Dingee Reservoir Final Seismic Report - East Bay Municipal Utility ...

Seismic Stability Evaluation Report
Dingee Reservoir Dam
Oakland, California
Table of Contents
EXECUTIVE SUMMARY...........................................................................................................................................1
1.0 INTRODUCTION....................................................................................................................................- 1 -
1.1 BACKGROUND........................................................................................................................................ - 1 -
1.2 SCOPE OF WORK .................................................................................................................................... - 1 -
1.3 PROJECT AUTHORIZATION...................................................................................................................... - 1 -
1.4 PROJECT TEAM....................................................................................................................................... - 1 -
1.4.1 District Staff......................................................................................................................................- 1 -
1.4.2 Consultants .......................................................................................................................................- 2 -
2.0 PROJECT DESCRIPTION.....................................................................................................................- 3 -
2.1 SITE SETTING ......................................................................................................................................... - 3 -
2.2 DESCRIPTION OF RESERVOIR AND DAM ................................................................................................. - 3 -
2.3 RESERVOIR OUTLET AND DRAINAGE ..................................................................................................... - 4 -
2.3.1 Emergency Spillway Structure..........................................................................................................- 4 -
2.3.2 Reservoir Lining ...............................................................................................................................- 4 -
2.3.3 Surface Drainage Facilities..............................................................................................................- 4 -
3.0 GEOTECHNICAL EXPLORATION AND LABORATORY TESTING...........................................- 5 -
3.1 REVIEW OF EXISTING INFORMATION...................................................................................................... - 5 -
3.2 FIELD EXPLORATION PROGRAM ............................................................................................................. - 5 -
3.2.1 Previous Investigations.....................................................................................................................- 5 -
3.2.2 Subsurface Investigation for This Study............................................................................................- 6 -
3.2.3 Dam Surveillance Instrumentation ...................................................................................................- 7 -
3.3 LABORATORY TESTING .......................................................................................................................... - 9 -
4.0 GEOLOGIC AND GROUND MOTIONS STUDIES .........................................................................- 10 -
4.1 GEOLOGIC STUDY ................................................................................................................................-10-
4.2 GROUND MOTION STUDY..................................................................................................................... - 10 -
5.0 SUBSURFACE CONDITIONS.............................................................................................................- 11 -
6.0 DAM MATERIAL PROPERTIES.......................................................................................................- 12 -
6.1 GENERAL.............................................................................................................................................. - 12 -
6.2 CLASSIFICATION AND INDEX TESTS ..................................................................................................... - 12 -
6.3 LIQUEFACTION POTENTIAL/LOSS OF SHEAR STRENGTH....................................................................... - 13 -
6.4 SHEAR STRENGTH ................................................................................................................................-14-
6.4.1 Effective Shear Strength Failure Envelope.....................................................................................- 14 -
6.4.2 Total Shear Strength Failure Envelope ..........................................................................................- 14 -
7.0 STABILITY EVALUATIONS..............................................................................................................- 16 -
7.1 GENERAL APPROACH TO EVALUATION ................................................................................................ - 16 -
7.2 DAM PROFILE AND CROSS-SECTION..................................................................................................... - 16 -
7.3 LONG-TERM STATIC STABILITY ........................................................................................................... - 17 -
7.4 SHORT-TERM SEISMIC STABILITY ........................................................................................................ - 17 -
7.4.1 Yield Acceleration Evaluation ........................................................................................................- 18 -
7.4.2 Earthquake-Induced Newmark Displacements...............................................................................- 19 -
7.5 SHORT-TERM RAPID DRAWDOWN STABILITY...................................................................................... - 20 -
8.0 CONCLUSIONS AND SUMMARY OF DAM PERFORMANCE....................................................- 21 -
REFERENCES .....................................................................................................................................................- 22 -
Seismic Stability Evaluation Report - i -
Dingee Reservoir Dam August 2008