Rock Indentation: Experiments and Analyses

Description

This book focusses on rock indentation and importance of specific drilling/cutting energy as a performance indicator for drilling/rock cutting. It aids in designing of drill bits and cutting picks, through performance evaluation for a given geometry. It further covers stress distribution along three axes in rock during load application, correlation of specific energy with properties of rocks and statistical modelling to generate mathematical equation to estimate the specific energy indentation, including performance prediction by artificial neural network modelling. Presented models can be used to assess the specific energy in rock indentation from the physic-mechanical properties of rocks. Presents synthesis of rock indentation experiments and analyses Deals with statistical modeling to generate mathematical equations to estimate the specific energy indentation from the rock parameters/properties Discusses how to find the performance of drill and cutting bits during drilling or cutting operations through indentation test Covers numerical modeling to explain stress distribution in rock during rock indentation Includes artificial neural network concepts used in field of rock mechanics This book is aimed at researchers and graduate students in mining/geological engineering, and mechanical engineering. Cover Half Title Title Page Copyright Page Dedication Table of Contents Preface Acknowledgments About the Author 1 Introduction 1.1 General 1.2 Principle and Phenomenon of Indentation in Rock Drilling/Cutting 1.3 Indentation Test and Its Operating Parameters 1.4 Studies On Indentation 1.5 Studies On Factors Affecting Indentation Process 1.5.1 Influence of Static/Quasi-Static Load and Dynamic Load 1.5.2 Influence of Rate of Loading Or Strain Rate of Penetration 1.5.3 Influence of Indenter Geometry 1.5.4 Influence of Index Angle 1.5.5 Influence of Confining Stress 1.5.6 Influence of Properties of Rocks References 2 Static and Impact Indentation Tests 2.1 Introduction 2.2 Static and Impact Indentation of Rocks 2.3 Static Indentation Test 2.3.1 Experimental Procedure 2.3.2 Impact Indentation Tests 2.3.2.1 Experimental Procedure 2.3.2.2 Fabrication of Dynamometer for Measuring Impact Force 2.3.2.3 Measurement of Impact Force 2.3.2.4 Calibration of the Dynamometer With Respect to Force 2.3.2.5 Experimental Procedure 2.4 Force-Penetration Curves in Static Indentation 2.4.1 Concept of Force-Penetration Curve 2.4.2 F-P Curves During Static Indentation Test References 3 Mechanics of Indentation Fracture 3.1 Introduction 3.2 Evaluation of Crack Pattern 3.2.1 Crack Nucleation 3.2.2 Crack Formation 3.2.3 Crack Propagation 3.2.4 Unloading Cracks 3.2.5 Similarity Relations – Loading Half-Cycle 3.2.6 Similarity Relations – Unloading Half-Cycle 3.3 Crack Paths 3.3.1 Crack Pattern With Sharp Cone 3.3.2 Crack Path in Spherical Indenters 3.3.3 Analysis of Fracture Mechanics in Rock Indentation 3.3.4 Sharp Indenters – Median Vent Crack (Propagation) 3.3.5 Indenters With Constant Elastic Contact – Cone Crack (Propagation) 3.3.6 Spherical Indenters – Cone Crack (Formation) 3.4 Measurement of Fracture Parameters 3.5 Modeling of Fracture in Indentation 3.6 Numerical Analysis of Fracture in Rock Indentation 3.6.1 Computational Modeling 3.6.2 Modeling of Crack Extension (i) Crack Nucleation (ii) Crack Extension (iii) Orientation of Quasi-Static Crack Growth References 4 Indentation of Rocks and Stress Fields 4.1 Introduction 4.2 Indentation of Rocks 4.2.1 By Wedge-Shaped Indenter (Chisel) 4.2.2 By Spherical Indenter 4.2.3 By Blunt Indenter 4.2.4 By Punch Indenter 4.2.5 By Flat Punch and Sphere Indenter 4.2.6 By Conical Indenter 4.3 Indentation Stress Fields 4.3.1 Point-Force Indenters – Boussinesq Elastic Field 4.3.2 Spherical Indenters – Hertzian Elastic Field