锚索应力增量法评价边坡稳定性

预应力锚索加固后，边坡岩体的力学性能得到改善，从而使其受力状态发生变化，此时如仍按一般边坡稳定性评价方法评价并不是很合理。因此，提出采用支护结构的受力特性来表征加固后边坡的稳定性，具体是指用预应力锚索在各工况下产生变形所引起的应力增量与允许应力增量的差值，将该差值与允许应力增量的比值来表示边坡的稳定性。某水电站左岸坝轴线边坡天然岸坡高、自然坡角大、片麻理陡倾岸外，与片麻理垂直的陡倾裂隙和平缓裂隙是控制边坡稳定性的主要因素，结合现场地质资料和监测数据，利用离散化有限元软件FINAL建立左岸边坡开挖变形分析模型。对比研究3种工况下不同预应力锚索加固设计方案的边坡稳定性，得出暴雨工况为最危险工况，然后分析了最危险工况下不同加固方案时的变形、位移及应力，所得结果与边坡稳定系数法得到的边坡稳定性状况一致。研究结果对该电站左岸坝轴线边坡后续加固有一定的参考作用。

Evaluation of stability of toppling slope by increment method of anchoring cable stress

After the pre-stressed anchor cable is reinforced, the mechanical property of slope rock mass is improved so as to lead to change of stress state. It will not be very reasonable if evaluation is made according to the normal stability of slope at this moment. Hence, in this paper, the mechanical properties of supporting structure are proposed and adopted to represent the stability of slope after reinforcement. Specifically, the difference value between the stress increment and the permissible stress increment caused by deformation of pre-stressed anchor cable under various working conditions is used, that is, the stability of slope can be indicated with the specific value of the difference value and permissible stress increment. The slope of axis of dam on the left bank of a certain hydropower station has features of high natural bank, large natural angle of repose and gneissic schistosity steep dip off the shore. Also, the steep dip crack and the flat crack perpendicular to gneissic schistosity are the main factors controlling the stability of slope. In this paper, the deformation analysis model of excavation of slope on the left bank is built through combination of site geological data, monitoring data and investigation conditions and utilization of discretization finite element software FINAL. A comparative study is made on the stability of slope of different design schemes of pre-stressed anchor cable reinforcement under three types of working conditions. The stability coefficient of slope is calculated by using the safety stability coefficient equation proposed in this paper to come to a conclusion that the working conditions of storm rainfall are the most dangerous working conditions. Then the deformation field, displacement field and stress field under the most dangerous working conditions are analyzed. The research findings have some reference value for subsequent reinforcement of the slope of the dam axis of the left bank.