利用定向岩心进行AE法原地应力测量

INSITU STRESS MEASUREMENT BY A METHOD USING ORIENTED CORE

在北京市房山区迎风坡花岗闪长岩３００ｍ深钻孔中，采用以水泥端帽法为主的岩心定向技术，并在钻进和取心过程中采取特殊措施，在钻孔中距地表２５ｍ～３０１ｍ整个深度段内取得了直径８６ｍｍ的定向岩心。对深度２９４ｍ的定向岩心进行了声发射Ｋａｉｓｅｒ效应试验。岩石试件为圆柱形，直径３０ｍｍ，高度７５ｍｍ。在垂直方向，利用声发射Ｋａｉｓｅｒ效应估计的垂直主应力为７．７ＭＰａ；在２９４ｍ岩体静岩压力为７．９ＭＰａ；两者基本相同。在水平面内，对４个方向的试件进行声发射Ｋａｉｓｅｒ效应试验，得到相应的各个方向的压应力，由此估算的水平最大和最小主应力分别为２１．２ＭＰａ和１２．１ＭＰａ。水平面内最大主应力的方向基本为ＳＮ方向。将声发射Ｋａｉｓｅｒ效应测量结果与水压致裂法的测量结果进行对比，二者具有很好的一致性。

A borehole was drilled in granodiorite rockmass at Fangshan, Beijing, China. The depth of the borehole is 301m with diameter of 110mm. From about 30m to 301m, all cores were oriented by cement end cap method. AE Kaiser effect tests on oriented core at depth of 294m were carried out. The rock specimens are the cylinders with 30mm diameter and 75mm height. In vertical direction, the vertical stress estimated by AE Kaiser effect tests is 7.7 MPa. The lithostatic pressure at the depth of 294m in granodiorite rockmass is 7.9 MPa. Both of them are almost same. In horizontal plane, for four directions rock specimen, AE Kaiser effect tests were carried out and their corresponding normal stresses were gotten. The horizontal maximum and minimum principal stresses are 21 2 MPa and 12 1 MPa respectively. The orientation of horizontal maximum principal stress is about the NS trending. Comparing the result of AE Kaiser effect tests with hydrofracturing shows that they are consistent fundamentally.