Rock Mechanics for TunnelingDiscrete Fracture Approach

Rock Mechanics for TunnelingRock Mechanics for TunnelingDiscrete Fracture ApproachDiscrete Fracture Approach

Dr. William Dershowitz

Dept of Civil EngineeringUniversity of Washington

FracMan Technology Group

Golder Associates Inc

Rock Quality -RQDRock Quality Rock Quality --RQDRQD

after Hoek, 2000

Rock Quality -RMRRock Quality Rock Quality --RMRRMR

after Hoek, 2000

Rock Quality -RMRRock Quality Rock Quality --RMRRMR

after Hoek, 2000

Rock Tunnel Design by RMRRock Tunnel Design by RMRRock Tunnel Design by RMR

after Hoek, 2000

Rock Quality –Q SystemRock Quality Rock Quality ––Q SystemQ System

after Hoek, 2000

Rock Quality –Q SystemRock Quality Rock Quality ––Q SystemQ System

after Hoek, 2000

Rock Quality –Q SystemRock Quality Rock Quality ––Q SystemQ System

after Hoek, 2000

Rock Tunnel Design Using Q-SystemRock Tunnel Design Using QRock Tunnel Design Using Q--SystemSystem

after Hoek, 2000

Rock Tunnel Design Using Q-SystemRock Tunnel Design Using QRock Tunnel Design Using Q--SystemSystem

after Hoek, 2000

Rock DowelsRock DowelsRock Dowels

after Hoek, 2000

Rock BoltsRock BoltsRock Bolts

after Hoek, 2000

Rock Bolt DesignRock Bolt DesignRock Bolt Design

after Hoek, 2000

ShotcreteShotcreteShotcrete

after Hoek, 2000

ShotcreteShotcreteShotcrete

after Hoek, 2000

Hallandsås Tunnel: Excitement Under (and above) GroundHallandsHallandsååss Tunnel: Excitement Under Tunnel: Excitement Under (and above) Ground(and above) Ground

HallandsåsHallandsHallandsååss

Hallandsås: Swedish Tunnel DisasterHallandsHallandsååss: Swedish Tunnel Disaster: Swedish Tunnel Disaster

Hallandsås Tunnel: Original Development by Drill and Blast with Grouting

HallandsHallandsååss Tunnel: Original Tunnel: Original Development by Drill and Blast with Development by Drill and Blast with GroutingGrouting

ShotcreteShotcreteShotcrete

after Hoek, 2000

ShotcreteShotcreteShotcrete

after Hoek, 2000

ShotcreteShotcreteShotcrete

after Hoek, 2000

Tunneling in Weak RockTunneling in Weak RockTunneling in Weak Rock

after Hoek, 2000

Tunneling in Weak RockTunneling in Weak RockTunneling in Weak Rock

after Hoek, 2000

Tunneling in Weak RockTunneling in Weak RockTunneling in Weak Rock

after Hoek, 2000

Tunneling in Weak RockTunneling in Weak RockTunneling in Weak Rock

after Hoek, 2000

Tunneling in Weak RockTunneling in Weak RockTunneling in Weak Rock

after Hoek, 2000

Tunneling in Weak RockTunneling in Weak RockTunneling in Weak Rock

after Hoek, 2000

Tunneling in Weak RockTunneling in Weak RockTunneling in Weak Rock

after Hoek, 2000

Hallandsås Tunnel: TBM TunnelingHallandsHallandsååss Tunnel: TBM TunnelingTunnel: TBM Tunneling

Inland Feeder ProjectInland Feeder ProjectInland Feeder Project

Structurally Controlled Tunnel StabilityWedge FormationStructurally Controlled Tunnel StabilityStructurally Controlled Tunnel StabilityWedge FormationWedge Formation

from Hoek, 2000

Small Wedges - RavelingSmall Wedges Small Wedges -- RavelingRaveling

from Hoek, 2000

Rock Bolt DesignRock Bolt DesignRock Bolt Design

from Hoek, 2000

Tunneling Sequence for Wedge StabilityTunneling Sequence for Wedge Tunneling Sequence for Wedge StabilityStability

from Hoek, 2000

Kinematic Stability AnalysisDFN ApproachKinematic Stability AnalysisKinematic Stability AnalysisDFN ApproachDFN Approach

3D Discrete Fracture Network Based on Field Measurement

Simulated Slope Surfaces Reflect Effect of Fracture Size

Rock Bridge Failure Reflected by Selective Increasing of Fracture Size

Tunnel SpecificationTunnel SpecificationTunnel Specification

Fracture GenerationFracture GenerationFracture Generation

Trace Maps and Wedge IdentificationTrace Maps and Wedge IdentificationTrace Maps and Wedge Identification

