尼泊尔那苏瓦卡里水电站地应力测量及围岩破坏机理分析

In-situ Stress Measurement and Analysis of Failure Mechanism of Surrounding Rocks at the Rasuwagadhi Hydropower Station in Nepal

尼泊尔那苏瓦卡里水电站隧洞工程大部分埋深较大,在高地应力状态下很可能会面临软岩变形和硬岩岩爆等复杂地质灾害。文章采用水压致裂法对尼泊尔那苏瓦卡里水电站进行了三维地应力测量,测点处的最大主应力为10.47 MPa,方位角为18°和15°,近水平;中间主应力为9.01 MPa,方位角和倾角分别为158°和71°,倾角较大;最小主应力为6.34 MPa,方位角和倾角分别为285°和12°。工程区现今地壳应力场表现为构造应力起主导作用的基本特征,工程区地应力状态为中等应力水平。根据测量结果对隧洞围岩破坏机理进行了研究,结果表明,隧洞围岩破坏形式为劈裂剥落,隧洞轴线与主应力方向大角度相交以及中等偏高的应力水平是导致围岩发生破坏的主要原因。

A three-dimensional in-situ stress measurement by hydraulic fracturing was conducted at the Rasuwagadhi hydropower station in Nepal.The results show that the major principal stress at the field is 10.47 MPa with the azimuth of 18°and dip angle of 15°which are almost horizontal;the intermediate principal stress and the minor principle stress are 9.01 MPa and 6.34 MPa respectively,with the azimuths and dip angles of 158°and 71°and 285°and 12°respectively.The crustal stress field of the construction area is characterized by dominant tectonic stress with medium stress level.Based on the measured data,it studied the failure mechanism of surrounding rocks,with the results showing that the failure is of splitting pattern and the main reasons for this are a large angle between tunnel axis and principal stress,and medium and higher stress levels.