Tutorial 5: Excavation between two walls connected with a slab

Tutorial 5: Two walls connected with strut and base slab

Deep Excavation LLCDeepEX 2015 – Advanced course 1

DeepEX is a software program for braced excavations in soils with 2D limit-equilibrium and non-linear analysis

methods, and structural verification of all elements (with AISC, ASD, Eurocodes).

It offers the ability to analyze walls with multiple braces (tiebacks) in multilayered soils.

The non-linear analysis considers elastoplastic behavior for the whole soil-wall-support system.

The program also offers the ability to perform traditional limit-equilibrium analyses.

The graphical interface is completely interactive and the input is simplified to a great extend.

The program utilizes archives of wall types, structural and soil materials, ground anchors etc.

The analysis can be performed in either an utlimate state or at a service state (allowable design, LRFD, or Eurocode 7

design approach methods).

The program offers the ability to automatically set all critical settings according to the desired design methodology.

Corso Paratie, Milano 30 settembre 2009

INTRODUCTION

DeepEX 2015 – Advanced course 2

Program layout

Wall selection

Project tree view

Design section list(right click)

General input tabsFile menu (click)

Model stages (right click options similar to

excel)Command prompt (enter coordinates)

Press to perform calculations.

Instruction box

Model space (left or right click on any item)

Mouse is over item Units

DeepEX 2015 – Advanced course

3D Model (Frames)

View and other

Enter basic project information1. Select this button

2. Define the project name etc.

3. Press OK


Move model elevations1. Select this button

2. Set new reference elevation to 100 ft

3. Check All boreholes (this moves all soil

layers)

4. Press OK

1. Add a 2nd wall2. Double click on right wall3. Change dimensions3.1 Change xwall= 60ftDepth L= 45ft

Define basic model limits (top, bottom, left, right)

1. Select this button

2. Set Top= 130ftBottom= 40ft

Left= -60ftRight= 120ft

3. Press OKDeepEX 2015 – Advanced course

Modify soil types (database of soils)1. Select this button.

Or

Expand the Soils Tree and Double click on FOptions: Right click or press Delete

Note: In DeepEX you can use any soil type in more than one borehole. For example the F soil can be used in boring 1 or boring 2 etc.

You can use any Boring on any design section. Thus changing any property of the F soil will affect all the excavation Design Sections where F is used!

Boring with F soil

Soil type data form

Available soil types

Add new, copy, delete, paste soil

DensityStrength

Short soil name, description and color.

Soil type & initial clay behavior

Test data for estimating soil properties


Soil type continuedSoil properties: GeneralSoil name: F (this appears in the boring)Description: Detailed soil description.Soil type: Sand gt= 125 kcf : Total unit weightgdry= 120 kcf : Dry unit weight (above water table)c‘= 0 : Effective cohesionF’= 30 degrees : Effective friction angle

v= 0.35 Poisson’s ratio

Kx = Horizontal permeabilityKz = Vertical permeability

Parameters only for claysSu = Undrained shear strengthFcv= Constant volume shearing angleFpeak= Peak shearing angle


Soil properties (Resistance and Elastic)

KoNC = At rest lateral earth pressure coefficient for normally consolidated state.

Enter elasticity values as shown before. Click on > buttons for more options.


Soil S1Soil properties: Change S1A. GeneralSoil name: S1 (this appears in the boring)Description: Sand Detailed soil description.Soil type: Sand gt =125 pcf : Total unit weightgdry= 120 pcf: Dry unitc‘ 0: Effective cohesionF’ = 36 degrees : Effective friction angleV = 0.35 Poisson’s ratio

C. Elasto-plasticE = 500 ksfrEur = 3

D. BondUltimate bond = 30 psi

Press OK

Edit Borings (soil layers)To edit the soil layers double click on the model boring.

The borings can also be edited from:

a) Edit Borings Button.

Or from the:

b) Tree View – Stratigraphy – boreholes

Double click here (or right click) with the mouse.


Enter Soil LayersTo edit the soil layers click on the blue button and enter the top of layer elevation.

For this example type 90 here:

Then select soil type S1 here:


Press OK


Double click on wall


2. Select edit section data, to change wall properties

1. Change wall depth to 45ft


Number of nodes controls the divisions

along the wall in a limit-equilibrium analysis.

(Suggested 200 min, or set so that small

intervals (0.25 ft) are generated)

Change wall section AZ 19 sheet pile

1. Change wall type

2. Select AZ-19 section

3. Select A50 steel(fy= 50 ksi)

4. Select OK


Wall using AZ-19 wall section

Select OK


Add a new stage (Model Tab)

Or right click (to add a stage, similar to Excel)


Stage 1 change center El. 90

Stage 1


Add Stage 2: Add a strut at El. +92

Right click and add stage 2


You can also drag the surface with your mouse

Select tool to add a strut

Note: After selecting the “Draw ground anchor button” the program tells you to select/enter the 1st tieback point at the wall (x z)


Add tieback with mouse1. Select 1st point on left wall (we will modify the coordinates later 2. Select 2nd point on right wall

Edit strut section• Typing PP24x0.375 will generate a pipe 24” OD x 0.375” thick wall• Typing PM600x12 will generate a pipe 600 mm OD x 12mm wall

Add 3rd stage and excavate to El. +80

Changing the water table• Double click or drag the water table• Change the water elevations in the general tab

• Click on the water table button• The drop down offers other possibilities for drawing user defined

water profiles.

Add stage 4: Draw in a slab between the two walls

Drawn model with slab

Edit slab properties• Create 3ft thick slab• Elevation refers to slab center• Specify +80 + 3ft/2 = El. +81.5• Change spacing to 1ft• Edit slab section to make a 3ft slab• Include slab weight in vertical

stress• Select “Use user defined unbraced

lengths” and use 10ft

Edit slab section to 3ft• Slab thickness d= 36inches• Slab width b= 12”• Change

reinforcement bars to #9• Ctop and Cbot are

clearances to center of bars

Completed model with 3ft slab• Green points show that

slab is supported at “rigid points”• Slab is not really on

ground.• Slab weight is added to

vertical soil stresses.

NOTE: EXCAVATION IS NOT YET SEALED

Change water levels and seal excavation

• Change water elevations to El. +90• Go to analysis tab, and

apply seal excavation

Purple line shows that excavation is sealed (lined).

Dashed water table inside excavation shows the water potential and that

the excavation is dry within.

Reviewing vertical soil stresses and water pressures:• Important that total

vertical stress is greater than water pressures• Must maintain positive

vertical effective stress• Program does not

consider contribution from wall side resistance and dead weight.

Review forces on slab• Double click on slab• Water pressure at bottom of

slab: 0.62 ksf (rounded)• Used FS STR= 1.6 shows the

safety factor used to determine the design capacities• This was defined in Design tab

Documents

Tutorial 5: Excavation between two walls connected with a slab