEC PROGRAMINTO YOUR COMPUTER INDICATES YOUR ACCEPTANCE OF THESE TERMS ANDCONDITIONS. IF YOU DO NOT AGREE WITH THEM, YOU SHOULD RETURN THEPACKAGE PROMPTLY AND YOUR MONEY WILL BE REFUNDED.

This program is provided by Itasca Consulting Group, Inc. Title to the media on which the programis recorded and to the documentation in support thereof is transferred to the customer, but title to theprogram is retained by Itasca. You assume responsibility for the selection of the program to achieveyour intended results and for the installation of the program, the use of and the results obtainedfrom the program.

LICENSE

You may use the program on only one machine at any one time. You may copy the program for back-up only in support of such use. You may not use, copy, modify, or transfer the program, or any copy, in whole or part,

except as expressly provided in this document.

You may not sell, sub-license, rent, or lease this program.

TERMS

The license is effective until terminated. You may terminate it any time by destroying the programtogether with any back-up copies and returning the hardware lock. It will also terminate if youfail to comply with any term or condition of this agreement. You agree upon such termination todestroy the program together with any back-up copies, modifications, and/or merged portions inany form and return the hardware lock to Itasca.

WARRANTY

Itasca will correct any errors in the code at no charge for twelve (12) months after the purchase dateof the code. Notification of a suspected error must be made in writing, with a complete listing ofthe input and output files and description of the error. If, in the judgment of Itasca, the code doescontain an error, Itasca will (at its option) correct or replace the copy at no cost to the user or refundthe initial purchase price of the code.

3DEC Version 3.0

Terms - 2 Users Guide

LIMITATION OF LIABILITY

Itasca assumes no liability whatsoever with respect to any use of 3DEC or any portion thereof orwith respect to any damages or losses that may result from such use, including (without limitation)loss of time, money or goodwill that may arise from the use of 3DEC (including any modifications orupdates that may follow). In no event shall Itasca be responsible for any indirect, special, incidentalor consequential damages arising from use of 3DEC.

CODE SUPPORT

Itasca will provide telephone support, at no charge, to assist the code owner in the installation ofthe 3DEC code on his or her computer system. Additionally, general assistance may be providedin aiding the owner in understanding the capabilities of the various features of the code. However,no-cost assistance is not provided for help in applying 3DEC to specific user-defined problems.

Technical support can be purchased on an as-needed basis. For users who envisage the need forsubstantial amounts of assistance, consulting support is available. In all instances, the user isencouraged to send the problem description to Itasca by electronic mail in order to minimize theamount of time spent trying to define the problem. See Section 6 in the Users Guide for details.

3DEC Version 3.0

Users Guide 1

PRECISThis volume is the users guide to 3DEC. This guide contains general information on the operationof 3DEC for engineering mechanics computation.

Section 1 gives an introduction to the capabilities and applications of 3DEC. An overview of thenew features in the latest version of 3DEC is also provided.

The first-time user should consult Section 2 for an introduction to the operation of 3DEC. Theinstallation and operation procedures are given along with a simple tutorial to guide the new userthrough a 3DEC analysis.

Section 3 provides general guidance in the use of 3DEC in problem solving for static mechanicalanalysis for geotechnical engineering.

An introduction to the built-in programming language, FISH, is given in Section 4. This includesa tutorial on the use of the FISH language. Note that no programming experience is assumed.

3DEC contains a graphical interface to assist with model creation and presentation of results. Thegraphical interface is described in Section 5.

Various items of interest to 3DEC users are contained in Section 6, including a 3DEC runtimebenchmark on several different types of computers, and procedures for reporting errors and re-questing technical assistance. Section 7 contains a bibliography of published papers describingsome applications of 3DEC in different fields of engineering.

The 3DEC Manual consists of seven documents. The following volumes, which comprise the 3DECManual, are available. (The titles in parentheses below are the names used to refer to the volumesin the text.)USERS GUIDE (Users Guide) an introduction to 3DEC and its capabilitiesCOMMAND REFERENCE (Command Reference) descriptions of all 3DEC commandsFISH in 3DEC (FISH volume) a complete guide to FISH as applied in 3DECTHEORY AND BACKGROUND (Theory and Background) thorough discussions of thebuilt-in features in 3DEC

OPTIONAL FEATURES (Optional Features) detailed descriptions of the optional features:thermal analysis, dynamic analysis, and the surface support (liner) modelVERIFICATION PROBLEMS (Verifications volume) and EXAMPLE APPLICATIONS (Ex-amples volume) a collection of verification problems and example applicationsCOMMAND AND FISH REFERENCE SUMMARY (Command and FISH Reference Sum-mary) a quick summary of all 3DEC commands and FISH statements

3DEC Version 3.0

2 Users Guide

3DEC Version 3.0

Users Guide Contents - 1

TABLE OF CONTENTS

1 INTRODUCTION1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 11.2 Comparison with Other Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 41.3 General Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 6

1.3.1 Basic Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 61.3.2 Optional Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 8

1.4 Summary of Updates from Version 2.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 91.4.1 Automatic Topographic Stress Initialization . . . . . . . . . . . . . . . . . . . . . . . . 1 - 91.4.2 User-Defined Models (UDM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 91.4.3 Additional Constitutive Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 91.4.4 Double Precision Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 91.4.5 Dynamic Free Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 91.4.6 Partial Density Scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 101.4.7 Higher Order Tetrahedral Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 101.4.8 Improved Bitmap and Printer Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 101.4.9 Poly Cube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 101.4.10 Structural Beam Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 101.4.11 Surface Stress Plotting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 101.4.12 Generalized Boundary Histories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 111.4.13 Joint Fluid Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 111.4.14 New Mouse Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 111.4.15 User-Controlled Colors for Contours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 111.4.16 User-Defined Stress Plot Planes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 11

1.5 Fields of Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 121.6 Guide to the 3DEC Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 131.7 Itasca Consulting Group, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 171.8 User Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 181.9 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 19

3DEC Version 3.0

Contents - 2 Users Guide

2 GETTING STARTED2.1 Installation and Start-up Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 2

2.1.1 Installation of 3DEC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 22.1.2 System Requirements for Windows 95/98/ME/NT/2000/XP . . . . . . . . . 2 - 32.1.3 Windows-Console Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 32.1.4 Utility Software and Graphics Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 42.1.5 Version Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 52.1.6 Start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 62.1.7 Program Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 62.1.8 Running 3DEC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 62.1.9 Installation Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 7

2.2 A Simple Tutorial Use of Common Commands . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 102.3 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 182.4 The 3DEC Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 212.5 Command Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 242.6 Mechanics of Using 3DEC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 26

2.6.1 Model Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 282.6.2 Assigning Material Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 31

2.6.2.1 Block Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 312.6.2.2 Joint Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 34

2.6.3 Applying Boundary and Initial Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 352.6.4 Stepping to Initial Equilibrium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 372.6.5 Performing Alterations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 392.6.6 Saving/Restoring Problem State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 422.6.7 Summary of Commands for Simple Analyses . . . . . . . . . . . . . . . . . . . . . . 2 - 44

2.7 Sign Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 452.8 Systems of Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 472.9 Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 482.10 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 50

3 PROBLEM SOLVING WITH 3DEC3.1 General Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2

3.1.1 Step 1: Define the Objectives for the Model Analysis . . . . . . . . . . . . . . . 3 - 33.1.2 Step 2: Create a Conceptual Picture of the Physical System . . . . . . . . . . 3 - 33.1.3 Step 3: Construct and Run Simple Idealized Models . . . . . . . . . . . . . . . . 3 - 43.1.4 Step 4: Assemble Problem-Specific Data . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 53.1.5 Step 5: Prepare a Series of Detailed Model Runs . . . . . . . . . . . . . . . . . . . 3 - 53.1.6 Step 6: Perform the Model Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 63.1.7 Step 7: Present Results for Interpretation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 6

