杨家湾水电站地下厂房区初始地应力反演分析

岩体初始地应力是影响地下厂房洞室群变形与稳定的主要荷载。结合杨家湾水电站地下厂房区地质条件和实测地应力资料，考虑自重和构造作用两个主控因素，运用三维有限元法，对区域初始地应力场进行回归反演，并与实测值对比分析。分析结果表明：地下厂房区存在较大水平地质构造作用，地应力以NNW水平地应力为主，且与河流大角度相交；经方案比选得出近厂房区三点实测地应力反演方案最优，其实测点回归主应力大小和方向均与实测值接近；通过反演方案获取的区域地应力场准确性较高，可作为地下厂房布置及稳定性分析的基础。

Inversion Analysis of Initial Geostress in Underground Powerhouse Zone of Yangjiawan Hydropower Station

Initial geostress is the main source of force which influences the deformation and stability of underground powerhouse. Based on the geological conditions and measured geostress data of Yangjiawan underground powerhouse , considering the controlling factors of gravity and tectonic, 3-dimensional finite element method is used to inverse the initial geostress of this area ,which makes comparative analysis with measured data. The analysis result indicates that the action of the horizontal tectonic plays a dominant role in the underground powerhouse, and the geostress gives priority to NNW horizontal geostress which intersects river with large angle; Through comparison between geostress inversion schemes, it is found that the three-situ stress measurement inversion scheme which is close to underground powerhouse is better than other schemes because its calculated result is similar in values and directions with the measured result; The regional stress field obtained by inversion scheme is highly accurate which lays the foundation for layout and stability analysis of underground powerhouse.