钻孔孔壁切缝解除地应力测试方法数值模拟研究及工程应用

Method of Geostress Relieving and Measuring by Borehole Slots:Numerical Analysis and Engineering Application

为解决高应力环境中的地应力测试的难题,通过数值分析方法对试验过程中切缝深度的优化及切缝布置方案进行了模拟研究,并将该方法应用于锦屏地下实验室应力测量中。数值模拟结果表明:当初始应力场以平行于切缝方向应力分量为主时,切缝两侧应力完全释放所需的切缝深度最大,为16 mm。进行现场试验时,为了提高试验的可靠性,避免切缝之间的相互影响,往往一个给定的钻孔深度只布置一个切缝,且切缝间距一般>200 mm。测试结果表明测试部位岩体处于极高应力状态下,与钻孔钻进过程中出现岩芯饼化现象相符合。

To overcome the difficulty of geostress measurement in high geostress environment,we discussed the optimization of narrow slot depth and slot layout by numerical simulation,and applied the method of geostress relieving by borehole slots to the stress measurement of Jinping projects' s underground laboratory. Numerical simulation suggest that when initial stress field is dominated by stress component parallel to the slot direction,the required depth of slot for complete release of stress on both sides of the slot reaches the maximum 16 mm. In field test,only one slot is arranged at a given depth in the borehole to improving the reliability of experiment and avoiding the mutual influence between the narrow slots. Meanwhile,the slot spacing is generally greater than 200 mm. The measured result shows that the rock mass at test site is in high geostress state,which is in accordance with the core disking in the process of drilling.