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Users Guide Contents - 3

3.2 Model Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 73.2.1 Fitting the 3DEC Model to a Problem Region . . . . . . . . . . . . . . . . . . . . . . 3 - 73.2.2 Joint Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 123.2.3 Creating Internal Boundary Shapes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 17

3.2.3.1 Tunnel Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 183.2.3.2 POLY cube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 19

3.2.4 Selecting the Coordinate System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 223.2.5 Orientation of Geologic Features to the Model Axes . . . . . . . . . . . . . . . . 3 - 223.2.6 Choice of Model Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 233.2.7 Incorporation of Discontinuities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 24

3.3 Selection of Deformable versus Rigid Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 263.3.1 Poissons Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 263.3.2 Zoning for Deformable Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 31

3.4 Boundary Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 323.4.1 Stress Boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 32

3.4.1.1 Applied Stress Gradient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 333.4.1.2 Changing Boundary Stresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 343.4.1.3 Checking the Boundary Condition . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 353.4.1.4 Cautions and Advice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 35

3.4.2 Displacement Boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 383.4.3 Real Boundaries Choosing the Right Type . . . . . . . . . . . . . . . . . . . . . . . 3 - 383.4.4 Artificial Boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 39

3.4.4.1 Symmetry Planes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 393.4.4.2 Boundary Truncation Location of the Far-Field Boundary . 3 - 39

3.5 Initial Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 423.5.1 Uniform Stresses in an Unjointed Medium: No Gravity . . . . . . . . . . . . . 3 - 423.5.2 Stresses with Gradients in an Unjointed Medium: Uniform Material . . 3 - 433.5.3 Stresses with Gradients in a Nonuniform Material . . . . . . . . . . . . . . . . . . 3 - 443.5.4 Compaction within a Model with Nonuniform Zoning . . . . . . . . . . . . . . . 3 - 463.5.5 Initial Stresses following a Model Change . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 483.5.6 Stresses in a Jointed Medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 493.5.7 Determination of the In-situ Stress State . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 513.5.8 Transferring Field Stresses to Model Stresses . . . . . . . . . . . . . . . . . . . . . . . 3 - 533.5.9 Topographical Stresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 54

3.6 Loading and Sequential Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 553.7 Choice of Constitutive Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 76

3.7.1 Deformable-Block Material Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 763.7.2 Joint Material Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 783.7.3 Selection of an Appropriate Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 79

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3.8 Material Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 863.8.1 Block Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 86

3.8.1.1 Mass Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 863.8.1.2 Intrinsic Deformability Properties . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 863.8.1.3 Intrinsic Strength Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 873.8.1.4 Post-Failure Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 893.8.1.5 Extrapolation to Field-Scale Properties . . . . . . . . . . . . . . . . . . . . . 3 - 96

3.8.2 Joint Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1003.9 Tips and Advice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1023.10 Interpretation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 108

3.10.1 Unbalanced Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1083.10.2 Block/Gridpoint Velocities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1083.10.3 Plastic Indicators for Block Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1093.10.4 Histories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 110

3.11 Modeling Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1113.11.1 Modeling of Data-Limited Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1113.11.2 Modeling of Chaotic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1113.11.3 Localization, Physical Instability and Path-Dependence . . . . . . . . . . . . . 3 - 113

3.12 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 115

4 FISH BEGINNERS GUIDE4.1 Introduction and Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 14.2 Tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 2

5 GRAPHICAL INTERFACE5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 25.2 Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 4

5.2.1 Main Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 45.2.2 Select Color Mode Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 105.2.3 Select Joint Mode Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 115.2.4 Target Active Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 125.2.5 Structure Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 175.2.6 Special Options Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 185.2.7 Stresses Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 205.2.8 Vectors (and Contours) Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 24

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6 MISCELLANEOUS6.1 3DEC Runtime Benchmark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 16.2 Error Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 3

6.2.1 Reporting via Internet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 36.2.2 Reporting via Fax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 3

6.3 Technical Support Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 3

7 BIBLIOGRAPHY

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TABLES

Table 2.1 Maximum number of 3DEC blocks in available RAM . . . . . . . . . . . . . . . . . . . . . 2 - 4Table 2.2 Typographical conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 25Table 2.3 Boundary condition command summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 35Table 2.4 Basic commands for simple analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 44Table 2.5 Systems of units mechanical parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 47Table 3.1 Recommended steps for numerical analysis in geomechanics . . . . . . . . . . . . . . . 3 - 3Table 3.2 3DEC block constitutive models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 77Table 3.3 3DEC joint constitutive models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 79Table 3.4 Selected elastic constants (laboratory-scale) for rocks (adapted from Goodman

1980) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 87Table 3.5 Selected strength properties (laboratory-scale) for rocks (adapted from Good-

man 1980) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 88Table 3.6 Typical values for Hoek-Brown rock-mass strength parameters

(adapted from Hoek and Brown (1988)) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 99Table 4.1 Commands that directly refer to FISH names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 4Table 6.1 3DEC runtime calculation rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 1

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FIGURES

Figure 2.1 PostScript plot from TEST3.DAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 9Figure 2.2 3DEC model of a rock slope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 12Figure 2.3 History of y-velocity for initial rock slope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 15Figure 2.4 Rock slope failure in progress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 17Figure 2.5 Vertical cross-section through wedge showing displacement vectors . . . . . . . 2 - 17Figure 2.6 Example of a 3DEC model (not to scale) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 18Figure 2.7 3DEC model block divided into two blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 22Figure 2.8 General solution procedure for static analysis in geomechanics . . . . . . . . . . . . 2 - 27Figure 2.9 Block model with three intersecting joint planes . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 29Figure 2.10 Tunnel in jointed rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 30Figure 2.11 Tunnel in jointed rock excavation and joint structure . . . . . . . . . . . . . . . . . . 2 - 31Figure 2.12 Maximum unbalanced force history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 38Figure 2.13 y-displacement history at (.3, .3, 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 39Figure 2.14 Sliding wedge in tunnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 41Figure 2.15 y-displacement history at (.3, .3, -0.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 41Figure 2.16 y-displacement history at (.3, .3, -0.1) wedge is stable . . . . . . . . . . . . . . . . . 2 - 43Figure 2.17 Sign convention for positive stress components . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 45Figure 3.1 Spectrum of modeling situations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2Figure 3.2 Cubic model created with the POLY face command . . . . . . . . . . . . . . . . . . . . . . 3 - 9Figure 3.3 An octahedral-shaped prism generated with the POLY prism command . . . . . 3 - 10Figure 3.4 Tunnel model created with the POLY tunnel command . . . . . . . . . . . . . . . . . . . . 3 - 11Figure 3.5 Terms describing the attitude of an inclined plane:

dip angle, , is positive measured downward from the horizontal (xz) plane;dip direction, , is positive measured clockwise from north (z) . . . . . . . . . 3 - 12

Figure 3.6 Model created with the JSET and HIDE commands . . . . . . . . . . . . . . . . . . . . . . . 3 - 14Figure 3.7 Concave block created with the JOIN command . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 15Figure 3.8 Rock slope containing continuous and noncontinuous joints . . . . . . . . . . . . . . 3 - 16Figure 3.9 Tunnel created with TUNNEL command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 19Figure 3.10 Elements of the POLY cube command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 20Figure 3.11 Resultant geometry from example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 21Figure 3.12 Orientation of 3DEC model axes (x,y,z) relative to north-east-up reference

axes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 23Figure 3.13 Stereonet plot of fault relative to model axes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 25Figure 3.14 Stereonet plot of pole to fault and model reference axes relative to problem

north-east axes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 25Figure 3.15 Model for Poissons effect in rock with vertical and horizontal jointing . . . . 3 - 27Figure 3.16 Poissons effect for vertically-jointed rock

