拉西瓦水电站坝址区高地应力场三维数值反演分析

3D Numerical Inversion Analysis of High Terrestrial Stress Field in the Damsite Area of Laxiwa Hydropower Station

拉西瓦水电工程坝址区为高山峡谷地貌,受地质构造应力、自重、地表剥蚀和河流侵蚀卸荷等多因素影响而赋存有高地应力,河谷区钻孔岩芯饼化与探洞片状剥落现象明显。该区地应力场及其空间分布特征与多期地质构造运动及河谷演化历史等因素有关,要合理确定其三维地应力分布状况与大小难度较大。为此,采用多元回归与逐步回归相结合的方法对工程区域初始地应力场进行了详细反演。在此基础上,深入研究了河谷区地应力场的空间分布特征与规律,并就其形成机理开展了多因素影响效应分析,可供我国高地应力区水电工程建设参考。

With the topographic feature of high mountain and deep valley and influenced by various factors such as geological tectonic stress, dead load, surface abrasion, river erosion and unloading, etc., the dam site area of Laxiwa Hydropower Station has the occurrence of high terrestrial stress and core disking in borehole at fiver valley area and sheet scaling in exploration adits are significant. Since the terrestrial stress field and the space distribution characteristics of the area are closely related to the geological tectonic movements of several stages and the evolution history of river valley, it is difficult and complicated to rationally define the distribution and size of the three-dimensional terrestrial stress of this area. In this paper, a detailed inversion analysis was carried out for the initial terrestrial stress filed of the project area by use of combined method of multiple regression and stepwise regression. On this basis, the space distribution characteristics and rules of the terrestrial stress field at river valley were deeply researched and the formation mechanics of it was analyzed from the multi-factor influence effect, which provides a meaningful experience for the construction of hydro-electric project in high terrestrial stress region.