1st Edition

Mechanical Behaviour of Rocks Under High Pressure Conditions

By Mitsuhiko Shimada Copyright 2000
    198 Pages
    by CRC Press

    Knowledge of the mechanical properties of rocks at high pressure and temperature is fundamental not only for material science but also for earth science, such as for solving the mechanism of earthquakes and tectonic processes. For example, physical bases of the earthquake prediction based on the rock mechanics have been proposed, and extensive seismological, geophysical and geochemical observations have been conducted to find precursory phenomena before large earthquakes. However, we cannot help telling for the present that we do not have sufficient knowledge of an effective and reliable method for earthquake prediction.

    The book is mainly concerned with comprehensive source of information on the mechanical properties and behavior of rocks under high pressure that scans current state-of-the-art knowledge and shows contribution in establishing an experimental basis for the understanding of the mechanism of rock deformation in the earth's interior.

    The book can be used as textbook for graduate students by university teachers to prepare courses and seminars, and for active scientists and engineers who want to become familiar with a fascinating new field.

    1. Introduction

    2. Triaxial testing under high confining pressures
    2.1. Triaxial testing
    2.2.1. Conventional apparatus
    2.2.2. Solid-medium Griggs type apparatus
    2.2.3. Cubic press
    2.2.4. Ultra-high pressure apparatus
    2.3. The method of triaxial testing in a cubic press
    2.3.1. Apparatus and sample assembly
    2.3.2. Experimental procedures at room temperature
    2.3.3. Experimental procedures at high temperatures
    Appendix 2.1. Pressure scale
    Appendix 2.2. Observed examples of the effect of axial loading on confining pressure

    3. Experimemtal results on low porosity silicate rocks
    3.1. Compressive strength
    3.1.1. Pressure dependence of strength at moderate confining pressures
    3.1.2. Pressure dependence of strength at high confining pressures
    3.2. Acoustic emission
    3.3. Frictional strength under high confining pressures
    3.4. Fault features
    3.4.1. Sample preparation
    3.4.2. Features of faulting
    Appendix 3.1. Stress-strain curves at room temperature
    Appendix 3.2. Strength data at room temperature

    4. Two types of brittle fracture
    4.1. High pressure type of fracture
    4.1.1. Comparison with previous high temperature experiments
    4.1.2. Transitional regime and semibrittle regime
    4.2. Other examples of two types of fracture
    4.2.1. Gneiss
    4.2.2. Experiments in a cubic press at high temperature
    4.2.3. Temperature dependence of strength in the high-pressure type regime
    4.3. Micromechanics
    4.3.1. Introduction
    4.3.2. Micro-fracture styles
    4.3.3. Discussion on the mechanisms of fracturing
    4.3.4. Summary
    Appendix 4.1. Strength data at elevated temperatures

    5. Geophysical and geological implications of the two types of fracture
    5.1. The conditions for application to the earth's interior
    5.2. The effect of size on rock strength under confining pressures
    5.2.1. The effect of size on uniaxial compressive strength and characteristic length
    5.2.2. The effect of size under confining pressure
    5.2.3. Implications in the earth's crust
    5.3. Strength of the lithosphere
    5.3.1. Brittle-ductile model
    5.3.2. A model including the high-pressure type fracture
    5.4. An approach to earthquake prediction research

    6. Mechanical behavior of porous silicate rocks
    6.1. Introduction
    6.2. Mechanical properties of a porous basalt under high confining pressure
    6.2.1. Volumetric strain
    6.2.2. AE activity
    6.2.3. Boundaries of mechanical states in the differential stress-confining pressure field
    6.3. Microstructural observations of porous basalt and the mechanism of cataclastic ductile flow
    6.3.1. Macroscopic observations
    6.3.2. Microscopic observations
    6.3.3. The mechanism of cataclastic ductile flow
    6.4. Change in the mechanism of cataclastic flow of porous rock under high confining pressure
    6.4.1. Creep analysis and equivalent viscosity
    6.4.2. Pressure-induced change in the mechanism of cataclastic flow
    6.5. High-pressure embrittlement
    6.5.1. High-pressure embrittlement in porous sandstone
    6.5.2. Microscopic observations of high-pressure embrittlement in eclogite
    6.5.3. Conditions and mechanism of high-pressure embrittlement
    6.6. Structure of a fault zone and related geophysical and geological implications

    Appendix 6.1. Experimental data on the deformation of dry Yakuno basalt with 7% porosity at room temperature
    Appendix 6.2. Characteristics of the cubic press with a large axial displacement



    Mitsuhiko Shimada