( = 0.3 for intact rock) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 28

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Figure 3.17 Model for Poissons effect in rock with joints dipping at angle from thehorizontal and with spacing S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 29

Figure 3.18 Poissons effect for jointed rock at various joint angles (blocks are rigid) . . . 3 - 29Figure 3.19 Poissons effect for rock with two equally spaced joint sets

with = 45 (blocks are deformable with = 0.2) . . . . . . . . . . . . . . . . . . . . 3 - 30Figure 3.20 Uplift when material is removed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 36Figure 3.21 Mixing stress and velocity boundary conditions . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 37Figure 3.22 Models used to transfer stress boundary conditions . . . . . . . . . . . . . . . . . . . . . . 3 - 40Figure 3.23 Nonuniform stresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 47Figure 3.24 Uniform stresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 48Figure 3.25 Slip of a confined joint; plot shows shear stress contours . . . . . . . . . . . . . . . . . 3 - 51Figure 3.26 3DEC model of tunnel region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 58Figure 3.27 Displacement histories at top of model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 61Figure 3.28 y-displacement history at tunnel roof . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 62Figure 3.29 Close-up view of wedge in roof (surrounding blocks hidden) . . . . . . . . . . . . . 3 - 62Figure 3.30 Cable bolts positioned around tunnel excavation . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 63Figure 3.31 y-displacement history at tunnel roof reinforcement element support . . . . 3 - 66Figure 3.32 y-displacement history at tunnel roof cable support . . . . . . . . . . . . . . . . . . . 3 - 66Figure 3.33 Axial forces in reinforcement elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 67Figure 3.34 Axial forces in cable elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 67Figure 3.35 Thick concrete liner support liner blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 70Figure 3.36 y-displacement history at tunnel roof tunnel liner added after tractions

reduced by 50% . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 70Figure 3.37 Thick concrete liner support prism-shaped liner blocks . . . . . . . . . . . . . . . . 3 - 73Figure 3.38 Thick concrete liner support mixed-discretization zoning in liner blocks . 3 - 74Figure 3.39 y-displacement history at tunnel roof support by prism-shaped liner blocks 3 - 75Figure 3.40 Principal stress distribution in top section of liner . . . . . . . . . . . . . . . . . . . . . . . . 3 - 75Figure 3.41 Direct shear test model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 80Figure 3.42 Average shear stress versus shear displacement

Coulomb slip model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 83Figure 3.43 Average normal displacement versus shear displacement

Coulomb slip model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 83Figure 3.44 Average shear stress versus shear displacement

Coulomb slip model with peak and residual strength . . . . . . . . . . . . . . . 3 - 84Figure 3.45 Average normal displacement versus shear displacement

Coulomb slip model with peak and residual strength . . . . . . . . . . . . . . . 3 - 85Figure 3.46 Idealized relation for dilation angle, , from triaxial test results (Vermeer and

de Borst 1984) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 89Figure 3.47 yy stress versus yy-strain for tension test with cons 2 model . . . . . . . . . . . . . 3 - 93Figure 3.48 yy stress versus yy-strain for tension test with cons 6 model and tensile-

softening table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 94Figure 3.49 xx-strain versus yy-strain for tension test with cons 2 model . . . . . . . . . . . . . . 3 - 95

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Figure 3.50 xx-strain versus yy-strain for tension test with cons 6 model and tensile-softening table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 95

Figure 3.51 A small portion of a jointed rock mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 112Figure 5.1 3DEC graphical interface (DOS version) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 1Figure 5.2 3DEC menu guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 3Figure 5.3 Location of viewing plane in terms of dip, dip direction and center distance

from model axes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 9Figure 5.4 Example interrogate block menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 13Figure 5.5 Symbols identifying failure mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 22

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EXAMPLES

Example 2.1 3DEC output from TEST1.DAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 8Example 2.2 3DEC model block divided into two blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 21Example 2.3 Block model with three intersecting joint planes . . . . . . . . . . . . . . . . . . . . . . . 2 - 28Example 2.4 Tunnel in jointed rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 29Example 2.5 Assigning material models and properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 34Example 2.6 Applying boundary and initial conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 36Example 2.7 Stepping to initial equilibrium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 38Example 2.8 Reduce the strength of the joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 40Example 2.9 Stabilize roof block with a cable bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 42Example 3.1 A cube generated with the POLY face command . . . . . . . . . . . . . . . . . . . . . . . . 3 - 8Example 3.2 A cube generated with the POLY brick command . . . . . . . . . . . . . . . . . . . . . . . 3 - 9Example 3.3 An octahedral-shaped prism generated with the POLY prism command . . . 3 - 10Example 3.4 A tunnel model generated with the POLY tunnel command . . . . . . . . . . . . . . 3 - 11Example 3.5 Creation of a noncontinuous vertical joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 13Example 3.6 Rock slope containing continuous and noncontinuous joints . . . . . . . . . . . . . 3 - 16Example 3.7 Tunnel created with the TUNNEL command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 18Example 3.8 Data file which generates a model using POLY cube command . . . . . . . . . . . 3 - 21Example 3.9 Uplift when material is removed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 35Example 3.10 Mixing stress and velocity boundary conditions . . . . . . . . . . . . . . . . . . . . . . . . 3 - 36Example 3.11 Initial and boundary stresses in equilibrium . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 43Example 3.12 Initial stress state with gravitational gradient . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 44Example 3.13 Initial stress gradient in a nonuniform material . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 45Example 3.14 Nonuniform stress initialized in a model with nonuniform zoning . . . . . . . . 3 - 46Example 3.15 Initial stresses following a model change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 49Example 3.16 Slip of a confined joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 50Example 3.17 Stability analysis of an underground excavation initial model . . . . . . . . . 3 - 56Example 3.18 Stability analysis of an underground excavation initial equilibrium stress

state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 59Example 3.19 Stability analysis of an underground excavation unsupported tunnel . . . 3 - 61Example 3.20 Stability analysis of an underground excavation local reinforcement sup-

port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 63Example 3.21 Stability analysis of an underground excavation fully grouted cable sup-

port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 64Example 3.22 Stability analysis of an underground excavation reduce tunnel tractions

by 50% and install liner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 68Example 3.23 Stability analysis of an underground excavation liner with m-d zoning . 3 - 71Example 3.24 Direct shear test with Coulomb slip model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 80Example 3.25 Tension test on tensile-softening material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 91Example 4.1 Defining a FISH function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 2

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Example 4.2 Using a variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 3Example 4.3 SETting variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 3Example 4.4 Test your understanding of function and variable names . . . . . . . . . . . . . . . . 4 - 4Example 4.5 Capturing the history of a FISH variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 4Example 4.6 FISH functions to calculate bulk and shear moduli . . . . . . . . . . . . . . . . . . . . . 4 - 6Example 4.7 Using symbolic variables in 3DEC input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 6Example 4.8 Controlled loop in FISH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 7Example 4.9 Applying a nonlinear initial distribution of moduli . . . . . . . . . . . . . . . . . . . . . 4 - 8Example 4.10 Splitting lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 9Example 4.11 Variable types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 9Example 4.12 Action of the IF ELSE ENDIF construct . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 11Example 6.1 Benchmark data file TIMING.DAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 2

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3DEC Version 3.0

INTRODUCTION 1 - 1

1 INTRODUCTION

1.1 Overview

3DEC is a three-dimensional numerical program based on the distinct element method for dis-continuum modeling. The basis for this program is the extensively tested numerical formulationused by the two-dimensional version, UDEC (Itasca 1996). 3DEC simulates the response of dis-continuous media (such as a jointed rock mass) subjected to either static or dynamic loading.The discontinuous medium is represented as an assemblage of discrete blocks. The discontinu-ities are treated as boundary conditions between blocks; large displacements along discontinuitiesand rotations of blocks are allowed. Individual blocks behave as either rigid or deformable ma-terial. Deformable blocks are subdivided into a mesh of finite difference elements, and eachelement responds according to a prescribed linear or nonlinear stress-strain law. The relative mo-tion of the discontinuities is also governed by linear or nonlinear force-displacement relationsfor movement in both the normal and shear directions. 3DEC has several built-in material be-havior models, for both the intact blocks and the discontinuities, that permit the simulation ofresponse representative of discontinuous geologic, or similar, materials. 3DEC is based on aLagrangian calculation scheme that is well-suited to model the large movements and deforma-tions of a blocky system.

