初始地应力是地下工程围岩稳定分析与支护结构设计的重要计算参数。文中根据双江口水电站地下厂房区实测地应力资料，考虑自重与地质构造运动对初始地应力场形成的影响，采用多元回归法对厂区三维初始地应力进行多元回归反演。在回归反演的基础上，考虑埋深和山体地形对初始地应力场分布的影响，建立初始地应力拟合方法，得到厂区初始地应力函数与应力分布变化规律。回归拟合计算应力与实测应力在量值大小和分布方向上吻合，表明反演获得的地下厂区初始地应力场是合理可靠的，这为地下厂房洞室群施工开挖及长期稳定性分析提供重要计算依据。%Initial geostress field is an important factor for the stability analysis and support design of surrounding rocks in the underground constructions. Based on the measured geostress data of underground powerhouse of Shuangjiangkou Hydropower station, considering the influence of gravity and tectonic movement on the formation of initial geostress field, three dimensional initial geostress of the underground powerhouse are back analyzed using the multiple regression method. An initial geostress fitting method is proposed in this paper based on the regressed stress field by taking into account the influence of the depth and terrain on the initial stress field distribution. The geostress functions and geostress variation patterns of powerhouse zone have been obtained. The back analyzed regressed geostresses are coincident with the measured stresses both on the magnitude and the distribution direction. This indicates that the back-analyzed geostress field is reliable, which provides an important basis for the constructional excavation and long-term stability analysis of underground powerhouses.
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