深基坑开挖对坑内基桩受力特性的影响分析

基坑开挖对基桩产生一定的侧摩阻力，如果处理不当，将危及地下结构与基桩的安全使用，同时也给基桩承载力与刚度的确定带来困难。根据应力路径与应力水平对土体刚度的影响，建立了受深基坑开挖影响的桩土界面荷载传递模型，通过应力路径试验确定了界面摩擦特性参数。对不同开挖深度的影响分析，得出了基坑开挖对桩周侧摩阻力的分布、基桩刚度与承载力的影响。分析结果表明，采用覆土条件下的基桩承载力与刚度值是偏于不安全的。

Study of loading characters of pile foundation due to unloading of deep foundation pit excavation

Due to unloading of deep foundation pit excavation, piles of underground structure will be applied skin friction in advance. This friction will endanger the underground structure and pile foundation if not be managed properly, and it will be more difficult to calculate the capacity and rigidity of pile due to this friction. According to the effect of stress path and stress level to the rigidity of soil, a new interface model considering the influence of deep foundation pit excavation is established. The friction parameters of interface model is confirmed by stress path test. Compared the results of different excavation depths, the influence of excavation on the skin friction, capacity and rigidity of pile is gained. The results show that it is unsafe to use the capacity and rigidity of pile under the conditions of earth covering.