The distinguishing features of 3DEC are summarized below.

The rock mass is modeled as a 3D assemblage of rigid or deformable blocks. Discontinuities are regarded as distinct boundary interactions between these

blocks; joint behavior is prescribed for these interactions. Continuous and discontinuous joint patterns can be generated on a statistical

basis. A joint structure can be built into the model directly from the geologicmapping.

3DEC employs an explicit in-time solution algorithm that accommodates bothlarge displacement and rotation and permits time domain calculations.

The graphics facility permits interactive manipulation of 3D objects. In thegraphics screen mode, the user can move into the model and make regionsinvisible for better viewing purposes. This allows the user to build the modelfor a geotechnical analysis and instantly view the 3D representation. Thisgreatly facilitates the generation of 3D models and interpretation of results.

3DEC also contains the powerful built-in programming language FISH (short for FLACish; FISHwas originally developed for our two-dimensional, finite-difference, continuum program FLAC).With FISH, you can write your own functions to extend 3DEC s usefulness. FISH offers a uniquecapability to 3DEC users who wish to tailor analyses to suit specific needs.

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With the exception of the graphics mode, 3DEC is a command-driven (rather than menu-driven)computer program. Although a menu-driven program is easier to learn for the first time, thecommand-driven structure in 3DEC offers several advantages when applied in engineering studies.

1. The input language is based upon recognizable word commands that allowyou to identify the application of each command easily and in a logical fashion(e.g., the BOUNDARY command applies boundary conditions to the model).

2. Engineering simulations usually consist of a lengthy sequence of operations e.g., establish in-situ stress, apply loads, excavate tunnel, install supportand so on. A series of input commands (from a file or from the keyboard)corresponds closely with the physical sequence that it represents.

3. A 3DEC data file can easily be modified with a text editor. Several data filescan be linked to run a number of 3DEC analyses in sequence. This is ideal forperforming parameter sensitivity studies.

4. The word-oriented input files provide an excellent means to keep a documentedrecord of the analyses performed for an engineering study. Often, it is con-venient to include these files as an appendix to the engineering report for thepurpose of quality assurance.

5. The command-driven structure allows you to develop pre- and post-processingprograms to manipulate 3DEC input/output as desired. For example, you maywish to write a joint-generation function to create a special joint structure for aseries of 3DEC simulations. This can readily be accomplished with the FISHprogramming language and incorporated directly in the input data file.

The formulation and development of the distinct element method embodied in 3DEC has progressedfor a period of over 25 years, beginning with the initial presentation by Cundall (1971). In 1988,Dr. Cundall and Itasca staff adapted 3DEC specifically to perform engineering calculations on aPC. The software is designed for high-speed computation of models containing several thousandblocks. With the advancements in floating-point operation speed and the ability to install additionalRAM at low cost, increasingly larger problems can be solved with 3DEC.

For example, 3DEC can solve a model containing up to 7500 rigid blocks (or 3000 deformableblocks with 24 degrees-of-freedom per block) on a microcomputer using 32 MB RAM. The solutionspeed for a model of this size is roughly 125 calculation steps per minute (or 200 calculation stepsper minute for the 3000 deformable block model) on a 2.23 GHz Pentium 4 microcomputer.* Thecalculation speed is essentially a linear function of the number of blocks in a model, and the numberof blocks is a linear function of the available RAM on the computer (see Table 2.1 in Section 2.1.3).For typical models, consisting of roughly 2000 rigid blocks (or 1000 deformable blocks) or fewer,the explicit solution scheme in 3DEC requires approximately 2000 to 4000 steps to reach a solved

* See Section 6 for a comparison of 3DEC runtimes on various computer systems.

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state.* For example, a 1000 deformable block model run on the Pentium computer describedabove would require roughly 6 minutes to perform 4000 calculation steps. Consequently, typicalengineering problems involving several hundred blocks and multiple solution stages can be solvedwith 3DEC on a microcomputer in a matter of minutes or a few hours.

A comparison of 3DEC to other numerical methods, a description of general features and newupdates in 3DEC Version 3.0, and a discussion of fields of application are provided in the followingsections. If you wish to try 3DEC right away, the program installation instructions and a simpletutorial are provided in Section 2.2.

* This will vary depending on the amount of relative motion that occurs between blocks. The explicitsolution scheme is explained in Section 1.2.2 in Theory and Background.

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1.2 Comparison with Other Methods

Some common questions asked about 3DEC are: Is 3DEC a distinct element or discrete elementprogram? What is the difference, and what is 3DEC s relation to other programs? We provide adefinition here which we hope will clarify these matters.

Many finite element, boundary element and Lagrangian finite difference programs have interfaceelements or slide lines that enable them to model a discontinuous material to some extent. How-ever, their formulation is usually restricted in one or more of the following ways. First, the logicmay break down when many intersecting interfaces are used; second, there may not be an automaticscheme for recognizing new contacts; and third, the formulation may be limited to small displace-ments and/or rotation. Such programs are usually adapted from existing continuum programs.

The name discrete element method applies to a computer program only if it:

(a) allows finite displacements and rotations of discrete bodies, including completedetachment; and

(b) recognizes new contacts automatically as the calculation progresses.Without the first attribute, a program cannot reproduce some important mechanisms in a discontin-uous medium; without the second, the program is limited to small numbers of bodies for which theinteractions are known in advance. The term distinct element method was coined by Cundall andStrack (1979) to refer to the particular discrete element scheme that uses deformable contacts andan explicit, time-domain solution of the original equations of motion (not the transformed, modalequations).There are four main classes of computer programs that conform to the proposed definition ofa discrete element method. (The classes and representative programs are discussed further inSection 1.1.1 in Theory and Background.)

1. Distinct Element Programs These programs use explicit time-marching tosolve the equations of motion directly. Bodies may be rigid or deformable(by subdivision into elements); contacts are deformable. 3DEC falls in thiscategory.

2. Modal Methods The method is similar to the distinct element method in thecase of rigid bodies but, for deformable bodies, modal superposition is used.

3. Discontinuous Deformation Analysis Contacts are rigid, and bodies maybe rigid or deformable. The condition of no-interpenetration is achieved by aniteration scheme; the body deformability comes from superposition of strainmodes.

4. Momentum-Exchange Methods Both the contacts and the bodies are rigid:momentum is exchanged between two contacting bodies during an instanta-neous collision. Frictional sliding can be represented.

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There are several published schemes that appear to resemble discrete element methods, but whichare different in character or are lacking one or more essential ingredients. For example, manypublications are concerned with the stability of one or more rigid bodies, using the limit equilibriummethod (Hoek (1973); Warburton (1981); Goodman and Shi (1985); Lin and Fairhurst (1988)). Thismethod computes the static force equilibrium of the bodies and does not address the changes inforce distribution that accompany displacements of the bodies.

