关键词: 蚀变岩, 常规三轴试验, 曲线类型, 脆－延转换, 围压, 临界状态应力比

Abstract: The altered rock is the soft rock which is scarce in the engineering. For a major engineering project in Southwest China, the altered rock is located in the key position of the project. In order to guarantee the project for long-term stability, the mechanical property of the altered rock should be deeply and fully studied. On the basis of systematic conventional triaxial compression test for the saturated altered rock under different porosities, the test results are analyzed and summarized. It has been put forward that there are three types of stress-strain curve before rock destruction and three types of stress-strain curves after rock destruction. The conclusions have been proposed that the altered rock destruction is effected by both confining pressure and porosity. When the confining pressure is 12 MPa, the brittle failure is dominating. Only when the porosity is more than 16 % and the confining pressure is more than 4 MPa, the brittle-ductile fracture diversion state is possibly found. Furthermore, the confining pressure of brittle-ductile fracture state diversion decreases along with the porosity increases; and the critical state stress ratio increases along with the porosity increases.

Key words: altered rock, conventional triaxial test, curve types, conversion of brittle-ductile property, confining pressure, critical stress ratio