新疆某高放废物预选处置库区地应力测量研究

In-situ stress measurement of candidate area for high level radioactive waste repository in Xinjiang

为了获得预选处置库区现今地应力的赋存特征,在该区花岗岩体内的4个深钻孔中采用水压致裂方法进行地应力测量。基于钻孔岩芯编录结果,在0~700 m深度范围内,成功取得地应力量值和最大水平主应力方向数据。依据获取的地应力实测资料,结合拜尔利定律和断层摩擦库伦准则,对预选区的地应力状态及断层活动性进行分析。结果表明:(1)3个主应力随深度呈现出较好的线性关系;(2)测试深度范围内,水平应力普遍高于垂向应力,预选区构造应力占主导地位,且随深度的增加逐渐减弱,岩体北部的水平力作用强于中部及南部,南部最弱;(3)最大水平应力优势方位为NEE,与区域构造应力场方向基本吻合,自青藏高原内部及边缘到东天山地区,现今最大主应力的作用方向表现为由NE^NEE的变化规律;(4)预选区地应力量值未达到断层摩擦滑动临界值,断层活动性较弱;(5)研究成果为处置库的开挖设计和稳定性评价提供科学的指导,实测资料填补了该区域地应力数据的空白,为我国西部地区地应力场分布规律研究提供重要参考资料。

In order to know the geostress characteristics of a candidate repository, in-situ stress measurement of hydraulic fracturing using a single loop system was carried out in four boreholes in granite rock. The data of geostress and the orientation of the maximum horizontal principal stress at depths ranging from 0 to 700 m below the ground surface were obtained successfully based on the information of borehole log. The geostress state and the fault activity in the candidate repository were analyzed according to the measured data, Byerlee law and Coulomb criterion for fault friction. Three principal stresses have the good linear relationships with depth. Within the range of tested depth, the horizontal stresses are generally higher than vertical stresses and the regional stress field is dominated by the tectonic horizontal stresses, which attenuate gradually with depths. The horizontal force in rock mass in the north is greater than that in the middle and south and it is the lowest in the south. The orientations of the maximum horizontal stress are dominantly in the NEE direction, which is in accordance with the direction of regional tectonic stress field. From the interior and the edge of the Tibetan plateau to the eastern Tianshan mountain, the maximum horizontal stress orientations show the variation of the NE to NEE. The geostress values do not reach the limit state of fault friction sliding and the fault activity is weak.