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1.3 General Features

1.3.1 Basic Features

3DEC is primarily intended for analysis in rock engineering projects, ranging from studies of theprogressive failure of rock slopes to evaluations of the influence of rock joints, faults, beddingplanes, etc. on underground excavations and rock foundations. 3DEC is ideally suited to studypotential modes of failure directly related to the presence of discontinuous features.

The program can best be used when the geologic structure is fairly well-defined for example,from observation or geologic mapping. Both a manual and automatic joint generator are built into3DEC to create individual, and sets of, discontinuities which represent jointed structure in a rockmass. A wide variety of joint patterns can be generated in the model. There are also two tunnelgenerators to set up models with long regularly-shaped excavations.

A pre-processor program (PGEN) is provided for reading AutoCad DXF files of section views ofa body that can be manipulated to provide a 3DEC data file to generate polyhedra which define amodels block structure. This program is particularly useful for defining complex excavations orgeologic shapes.

Different representations of joint material behavior are available. The basic model is the Coulombslip criterion, which assigns elastic stiffness, frictional, cohesive and tensile strengths and dilationcharacteristics to a joint. A modification to this model is the inclusion of displacement weakeningas a result of loss in cohesive and tensile strength at the onset of shear failure. A more complexmodel, the continuously yielding joint model, is also available and simulates continuous weakeningbehavior as a function of accumulated plastic shear displacement. Joint models and properties canbe assigned separately to individual or sets of discontinuities in a 3DEC model. It should be notedthat the geometric roughness of a joint is represented via the joint material model, even though theplot of discontinuities shows the joint as a planar segment.Blocks in 3DEC can be either rigid or deformable. There are five built-in (19 with the user-defined/extended models option (UDM)) material models for deformable blocks, ranging from thenull block material, which represents holes (excavations), to the shear yielding models, which in-clude strain-hardening/softening behavior and represent nonlinear, irreversible shear failure. Thus,blocks can be used to simulate backfill and soil materials as well as intact rock. (Purchasers ofthe UDM option may write their own models.) An effective-stress analysis can be performed byassigning a pore-pressure distribution that acts on both the blocks and the contacts.

The automatic zone generator in 3DEC allows the user to divide deformable blocks into finitedifference tetrahedral zones. A single command allows the user to specify as fine a discretizationas needed, and to vary the discretization throughout the model. Thus, a fine tetrahedral mesh canbe prescribed for blocks in the region of interest, and a coarser mesh can be used for blocks fartherout. 3DEC also has inner/outer region coupling and automatic radially-graded mesh generationwithin polyhedra for modeling infinite domain problems. For block plasticity analysis, a specialzone generator can be used to create mixed-discretization blocks for improved accuracy when

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modeling plastic collapse. The user may also use high order tetrahedral elements for plasticityproblems.

The explicit solution algorithm in 3DEC permits either static or dynamic analysis. Static analysisis the default solution mode. Dynamic analysis is provided as an optional feature and is discussedbelow, in Section 1.3.2.

Both stress (force) and fixed displacement (zero velocity) boundary conditions are available forstatic analysis. Boundary conditions may be different at different locations.

3DEC includes the ability to model steady state or transient fracture fluid flow. The flow logicincludes a system of flow planes, flow pipes and flow knots.

Structural element logic is implemented to simulate rock reinforcement. Reinforcement includespoint-anchored and fully-grouted cables and bolts. An optional surface support/liner model is alsoavailable and is described in Section 1.3.2.

3DEC contains a powerful built-in programming language, FISH, that enables the user to define newvariables and functions. FISH is a compiler; programs entered via a 3DEC data file are translatedinto a list of instructions stored in 3DEC s memory space; these are executed whenever a FISHfunction is invoked. FISH permits:

user-prescribed property variations in the block structure (e.g., non-linear increase in modulus with depth);

plotting and printing of user-defined variables (custom-designedplots);

implementation of special joint generators; servo-control of numerical tests; specification of unusual boundary conditions; variations in time and

space; and

automation of parameter studies.Interactive manipulation of screen images is built directly into 3DEC. This allows the user togenerate shaded perspective views, wire-frames, vectors, tensors, contours, time histories, etc. Thehistory plots are especially helpful to ascertain when an equilibrium state or failure state has beenreached. 3DEC also has the facility to create two-dimensional windows through the 3D model.On these windows, output can be presented in the form of principal stress plots, stress contour plots,relative shear plots, and vector plots. All plots can be created in screen mode by single keystrokesthat move and rotate the 3D model, orient the window, and produce the required output (vectors,contours, etc.). The output can then be directed to a hardcopy device for incorporation into reports.

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1.3.2 Optional Features

Four optional features (for dynamic analysis, thermal analysis, user-defined models (UDM) andmodeling surface support) are available as separate modules that can be included in 3DEC at anadditional cost per module.

Dynamic analysis can be performed with 3DEC, using the optional dynamic calculation module.User-specified velocity or stress waves can be input directly to the model either as an exteriorboundary condition or an interior excitation to the model. A library of simple dynamic wave formsis also available for input. 3DEC contains absorbing boundary conditions to simulate the effectof an infinite elastic medium surrounding the model. The dynamic analysis option is described inSection 2 in Optional Features.

There is a limited thermal analysis option available as a special module in 3DEC. This modelsimulates the transient conduction of heat in materials and the subsequent development of thermally-induced stresses. Heat sources can be added and can be made to decay exponentially with time.The thermal option is described in Section 1 in Optional Features.

The user-defined model (UDM) option provides the capability for the user to write their own blockmaterial models. The models are compiled as a DLL and are linked when requested by the user.As part of the UDM option, an additional 14 block constitutive models are available. This includes8 viscous models, two non-isotropic elastic models and 4 plasticity models.

A surface-support model is available to simulate structures such as concrete linings, shotcrete andother forms of tunnel support, and stabilizing lining for open cuts or natural slopes. The optionalsurface-support model is described in Section 3 in Optional Features.

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1.4 Summary of Updates from Version 2.0

3DEC 3.00 contains several improvements. The new features are summarized in the followingsections. Please note that, due to these changes, existing data files created for 2.00 may not operatecorrectly. Data files that contain memory addressees or indices must be modified. 3DEC 3.00 willnot restart save files from 3DEC 2.00

1.4.1 Automatic Topographic Stress Initialization

This feature is used to calculate gravity-induced stresses in models that have a large topologicalvariation on the free surface. Previously, the models had to be cycled to equilibrate the gravityloads. In some cases, cycling to equilibrium induced unwanted shear displacements and stresses.This is a new keyword under the INSITU command. Some cycling will still be required, but this willbe less than without the topographical stress initialization.

1.4.2 User-Defined Models (UDM)

Purchasers of the UDM option will have the ability to write their own block constitutive models.The models are then compiled as a DLL file and are linked during runtime (see Section 4 inOptional Features and the ZONE command in the Command Reference) as requested by the user.Instructions and examples on how to write these models are included.

1.4.3 Additional Constitutive Models

Purchasers of the UDM option will also have access to several new block constitutive models. Thesemodels include: anisotropic, cam-clay, double-yield, drucker, mohr, orthotropic, ss, subiquitous,ubiquitous and creep models (burger, cpower, cvisc, cwipp, power, pwipp, viscous, wipp).

1.4.4 Double Precision Version

3DEC now includes a separate executable that is written entirely in double precision. The doubleprecision version requires three times the amount of memory required by the single precisionversion. The double precision version is useful in models where critical information is lost becauseof the dimension of the models. This can occur in fluid flow models and also in creep modes wheremore than 1,000,000 cycles may be executed.

1.4.5 Dynamic Free Field

A dynamic free field logic has been added to 3DEC. The free field logic allows the lateral boundariesof a model to be closer to the area of interest without causing unwanted side effects.

