为了对尼泊尔东北部某水电站大埋深引水隧洞初始地应力场分布特征进行研究与评价,以现场水压致裂法地应力实测资料为基础,通过构建回归方程并拟合实测数据,采用三维有限元回归分析方法获得了工程区初始地应力场分布规律。应力场反演结果表明,测点位置处的应力回归计算值与现场实测值拟合程度较高,充分体现了回归结果的合理性。隧洞轴线所处区域水平构造应力场占主导地位,地应力水平总体为中-低地应力,但是在局部埋深较大的位置存在高-极高应力,发生岩爆的可能性较大。最大水平主应力与隧洞轴线的交角在隧洞出口附近较大,不利于围岩的稳定性。研究结果可为工程建设提供有效的数据支撑。

The aim of this study is to investigate and evaluate the distribution of initial in-situ stress field of the deep buried diversion tunnel of a hydropower station in northeastern Nepal. By constructing a regression equation and fitting the initial in-situ stress data measured by hydraulic fracturing technique, we obtained the distribution law of initial in-situ stress field of the project area via 3D finite element regression analysis. The inversion results of stress field suggest that the regression calculation results highly fit the measured values, verifying the rationality of regression results. The area where the axis of the tunnel located is dominated by horizontal tectonic stress field, and the in-situ stress level is generally medium and low; but at the location where buried depth is large, the in-situ stress is high and extremely high, and rock burst is highly possible. The intersection angle between maximum horizontal principal stress and tunnel axis is large near the tunnel exit, which is unfavorable to the stability of surrounding rocks. The research findings offer effective data support for engineering construction.