Geomechanical Behaviors of Bimrocks

Description

"This book is intended as a reference book for advanced graduate students and research engineers in block-in-matrix rocks (bimrocks) or soil and rock mixtures (SRMs) or rock and soil aggregate (RSA). Bimrocks are complex formations characterized by competent rock inclusions floating in a weaker matrix. Typical types of bimrocks include a series of mixed geological or engineering masses such as m�elanges, fault rocks, coarse pyroclastic rocks, breccias, sheared serpentines and waste dump mixture. Bimrock is especially different from the general soil and rock material, and the detection of the damage and fracture is still wide open to innovative research. Globally, there is widespread interest in investigating the geomechanical behaviors of bimrocks, such as deformation and strength characteristics, damage and fracture evolution and stability prediction of bimrock construction. However, the meso-structure factors control the whole mechanical properties of bimrocks, the source of the macroscopic deformation phenomenon is the meso-structural changes. Therefore, evaluation of the mesoscopic physical and mechanical properties, together with advanced testing technique, are attractive research topics in rock mechanics. As a result, comprehensive macroscopic and mesoscopic experimental investigations should be conducted to reveal the damage and fracturing mechanical behaviors of bimrock. The readers of this work can gain new insights into the meso-structural changes of bimrocks subjected to different stress paths. The book is expected to improve the understanding of the mesoscopic damage and fracturing mechanisms of bimrocks and can be helpful to predict the stability of rock structures where rock mass is subjected to complex loading conditions"-- Cover Half Title Title Page Copyright Page Table of Contents About the author Notations Preface 1 Macro–meso geomechanical behaviors of bimrocks 1.1 Mechanical behaviors revealed by variable-angle shear experiments 1.1.1 Introduction 1.1.2 Material description and sample preparation 1.1.3 Brief description of the loading system 1.1.4 Research idea 1.1.5 Results and discussions 1.1.5.1 Typical shear force–displacement curve 1.1.5.2 Effect of the block size on shear behavior 1.1.5.3 Morphology of shear fracture surface 1.1.5.4 Strength parameter analysis 1.1.5.5 Discussions 1.1.6 Conclusions 1.2 Macro–meso failure mechanism of bimrock at medium strain rates 1.2.1 Introduction 1.2.2 Specimen preparation and testing method 1.2.2.1 The testing material 1.2.2.2 Remolded specimen preparation 1.2.2.3 Experimental system 1.2.3 Typical stress–strain curve of SRM 1.2.4 Elastic moduli analysis 1.2.5 Characteristic stress analysis 1.2.6 Strain rate dependency analysis 1.2.7 Failure mechanism 1.2.8 Failure mechanism 1.2.9 Conclusions References 2 Ultrasonic and mechanical characteristics of bimrocks 2.1 Real-time ultrasonic detection of bimrock under uniaxial deformation 2.1.1 Introduction 2.1.2 Principle of ultrasonic test 2.1.3 Experimental procedure 2.1.3.1 The testing material 2.1.3.2 Remolded specimen preparation 2.1.3.3 Experimental system 2.1.3.4 Testing procedure 2.1.4 The UPV and AC characteristics before loading 2.1.5 UCS against rock percentage 2.1.6 Failure mechanism 2.1.7 Ultrasonic pulse velocity 2.1.8 Transmission ratio 2.1.9 Relationship between UCS and UPV 2.1.10 Comparison of cracking behaviors of bimrocks with those of soil and rock material 2.1.11 Conclusions 2.2 Cracking damage evolution of bimrock under real-time ultrasonic testing 2.2.1 Introduction 2.2.2 Experimental procedure 2.2.2.1 The testing material 2.2.2.2 Specimen preparation 2.2.2.3 Experimental system 2.2.2.4 Testing procedure 2.2.2.5 Research idea 2.2.3 Peak strength variation against rock percentage 2.2.4 Failure mechanism 2.2.5 Ultrasonic pulse velocity 2.2.6 Cracking evolution analysis 2.2.7 Damage Constitutive Model 2.2.8 Conclusions 2.3 Real-time ultrasonic testing for air-dried bimrock under triaxial deformation 