dr. william dershowitz dept of civil engineering ...€¦ · engineering geology issues in dams,...
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Dams, Foundations, and Abutments Engineering Geology
Dams, Foundations, and Abutments Dams, Foundations, and Abutments Engineering GeologyEngineering Geology
Dr. William Dershowitz
Dept of Civil EngineeringUniversity of Washington
FracMan Technology Group
Golder Associates Inc
Engineering Geology Issues in Dams, Foundations, and AbutmentsEngineering Geology Issues in Dams, Engineering Geology Issues in Dams, Foundations, and AbutmentsFoundations, and Abutments
Rock Mass Deformation
Rock Mass Strength
Faults and Seismic Loads
Fractures and Wedge Stability
Rock Mass and Discrete Feature Permeability
Empirical Correlation of RMR to EdEmpirical Correlation of RMR to EEmpirical Correlation of RMR to Edd
RMR and Modulus (Serafin and Pereira, 1983)RMR and Modulus (RMR and Modulus (SerafinSerafin and Pereira, 1983)and Pereira, 1983)
VVERYPOORROCK
IVPOORROCK
IIIFAIR
ROCK
IIGOODROCK
IVERYGOODROCK
RMR 0 to 20 21 to 40 41 to 60 61 to 80 81 to 100C
KkPa) < 100 100 to 200 200 to300
300 to400 > 400
φ(degrees) < 15 15 to 25 25 to 35 35 to 45 > 45
YoungsModulus
E(GPa)
< 1.8 1.8 to 5.6GPa 5.6 to 18 18 to 56 E > 56
Settlement ProcessesFractured Rock MassesSettlement ProcessesSettlement ProcessesFractured Rock MassesFractured Rock Masses
DFN Settlement AnalysisDFN Settlement AnalysisDFN Settlement AnalysisDam Load at SurfaceShear and Normal Stress Propagated from Dam Load to FracturesCalculate Shear and Normal Deformation on Fractures based on Applied Effective Stress ChangePropagate Shear and Normal Displacements on Fractures to Surface
Displacement on Fracture PlaneDisplacement on Fracture Displacement on Fracture PlanePlane
isns
ii KKKnn σσδ rrrrr 111)( +⎟⎟
⎠
⎞⎜⎜⎝
⎛−⋅⋅⋅=
nδ is the normal displacement vector at the fracture planer
Kn is the fracture normal stiffness
sδr
is the shear d isp lacement vector at the fracture p laneKs is the fracture shear stiffness
iδr
is the total displacement vector at the fracture plane
DFN Model Used to Verify ApproachDFN Model Used to Verify ApproachDFN Model Used to Verify ApproachParameter Value Basis
Model Region 25 m by 25 m by 100 m Largest Volume Modelableat RQD = 5%
Size Lognormal DistributionMean = 6mStDev = 7m
Fracture size consistentwith model region, similarto Portugués dambackground fracture case
Intensity P32 = 5 to 200 m2/m3 To produce RQD = 10% to98%
Orientation Bootstrap from the fivemapping sectionorientations file,Sections.ORS. FisherK=100
Similar to FracMan/Poly3Danalysis for Portugués Dam
Transmissivity ExponentialMean 10-7 m2/s
Generic Assumption
Stiffness Kn, Ks Distributions andCorrelations as Shown inFigure 7-23
Stiffness values increasedby one order of magnituderelative to dam settlementvalues to reflect the smallersize and lowertransmissivity of thefractures considered.
Settlement Approach ConfirmationDFN ModelSettlement Approach ConfirmationSettlement Approach ConfirmationDFN ModelDFN Model
Verification of Approach: RQD vs ModulusVerification of Approach: RQD Verification of Approach: RQD vsvs ModulusModulus
Verification of Approach: RMR vs ModulusVerification of Approach: RMR Verification of Approach: RMR vsvs ModulusModulus
Verification of Approach: RQD vs IntensityVerification of Approach: RQD Verification of Approach: RQD vsvs IntensityIntensity
Portugues Dam, Ponce Puerto RicoPortuguesPortugues Dam, Ponce Puerto RicoDam, Ponce Puerto Rico
Ponce City
Earthfill dam Thin arch dam
Heterogeneous Effective Deformability based on Rock Mass Quality (Glynn, 1999)Heterogeneous Effective Deformability Heterogeneous Effective Deformability based on Rock Mass Quality (Glynn, 1999)based on Rock Mass Quality (Glynn, 1999)
Lithologic Units(condition)
AccumulatedVertical
Footage, (ft)out of 2066 ft.