Wedge Stability AnalysisWedge Stability AnalysisWedge Stability Analysis

DFN Approach: Tunnel Scale ModelingDFN Approach: Tunnel Scale ModelingDFN Approach: Tunnel Scale Modeling

Integrate Hydraulic, Grout, and Geologic Data During Tunnel Advance

Condition Model to Groundwater Monitoring and Grout Take

Update Model to Predict Structural Intersection Events

Äspö Project, SwedenÄÄspspöö Project, SwedenProject, Sweden

Äspö TunnelsSwedish GraniteÄÄspspöö TunnelsTunnelsSwedish GraniteSwedish Granite

Task 5 DFN Model - Deterministic FracturesTask 5 DFN Model Task 5 DFN Model -- Deterministic FracturesDeterministic Fractures

Weir Flux Time History Boundary ConditionWeir Flux Time History Boundary Weir Flux Time History Boundary ConditionCondition

Total Flow into Weir

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

03-Mar-91

01-Jun-91

30-Aug-91

28-Nov-91

26-Feb-92

26-May-92

24-Aug-92

22-Nov-92

20-Feb-93

21-May-93

19-Aug-93

17-Nov-93

15-Feb-94

16-May-94

14-Aug-94

12-Nov-94

10-Feb-95

11-May-95

09-Aug-95

07-Nov-95

05-Feb-96

05-May-96

03-Aug-96

01-Nov-96

30-Jan-97

30-Apr-97

Date

Wei

r Fl

ow R

ate

(l/m

in)

Head in Monitoring Section KAS06 MA66Head in Monitoring Section KAS06 Head in Monitoring Section KAS06 MA66MA66

KAS06 MA66

-60.0

-50.0

-40.0

-30.0

-20.0

-10.0

0.0

10.001

-Oct

-90

30-D

ec-9

0

30-M

ar-9

1

28-J

un-9

1

26-S

ep-9

1

25-D

ec-9

1

24-M

ar-9

2

22-J

un-9

2

20-S

ep-9

2

19-D

ec-9

2

19-M

ar-9

3

17-J

un-9

3

15-S

ep-9

3

14-D

ec-9

3

Date

Hea

d (m

)

Measured

H-8

Head in Monitoring Section KAS08 MA81Head in Monitoring Section KAS08 Head in Monitoring Section KAS08 MA81MA81

KAS08 MA81

-30.0

-25.0

-20.0

-15.0

-10.0

-5.0

0.0

5.001

-Oct

-90

30-D

ec-9

0

30-M

ar-9

1

28-J

un-9

1

26-S

ep-9

1

25-D

ec-9

1

24-M

ar-9

2

22-J

un-9

2

20-S

ep-9

2

19-D

ec-9

2

19-M

ar-9

3

17-J

un-9

3

15-S

ep-9

3

14-D

ec-9

3

Date

Hea

d (m

)

Measured

H-8

Head in Monitoring Section KAS07 MA74Head in Monitoring Section KAS07 Head in Monitoring Section KAS07 MA74MA74

KAS07 MA74

-60.0

-50.0

-40.0

-30.0

-20.0

-10.0

0.0

10.0

01-10-90

29-01-91

29-05-91

26-09-91

24-01-92

23-05-92

20-09-92

18-01-93

18-05-93

15-09-93

13-01-94

Date

Hea

d (m

)

Measured

Simulated

Geochemistry in Monitoring Well SA0813BGeochemistry in Monitoring Well Geochemistry in Monitoring Well SA0813BSA0813B

SA0813B

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

01-O

ct-9

0

30-M

ar-9

1

26-S

ep-9

1

24-M

ar-9

2

20-S

ep-9

2

19-M

ar-9

3

15-S

ep-9

3

14-M

ar-9

4

10-S

ep-9

4

09-M

ar-9

5

05-S

ep-9

5

03-M

ar-9

6

30-A

ug-9

6

26-F

eb-9

7

Date

Com

pone

nt P

erce

ntag

e

Sim Cpt 1 Sim Cpt 2 Sim Cpt 3 Sim Cpt 4 Sim Cpt 5 Sim Cpt 6 Sim Cpt 7Data Cpt 1 Data Cpt 2 Data Cpt 3 Data Cpt 4 Data Cpt 5 Data Cpt 6 Data Cpt 7

Geochemistry in Monitoring Well SA2783AGeochemistry in Monitoring Well Geochemistry in Monitoring Well SA2783ASA2783A