2.3.1 Introduction 2.3.2 Materials and specimen preparation 2.3.3 Test system and procedure 2.3.4 Axial stress–strain–UPV curves 2.3.5 Stress–UPV dependency analysis 2.3.6 Shear strength characteristics 2.3.7 Ultimate failure mode analysis 2.3.8 Conclusion 2.4 Triaxial deformation characteristics of wet bimrock revealed using the real-time ultrasonic detection 2.4.1 Introduction 2.4.2 Samples and testing procedure 2.4.2.1 Characteristics of materials used in bimsoil 2.4.2.2 Sample preparation 2.4.2.3 Testing system 2.4.2.4 Testing procedure 2.4.3 Triaxial stress–strain responses 2.4.4 UPV analysis during deformation 2.4.5 Analysis of dependency of velocity to stress 2.4.6 Correlation between RBP and strength parameters 2.4.7 Analysis of failure mechanisms 2.4.8 Conclusions 2.5 Investigation on fracture evolution for bimrock under splitting loads 2.5.1 Introduction 2.5.2 Experimental methods 2.5.2.1 Materials and specimen preparation 2.5.2.2 Brief description of the testing system 2.5.2.3 Research idea 2.5.3 Typical splitting stress–displacement curves 2.5.4 Typical stress–displacement–UPV curve 2.5.5 Stress–UPV dependency analysis 2.5.6 Fracturing evolution analysis 2.5.7 Fracture morphology analysis 2.5.8 Post-Test 3-D laser scanning analysis 2.5.9 Conclusions References 3 Static fracture evolution of bimrock revealed by in situ CT technique 3.1 Meso-damage cracking characteristics of bimrock by CT scanning 3.1.1 Introduction 3.1.2 Experimental procedures 3.1.2.1 Physical principles of X-Ray tomography 3.1.2.2 Experimental system 3.1.2.3 Specimen preparation 3.1.2.4 Research idea 3.1.2.5 Testing procedure 3.1.3 Calibration of rock percentage 3.1.4 Meso-damage cracking analysis 3.1.5 ROI_CT value characteristics 3.1.6 Porosity evolution analysis 3.1.7 Damage constitutive model 3.1.8 Crack statistical characteristics 3.1.9 Conclusions 3.2 In situ CT investigation on meso-structural changes in bimrocks under uniaxial deformation 3.2.1 Introduction 3.2.2 Experimental materials and methods 3.2.2.1 Tested material, sampling, and preparation 3.2.2.2 Experimental apparatus 3.2.2.3 Experimental procedure 3.2.3 Uniaxial test and CT scanning 3.2.4 Identification and extraction of cracks 3.2.5 Crack geometry characteristics analysis 3.2.6 Damage evolution model 3.2.7 Conclusions 3.3 Meso-structural changes in bimsoil under triaxial compression 3.3.1 Introduction 3.3.2 Experimental materials and methods 3.3.3 In situ triaxial compression test 3.3.3.1 Imaging process method 3.3.4 General observations of bimsoil damage and fracture evolution 3.3.5 Meso-structural identification and extraction 3.3.6 D Meso-structural evolution analysis 3.3.7 Localized deformation analysis 3.3.7.1 Nonhomogeneity analysis of deformed sample 3.3.8 Dilatation behavior analysis 3.3.9 Failure morphological analysis 3.3.10 Conclusions 3.4 Effects of rock blocks on meso-structural changes in bimrock 3.4.1 Introduction 3.4.2 Materials and methods 3.4.2.1 The tested material, sampling, and preparation 3.4.2.2 X-ray CT apparatus 3.4.2.3 Triaxial loading device 3.4.2.4 Testing program 3.4.2.5 Image analysis 3.4.3 General observations 3.4.4 Meso-structural evolution analysis 3.4.5 Dilatation behavior analysis 3.4.6 Failure morphology analysis 3.4.7 Conclusions and outlook 3.5 Effects of confining pressure on meso-structural changes in bimrock 3.5.1 Introduction 3.5.2 Materials and methods 3.5.2.1 Tested material and sample preparation 3.5.2.2 X-ray CT apparatus 3.5.2.3 Triaxial loading device 3.5.2.4 Testing procedure for triaxial test 3.5.2.5 Image analysis 3.5.3 Testing program during in situ CT scanning 3.5.4 General observations 3.5.5 Meso-structural evolution analysis 3.5.6 Dilatation behavior analysis 3.5.7 Conclusions References 4 Dynamic behavior characterization of bimrocks using the CT technique 4.1 Dynamic behavior of bimrock under cyclic triaxial test 4.1.1 Introduction 4.1.2 Materials 4.1.3 Experimental methods 4.1.3.1 Sample preparation 4.1.3.2 Cyclic triaxial apparatus 4.1.3.3 Test procedure 4.1.4 