RMRDepth
WeightedAverage
Ed DepthWeightedAverage
(psi x 106)
RMRMax
Ed Max(psi x 106)
RMRMin
Ed Min(psi x 106)
meta-sandstone(sound) 1140 66 3.7 75 6.1 43 1.0
meta-conglomerate(sound) 340 64 3.3 74 5.8 49 1.4
meta-siltstone *(sound) 66 63 3.0 75 6.1 57 2.2
dike (sound) 47 66 3.6 78 7.3 56 2.0
meta-sandstone &meta-conglomerate
(fractured orsheared)
60 52 1.6 60 2.6 41 0.9
All rock types(weathered) 344 33 0.5 63 3.1 19 0.2
* not present on cross sections, but occurred in proximate borings
Integration of Geological InformationIntegration of Geological InformationIntegration of Geological Information
Leverage the Data You Have
Sensitivity for the Data You Don’t
Sources for Geometric Information
BoreholeImagery
Seismic
Core
Outcrop
Data Source #1: Camera LogsData Source #1: Camera LogsData Source #1: Camera Logs
Borehole Index Survey ID#
RockCode
Type Weathering TerminationMode
Censoring # ofFillings
Minerals Position(depth)
Trend(deg)
Plunge(deg)
CB-PD-47 1 1 3 45 45 45 45 1 52 42.74 126 45.96CB-PD-47 2 1 3 45 45 45 45 1 52 42.96 1 65.53CB-PD-47 3 1 3 45 45 45 45 1 52 43.4 136 21.19CB-PD-47 4 1 3 45 45 45 45 1 52 46.89 106 51.57CB-PD-47 5 1 3 45 45 45 45 1 52 47.05 226 16.21CB-PD-47 6 1 3 45 45 45 45 1 52 47.13 116 61.07CB-PD-52 199 1 3 45 45 45 45 1 52 42.65 261.03 74.99CB-PD-52 200 1 3 45 45 45 45 1 52 44.04 303.36 27.51CB-PD-52 201 1 3 45 45 45 45 1 52 44.21 152.83 10.59CB-PD-52 202 1 3 45 45 45 45 1 52 44.29 334.79 63.78CB-PD-52 203 1 1 45 45 45 45 1 52 46.36 243.02 45.06CB-PD-52 204 1 1 45 45 45 45 1 52 47.06 356.7 72.71CB-PD-52 205 1 1 45 45 45 45 1 52 47.19 219.49 22.28CB-PD-55 627 1 1 45 45 45 45 1 52 181.43 101 70.21CB-PD-55 628 1 1 45 45 45 45 1 52 182.7 261 54.88CB-PD-55 629 1 0 45 45 45 45 1 52 183.7 81 50.84CB-PD-55 630 1 1 45 45 45 45 1 52 185.17 51 76.51CB-PD-55 631 1 1 45 45 45 45 1 52 185.76 11 44.11CB-PD-55 632 1 1 45 45 45 45 1 52 186.59 101 71.41
Data Source #2: Trace MappingShear Zones on Left AbutmentData Source #2: Trace MappingData Source #2: Trace MappingShear Zones on Left AbutmentShear Zones on Left Abutment
Data Sournce #3Faults Mapped Directly from VSPVertical Seismic Profiling
Data Data SournceSournce #3#3Faults Mapped Directly from VSPFaults Mapped Directly from VSPVertical Seismic ProfilingVertical Seismic Profiling
Data Source #4: Hydraulic Tests, Grout Take, and Confirmation TestsData Source Data Source #4:#4: Hydraulic Tests, Grout Hydraulic Tests, Grout Take, and Confirmation TestsTake, and Confirmation Tests
Spatial Models for Background FracturesSpatial Models for Background Spatial Models for Background FracturesFractures
Baecher Model(Poisson Process) Geostatistical
Variogram ModelsLevy-Lee
Mass Fractal Model
Spatial Analysis from Spacing DistributionSpatial Analysis from Spatial Analysis from Spacing DistributionSpacing Distribution
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.001 0.01 0.1 1 10
Spacing (m)
Cum
ulat
ive
Den
sity
Fun
ctio
n (C
DF)
BH and GH Camera Log SpacingsFitted Exponential DistributionFitted Pareto Distribution
Fractal Spatial Analysis:Box DimensionBorehole Camera and Grouthole Logs
Fractal Spatial Analysis:Fractal Spatial Analysis:Box DimensionBox DimensionBorehole Camera and Borehole Camera and GroutholeGrouthole LogsLogs
Box Dimension
1
10
100
0.1 1 10 100
Box Size
Num
ber o
f Box
es
