CONFIRMATION OF SUBSURFACE GEOLOGIC CONDITIONS OF THE UC BERKELEY STANLEY HALL REPLACEMENT PROJECT BY

CONSTRUCTION FIELD OBSERVATIONS

Presented by:William Godwin CEG, Ryan Shafer PE, and Chris Muller GE

MACTEC Engineering & Consulting, Inc.

Annual MeetingThe Geological Society of America

Seattle, Washington

November 2, 2003

Introduction

Purpose of Paper:Discuss the importance of geologic

mapping of large excavations that expose heterogenous materialsPresent engineering geologic

conditions of the project

Topics

Project Description Challenges Geotechnical Investigation Geologic Conditions Construction Methodology Geologic Mapping Conclusions

Project Description

Bay Area Hazard Zoneshttp://gmw.consrv.ca.gov/shmp

Site

Project Description

U.C. Berkeley Campus

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Key ElementsReplacement of existing

classroom buildingAccommodate 3 basement

levels to -75 feetSeismic design to

withstand Mmax 7.1 on Hayward Fault 500 feet away

Project Description

Team UCB Capital Projects – Owner/Builder Zimmer Gunsul Frasca Partnership –

Architect BKF Engineers/Surveyors/Planners –

Civil Engineer MACTEC E&C – Geotechnical Engineer Rutherford & Chekene – Structural Engineer Pirooz Baraar Associates – Retention

Systems Engineer McCarthy – General Contractor

Project Description

Challenges

Urban environment Adjacent structures Complex ground conditions

and geology

Geotechnical Investigation

Exploration Plan

Geotechnical Investigation

Program Previous Investigations Deep coreholes Laboratory testing Geophysical surface surveys

Recommendations Stability Excavatability Dewatering Shoring design criteria

Geotechnical Investigation

Geologic Conditions

Local Fault Map

Geologic Conditions

Geologic Units and Structure Fill and Alluvium Greywacke Sandstone Shale and Mudstone Breccia Serpentinite and Melange Louderback Shear Zone

Construction Methodology

Demolition and excavation Dewatering Foundations Shoring

Construction Methodology

Demolition Excavation

Construction Methodology

Dewatering and Seepage Control

Construction Methodology

Foundations Micropiles Conventional

Footings and Structural Mat

Construction Methodology

South Wall Shoring Plan

Construction Methodology

Shoring Plan: Soil Nails

Geologic Mapping

Digital photography Sequential face mapping Seepage and overbreak Geologic contacts

Geologic Mapping

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ELEVATIONIN FEET

SOUTH WALL ELEVATION

Geologic Mapping

Geologic Mapping

Geologic Mapping

East Wall Mudstone Breccia/Melange

West Wall Interbedded Sandstone/Shale

Geologic Mapping

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S O U T H W A L L

DONNER LAB

GRAYWACKESANDSTONE

BRECCIATED

MUDSTONE

AND SHALE

INTERBEDDEDSANDSTONE AND SHALE

CARBONACEOUS

SHEARED AND

SERPENTINITE

SHALE WITH

Site Geology

Conclusions

Conditions: Interpreted vs. Actual– Bedrock contacts– Excavatability– Stability– Groundwater– Bonding strength– Wall movement

Conclusions

Identify potential unstable zones that could impact shoring system or worker safety

Presence of Louderback Shear zone and understanding of local geology

Integration of observational and construction methodology and applicability to future projects