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嵌岩桩因单桩承载力高、沉降量小等优点而在工程中,尤其是高层建筑及大型构筑物中得到了广泛的应用。岩溶区嵌岩桩桩端岩层极易发生冲切破坏。引入用小而非零拉伸截断改进的M-C强度准则描述岩体的破坏特性,确定破坏面上单位面积的能量耗损率;从极限分析上限定理出发,构建了岩楔体平移破坏机构;根据桩端荷载和冲切圆台自重所做的外功率与冲切圆台破坏锥面的能量耗损率相等的条件,建立了虚功率方程,并由此得到了岩溶区桩端极限承载力的上限解及其下伏溶洞顶板安全厚度的计算公式。工程实例分析表明,该方法具有一定的可靠性,可为岩溶区类似建筑桩基的设计和施工提供参考。
Rock-socketed piles are widely used in engineering, especially in high-rise buildings and large structures because of their high bearing capacity and small settlement. Karst rockfill pile end rock prone to punching failure. The improved MC strength criterion is introduced to describe the failure characteristics of rock mass with small but not zero stretch truncation to determine the energy loss rate per unit area on the failure surface. Based on the upper bound limit analysis, a rock wedge translational failure mechanism is constructed. End load and punching round table self-respect of the outer power and punching frustum conical frustration energy loss rate equal to the conditions, the virtual power equation was established, and the upper limit solution of the ultimate bearing capacity of pile tip in karst area and its The formula for calculating the safe thickness of the underlying cave roof. The analysis of engineering examples shows that this method has certain reliability and can provide references for the design and construction of similar building pile foundation in karst area.