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处于复杂地质条件下的拱坝,坝肩岩体稳定性问题是其发生事故的重要原因之一。某水电站拱坝右坝肩发育有靠近坝体的蚀变集中带及沿该集中带的多条断层,左坝肩在坝肩槽不同高程有多条断层出露,地形地质复杂。为了正确合理地研究其坝肩岩体的稳定特性,根据水电站坝址区地形地质条件,充分考虑拱坝左右坝肩的主要断层及蚀变带等不利地质构造,建立3维有限元模型,模拟拱坝及坝区岩体在正常运行及温降工况下的应力场;采用点安全系数法分析坝肩岩体在加固和未加固的情况下的稳定性,并运用综合强度储备法评价坝肩的极限承载能力。结果表明:坝肩岩体点安全系数均处于合理范围内且相对较高,综合安全系数相对较大,说明坝基加固措施合理有效,坝肩具有较强的承载能力。
Under the complex geological conditions, the stability of arch dam and abutment rock mass is one of the important reasons for its occurrence. At the right abutment of a hydropower station, there are alteration concentrating zones near the dam body and multiple faults along the concentrated zone. There are several faults exposed at different elevation of the abutment shoulders of the dam dam. The terrain and geology are complex. In order to study the stability characteristics of the abutment rock mass accurately and reasonably, according to the topographic and geologic conditions of the dam site of the hydropower station, the unfavorable geological structures such as the main faults and alteration belts on the left and right abutments of the arch dam are fully considered. A 3-D finite element model is established to simulate Arch dam and dam rock mass under normal operation and temperature drop conditions; using point safety factor method to analyze the stability of the abutment rock mass with and without reinforcement, and using comprehensive strength reserve method to evaluate the dam Shoulder ultimate carrying capacity. The results show that the safety factor of rock abutment is within a reasonable range and relatively high, and the comprehensive safety factor is relatively large, which shows that the reinforcement measures of the dam foundation are reasonable and effective, and the abutment has strong bearing capacity.