1 Introduction

1.1 Experimental Studies for Rock-Like Materials

1.2 Experimental Studies for Real Rock Materials

1.3 Numerical Studies for Crack Evolution Behavior

1.4 Study of Fracture Coalescence Behavior by AE Technique

1.5 Main Contents in This Book

References

2 Experimental Investigation on Strength Failure

and Crack Evolution Behavior of Brittle Sandstone

Containing a Single Fissure

2.1 Experimental Studies

2.1.1 Sandstone Material

2.1.2 Preparation for Specimen with Single Fissure

2.1.3 Experimental Equipment and Procedure

2.2 Strength and Deformation Behavior

2.2.1 Uniaxial Stress-Strain Curves of Sandstone

2.2.2 Effect of Single Fissure Geometry on Mechanical

Parameters of Sandstone

2.3 Crack Evolution Behavior

2.3.1 Crack Coalescence Type of Sandstone Specimens

Containing a Single Fissure

2.3.2 AE Behaviors of Intact and Flawed Sandstone

Specimens with Single Fissure Geometries

2.3.3 Real-Time Crack Evolution Process of Sandstone

Containing a Single Fissure

2.4 Conclusions

References

3 Experimental Investigation on Crack Evolution Behavior

of Brittle Sandstone Containing Two Coplanar Fissures

in the Process of Deformation Failure

3.1 Experimental Material and Procedure

3.1.1 Physical Behavior of Tested Specimens

3.1.2 Specimens Containing Two Coplanar Fissures

3.1.3 Testing Equipment and Procedure

3.2 Influence of Coplanar Fissure Angle on Strength

and Deformation Behavior

3.2.1 Deformation Failure Behavior of Intact Sandstone

Specimen

3.2.2 Deformation Failure Behavior of Flawed Sandstone

with Two Coplanar Fissures

3.2.3 Relationship Between Coplanar Fissure Angle

and Mechanical Parameters

3.3 Crack Initiation and Coalescence Behavior Analysis

3.3.1 Crack Coalescence Type of Sandstone Containing

Two Coplanar Fissures

3.3.2 Crack Initiation and Coalescence Behavior

of Pre-fissured Sandstone

3.4 Conclusions

References

4 Experimental Investigation on Fracture Evolution

Behavior of Brittle Sandstone Containing Three Fissures

4.1 Specimen Preparation and Testing Procedure

4.1.1 Sandstone Material and Specimen Preparation

4.1.2 Testing Procedure

4.2 Analysis of Experimental Results

4.2.1 Axial Stress-Strain Curve of Intact Specimen

4.2.2 Axial Stress-Strain Curve of Flawed Specimens

Containing Three Fissures

4.3 Crack Initiation Mode and Analysis of the Coalescence Process ..

4.3.1 Crack Initiation Mode and Stress Analysis

4.3.2 Real-Time Crack Coalescence Process of Specimens

for 132 = 75~ and 90~.

4.3.3 Real-Time Crack Coalescence Process

of Sandstone Specimens Containing Three

Fissures (132 ---- 105~ and 120~

4.4 Crack Coalescence Type and Strain Evolution Analysis

4.4.1 Crack Coalescence Type Analysis

4.4.2 Strain Evolution Analysis

4.5 Conclusions

References

5 Experimental Investigation on Fracture Coalescence Behavior

of Red Sandstone Containing Two Unparallel Fissures

5.1 Experimental Material and Loading Procedure

5.1.1 Experimental Material and Specimen Preparation

5.1.2 Loading Procedure and AE Monitoring

5.2 Strength and Deformation Behavior

5.2.1 Axial Stress-Axial Strain Behavior

5.2.2 Strength and Deformation Parameters

5.3 Cracking Mode and Characteristics

5.4 Crack Coalescence Process and AE Behavior

5.5 Conclusions

References

6 Discrete Element Modeling on Fracture Coalescence Behavior

of Red Sandstone Containing Two Unparallel Fissures

6.1 Discrete Element Modeling Method

6.1.1 Micro-Bond Model

6.1.2 Numerical Specimen

6.1.3 Simulation Procedure

6.2 Confirmation for Micro-Parameters of Red Sandstone

6.2.1 Confirming Method for Micro-Parameters

of Red Sandstone

6.2.2 Calibrating Micro-parameters by Experimental

Results of Intact Specimen

6.3 Numerical Results of Red Sandstone Containing Two

Unparallel Fissures

6.3.1 Strength and Deformation Behavior

6.3.2 Cracking Characteristics

6.4 Stress Field in Red Sandstone Containing Two

Unparallel Fissures

6.5 Conclusions

References

7 Fracture Mechanical Behavior of Red Sandstone Containing

a Single Fissure and Two Parallel Fissures After Exposure

to Different High-Temperature Treatments

7.1 Rock Material and Testing Procedure

7.1.1 , The Experimental Material and Heating Procedure

7.1.2 Specimen Preparation and Fissure Geometry

7.1.3 Testing Procedure and AE Monitoring

7.2 Strength and Deformation Behavior

7.3 Fracture Evolution Behavior

7.4 Interpretation and Discussion

7.5 Conclusions

References

8 Experimental Investigation on Strength and Failure Behavior

of Pre-cracked Marble Under Conventional Triaxial Compression.

8.1 Experimental Methodology

8.1.1 Marble Material

8.1.2 Pre-cracked Sample Preparation

8.1.3 Experimental Procedure

8.2 Triaxial Experimental Results of Pre-cracked Marble

8.2.1 Brittle-Ductile Transition Mechanism of Intact Marble...

8.2.2 Triaxial Stress-Strain Curves of Pre-cracked Marble

8.3 Strength Behavior of Pre-cracked Marble

8.3.1 Strength Behavior in Accordance with Mohr-Coulomb

Criterion

8.3.2 Strength Behavior in Accordance with Hoek-Brown

Criterion

8.3.3 A New Evaluation Criterion Based on Optimal

Approximation Polynomial Theory

8.4 Failure Mode of Pre-cracked Marble

8.5 Conclusions

References

9 Numerical Investigation on the Failure Mechanical Behavior

of Red Sandstone Containing Two Coplanar Fissures Under

Conventional Triaxial Compression

9.1 Discrete Element Model and Micro-Parameters

9.1.1 Intact Red Sandstone Material and Micro-Parameters

9.1.2 Comparison of Triaxial Experimental and Numerical

Results of Intact Specimen

9.2 Macroscopic Strength and Deformation Behavior

9.2.1 Triaxial Deformation Behavior of Red Sandstone

Containing Two Coplanar Fissures

9.2.2 Triaxial Strength Behavior of Red Sandstone

Containing Two Coplanar Fissures

9.3 Fracture Evolution Behavior

9.3.1 Fracture Evolution Process of Intact SpeCimen

9.3.2 Fracture Evolution Process of Flawed Specimen

9.3.3 Effect of Confining Pressure and Coplanar Fissure Angle.

9.3.4 Stress and Displacement Field

9.4 Conclusions

References