City of Winnipeg

SOUTHWESTERN RAPID TRANSIT CORRIDOR

Bidder Meeting

October 16th, 2009

Site Location

Field Investigations

- Klohn Krippen (2003) - Geotechnical• 4 deep test holes, 1 shallow• Groundwater monitoring• Laboratory testing

– AECOM (2009) - Geotechnical• 2 deep test holes ( rock coring)• Groundwater monitoring• Laboratory testing

– AECOM (2009) – Hydrogeological• Two test wells drilling• Field pump tests

Location of Test Holes

TW 2

TW 1

Soil Stratigraphy

Field and Lab Results

Groundwater Conditions–Clay : 2 m below ground, Elv. 231 m–Bedrock/Till : Elv. 224 to 226 m

–Impact on:• Excavation stability• Global stability• Seepage

Geotechnical Concerns

– Foundation type– Rebound, heave and settlement– Retaining walls– Base heave – Temporary shoring and excavation plan

Bearing capacity and foundation type

– Raft foundation – Design based on the concept of floating foundation– Bearing capacity and settlement pressure are defined

Rebound, Heave and Settlement

BRT - Heave Estimates for Excavations

223

224

225

226

227

228

229

230

231

0 25 50 75 100 125 150 175 200 225 250

Heave, mm

Excavati

on

Ele

vati

on

, m

elastic rebound

elastic rebound + sw ell @ 6 months

elastic rebound + sw ell @ 12 months

elastic rebound + ult sw ell

Retaining walls

- Reinforced Concrete U-shaped section - Reinforced Concrete Cantilever wall- Coulomb Theory- Design for surcharge from compaction during construction- Design for live load surcharge from Cooper E90 loading-

Clay

Till/Bedrock

FS = Wclay /γw h

Base heave

hWclay

FS against Base Heave

1.00

1.50

2.00

2.50

3.00

222.5 223.0 223.5 224.0 224.5 225.0 225.5 226.0 226.5

GWL in Bedrock Aquifer

FS

Excv 225.0

Excv 224.0

Excv 223.0

TYPICAL

EXTREME HISTORICAL

Temporary shoring and Excavation plan

– Cut and cover construction– Staged construction, Stage I and II– Site constrains:

• Limited space• Utilities• Private property• Proximity to CN tracks

– Excavations plan include:• Open excavation• Cantilever / Braced Shoring• Combination of shoring and open excavation

Temporary shoring and Excavation plan

– Excavation configurations• Open Excavation, up to 6 m cut• Other geometry < 6m cut

3

1

14

3

33

Temporary shoring and Excavation plan

– Excavation configurations• Braced Shoring up to 9.5 m

~ 9.5

4.6 Min

~ 5

Temporary shoring and Excavation plan

– Excavation configurations• Combination of Braced Shoring and Open excavation

4.6

3 - 5

2-3

1 37m bench

5 m Crane pad

varies 5 m Min.

varies 7 Max.

Temporary shoring and Excavation plan Lateral Loads from Surcharge

Temporary shoring and Excavation plan

Base Instability : analogous to bearing capacity

Global Stability

- Stress – stability coupled finite element analysis- Locally acceptable soil parameters- Account for excavation unloading - Model train loading- Design objective FS = 1.30

Stability output

Stability output

Stability output

Stress-Deformation Analysis

Stress-Deformation Analysis

Performance Monitoring Program

Instrumentation will be installed to monitor

– Displacement of railway tracks – Displacement of shoring system– Horizontal subsoil displacement– Excavation heave– Groundwater levels

THANK YOU