A Study Of Stress Dependent Stiffness Of Rock Using The Multistage Triaxial Test

Compression tests for investigating the time-dependence of rock under confining pressures are time consuming and require more specimens than do uniaxial compression tests. In this study, a new testing method combining multi-stage confining pressure and alternating loading rate is proposed to investigate the loading-rate dependence of triaxial compressive strength from a small amount of rock sample. In the test, a small-size rock specimen 10 mm in diameter and 20 mm in height was loaded under a strain rate alternating between slow and fast and under a confining pressure increased once just after reaching the peak strength. Strengths corresponding to two strain rates and two confining pressures could be obtained from one specimen. The cohesion, angle of internal friction, and loading-rate dependence of strength from the data were consistent with those from the commonly used triaxial compression tests under a constant strain rate or constant confining pressure. The proposed test with a small amount of rock sample can reduce not only the time and cost but also the environmental load of sampling in situ.

This is the first book ever published on the problems of true triaxial testing of rocks addressing all aspects of true triaxial testing of rocks, including: (i) true triaxial testing techniques and procedures; (ii) test results: strength, deformability, failure mode, permeability, acoustic emission, and elastic wave velocity; (iii) constitutive laws and failure criteria; and (iv) applications to geoengineering and geosciences. Recent developments in the field of true triaxial testing of rocks are presented, as well as a thorough review of the most important achievements in the whole history of true triaxial testing of rocks. Almost all researchers from around the world engaged in the true triaxial testing of rocks over the last three decades have contributed to this work. The authors originate from different branches of geoengineering and geosciences, including civil engineering, engineering geology, geotechnical engineering, mining engineering, petroleum engineering, seismology, and tectonophysics.

Rock Characterisation, Modelling and Engineering Design Methods contains the contributions presented at the 3rd ISRM SINOROCK Symposium (Shanghai, China, 1820 June 2013). The papers contribute to the further development of the overall rock engineering design process through the sequential linkage of the three themes of rock characterisation, model

Rock Mechanics: Achievements and Ambitions contains the papers accepted for the 2nd ISRM International Young Scholars’ Symposium on Rock Mechanics, which was sponsored by the ISRM and held on 14–16 October 2011 in Beijing, China, immediately preceding the 12th ISRM Congress on Rock Mechanics. Highlighting the work of young teachers, researchers and practitioners, the present work provides an important stimulus for the next generation of rock engineers, because in the future there will be more emphasis on the use of the Earth’s resources and their sustainability, and more accountability of engineers’ decisions. In this context, it is entirely appropriate that the Symposium venue for the young scholars was in China — because of the rock mechanics related work that is anticipated in the future. For example, in the Chinese Academy of Sciences report, “Energy Science and Technology in China: A Roadmap to 2050”, it is predicted that China’s total energy demand will reach 31, 45, 61 and 66 x 108 tce (tonnes of coal equivalent) in 2010, 2020, 2035, 2050. The associated per capita energy consumption for the same years is estimated at 2.3, 3.1, 4.1 and 4.6 tce. This increasing demand will be met, inter alia, by the continued operation and development of new coal mines, hydroelectric plants and nuclear power stations with one or more underground nuclear waste repositories, all of which will be improved by more modern methods of rock engineering design developed by young scholars. In particular, enhanced methods of site investigation, rock characterisation, rock failure understanding, computer modelling, and rock excavation and support are needed. The topics in the book include contributions on: - Field investigation and observation - Rock constitutive relations and property testing - Numerical and physical modeling for rock engineering - Information technology, artificial intelligence and other advanced techniques - Underground and surface excavation and reinforcement techniques - Dynamic rock mechanics and blasting - Predication and prevention of geo-environmental hazard - Case studies of typical rock engineering Many of the 200 papers address these topics and demonstrate the skills of the young scholars, indicating that we can be confident in the continuing development of rock mechanics and rock engineering, leading to more efficient, safer and economical structures built on and in rock masses. Rock Mechanics: Achievements and Ambitions will appeal to professionals, engineers and academics in rock mechanics, rock engineering, tunnelling, mining, earthquake engineering, rock dynamics and geotechnical engineering.

Fracture and flow of rocks under stress and their geophysical and seismological implications raise fundamental questions in rock mechanics, particularly in the areas of tectonophysics and seismology. This text exclusively addresses the deformation and fracture of rock specimens under general triaxial compression, in which all three principal stresses are different; which significantly affects the ultimate strength of rocks. It moreover deals with deformation and failure folloiwng intermediate principal stress in graphic and numerical form. The effect of the intrinsic features of rock masses of inhomogeneous or anisotropic structure are taken into account, as are acoustic emission phenomena in rocks under various stress states. Friction in rocks, measured by a newly-designed shear-testing machine, is discussed in relation to earthquake phenomena.