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1.4.6 Partial Density Scaling

Normally, the timestep in 3DEC is controlled by the smallest gridpoint masses in the model. Indynamic simulations, this can produce a timestep which results in unacceptable solution times.Density scaling is not usually used in dynamic problems since the true gridpoint masses are importantto the solution. However, in many models the timestep is controlled by a few very tiny zones that donot contribute significantly to the overall solution. Partial density scaling allows 3DEC to eliminatethe effect of these few small zones without affecting the rest of the model.

1.4.7 Higher Order Tetrahedral Elements

The normal tetrahedral zoning in 3DEC can be relatively inaccurate in models with a high degreeof plastic strain (depending on loading conditions). The mixed discretization zoning solves thisinaccuracy but is limited to six-sided blocks. The higher order elements are more accurate inplasticity than the normal tetrahedral elements and do not have the shape restriction of the mixeddiscretized zones.

1.4.8 Improved Bitmap and Printer Output

Several improvements have been made to make the legends, colors, backgrounds, fill shading, andline typing better-suited for printing and output to bitmap files. This makes inclusion of 3DECgraphics directly into report documents much easier.

1.4.9 Poly Cube

Poly cube is new model building tool which can be used to generate a complex geometry in 3DEC.This is provided as an alternative to the PGEN pre-processor. Either user-defined outlines orextractions from AutoCAD DXF files can be used to generate the geometry. The blocks generatedusing poly cube are easier to zone than those generated by PGEN.

1.4.10 Structural Beam Elements

Structural beam elements have been added to allow the simulation of spaced support such as steelribs.

1.4.11 Surface Stress Plotting

Filled stress plots can now be generated on the surface of the 3D bodies (as opposed to crosssections). These plots are currently limited to stresses and appear as block filled plots.

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1.4.12 Generalized Boundary Histories

The boundary logic has been modified to allow the use of multiple boundary histories. Previously,only one history could be defined in each of the 3 axes. Each gridpoint may now have its ownhistory terms in each of the 3 axes.

1.4.13 Joint Fluid Flow

3DEC now has the capability to calculate fluid flow in joints. The flow logic is set up to use flowplanes, flow pipes, and flow knots. These objects represent the joint surfaces, intersections of joints,and meeting at block corners.

1.4.14 New Mouse Controls

In graphics mode, the left mouse button may be used in place of the arrow keys to translate or rotatethe model. The right mouse button can be used to center the model on the centroid of the selectedblock. The model will then rotate about the center of that block.

1.4.15 User-Controlled Colors for Contours

By specifying colors in a contour plot command the user can select the color filling. For example,plot xsec syy red green

will use a red to green variation for the contour colors.

1.4.16 User-Defined Stress Plot Planes

The user can define arbitrary planes in space to plot stresses. The planes are 3D objects and canbe rotated along with visible blocks or excavated blocks. This improves the visualization of thestresses around an opening.

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1.5 Fields of Application

3DEC was originally developed to perform stability analysis of jointed rock slopes. The discon-tinuum formulation for rigid blocks and the explicit time-marching solution of the full equationsof motion (including inertial terms) facilitate the analysis of progressive, large-scale movements ofslopes in blocky rock.

3DEC has been applied most often in studies related to mining engineering. Both static and dynamicanalyses for deep underground mine openings have been performed. Fault-slip induced failurearound excavations is one example of analyses conducted with 3DEC. Blasting effects have beenstudied by applying dynamic stress or velocity waves at model boundaries. Research in the areaof fault-slip induced seismicity has also been conducted by use of the continuously-yielding jointmodel. Structural elements have been employed to simulate various rock reinforcement systemssuch as grouted rockbolting.

3DEC has also been applied in the fields of underground construction and deep underground storageof high-level radioactive waste. Through the use of the optional thermal model, 3DEC has beenused to simulate effects of thermal loading in connection with buried nuclear waste.

3DEC has been used to a limited extent as a computational design tool. However, the program isbetter-suited to investigate potential failure mechanisms associated with the response of a jointedrock mass. The nature of a jointed rock mass is that it is a data-limited system i.e., the internalstructure and stress state are, in large part, unknown and unknowable. Thus, it is impossible, inprinciple, to make a complete model of a rock mass system. Nevertheless, an understanding ofthe response of underground openings in jointed rock can be achieved at a phenomenological levelusing 3DEC. This methodology seeks to improve the engineering understanding of the relativeimpact of various phenomena on the rock mechanics design. In this way, the engineer can antic-ipate potential problem areas by identifying mechanisms that may lead to unacceptable states ofdeformation/loading (or failure) of the underground opening. The paper by Starfield and Cundall(1988) is recommended as a guide for using 3DEC in rock engineering projects.Section 7 presents a bibliography of published reports on the application of 3DEC in the fields ofmining and underground engineering. Additionally, 3DEC has potential for application in otherfields of engineering, as discussed below and listed in Section 7.

3DEC has the potential for application in studies related to earthquake engineering. For example,the program may be used to provide explanations of phenomena related to fault movement.

3DEC is particularly well-suited to simulate blocky structures, such as stone masonry arches.Example studies are the assessment of safety conditions of old masonry bridges (see Lemos 1997in Section 7) and the seismic behavior of stone masonry arches (see Lemos 1995 in Section 7).3DEC has also been used to simulate the behavior of a concrete arch dam constructed on a jointedrock foundation (see Lemos 1996 in Section 7) and the stability condition of underground powerstations (see Dasgupta and Lorig 1995 and Dasgupta et al. 1995 in Section 7).

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1.6 Guide to the 3DEC Manual

The 3DEC Version 3.0 manual consists of eight documents. This document, the Users Guide,is the main guide to using 3DEC and contains descriptions of the features and capabilities ofthe program along with recommendations on the best use of 3DEC for problem solving. Theremaining documents cover various aspects of 3DEC, including theoretical background information,verification testing and example applications. The complete manual is available in electronic formaton the Itasca software CD-ROM (viewed with Acrobat Reader), as well as in paper format.The organization of the eight documents and brief summaries of the contents of each section follows.Please note that if you are viewing the manual in the Acrobat Reader, double-clicking on a sectionnumber given below will immediately open that section for viewing.

Users Guide

Section 1 Introduction

This section introduces you to 3DEC and its capabilities and features. An overviewof the new features in the latest version of 3DEC is also provided.

Section 2 Getting Started

If you are just beginning to use 3DEC or are only an occasional user, we recom-mend that you read Section 2. This section provides instructions on installation andoperation of the program as well as a simple tutorial to guide the new user througha 3DEC analysis.

Section 3 Problem Solving

Section 3 is a guide to practical problem solving. Turn to this section once you arefamiliar with the program operation. Each step in a 3DEC analysis is discussed indetail, and advice is given on the most effective procedures to follow when creating,solving and interpreting a 3DEC model simulation.

Section 4 FISH Beginners Guide

Section 4 provides the new user with an introduction to the FISH programminglanguage in 3DEC. This includes a tutorial on the use of the FISH language. FISHis described in detail in Section 2 in the FISH volume.

Section 5 Graphical Interface

3DEC contains a graphical interface to facilitate both model creation and presentationof results. Section 5 describes the features of this interface.

Section 6 Miscellaneous

Various information is contained in Section 6, including the 3DEC runtime bench-mark and procedures for reporting errors and requesting technical support.

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Section 7 Bibliography

Section 7 contains a bibliography of published papers describing some uses of 3DEC.

Command Reference

Section 1 Command Reference

All the commands that can be entered in the command-driven mode in 3DEC aredescribed in Section 1 in the Command Reference.

Section 2 Error Messages

Section 2 in the Command Reference lists all the error messages and their meanings.

FISH in 3DEC

Section 1 FISH Beginners Guide

Section 1 in the FISH volume provides the new user with an introduction to theFISH programming language in 3DEC. This includes a tutorial on the use of theFISH language.

