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

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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

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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

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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)

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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

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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

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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