Spatial Analysis of Background FracturesIntensity Variation with DepthSpatial Analysis of Background FracturesSpatial Analysis of Background FracturesIntensity Variation with DepthIntensity Variation with Depth
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0 to 5 5 to 10 10 to 20 20 to 65
Borehole Depth Interval (m)
Inte
nsity
P10
(#/m
)
averagestdevaverage non zero
Background Fracture Relative IntensityBackground Fracture Relative IntensityBackground Fracture Relative Intensity
Zone Set 1 Set 5 Set 2 Set 3
P32 Surface to 7 m 0.810844.2%
0.343518.7%
0.415622.6%
0.26614.5%8
P32 7 m to 14 m 0.810854.2%
0.343523.0%
0.207813.9%
0.13348.9%
P32 14 m to 70 m 0.810870.2%
0.343529.8%
- -
Mean Pole(trend, p lunge)
144.0,2.2
40.2,70.1
43.5,2.5
271.8,30
Distribution K Fisher6.15
Fisher2.92
Fisher4.27
Fisher15.39
FracSize Fracture Size AnalysisFracSize Fracture Size AnalysisFracSize Fracture Size Analysis
Fracture Size StatisticsFracture Size StatisticsFracture Size Statistics
Trace Length Histogram
Version: FracSys 2.602 Date: 16:07 Dec 01 1998====================================Input File: lm20.ors # of fracs: 145.0
Orientation : Mean pole (tr,pl)= (230.2, 7.7)Major axis (tr,pl)= (50.2, 82.3)
Trace Length : 1.13 +- 0.82 [meters] K-S = (0.212, 0.000434%)
FracSize Analysis, Left Abutment
lb20, ld20, lm20, lp20, lt20 and lx20
FracSize Analysis, FracSize Analysis, Left AbutmentLeft Abutment
lb20, ld20, lm20, lp20, lt20 and lx20lb20, ld20, lm20, lp20, lt20 and lx20
Transmissivity and Conductive Intensity: OxFilet AnalysisTransmissivity and Conductive Intensity: Transmissivity and Conductive Intensity: OxFilet AnalysisOxFilet Analysis
Transmissivity Analysis of Shear Zonesfrom Borehole Pressure TestsTransmissivity Analysis of Shear ZonesTransmissivity Analysis of Shear Zonesfrom Borehole Pressure Testsfrom Borehole Pressure Tests
Orientation Analysis fromTrace Map Fracture DataOrientation Analysis fromOrientation Analysis fromTrace Map Fracture DataTrace Map Fracture Data
• Left abutment: Elevation of 497 ft to 417 ft (Section L2)
Aperture Data from Camera LogsAperture Data from Camera LogsAperture Data from Camera Logs
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
-5.5 -5 -4.5 -4 -3.5 -3 -2.5 -2 -1.5 -1
log10 Aperture
CD
F
Raw Data
Theory
DFN Model Properties: SummaryDFN Model Properties: SummaryDFN Model Properties: Summary
ModelElements
Geology # ofSets
Fracture Orientations(trend, plunge)
Fracture Size(mean, std dev)
Transmissivity(mean, std dev)
BackgroundFractures
Dikes, Meta-Sandstones,Meta-Siltstones, Meta-Conglomerates
4 Set 1 : 144.0, 2.2Set 2 : 43.5, 2.5Set 3 : 271.8, 30.0Set 5 : 40.2, 70.1
Set 1 : 0.504, 0.873Set 2 : 0.274, 0.524Set 3 : 1.27, 0.911Set 5 : 0.504, 0.873Log Normal Distribution
All Sets:1.08E-05, 9.16E-05Log NormalDistribution
Meta-Conglomerate
Meta-Conglomerate(additional fracturing)
1 Set 1: 310, 85 Set 1: 5, 5Log Normal Distribution
Set 1:2.13E-05, 2.85E-04Log NormalDistribution
ShearZones
Shears and Shear Zones 2 Set 1 : 272.4 19.7Set 2 : 174.6, 6.8
Set 1 : 33, 27Set 2 : 14, 11Uniform Distribution
All Sets:1.14E-05, 9.29E-05Log NormalDistribution
Portugues Dam, Ponce Puerto RicoPortuguesPortugues Dam, Ponce Puerto RicoDam, Ponce Puerto Rico
20% Shears,Meta-Conglomerate & 10% Background Fractures, Colored by Transmissivity, Looking Down Right Abutment (10%
transparent)
1000
Met
er S
cale
DFN Model Properties: SummaryDFN Model Properties: SummaryDFN Model Properties: SummaryModelElements