Section 2 FISH Reference

Section 2 in the FISH volume contains a detailed reference to the FISH language.All FISH statements, variables and functions are explained and examples given.

Section 3 Library of FISH Functions

A library of common and general purpose FISH functions is given in Section 3 inthe FISH volume. These functions can assist with various aspects of 3DEC modelgeneration and solution.

Section 4 Program Guide

Section 4 in the FISH volume contains a program guide to 3DEC s linked-list datastructure. This is provided for advanced users to have more direct access to 3DECvariables.

Section 5 FISH Error Messages

A complete list of FISH error messages is given in Section 5 in the FISH volume.

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Theory and Background

Section 1 Background The Distinct Element Method

The theoretical formulation for 3DEC is described in detail in Section 1 in Theoryand Background.

Section 2 Block Constitutive Models

The theoretical formulation and implementation of the various block constitutivemodels are described in Section 2 in Theory and Background.

Section 3 Continuously-Yielding Joint Model

Section 3 in Theory and Background describes the formulation for the continuouslyyielding joint model. A simulation of a direct shear test with the model is also given.

Section 4 Structural Elements

Section 4 in Theory and Background describes the structural element reinforcementmodels available in 3DEC.

Section 5 Polygon Generator

The pre-processor program, PGEN, that assists with the creation of complex modelsis described in Section 5 in Theory and Background.

Section 6 Joint Fluid Flow

Section 6 in Theory and Background describes the implementation of joint fluidflow in 3DEC.

Optional Features

Section 1 Thermal Option

Section 1 in Optional Features describes the thermal model option and presentsseveral verification problems that illustrate its application both with and withoutinteraction with mechanical stress.

Section 2 Dynamic Analysis

The dynamic analysis option is described and considerations for running a dynamicmodel are provided in Section 2 in Optional Features. Several verification examplesare also included in this section.

Section 3 Surface Support Model

A surface support model option is provided to simulate tunnel lining and slopestabilizing lining. Section 3 in Optional Features describes the surface supportmodel.

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Section 4 User-Defined Models and Extended Constitutive Models

Section 4 in Optional Features contains theoretical descriptions of several materialconstitutive models and instructions needed to write new models which can be usedby 3DEC.

Verification Problems and Example Applications

This volume is divided into two sections. The first section contains a collection of3DEC verification problems. These are tests in which a 3DEC solution is compareddirectly to an analytical (i.e., closed-form) solution. See Table 1 in the Verificationand Examples volume for a list of the verification problems.

The second section contains example applications of 3DEC that demonstrate thevarious classes of problems to which 3DEC may be applied. See Table 2 in theVerification and Examples volume for a list of the example applications.

Command and FISH Reference Summary

A quick summary of all 3DEC commands and FISH statements is contained in theCommand and FISH Reference Summary.

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1.7 Itasca Consulting Group, Inc.

Itasca Consulting Group, Inc. is more than a developer and distributor of engineering software.Itasca is a consulting and research firm comprised of a specialized team of civil, geotechnical andmining engineers with an established record in solving problems in the areas of:

Civil EngineeringMining Engineering and Energy Resource RecoveryNuclear Waste Isolation and Underground SpaceDefense ResearchSoftware EngineeringGroundwater Analysis and Dewatering

Itasca was established in 1981 to provide advanced rock mechanics services to the mining industry.Today, Itasca is a multidisciplinary geotechnical firm with 53 professionals and offices worldwide.The corporate headquarters for Itasca is located in Minneapolis, Minnesota. Worldwide officesof Itasca are operated as subsidiaries of HCItasca, Inc.: Hydrologic Consultants, Inc. (Denver,Colorado); Itasca Geomekanik AB (Stockholm, Sweden); Itasca Consultants S.A. (Ecully, France);Itasca Consultants GmbH (Gelsenkirchen, Germany); Itasca Consultores S.L. (Llanera, Spain);Itasca S.A. (Santiago, Chile); Itasca Africa (Johannesburg, South Africa); and Itasca ConsultantsCanada Inc. (Sudbury, Canada).Itascas staff members are internationally recognized for their accomplishments in geological, min-ing and civil engineering projects. Itasca staff consists of geological, mining, hydrological andcivil engineers who provide a range of comprehensive services such as (1) computational anal-ysis in support of geo-engineering designs, (2) design and performance of field experiments anddemonstrations, (3) laboratory characterization of rock properties, (4) data acquisition, analysis,and system identification, (5) groundwater modeling, and (6) short courses and instruction in thegeomechanics application of computational methods. If you should need assistance in any of theseareas, we would be glad to offer our services.

Itasca Consulting Group is a subsidiary of HCItasca, Inc. HCItasca was formed in 1999 withthe merger of Hydrologic Consultants, Inc. (HCI) of Denver, Colorado with Itasca ConsultingGroup, Inc. of Minneapolis, Minnesota. HCI adds advanced groundwater modeling and dewateringexpertise to Itasca.

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1.8 User Support

We believe that the support that Itasca provides to code users is a major reason for the popularityof our software. We encourage you to contact us when you have a modeling question. We providea timely response via telephone, electronic mail or fax. General assistance in the installation of3DEC on your computer, plus answers to questions concerning capabilities of the various featuresof the code, are provided free of charge. Technical assistance for specific user-defined problemscan be purchased on an as-needed basis.

If you have a question, or desire technical support, please contact us at:

Itasca Consulting Group, Inc.Mill Place111 Third Avenue South, Suite 450Minneapolis, Minnesota 55401 USA

Phone: (+1) 612-371-4711Fax: (+1) 6123714717Email: software@itascacg.comWeb: www.itascacg.com

We also have a worldwide network of code agents who provide local technical support. Detailsmay be obtained from Itasca.

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1.9 References

Cundall, P. A. A Computer Model for Simulating Progressive Large Scale Movements in BlockyRock Systems, in Proceedings of the Symposium of the International Society for Rock Mechanics(Nancy, France, 1971), Vol. 1, Paper No. II-8, 1971.Cundall, P. A., and O. D. L. Strack. A Discrete Numerical Model for Granular Assemblies,Geotechnique, 29, 47-65 (1979).Goodman, R. E., and G.-H. Shi. Block Theory and Its Application to Rock Engineering. NewJersey: Prentice Hall, 1985.

Hoek, E. Methods for the Rapid Assessment of the Stability of Three-Dimensional Rock Slopes,Quarterly J. Eng. Geol., 6, 3 (1973).Itasca Consulting Group, Inc. UDEC (Universal Distinct Element Code), Version 3.0. Minneapo-lis: ICG, 1996.

Lin, D., and C. Fairhurst. Static Analysis of the Stability of Three-Dimensional Blocky Systemsaround Excavations in Rock, Int. J. Rock Mech. Min. Sci. & Geomech. Abstr., 25(3), 138-147(1988).Starfield, A. M., and P. A. Cundall. Towards a Methodology for Rock Mechanics Modelling, Int.J. Rock Mech. Min. Sci. & Geomech. Abstr., 25, 99-106 (1988).Warburton, P. M. Vector Stability Analysis of an Arbitrary Polyhedral Rock Block with anyNumber of Free Faces, Int. J. Rock Mech. Min. Sci. & Geomech. Abstr., 18, 415-427 (1981).

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2 GETTING STARTED

This section provides the first-time user with an introduction to 3DEC. If you are familiar with theprogram but only use it occasionally, you may find this section (in particular, Section 2.6) helpful inrefreshing your memory on the mechanics of running 3DEC. Getting Started provides instructionsfor program installation and start-up on your computer. It also outlines the recommended procedurefor applying 3DEC to problems in geo-engineering and includes simple examples that demonstrateeach step of this procedure. More complete information on problem solving is provided in Section 3.

