黄河黑山峡大柳树坝址区地应力模拟计算及破裂危险性评价

Ground Stress Simulation near Daliushu Dam-site in Heishan Gorge of Yellow River and Estimation of Ground Rupture Risk

在区域构造应力场模拟的基础上,采用子模型方式提取出黑山峡大柳树坝址区应力边界条件,对大柳树坝址区应力场进行了模拟计算及破裂危险性评价。计算结果显示,大柳树坝址区浅层应力场以水平应力为主,断裂对应力场有明显的控制作用。破裂危险性分析表明,对坝址构造稳定性起决定作用的主要是坝址北侧F 201地震断层的活动,以震源的垂直投影位置看,如果F 201发生强震,其南盘岩体至少5 km范围内将受到严重影响而产生地表破裂,危及坝体安全。

In this paper the ground ＇stresses are calculated near Daliushu dam-site in Heishan gorge of Yellow River by extracting the boundary condition using sub-model of the region tectonic stress simulation and the rupture risk is estimated in the area. The results show that the major principal ground stress is mainly horizontal and controlled by the faults. In the plane model, the faults and the soft rock can cushion and digest the stress and in the cross sectional model, and the stresses are always concentrated in the joint and inflection point of faults. The color contour map of rock rupture risk coefficient KR shows that the risky rock rupture area is mainly around the faults and especially around the fault F201 in deeper crust. The color contour map of fault gliding risk coefficient KF shows that in plane model fault F201 and parts of other faults are in critical status of gliding and in profile model the critical area is mainly in fault F201 within depth of 12-17 km, which indicates that earthquake may occur along the fault F201 followed by ruptures of other faults near the joint. Therefore, the activity of fault F201 is the key to the tectonic stability of dam-site and if earthquake occurred along fault F201 the ground surface will rupture for at least 5 km in the south plate in view of the epicenter which would damage the dam.