大岗山水电站坝区初始地应力场反演分析

Regression analysis of initial geostress field in dam zone of Dagangshan hydropower station

针对大岗山水电站坝区V型河谷地形地貌特征,根据地应力实测资料及地质构造条件,考虑边坡浅表全风化、强风化地层以及断层破碎带对坝区初始地应力场的影响,建立了坝区初始地应力场三维回归计算分析模型。通过多元回归三维数值计算,求得地应力最优回归系数,较为准确地反演了大岗山坝区的初始地应力场。计算结果表明,大岗山坝区初始地应力场是一个在浅部以构造应力为主、在深部以自重应力为主、由构造应力和自重应力联合组成的中等偏高的地应力场,研究结果为坝区边坡开挖及长期稳定性分析提供了重要依据。

In view of the influence of completely and intensively weathered stratum in the shallow surface of slope and fault fracture belt on the initial geostress field in dam zone of Dagangshan hydropower station, the 3D initial geostress regression analysis model is established based on the measured geostress data and geologic structure as well as topography features of V-shaped river valley. The optimal geostress regression coefficients have been achieved through 3D multivariate regression numerical analysis and the initial geostress field in dam zone of Dagangshan hydropower station is exactly simulated. The calculation results show that the initial geostress field in dam zone is a medium to high stress field composed of tectonic stress and dead-weight stress. The tectonic stress is prominent at shallow level and the dead-weight stress is prominent at deep level, which provides important reference basis for excavating simulation and long-term stability analysis of slope.