Study on time-dependent failure of rock and geological discontinuity under high temperature and pressure.

1)为了研究温度和时间对结晶岩石力学性质的影响，进行了花岗岩在90ﾟC水中浸泡2000d的室内试验。在测试期间，同时进行了各种测量，以调查样品物理性能的长期变化。此外，还研究了微裂纹的扩展和粘土矿物的合成，为强度特性随时间的变化提供了基础数据。结果表明，微裂纹是由于残余应力引起的应力腐蚀而产生的。2)岩石的时间相关行为与微裂纹的扩展密切相关，与短期行为相似。结果表明，可以用裂纹张量的不变量来定义破裂面。3)基于细观力学的连续体理论称为相互作用场理论，可以再现岩石在压缩作用下的剪切断裂和轴向劈裂等局部化现象。微裂纹的扩展可能通过两种机制发生：应力诱导裂纹扩展和应力腐蚀。该理论引入了一个新的场量来表示相互作用效应和相应的控制积分方程，不仅再现了岩石的非弹性变形，而且再现了由于微裂纹局部化而导致的最终宏观破坏。4)在一对中空-圆柱辉长岩试件上进行了高速摩擦实验。在滑移速率约为100 mm/S(速度增强)时，稳态摩擦力随滑移速率的增加而略有增加(速度增强)，在较高速度下随滑移速率的增加而显着减小(速度减弱)。

This research can be concluded as follow :1) To study the effects of temperature and time on mechanical properties of crystalline rocks, a laboratory test was carried out by immersing granite in 90ﾟC water for 2000 days. During the test, various measurements were made, in parallel, to investigate the long term changes in the specimens' physical properties. Growth of microcracks and synthesis of clay minerals were also investigated to supply fundamental data for the time-dependent strength properties. It is found that microcracks grow due to stress corrosion induced by residual stress. 2) Time dependent behavior of rocks is closely related to microcrack growth in a similar manner to short term behavior. It is found that a failure surface can be defined in terms of invariants of crack tensor. 3) A micromechanics-based continuum theory called interaction field theory can reproduce localization phenomena such as shear faulting and axial splitting of rock under compression. The growth of the microcracks is assumed to occur through two mechanisms : stress-induced crack growth and stress corrosion. This theory introduces a new field quantity which represents the interaction effect and the associated governing integral equation, and reproduces not only inelastic deformation of rock but also eventual macroscopic failure due to localization of microcracking. 4) High-velocity friction experiments have been performed on a pair of hollow- cylindrical specimens of gabbro. Steady-state friction increases slightly with increasing slip rate at slip rates to about 100 mm/s (velocity strengthening) and it decreases markedly with increasing slip rate at higher velocities (velocity weakening).