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运用三维非线性有限差分数值分析方法,研究小湾拱坝在多种工况下的应力场和位移场以及蚀变带、卸荷松弛岩体对拱坝安全度的影响。坝体建基面的抗剪验算表明小湾拱坝建基面的面安全度偏低,其主要原因除了小湾拱坝所受水推力超大外,建基面上由于开挖引起的岩体松弛效应也是重要原因。分析表明坝踵部位的受拉屈服范围已经接近于帷幕位置,必须引起重视并采区必要的防范措施。坝体分别按线弹性和非线性弹塑性进行超载分析,上游水压力超载引起小湾拱坝丧失承载力的安全度,前者约为6.5,后者约为3.5,因此小湾拱坝的整体安全度为3.5,应受坝体强度控制,右岸坝基安全度小于左岸。根据屈服破坏区的分布指出在右岸高程1 160～1 190 m之间由于坝肩下游深沟和蚀变带的存在,在超载系数大于5.0时,该将出现贯通性屈服。
The influence of stress field and displacement field of Xiaowan arch dam under various working conditions, as well as the influence of alteration zone and unloading and relaxation rock mass on the safety of arch dams were studied by using three-dimensional nonlinear finite difference numerical analysis method. The shear checking of the dam foundation surface shows that the surface safety of the Xiaowan arch dam is low due to the large water thrust caused by the Xiaowan arch dam and the rock mass due to excavation on the foundation surface Relaxation effect is also an important reason. Analysis shows that the tensile yield area of the dam heel is close to the curtain position, and the necessary precautionary measures must be taken seriously. The dam body is analyzed according to linear elasticity and nonlinear elasto-plasticity respectively. The upstream water pressure overload causes the safety of Xiaowan arch dam loss of bearing capacity, the former is about 6.5 and the latter is about 3.5, so the overall safety of Xiaowan arch dam The degree is 3.5, which should be controlled by the dam strength. The safety of dam foundation on the right bank is less than that of the left bank. According to the distribution of yield failure zone, it is pointed out that through the existence of deep ditch and alteration zone downstream of dam abutment in the range of 1 160-1 190 m on the right bank, the yield yield will occur when the overload coefficient is greater than 5.0.