深部地应力场下砂岩力学性质的变化

The changes of mechanical properties of sandstone in deep in-situ stress field

山东万福煤矿位于鲁西南成武县和巨野县交界处,煤田上覆土层厚度高达700 m.在该矿区采用水压致裂法对深部地应力进行了测量,获得了矿区较为准确的地应力状态和分布规律.在此基础上,结合万福矿区地下900 m以下砂岩所处的地压环境,采用三轴岩石力学测试系统研究深部地应力条件对不同砂岩力学性质的影响,建立砂岩力学性质与深部地应力之间的相关关系.结果表明,砂岩的刚度和强度随围压的增大而增大;同时,在高围压情况下,砂岩由低围压条件下的剪切破裂转变为塑性流动破坏.

Wanfu Coal Mine is located in the juncture of Juye Country and Chengwu Country that is in south-west of Shandong Province, China. The overburden soil layer in the mine is over 700 m thick which belongs to the alluvium of Yellow River. In order to provide accurate in-situ stress condition and its attribution law, in-situ stress measurement in the mine was carried out. According to the ground pressure environment of different sandstone at more than 900 m depth in Wanfu Coal Mine field, the effects of deep in-situ stress condition on mechanical property of sandstone were studied by using triaxial rock mechanics experimental system and the relative relationships between the mechanical properties of sandstone and confining pressure were established. It is shown that the stiffness and strength of the sandstone increase with confining pressure increasing; And under lower confining pressure, shear failure occurs while under higher confining pressure plastic fluent failure occurs.