3DEC is a command-driven code. This is an important distinction, especially if you are used tousing menu-driven software. As explained previously in Section 1.1, the command-driven structureallows 3DEC to be a very versatile tool for use in engineering analysis. However, this structure canpresent difficulties for new, or occasional, users. Command lines must be entered as input to 3DEC,either interactively via the keyboard or from a remote data file, in order for the code to operate.There are over 40 main commands and nearly 400 command modifiers (called keywords) which arerecognized by 3DEC.

To the new user, it may seem an insurmountable task to wade through all the commands to selectthose necessary for a desired analysis. This difficulty is not as formidable as it first appears if theuser recognizes that only a very few commands are actually needed to perform simple analyses. Asthe user becomes more comfortable with 3DEC and uses the code regularly, more commands canbe applied and more complex analyses performed. In this section, we provide a primer on the fewbasic commands the new (or occasional) user needs to perform simple 3DEC calculations.This section contains the following information. A step-by-step procedure is given in Section 2.1 toinstall, load and test the operation of 3DEC on your computer. This is followed by a tutorial example(Section 2.2) which demonstrates the use of common input commands to execute a 3DEC model.There are a few things that you will need to know before creating and running your own 3DECmodel i.e., you need to know the 3DEC terminology. The nomenclature used for this program isdescribed in Section 2.3. The definition of a 3DEC finite difference grid is given in Section 2.4. Youshould also know the syntax for the 3DEC input language when running in command-driven mode;an overview is provided in Section 2.5. The mechanics of running a 3DEC model are described inseparate steps; in Section 2.6, each step is discussed separately and simple examples are provided.The sign conventions and systems of units used in the program appear in Sections 2.7 and 2.8,respectively. The different types of files used and created by 3DEC are described in Section 2.9.

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2.1 Installation and Start-up Procedures

2.1.1 Installation of 3DEC

The 3DEC package, which includes a Windows95/98/ME/NT/2000/XP-console version (see Sec-tion 2.1.3 for a description), is installed in Windows from a CD-ROM using standard Windowsprocedures. The code installation, including the executables, utilities, data files and manual, re-quires approximately 24 MB of disk space.

A default installation of 3DEC from the CD-ROM will install the program, its example files, andthe complete 3DEC manual. The Adobe Acrobat Reader is necessary for viewing the manual; aninstallation for the Reader is also included on the CD-ROM for users who wish to install it.

To begin installation, insert the CD-ROM into the appropriate drive. If the autorun feature for the CDdrive is enabled, a menu providing options for using the CD will appear automatically. If this menudoes not appear, at the command line ( START > RUN in Windows) type [cd drive]:\start.exeto access the CD-ROM menu. The option to install 3DEC may be selected from this menu.

The installation program will guide you through installation. When the installation is finished, afile named INSTNOTE.PDF will be found in the program sub-folder (3DEC) that resides inthe main installation folder. (This is the folder that is specified during the installation process as thelocation to which files will be copied; by default, this is \ITASCA.) The INSTNOTE.PDF fileprovides a listing of the directory structure that is created on installation and a description of theactions that have been performed as part of the installation. This information may be used, in theunlikely event it is necessary or desirable, to either manually install or manually uninstall 3DEC.The recommended method for uninstalling 3DEC is to use the Windows Add/Remove Programsapplet ( START > SETTINGS > CONTROL PANEL > ADD/REMOVE PROGRAMS ). Please note that references made in the3DEC manual to files presume the default directory structure described in INSTNOTE.PDF; alldata files described in the manual are contained in these folders.

The first time you load 3DEC you will be asked to enter a customer title. This title will appearon graphics screen plots and hardcopy plots. The title can be changed by using the SET cust1command.

After installing the software, connect the 3DEC hardware key to the LPT1 port on the computerbefore using the code.

The executable file for 3DEC is 3DEC.EXE, which is stored in the \ITASCA\3DEC directory.In addition to the executable code, two sets of dynamic linked libraries (DLLs) are provided. Oneset of DLLs is used to access the various graphics formats in 3DEC. The other set corresponds tothe optional user-defined constitutive models available with 3DEC. All of these DLLs are locatedin the \ITASCA\3DEC directory.

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2.1.2 System Requirements for Windows 95/98/ME/NT/2000/XP

3DEC for Windows 95/98/ME/NT/2000/XP is a 32-bit Windows-console application. Any com-puter capable of running Win95/98/ME/NT/2000/XP is suitable for use with this version of 3DEC.The minimum hardware specifications to operate Windows 95 are adequate for the Windows-consoleversion of 3DEC. This code will not run on 16-bit systems such as Win3.x. The executable file is3DEC.EXE.

2.1.3 Windows-Console Version

The Windows-console version of 3DEC operates in text mode in Windows. Plots can be sent directlyto Windows native printers (using the SET plot windows command). Plots can also be directed tothe Windows clipboard (using the SET plot clipboard command), to an Enhanced Metafile format(using the SET plot emf command), and to PCX, BMP, or JPEG bitmap files. See Section 2.1.4 fordetails.

The Windows-console version of 3DEC is compiled with the Absoft Fortran compiler. TheWindows-console executable program will operate under Windows 95, 98, ME, Windows NT4.0, Win2000 or XP.

Multitasking You may find yourself switching constantly between your favorite text editor and3DEC while developing a model. Task switching or multitasking software helps considerably inthis process. Multitasking with the Windows-console version of 3DEC operates in the same manneras other native Windows applications. There is no difficulty with task switching even with a 3DECplot displayed. Please note that you cannot edit and save a data file while it is open in 3DEC. Type to close the data file in 3DEC.

Memory Allocation Automatic memory allocation logic has been implemented in 3DEC. Whenloaded, 3DEC will automatically attempt to allocate 16 MB of RAM.

You can change the memory allocation for 3DEC by typing the following when loading 3DEC froma DOS shell or Windows shortcut; type

3dec m

m is the amount of RAM, in MB, that will be made available for a 3DEC model. For example, ifyou wish to allocate 30 MB for a model, type

3dec 30

After loading 3DEC, typeprint mem

for a listing of the total memory available and the amount of memory, and percentage, currentlyused for the model.

If the amount of memory requested is more than that available, Windows will swap memory ontothe hard drive. This will slow execution considerably, and is not recommended. Note that 3DEC

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requires approximately 3.0 MB to load. You must account for this memory in the total memoryrequested. As a guide, Table 2.1 summarizes the approximate maximum numbers of rigid ordeformable blocks that can be created for different sizes of available RAM.

Table 2.1 Maximum number of 3DEC blocks in available RAMAvailable RAM Maximum number of Maximum number of

(MB) rigid blocks deformable blocks8 2,000 1,000

16 4,500 2,00032 7,500 3,00064 15,000 7,000* Assumes 24 translational degrees-of-freedom per block.

Maximum number of blocks will be reduced for more degrees-of-freedom.

2.1.4 Utility Software and Graphics Devices

Several types of utility software and graphics devices are available that can be of great help whileoperating 3DEC.

Editors A text editor is used to create 3DEC input data files. Any text editor that producesstandard ASCII text files may be used. Care must be taken if more advanced word-processingsoftware (e.g., WordPerfect, Word) is used: this software typically encodes format descriptions intothe standard output format; these descriptions are not recognized by 3DEC and will cause an error.3DEC input files must be in standard ASCII format.

Graphic Output 3DEC supports all Windows-compatible printers. Also, black-and-white or coloroutput may be written to a file that can be read by some graphics programs, such as CorelDraw. Inaddition, a PCX-format screen dump can be imported into other applications, such as Paintbrushfor Windows (see the SET pcx command