Geology # ofSets
Fracture Orientations(trend, plunge)
Fracture Size(mean, std dev)
Transmissivity(mean, std dev)
BackgroundFractures
Dikes, Meta-Sandstones,Meta-Siltstones, Meta-Conglomerates
4 Set 1 : 144.0, 2.2Set 2 : 43.5, 2.5Set 3 : 271.8, 30.0Set 5 : 40.2, 70.1
Set 1 : 0.504, 0.873Set 2 : 0.274, 0.524Set 3 : 1.27, 0.911Set 5 : 0.504, 0.873Log Normal Distribution
All Sets:1.08E-05, 9.16E-05Log NormalDistribution
Meta-Conglomerate
Meta-Conglomerate(additional fracturing)
1 Set 1: 310, 85 Set 1: 5, 5Log Normal Distribution
Set 1:2.13E-05, 2.85E-04Log NormalDistribution
ShearZones
Shears and Shear Zones 2 Set 1 : 272.4 19.7Set 2 : 174.6, 6.8
Set 1 : 33, 27Set 2 : 14, 11Uniform Distribution
All Sets:1.14E-05, 9.29E-05Log NormalDistribution
DFN Model: All LithologiesDFN Model: All DFN Model: All LithologiesLithologies10% of all background fractures, 20% of all shears, all meta-conglomerates
Fractures colored by Set Fractures colored by log of transmissivity
Assumed Correlation of Shear Stiffness to Fracture AreaAssumed Correlation of Shear Stiffness to Assumed Correlation of Shear Stiffness to Fracture AreaFracture Area
Assumed Correlation of Normal Stiffness to Fracture Transmissivity (Thickness)Assumed Correlation of Normal Stiffness Assumed Correlation of Normal Stiffness to Fracture Transmissivity (Thickness)to Fracture Transmissivity (Thickness)
Distributions of Shear and Normal Stiffness Assigned to Fractures in ModelDistributions of Shear and Normal Distributions of Shear and Normal Stiffness Assigned to Fractures in ModelStiffness Assigned to Fractures in Model
DFN Model: Background FracturesDFN Model: Background FracturesDFN Model: Background Fractures
DFN Model: Shear Zones (by sets)DFN Model: Shear Zones (by sets)DFN Model: Shear Zones (by sets)
Stress on Foundation from Thin Arch Concrete DamStress on Foundation from Thin Stress on Foundation from Thin Arch Concrete DamArch Concrete Dam
Calculated by US ACE Based on Structural Engineering Information
Settlement AnalysisSettlement AnalysisSettlement Analysis
Settlement Under Dam Foundation10 Realizations - DownstreamSettlement Under Dam FoundationSettlement Under Dam Foundation10 Realizations 10 Realizations -- DownstreamDownstream
Settlement Under Dam Foundation10 Realizations - UpstreamSettlement Under Dam FoundationSettlement Under Dam Foundation10 Realizations 10 Realizations -- UpstreamUpstream
Dam Foundation SettlementDam Foundation SettlementDam Foundation Settlement
Line ofSettlement
Location ofSettlement
AverageSettlement
(m)
MaximumSettlement
(m)
UpstreamLine
AverageLocation
-0.0041 -0.0114
UpstreamLine
MinimumLocation
-0.0030 -0.0094
UpstreamLine
MaximumLocation
-0.0055 -0.0195
DownstreamLine
AverageLocation
-0.0027 -0.0072
DownstreamLine
MinimumLocation
-0.0019 -0.0064
DownstreamLine
MaximumLocation
-0.0037 -0.0099
Failure of Malpasset DamFailure of Failure of MalpassetMalpasset DamDam• dam type: thin double curvature concrete arch with a variable radius
• purpose: water supply and irrigation
• height: 196.9 ft (60 m)
• width at foundation: 22.2 ft (6.78 m)
• width at crest 4.92 ft (1.5 m)
• length of crest: 732 ft (223 m)
• construction: 1941-1959
A tectonic fault was identified on the downstream side of the dam that was not realized during design or construction because of its distance from the dam.