SA2783A

-20%

-10%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

01-O

ct-9

0

30-M

ar-9

1

26-S

ep-9

1

24-M

ar-9

2

20-S

ep-9

2

19-M

ar-9

3

15-S

ep-9

3

14-M

ar-9

4

10-S

ep-9

4

09-M

ar-9

5

05-S

ep-9

5

03-M

ar-9

6

30-A

ug-9

6

26-F

eb-9

7

Date

Com

pone

nt P

erce

ntag

e

Brine, Simulated Baltic Sea, Simulated Glacial, Simulated Meteoric, SimulatedBrine, Measured Baltic Sea, Measured Glacial, Measured Meteoric, Measured

Grout Reliability IssuesGrout Uptake to a Dominant FractureGrout Reliability IssuesGrout Reliability IssuesGrout Uptake to a Dominant Fracture

Grout Reliability IssuesSubvertical Fractures Missed by Grouting and Confirmation Test Holes

Grout Reliability IssuesGrout Reliability IssuesSubvertical Fractures Missed by Grouting and Confirmation Test Holes

Grout Reliability IssuesSuccessful Confirmation Tests Signifying Nothing

Grout Reliability IssuesGrout Reliability IssuesSuccessful Confirmation Tests Signifying Nothing

Grout Reliability IssuesPeriodic/Regular Ungrouted FracturesGrout Reliability IssuesGrout Reliability IssuesPeriodic/Regular Ungrouted Fractures

DFN Approach: Real time ModelingDFN Approach: Real time ModelingDFN Approach: Real time Modeling

Tunneling Model: Realistic Geology and HydrogeologyTunneling Model: Realistic Geology and Tunneling Model: Realistic Geology and HydrogeologyHydrogeology

Streamline for flow andtransport definedperpendicular to

pressure contoursPressureContours

Source

Sink

a) Continuum Model

b) Pathways Controlled by Fracture Geometry

DFN Tunneling Model: Prediction of Difficult GroundDFN Tunneling Model: DFN Tunneling Model: Prediction of Difficult GroundPrediction of Difficult Ground

DFN Incorporates Flow Barrier and Conductive Structures

Correlate Geology,Grout Take and Hydraulic Response to Upcoming Structures

Predict Structure Intersections

Direct Interaction with Contractor

Tunneling ModelDemonstrate Grout EffectivenessTunneling ModelTunneling ModelDemonstrate Grout EffectivenessDemonstrate Grout Effectiveness

Tunnel Impact Modeling without Grout

Grouting Simulation

Phreatic Surface Impacts at Distance

Tunnel Inflows and Chemistry w/ and w/o Grouting

Monitoring Model: Establish Seasonal/ Diurnal VariationsMonitoring Model: Monitoring Model: Establish Seasonal/ Diurnal VariationsEstablish Seasonal/ Diurnal Variations

Site 910

1880

1890

1900

1910

1920

1930

1940

1950

1960

01-0

4-95

01-0

7-95

01-1

0-95

01-0

1-96

01-0

4-96

01-0

7-96

01-1

0-96

01-0

1-97

01-0

4-97

01-0

7-97

01-1

0-97

01-0

1-98

01-0

4-98

01-0

7-98

01-1

0-98

01-0

1-99

01-0

4-99

01-0

7-99

01-1

0-99

01-0

1-00

01-0

4-00

01-0

7-00

01-1

0-00

01-0

1-01

01-0

4-01

01-0

7-01

01-1

0-01

Date

Elev

atio

n (ft

, MSL

)

Model Natural Variation in Phreatic Surface

Establish Criteria for Identifying Potential Tunnel Effects

Model Phreatic Surface as Tunneling Progresses

Monitoring ModelCorrelation to Tunnel AdvanceMonitoring ModelMonitoring ModelCorrelation to Tunnel AdvanceCorrelation to Tunnel Advance

Simulate Head Reponse(Predictive) at different tunnel inflow rates

Update Model as tunnel advances

Correlate phreatic responses to Tunnel Advance (if any)

KAS07 MA74

-60.0

-50.0

-40.0

-30.0

-20.0

-10.0

0.0

10.0

01-10-90

29-01-91

29-05-91

26-09-91

24-01-92

23-05-92

20-09-92

18-01-93

18-05-93

15-09-93

13-01-94Date

Hea

d (m

)

Measured

Simulated

Concluding RemarksConcluding RemarksConcluding Remarks

DFN Approach can provide a methodology for:• Constructing a realistic hydrogeological model of

local and regional scale responses

• Predicting grout efficiency

• Predicting inflows into the tunnel

• Mitigating reduction in the groundwater table