Cyclic stress–strain response 4.1.5 Characterizations of M[sub(r)] and D[sub(r)] 4.1.6 Meso-damage evolution analysis 4.1.7 Identification and extraction of cracks 4.1.8 Dilatancy behavior analysis 4.1.9 Conclusions 4.2 Influence of confining pressure on dynamic mechanical properties 4.2.1 Introduction 4.2.2 Materials and methods 4.2.2.1 Materials and sampling 4.2.2.2 X-ray CT machine 4.2.2.3 Loading apparatus 4.2.2.4 Testing scheme 4.2.3 Cyclic stress–strain responses 4.2.4 Damage and fracture observations 4.2.5 Analysis of meso-structural changes 4.2.6 Stress dilatancy behavior analysis 4.2.7 Conclusions 4.3 Influence of rock blocks on fatigue damage evolution of bimrock 4.3.1 Introduction 4.3.2 Materials and experimental methods 4.3.2.1 Materials and sample preparation 4.3.2.2 X-ray CT machine 4.3.2.3 Loading apparatus 4.3.2.4 Test procedure 4.3.3 Testing program 4.3.4 Cyclic stress–strain response 4.3.5 General observations 4.3.6 Analysis of meso-structural changes 4.3.7 Stress dilatancy analysis References 5 Flow and stress coupled characteristics of bimrock 5.1 The effect of soil matrix on flow characteristics for  bimrocks 5.1.1 Introduction 5.1.2 Materials and specimen preparation 5.1.3 Test system and procedure 5.1.4 Seepage properties of matrix materials 5.1.5 Seepage properties of the SRM with clay matrix 5.1.6 Seepage properties of the SRM with a mucky matrix 5.1.7 Seepage properties of the SRM with a sand matrix 5.1.8 Conclusions 5.2 Investigation on Non-Darcy flow characteristics of bimrock 5.2.1 Introduction 5.2.2 Experimental methods 5.2.2.1 The testing material 5.2.2.2 Preparation of remolded specimens 5.2.2.3 Experimental system 5.2.2.4 Test procedure 5.2.3 General description of the flow phenomenon 5.2.4 Non-Darcy’s flow of SRMs 5.2.5 Effect of rock block on permeability coefficient 5.2.6 Critical hydraulic gradient for SRMs 5.2.7 Forchheimer flow for SRMs 5.2.8 Conclusions 5.3 Effect of Slenderness on the Non-Darcy flow in bimsoils 5.3.1 Introduction 5.3.2 Experimental methods 5.3.2.1 Experimental setup 5.3.2.2 Material properties 5.3.2.3 Remolded sample preparation 5.3.2.4 Test procedure 5.3.3 General descriptions 5.3.4 The non-Darcy’s flow of bimsoils 5.3.5 Slenderness effect on flow characteristics 5.3.6 Conclusions 5.4 The effect of confining pressure on permeable properties in bimrocks 5.4.1 Introduction 5.4.2 Experimental methods 5.4.2.1 The testing material 5.4.2.2 Preparation of remolded specimens 5.4.2.3 Experimental system 5.4.2.4 Test procedure 5.4.3 General observation 5.4.4 Relationship between permeability coefficient and confining pressure 5.4.5 Comparison analysis of the experimental curve 5.4.6 Effect of hydraulic gradient on flow-stress property 5.4.7 Conclusions 5.5 Flow-stress coupling characteristics of bimrocks under compression 5.5.1 Introduction 5.5.2 Experimental methods 5.5.2.1 The testing material 5.5.2.2 Remolded specimen preparation 5.5.2.3 Experimental system 5.5.2.4 Test procedure 5.5.3 General description 5.5.4 Uniaxial flow-stress coupling test 5.5.5 Triaxial flow-stress coupling test 5.5.6 Conclusions References 6 Investigation on piping disaster in bimsoils 6.1 Seepage piping evolution characteristics in bimsoils 6.1.1 Introduction 6.1.2 Materials and methods 6.1.2.1 The testing materials 6.1.2.2 Remolded sample preparation 6.1.2.3 Experimental setup 6.1.2.4 Piping test procedure 6.1.3 General observations 6.1.4 Piping characteristic curve analysis 6.1.5 Seepage force analysis 6.1.6 Eroded soil mass analysis 6.1.7 Effect of confining pressure on piping evolution 6.1.8 Conclusions 6.2 Optimization of multiple seepage piping parameters in bimsoils 6.2.1 Introduction 6.2.2 Experimental methods 6.2.2.1 Materials and sample preparation 6.2.2.2 Experimental setup 6.2.2.3 Piping test procedure 6.2.3 Box-Behnken design of multiparameter evaluation and analysis 6.2.4 RSM model analysis of multiple piping parameters 6.2.5 Critical hydraulic gradient optimization 6.2.6 Summary of piping disaster 6.2.7 Conclusions References Index