嵌岩桩破坏模式有限元极限分析

以某嵌岩桩现场静荷载试验为背景,基于有限元分析软件ANSYS这一平台,利用有限元极限分析法中的荷载增量法,探讨了不同情况下的嵌岩桩破坏模式。由数值模拟的分析结果可看出,当桩身承载力比基岩承载力低时,破坏一般发生在桩体;当桩身承载力比基岩承载力高时,破坏多发生在桩底基岩及桩与周围岩土界面上;当基岩中存在结构面时,尤其是软弱结构面,破坏多发生在桩周基岩与软弱结构面上。基岩中倾斜的软弱结构面对嵌岩桩的极限承载力影响较大,建立无结构面情况下嵌岩桩桩基模型进行对比,可以看出无结构面情况下的嵌岩桩桩基承载力是有结构面的嵌岩桩桩基承载力的4倍,当软弱结构面与嵌岩桩的距离较近时,嵌岩桩的承载力会急剧降低。

FEM Limit Analysis for Failure Mode of Rock-socketed Pile

Through the experiment of static load in a rock-socketed pile field as the background and taking the FEM program ANSYS as basis, this paper discusses the failure modes of rock-socketed piles under different conditions by the method of load increment of FEM limit analysis. Analysis on the numerical simulation results shows, when the pile bearing capacity is lower than the carrying capacity of the bedrock, the damage occurs in the pile; when the pile bearing capacity is higher than the carrying capacity of the bedrock, the damage occurs on the bottom of the pile and at the interface between the pile and surrounding soil bedrock; when there was structural surface in bedrock, especially weak structural plane, the destruction occurred at the pile surface bedrock or weak structural plane. The weak structural face in the sloping bedrock has greater impact on the ultimate bearing capacity of rock-socketed piles. Contrast with the case of rock-socketed pile without structural surfaces. The bearing capacity of rock-socketed pile without structural surfaces is four times higher than the bearing capacity of rock-socketed pile with structural surfaces, when the weak structural plane is in close proximity to rock-socketed piles, the bearing capacity of rock-socketed piles drastically reduced.