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

研究结果如下：1)为研究温度和时间对结晶岩石力学性能的影响，在室内进行了花岗岩浸泡在90℃的水中2000天的试验。在测试过程中，同时进行了各种测量，以研究样品物理性质的长期变化。研究了微裂纹的生长和粘土矿物的合成，为研究随时间变化的强度特性提供了基础数据。结果表明，微裂纹是由残余应力引起的应力腐蚀引起的。2)岩石的时间依赖行为与微裂纹扩展密切相关，其方式与短期行为相似。发现失效面可以用裂纹张量的不变量来定义。3)基于细观力学的连续介质理论——相互作用场理论可以再现岩石在压缩作用下的剪切断裂、轴向分裂等局部化现象。假设微裂纹的扩展通过应力诱导裂纹扩展和应力腐蚀两种机制发生。该理论引入了一个新的场量，它代表了相互作用效应和相关的控制积分方程，不仅再现了岩石的非弹性变形，而且还再现了由于微裂纹局部化而导致的最终宏观破坏。4)对一对辉长岩空心圆柱形试样进行了高速摩擦试验。当滑移率达到100 mm/s左右时，稳态摩擦随滑移率的增加而略有增加（速度增强）；当滑移率较高时，稳态摩擦随滑移率的增加而显著降低（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).