Scale-Size and Structural Effects of Rock Materials

Scale-Size and Structural Effects of Rock Materials presents the latest research on the scale-size and structural effects of rock materials, including test methods, innovative technologies, and applications in indoor testing, rock mechanics and rock engineering. Importantly, the book explains size-dependent failure criteria, including the multiaxial failure and Hoek-Brown failure criterion. Five chapters cover the size effect of rock samples, rock fracture toughness, scale effects of rock joints, microseismic monitoring and application, and structural effects of rock blocks. The book reflects on the scientific and technical challenges from extensive research in Australia and China.

The title is innovative, practical and content-rich. It will be useful to mining and geotechnical engineers researching the scale-size and structural effects of rock materials, including test methods, innovative technologies and applications in indoor testing, rock mechanics, and engineering, and to those on-site technical specialists who need a reliable and up to date reference.

Table of contents :
Cover
Scale-Size and
Structural Effects
of Rock Materials
Copyright
Contributors
About the authors
Preface
Acknowledgments
1
Size effect of rock samples
Chapter outline
Size effect law for intact rock
Introduction
Background
Descending models
Statistical models
Fracture energy model
Fractal and multifractal models
Empirical and semiempirical models
Ascending model
Experimental study
Rock sample selection
UCS results
Point load results
Diametral loading
Axial loading
Unified size effect law
Reverse size effects in UCS results
Contact area in size effects of point load results
Conventional approach to highlight size effects
A new approach incorporating contact area
Conclusions
Length-to-diameter ratio on point load strength index
Introduction
Background
Point load test size effect
Size effect models
Methodology
Valid and invalid failure modes
Failure mode in axial testing
Failure mode in diametral testing
Impact of stress distribution on failure mode
Conventional point load strength index size effect
Axial and diametral point load strength index results
Applicability of existing size effect models
Size effect of point load strength index
Axial and diametral point load strength index
Applicability of existing size effect models
Conclusions
Plasticity model for size-dependent behavior
Introduction
Notation and unified size effect law
Bounding surface plasticity
Model ingredients
Elasticity
Bounding surface and image point
Hardening law
Plastic potential and elastic-plastic matrix
Model outputs and parameter sensitivity
Initial stiffness
Incorporating size effects
Model calibration
Fitting the unified size effect law
Simulation for 96-mm diameter samples
Simulation for 50-mm diameter samples
Simulation for 25mm diameter samples
Comparing models for different diameter samples
Conclusions
Scale-size dependency of intact rock
Introduction
Rock types
Experimental procedure
Point load testing
Indirect tensile (Brazilian) testing
Comparative study
Size effect models
Statistical model
Fracture energy model
Multifractal model
Existing size effect models to point load
Existing size effect models to tensile strength
Conclusion
Scale effect into multiaxial failure criterion
Introduction
Background
Scale and Weibull statistics into strength measurements
Scale effect in uniaxial compressive strength
Scale effect in point load strength index
Scale effect in tensile strength
Scale effect in pure shear strength
The modified failure criteria
Comparison with experimental data
Conclusions
Size-dependent Hoek-Brown failure criterion
Introduction
Background
Analytical study
Experimental study
Testing procedure
Experimental results
Size-dependent Hoek-Brown failure criterion
Model development
Model calibration
Example of application
Conclusions
References
Further reading
2
Rock fracture toughness
Chapter outline
Fracture toughness of splitting disc specimens
Introduction
Preparation of disc specimens
Fracture toughness of five types of specimens
Fracture toughness formula of FBD and HFBD
Fracture toughness formula of CCNBD
Fracture toughness formula of CSTBD and HCFBD
Load-displacement curve of disc splitting test
Comparison of disc splitting test results
Conclusions
Fracture toughness of HCFBD
Introduction
Test method and principle
HCFBD specimens with prefabricated cracks
Calibration of maximum dimensionless SIF Ymax
Results and analysis
Conclusions
Crack length on dynamic fracture toughness
Introduction
Dynamic impact splitting test
Configuration and dimensions of specimens
Dynamic test process
Results and discussion
Comparison of dynamic and static fracture toughness
Fracture mode of specimens
DFT irrespective of configuration and size
Conclusions
Crack width on fracture toughness
Introduction
NSCB three-point flexural test
Specimen preparation
Test equipment and test plan
Width influence on prefabricated crack
Width influence of cracks on tested fracture toughness
Method for eliminating influence of crack width
Conclusions
Loading rate effect of fracture toughness
Introduction