Analyses of the dam were performed to try to determine the cause of failure, concentrating on the following:
•concrete stresses
•buckling of the arch
•sliding of the abutment block
•sliding of the dam at the contact with rock
•sliding on the downstream fault.
But none of these resulted in a definitive answer.
A combination of unusual pressure build-up under the dam, the state of the rock on the left bank, and the downstream fault were proposed as the cause of the failure.
Heavy rain just before the failure had increased the reservoir level by more than 15 feet; this also is thought to have contributed to the failure by increasing the pressure under the dam. No other dam of its type had failed before or since.(www.simscience.org)
Failure of Teton Dam (1976)Failure of Teton Dam (1976)Failure of Teton Dam (1976)http://www.geol.ucsb.edu/faculty/sylvester/Teton%20Dam/FrameSet.htm
Earthquake Risk AssessmentEarthquake Risk AssessmentEarthquake Risk Assessment
3D Discrete Fracture Network Based on Field Measurement
Simulate Pattern of Potentially Active Faults
Simulate Range of Possible Fault Locations, Magnitudes and Time Histories
Apply Displacement to each Assumed Fault
Calculate Displacements on Affected Fractures by Linear Elastic Stress Propagation
Earthquake@ 1km distant
Canister Ho le
Fracture IntersectingCanister Ho le
Four-Stage Processes for Estimating Earthquake-Induced DisplacementsFourFour--Stage Processes for Estimating Stage Processes for Estimating EarthquakeEarthquake--Induced DisplacementsInduced Displacements
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01Displacement (meters)
AbergBebergCeberg
Lake
MountainSurface
S t a g e 1 : Analyze T race Data
S t a g e 2 : DFN Model Generation
S t a g e 3 : Select a FaultLineament and Assign FaultWidth and Displacements fromRegression Relations
S t a g e 4 : SimulateE a r t h q uPoly 3D
Poly 3-D Fracture ModelPoly 3Poly 3--D Fracture ModelD Fracture Model
Primary Faulton which
earthquakeoccurs
500m
2km(not toscale)
Secondaryfracturing around
repository
Surface
(+Z)(N)
(+Y)(W)
(+X)(Down)
Lineament Map of Southern Sweden Including Aberg (Aspo) Region at Scale of 1:1,000,000Lineament Map of Southern Sweden Including Aberg Lineament Map of Southern Sweden Including Aberg ((AspoAspo) Region at Scale of 1:1,000,000) Region at Scale of 1:1,000,000
After Tiren and Beckholmen 1990
Locations and Fracture Generation RegionsLocations and Fracture Generation Locations and Fracture Generation RegionsRegions
1550800.006366800.00
6367000.00
6367200.00
6367400.00
6367600.00
6367800.00
6368000.00
6368200.00
6368400.00
1551000.00 1551200.00 1551400.00 1551600.00 1551800.00 1552000.00
Generation Region
1661.5 1662.0 1662.5 1663.0 1663.5 1664.07043.5
7044.0
7044.5
7045.0
7045.5
7046.0
7046.5
Model Boundary
Generation Region
Model Center
1614.5 1615.0 1615.5 1616.0 1616.5 1617.0 1617.5 1618.0
6697.0
6697.5Model Boundary
Generation Region #1
Generation Region #2
Model Center
6694.0
6694.5
6695.0
6695.5
6696.0
6696.5
Aberg Beberg
Ceberg
Frequency Histogram of Displacements for All Fractures Intersecting CanistersFrequency Histogram of Displacements for All Frequency Histogram of Displacements for All Fractures Intersecting CanistersFractures Intersecting Canisters
A b e r g D i s p l a c e m e n t
B e b e r g D i s p l a c e m e n t
C e b e r g D i s p l a c e m e n t
0
1000
2000
3000
4000
5000
6000
1E-10 1E-09 1E-08 1E-07 0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10Displacements (meters)
0.0%
1.0%
2.0%
3.0%
4.0%
5.0%
6.0%
7.0%
1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01Displacement (meters)
0
2000
4000
6000
8000
10000
12000
14000
1.00E-10 1.00E-09 1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00Displacement (meters)
Cumulative Density Function for Displacements on all Fractures Intersecting CanistersCumulative Density Function for Displacements on all Cumulative Density Function for Displacements on all Fractures Intersecting CanistersFractures Intersecting Canisters
A b e r g
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00Displacement (meters)
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
100.0%
1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01Displacement (meters)
B e b e r g
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01Displacements (meters)
C e b e r g