基坑开挖与邻近桩基相互作用的弹塑性解

基于弹性理论法和p–y曲线法,通过桩土间设置的界面滑块和土体统一极限抗力来考虑土体塑性屈服,提出了基坑开挖对邻近桩基影响的弹塑性解。其基本思想是将桩基视为一维杆系结构,其和周围土体的相互作用通过设置的由弹簧和滑块构成的界面单元实现。当土体处于弹性状态时,桩土变形协调,滑块不发生作用;当土体应力达到极限抗力时,土体发生塑性变形,滑块承受极限抗力并发生塑性滑动。计算中,土体弹性模量随土体位移变化,即桩土之间非线性关系,其值可通过各土层处p–y曲线确定。实例分析表明,该方法计算结果合理可行,能够较为有效的分析基坑开挖对邻近桩基的影响。

Elastoplastic solution for excavation-pile interaction

Based on the elastic theory method and p-y curve method,the elastoplastic solutions for the problem of excavation adjacent to the existing pile foundations were given.The solution utilized the sliding interface element between soil and piles and the uniform limiting soil-pile interaction force to consider plastic yield of soil.In the solution,the pile foundation was regarded as one-dimensional bar structure and its interaction with the soil was realized through spring and sliding interface element.When the soil was in elastic state,the deformations of pile and soil were coordinated and the sliding element didn’t work.When the soil stress reached the limiting value,the plastic deformation appeared in the soil and the sliding element was acted under the limiting force and plastic sliding occurred at the same time.In the calculation,Young’s modulus of p-y curves of soil layers varied with the soil displacement,so the interaction between the piles and soil was nonlinear.It was indicated by analysis of example that the calculated results of the elastoplastic solution were reasonable and could be used to analyze the problem of excavation adjacent to pile foundations.