Specimen preparation
Test process and data processing
Test method
Fracture toughness calculation formula
Results and analysis
Load-displacement curve
Fracture toughness test value
Loading rate effect on fracture toughness
Size effect on fracture toughness
Discussion on loading rate and size effects
Conclusions
Hole influence on dynamic fracture toughness
Introduction
Dynamic cleaving specimens and equipment
SHPB test and data record
Pulse signal on elastic pressure bar
Determination of cracking time
Dynamic finite element analysis
Load determination of model
Dynamic loading of model
Dynamic stress intensity factor
Results analysis and discussion
Central aperture influence on test values
Final fracture mode of specimen
Conclusions
Dynamic fracture toughness of holed-cracked discs
Introduction
Dynamic fracture toughness test
Test specimens
Test setup
Experimental recordings and results
Strain signals on bars
Fracture patterns of specimens
Test results analysis
Dynamic stress intensity factor in spatial-temporal domain
Conclusions
Dynamic fracture propagation toughness of P-CCNBD
Introduction
Experimental preparation
P-CCNBD specimen
SHPB loading device
Strain gauges and crack extension meters
Experimental recording and data processing
Load determination
Determination of cracking time
Determination of crack propagation speed
Numerical calculation of dynamic stress intensity factor
Loading of model
P-CCNBD numerical model
Dynamic stress intensity factor
Determine dynamic fracture toughness
Universal function
Dynamic cracking and propagated toughness
Loading rate effect on dynamic cracking toughness
Crack propagation speed on dynamic expansion toughness
Dynamic crack arrest and DFT rationality
Conclusions
References
Further reading
3
Scale effect of the rock joint
Chapter outline
Fractal scale effect of opened joints
Introduction
Scale effect based on fractal method
Scale dependence of joint roughness
Peak shear displacement for field-scale rock joints
Constitutive model for opened rock joints
Validation of proposed scaling relationships
Validation of scale dependence of joint roughness
Predictive equation for peak shear displacement
Conclusions
Joint constitutive model for multiscale asperity degradation
Introduction
Quantification of irregular joint profile
Description of proposed model
Joint model validation
Model implementation
Model validation
Correlation with JRC-profiled rock joints
Correlation with experimental data
Simulation of Bandis direct shear test
Simulation of Flamand et al.s direct shear test
Conclusions
Shear model incorporating small- and large-scale irregularities
Introduction
Constitutive model for small-scale joints
Mobilized shear strength
Asperity degradation
Dilation
Constitutive model for large-scale joints
Evaluation of peak shear strength
Evaluation of peak shear displacement
Degradation in dilation and postpeak strength
Summary of proposed joint models
Correlation with experimental data
Simulation of Flamand et al.s test
Simulation of Yang and Chiangs test
Simulation of Bandiss test
Conclusions
Opening effect on joint shear behavior
Introduction
Constitutive model for joint opening effect
Opening model performance
Initial joint opening effect
Joint opening effect induced by excavation
Discussion
Conclusions
Dilation of saw-toothed rock joint
Introduction
Constitutive law for contacts in DEM
Model calibration
Direct shear test simulation
Joint surface calibration
Parametric study on dilation of rock joints
Relative confining pressure effect
Asperity wavelength effect
Effect of multifaceted factors
Conclusions
Joint mechanical behavior with opening values
Introduction
Normal deformation of opened joints
Semilogarithmic model
Experiments and correlation
Compression tests
Results analysis
Shear deformation of opened joints
Direct shear tests
Results analysis and discussion
Conclusions
Joint constitutive model correlation with field observations
Introduction
Model description and implementation
Stability analysis of large-scale rock structures
Rock slope case
Site description
Properties of rock mass
Comparison numerical results with site investigation
The underground powerhouse case
Site description
Properties of rock and joints
Excavation process and reinforcements
Site monitoring and result analysis
The gold mine case
Site description
Rock mass properties
Comparison between predicted and measured performance
Conclusions
References
Further reading
4
Microseismic monitoring and application
Chapter outline
Acoustic emission of rock plate instability
Introduction
Materials and methods
Samples of rock plates
Equipment and AE acquisition system
Numerical simulation scheme
Computational model and parameters
Loading and boundary conditions
Results analysis
AE in the failure process of the rock plate
AE characteristics in numerical simulation test
Discussion of the magnitudes of AE events
Conclusions
Prediction method of rockburst
Introduction
Microseismic monitoring system
Active microseismicity and faults
Microseismic event distribution
Fault structures on rockburst distribution
Rockburst prediction indicators
Constructing prediction indicators