and Its Variants (i) The Ideal Hertzian Field (ii) Time-Dependent Loading (iii) Tangential Friction Forces – Elastic Mismatch at Static Interface (iv) Tangential Friction Forces – Sliding Interface 4.3.3 Inelastic Deformation Fields 4.3.4 Stress Field in Normal Wedge Indentation in Rocks With Lateral Confinement 4.3.5 Plasticity Analysis of Stresses for Wedge Bit 4.3.5.1 Smooth Bit 4.3.5.2 Rough Bit 4.3.5.3 General Case 4.3.5.4 Role of Interfacial Friction 4.4 Numerical Analysis of Stresses in Rock Indentation 4.4.1 Blunt Bit, Sharp Wedge, and Cylindrical Bit 4.4.1.1 Blunt Point Bit 4.4.1.2 Sharp Wedge Bit 4.4.1.3 Cylindrical Bit 4.4.2 Punch Indenter 4.4.3 Chisel, Cross, and Spherical Button References 5 Analytical Models for Rock Indentation 5.1 Introduction 5.2 Cavity Expansion Model 5.2.1 Basic Assumptions 5.2.2 Dimensional Analysis and Similarity Consideration 5.2.3 Self-Similar Solution for Blunt Wedge and Cone Indentation 5.2.4 A General Solution of Rock Indentation 5.2.5 Spatial and Material Derivatives 5.2.6 Stress Field 5.2.7 Velocity Field 5.2.8 Velocity Boundary Conditions 5.2.9 Size of the Damaged Zone and Indentation Force 5.3 General Solution for Blunt Indenter 5.4 Analytical Model for Indentation By a Sphere 5.5 Analytical Model for Indentation By a Truncated Wedge 5.6 Analytical Model for Indentation By a Wedge 5.6.1 The Mathematical Models for Chipping 5.6.2 Analytical Model of Wedge–Bit Penetration 5.6.3 Angle of Fracture 5.6.4 Second Chipping 5.6.5 The Effect of the Physico-Mechanical Properties of Rocks On Chipping 5.7 Analytical Model for Bit Penetration Into Rock By Conical Indenter References 6 Indentation Indices and Their Correlation With Rock Properties 6.1 Introduction 6.2 Indentation Hardness Index 6.2.1 Standardized Indentation Hardness Test 6.3 Brittleness Index 6.4 Studies On Indentation to Correlate the Indentation Indices With Mechanical Properties of Rocks 6.5 Indentation Modulus and Critical Transition Force 6.5.1 Methodology 6.6 Rolling Indentation Abrasion Test (RIAT) 6.7 Concept of Rock Penetration Resistance (RPR) to Predict Penetration Rate in Percussive Drilling References 7 Specific Energy in Rock Indentation 7.1 Introduction 7.2 Studies On Specific Energy On Rock Drilling 7.3 Studies On Specific Energy On Rock Cutting 7.4 Influence of Indexing Angle On Specific Energy 7.4.1 Specific Energy in Impact Indentation 7.4.2 Comparison of Specific Energy in Static and Impact Indentation 7.5 Influence of Rock Properties On Specific Energy in Rock Indentation 7.5.1 Residual Plots for Specific Energy 7.5.2 Performance Prediction of the Derived Models 7.6 Influence of Mineralogical Properties On Specific Energy 7.7 Influence of Elements/Minerals in Oxides Form Obtained From X-Ray Florescence (XRF) Test On Specific Energy References 8 Development of Models to Predict Specific Energy 8.1 Introduction 8.2 Mathematical Models Using Multiple Regression Analysis 8.2.1 Multiple Regression Analysis of Chisel Bit Regression Equation 8.3 Development of Artificial Neural Network Models to Predict Specific Energy From Properties of Rock 8.3.1 Fundamental Concepts in ANN 8.3.2 Multilayer Perceptron 8.3.3 Back Propagation Algorithm 8.4 Development of ANN Model 8.5 Performance Prediction of the Regression and ANN Models 8.5.1 Analysis of Artificial Neural Network Results References 9 Numerical Modeling of Rock Indentation 9.1 Introduction 9.2 Studies On Numerical Simulation of Indentation and Cutting in Rock 9.2.1 Influence of Microstructure of Rocks 9.2.2 Influence of Scale Effect 9.3 FEM Analysis of Bit Penetration Into Rock 9.3.1 Description of the Numerical Model 9.3.2 Assumptions in FEM Analysis 9.3.3 Defining Element Type 9.3.4 Material Properties 9.3.5 Mesh Generation 9.3.6 Boundary Conditions Adopted 9.3.7 Numerical Analysis of Wedge Indentation References Index