5-6 Nima Eslaminasab- Trench Less Presentation V1

STRESS ANALYSIS, MODELING, AND SENSITIVITY STUDY OF PIPELINES DUE TO CONSTRUCTION INDUCED SETTLEMENTS

Nima Eslaminasab, Ph.D., P.Eng.Senior Project Engineer

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Presentation Outline• Hatch Mott MacDonald (HMM) in Brief• Examples of Current Tunneling/Trenchless Projects• Overall Review of the Project • Challenges and Problems• Ground Settlement • Existing Pipelines• Modeling Methodology and Process• Results• Conclusions and Recommendations

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Hatch Mott MacDonald in Brief

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Hatch Mott MacDonald• 2008 Revenues: $333M• Employees: 1,900

Hatch•2008 Revenues: $1.46B•Employees: 9,000

Mott MacDonald Group• 2008 Revenues: $1.48B• Employees: 14,500

Hatch Mott MacDonald in Brief

• 1,900 Staff & 60 North American locations• Working in North America since 1950s• Employee‐Owned• An Infrastructure Consulting Firm

– Transportation:Rail, Transit, Air, Highways and Bridges, Pipelines, Tunnels, Structures

– Water/Wastewater– Environmental

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Examples of Current Tunneling/Trenchless Projects

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Dulles Airport AeroTrain Project:– Construction of a passenger transport system, with a minimal disruption to

flight service. A TBM was used to create approximately 1.3km of 7m diameter tunnel

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Madrid M‐30 Motorway Tunnels:– Upgrades to the existing M‐30 included the longest urban motorway

tunnels in Europe, almost 10km in length. Construction of the northern tunnels used one of the largest TBMs ever built, at a diameter of 15.2m

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New York Subway:– Extending the line from Times Square to the Hudson Yards

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Niagara Falls OPG Tunnel Project:– “Big Becky” a 14.4m diameter TBM bored 10.4km of tunnel to divert

water from the Niagara River to the SAB power generation complex

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Seattle Sound Transit U‐Link:– LRT system connecting downtown to the University of Washington

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• Transit Expansion Projects in Toronto:– TYSSE 6.8km Subway Expansion of University Line– Eglinton Cross‐Town LRT

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• Common Elements:– In Dense and Populated Areas– Lots of Existing Underground Utilities– They Use Trench Less Technology, for the most Part

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What Is the Problem?

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What Needs to Be Done To Predict A Possible Issue

• To Properly Address The Issue We Follow the Following 3 Steps:– Predicting Ground Settlement – Calculating Pipe Stress/Strain Levels Due to Ground Settlements

– Performing Sensitivity Analysis

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Predicting Ground Settlement

• Ground Settlement is a Function of: – Ground Characteristics– Volume Loss Potential– Depth of Cover

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VL

Calculating Pipe Stress/Strain Levels

• The Utility Pipeline is Modeled Using A Commercial Stress Analysis Software Such As AutoPIPE by Bentley.

• All External/Internal Loads Are Modeled • Predicted Ground Settlements are Added into the Model

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Performing Sensitivity Analysis

• Sensitivity Analysis is Carried For Major Parameters:– Ground Settlement– Soil Properties and Stiffness

• Based on the Results the Worst Case Scenario and the Most Possible Scenarios for Pipe Stress Levels are Checked

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Real Life Example

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Pipe line Location

Real Life Example

• Predicting Ground Settlements

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Design Basis Settlements

10

20

30

40

50

60

70

80

90

-30 -20 -10 0 10 20 30

Expected Settlements

Distance from Alignment Centerline (m)

Settl

emen

t (m

m)

Real Life Example

• Existing Pipeline Modeling

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Concrete EncasementSteelPipe

Item Outside Diameter Material Internal

Pressure Wall Thk.

Design Standard

1 1876 mm A -193 GR C

793 kPa 11mm AWWA- M 11

2 1417 mm A -193 GR C 793 kPa 10 mm AWWA-

M 11

Real Life Example

• Modeling Methodology and Process

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K2

K1

Soil

Pres

sure

Soil Displacement

5.09.0,1 RD

AREk s

0: 2 kCaseOurFor

Real Life Example

• Modeling Methodology and Process

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Settlement

Settlement ShapePredicted Ground )(

K1

Soil Displacement

Settlement Gap

Soil

Pres

sure

Real Life Example

• Modeling Methodology and Process– To Analyze the Pipe Failure Mode, “Pipe Stress Calculation” Method is Implemented

– “AutoPIPE” Software (By Bentley) is Used– In This Methodology the Stress/Strain Levels due to Internal and External Imposed Loading in a Pipe are Calculated and Ultimately Compared with the Allowable Levels as Recommended by Design Codes and Standards

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Real Life Example

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Real Life Example

• Other Considerations– AUTOPIPE Does not Cover AWWA Material Library– AWWA M11 is a Design Manual Not a Code– Ground Settlement Needs to be Calculated Off‐line

– Winter and Summer Cases should be considered for the Soil Properties (Toronto Area)

– Buoyancy Forces Should be Considered regarding the Ground Water Levels

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Real Life Example

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Real Life Example

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Real Life Example

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Conclusions

• Using Hands‐on Methodology and Techniques Will:– Improve the Overall Project Quality– Reduce the Costs and Project Risk – Improve Public Safety and Satisfaction– And…

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Acknowledgement

Author would like to thank:

– TYSSE Project Team Members of Hatch Mott MacDonald

– Hatch Mott MacDonald Mississauga Office and TYSSE’s Project Manager Mr. Chris Tattersall

– TYSSE Project Team and it’s Tunneling Project Engineering Coordinator Mr. Ed Poon

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Questions

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Documents

5-6 Nima Eslaminasab- Trench Less Presentation V1