Experimental Study of Fracture and Deformation of Rocks at High Confining Pressure and Temperature

1. 在围压为3gpa、温度为300ºC的条件下进行了三轴压缩试验。证实了在高温下，当抗压强度与摩擦强度相等时，断裂机制发生变化，由普通脆性断裂（低压型）转变为高压型断裂。除了孔隙压力非常高的情况外，高压型裂缝被认为在地壳中占主导地位。结合岩石圈强度的尺度效应估算，提出了岩石圈强度的新模型。对低压和高压条件下较精确测量的成因声发射数据的分析表明，两种类型的裂缝最终破裂前的b值行为在两种类型的裂缝之间发生变化。从榴辉岩的实验中发现，高压脆化是具有碎裂延性的岩石的特征现象。利用新设计的无摩擦活塞，利用围压下弹性波层析成像技术测量了岩石试样中多条路径的弹性波速，阐明了裂缝成核的过程。

1. Triaxial compression test was conducted at confining pressure up to 3 GPa and temperature to 300ﾟC. It was confirmed that the fracture mechanism changes at elevated temperature when the compressive strength becomes equal to the frictional strength, from ordinary brittle fracture (low-pressure type) to a high-pressure type fracture. The high-pressure type fracture is considered to be predominant in the earth's crust, excepting in the case of very high pore pressure. Combining these experimental results with the estimation of the scale effect on the rock strength, a new model for the lithosphere strength was proposed.2. An analysis of the AE data on genesis which had been measured more precisely both in the low-and high-pressure regimes, showed that the behavior of b-value before the final fracture changes between the both types of fracture.3. From the experiments on eclogite, the high pressure embrittlement was found to be a characteristic phenomenon for the rocks which exhibit cataclastic ductile behavior.4. A process of fracture nucleation was clarified from the measurement of elastic wave velocity through many paths in a rock specimen by the aid of elastic wave tomography under confining pressure by means of a new designed friction-less piston.