不同温压条件下饱水砂岩的变形破坏与孔隙压力问题的试验研究

THE TEST STUDY ON DEFORMATION FAILURE AND PORE PRESSURE OF THE SATURATED SANDSTONE UNDER THE CONDITIONS OF VARIOUS TEMPERATURE AND CONFINING PRESSURE

本文通过不同温度与围压条件下的岩石三轴试验,研究了水、温度、有效围压对饱水的新沂砂岩变形破坏过程的影响及此过程中孔隙压力变化的特征。研究结果表明:(1)饱水砂岩的强度比风干岩石低20—30％,而排水条件下的这种差异更大;(2)岩石变形破坏过程中,孔隙压力的变化可划分出四个基本阶段:上升、缓升、下降与保持不变阶段,其中第二阶段相当于微破裂发生阶段,第三阶段相当于微破裂发展成为宏观破坏的阶段;(3)饱水砂岩的强度随环境温度的升高和有效围压的下降而减小,而且排水条件也促使强度降低,因此可以推断,井孔水位对震前异常反映灵敏的岩石力学与水动力学条件是:含水层的渗透性强、温度高、埋深浅、水头高。

The effects of water, temperature and effective confining pressure on Xinyi sandstone and response of pore pressure to defomation and failure process of the sandstone,have been investigated. The test under various temperature and confining pressure are conducted. It has been found that(1) the strength of saturated sandstone is lower as 20-30% than strength of the air dried sandstone,and the influence under drained test is more clear than undrained test; (2)the changes of pore pressurd in a process of deformation and failure may be divided into four phases: rise, slow rise, drop and steady phases,the 2nd phase is corresponded to the micro fracturing stage of rock,the 3rd phase to micro -fracture growth and the macro fracturing stage; (3)the strength of saturated sandstone is dropped with the increase of temperature and the drop of effective confining pressure. According to those test results, in the viewpoints of rock mechanics and hydrodynamics,the sensitive conditions qf response of a well-aquifer system to the breed and occurrence of a strong earthquake are: (1)the aquifer is strong permeable; (2)the buried depth is shallower and the water head is higher; (3)the aquifer temperature is higher.