Average number N and average released energy E
Seismological parameter b and its decrease Deltab
Potential maximum magnitude Mm
Assessing prediction indicators
Conclusions
Near-fault mining-induced microseismic
Introduction
Engineering situations
Computational model
Result analysis and discussion
Average energy of microseismic events
Different characteristics of parameter b value
Local-mechanism solutions and fracture modes
Distribution of microseismic events
Principal stress difference and elastic energy
Sensitive factors of microseismic events
Conclusions
Acoustic emission recognition of different rocks
Introduction
Experiment preparation and methods
Laboratory experiments
AE signals
AE signals in the time domain
AE signals in different domains
Artificial neural network
Results and discussion
Mechanical experiment results
AE characteristics
AE signal recognition using ANN
ANN structure
BP network training
ANN recognition
Conclusions
Acoustic emission in tunnels
Introduction
Rockburst experiments in a tunnel
Sample preparation
Laboratory equipment
Loading condition
Experimental results
Rockburst tendency
Mineral composition analysis
Analysis of rockburst tendency
Destruction phenomenon of rockburst
Horizontal stress and rockburst intensity
Macroscopic morphology of rockbursts
AE characteristics of rockburst
AE characteristics under different horizontal stresses
Rockburst fracturing model
Discussion
Tunneling model of excavation mechanics
Key areas of rockbursts
Conclusions
AE and infrared monitoring in tunnels
Introduction
Simulating rockbursts in a tunnel
Sample preparation
Laboratory equipment
Experimental results
Rockburst evolution process
AE characteristics
IR characteristics
Rockburst characteristics in tunnels
Conclusions
References
Further reading
5
Structural effect of rock blocks
Chapter outline
Cracked roof rock beams
Introduction
Mechanical model of a cracked roof beam
Formation of cracked roof beam
Model of roof rock beam
Instability process of cracked roof beam
Voussoir beam of cracked roof beam
Instability feature of cracked roof beams
Influence factors of critical deflection
Hinged blocks structure after roof instability
Mechanical analysis of roof rock beams
Building computational model
Results analysis and discussion
Conclusions
Evolution characteristics of fractured strata structures
Introduction
Engineering background
Mechanical and computational model
Simplified mechanical model
Building computational model
Results and discussion
Conclusions
Pressure arching characteristics in roof blocks
Introduction
Pressure arching characteristics
Symmetric pressure arch of two key blocks
Step pressure arch structure of key blocks
Rotative pressure arch structure of key blocks
Key block stability of initial fractured roof
Key block stability of periodic fractured roof
Evolution characteristics of pressure arch
Building computational model
Evolution process of key blocks pressure arch
Structure characteristics of symmetrical pressure arch
Results and discussion
Conclusions
Composite pressure arch in thin bedrock
Introduction
Engineering background and pressure arch structure
Engineering background
Macroscopic pressure arch in far field
Fractured pressure arch in near field
Computational model and similar experiment
Building a computational model
Similar materials experiment
Results and discussion
Structures of symmetrical and stepped pressure arches
Stress distribution of rotating-squeezed pressure arch
Experimental verification on strata fracture structure
Conclusions
Pressure arch performances in thick bedrock
Introduction
Engineering background
Pressure-arch analysis and experimental methods
Theoretical analysis
Building computational model
Similar materials experiment
Results and discussion
Arching characteristics of principal stress
Characteristic parameters of pressure arch
Relationships between pressure arch and caving arch
Conclusions
Elastic energy of pressure arch evolution
Introduction
Engineering background
Pressure-arch analysis and computational model
Pressure-arch analysis
Computational model
Simulation results and discussion
Conclusions
Height predicting of water-conducting zone
Introduction
High-intensity mining in China
OFT influence on FWCZ development
Processes of overburden failure transfer
Division of OFT into stages
Development characteristics of FWCZ
Development mechanism of FWCZ based on OFT
Maximum unsupported and overhang lengths
Failure criteria of stratum
Mechanical models of OFT
Model of unsupported strata
Model of overhanging strata
Example analysis and numerical simulation
Example analysis
General situation
Calculation of maximum unsupported and overhang lengths
Height calculation of FWCZ
Numerical simulation of FWCZ height
Numerical simulation model
Simulation results analysis
Engineering analogy
Predicted FWCZ height
Overall comparison and analysis
Conclusions
References
Further reading
Index

Details

Title	Scale-Size and Structural Effects of Rock Materials
Author	Shuren Wang, Hossein Masoumi, Joung Oh, Sheng Zhang
Language	English
ISBN	ISBN 0128200316,9780128200315
Size	12 MB
Download Method	Direct Download
Download Links	BECOME A MEMBER VIEW DOWNLOAD LINKS