基于土压力的桩土相互作用分析方法

Pressure-based Method of Soil-pile Interaction

地面堆载引起地基软土侧移,导致邻近建筑桩基产生变形。采用两阶段分析方法,提出了堆载与邻近桩基相互作用的弹塑性解。首先通过解析方法或实测数据求得堆载引起的作用于桩上的土压力,然后基于地基反力法,通过设置由弹簧和滑块组成的界面单元来模拟被动桩土之间的相互作用。用弹性模量模拟弹簧的作用,其值可根据p-y曲线确定,同时引入统一极限抗力来考虑滑块的作用。当土体处于弹性状态时,桩土变形协调,滑块不发生作用;当土体作用达到极限抗力时,土体发生塑性变形,滑块承受极限抗力并发生塑性滑动。将该计算结果与有限元解答和现场试验的结果进行对比,验证了该方法的合理性和实用性。

Lateral soil movement induced by surcharge might adversely affect any nearby pile foundation systems. Based on a two - stage method, a simple elastoplastic solution was outlined for computing the lateral response of passive pile subjected to surcharge action. First, an analytical solution was adopted to calculate the lateral soil pressure, then, based on elastic subgrade reaction method, the effect of pile - soil interaction was simulated by the inter- face element, composed of spring and sliding block. The elastic modulus determined according to p - y curves was adopted to study the effect of the spring, while the uniform limiting soil - pile interaction force was adopted to consider the role of the sliding block. When the soil was in elastic state, the deformation of pile and soil were coordinated, and the sliding element didn＇t work; when the limiting soil -pile interaction force was reached , the plastic deformation appeared in soil, and the sliding element was acting under the limiting force and plastic sliding occurred then. Comparisons were made among the behaviors obtained from finite element analysis, in - situ observations and those computed by the proposed elastoplastic solution. Generally, the calculated result of the proposed method was reasonable and could be used to analyze the passive pile due to surcharge.