考虑土体结构扰动的三维柱孔扩张模型研究

Research on three-dimensional cylindrical cavity expansion model considering structural disturbance of soil

基于考虑土体结构扰动的三维柱孔扩张模型分析沉桩挤土效应,提出对数式的土体原位强度扰动函数,引入土体灵敏度参数描述扰动的影响,推导出饱和土不排水条件下柱孔扩张的应力场、应变场及超孔隙水压力的解析解。参数分析结果显示:考虑土体结构扰动下的应力场及超孔隙水压力均高于不考虑扰动情况;应力在径向方向呈非线性变化,在深度方向呈线性变化;极限扩张压力随深度呈非线性变化,且受土体内摩擦角影响较大;一定深度时,扩张产生的相对超孔隙水压力恒定不变。通过案例比较,验证了所提出的三维柱孔扩张模型在挤土效应分析上具有更高的适用性,将传统理论由平面应变问题扩展到三维空间分析上,可以为沉桩施工提供更加科学的理论指导。

Based on the analysis of pile driving by the three-dimensional model of cylindrical expansion considering the structural disturbance of soil,a logarithmic in-situ strength disturbance function is proposed,and the soil sensitivity is introduced to describe the disturbance.The analytical solutions of stress field,strain field and excess pore water pressure of expansion under the undrained condition in saturated soil are derived.Results of parameter analysis show that the stress field and excess pore water pressure under disturbance are higher than those without disturbance.The stress changes nonlinearly with the radial distance and linearly with depth.The ultimate expansion pressure changes nonlinearly with depth and is greatly affected by internal friction angle of soil.The normalized excess pore water pressure is constant at a certain depth.Through the case comparison,it is verified that the three-dimensional expansion model proposed in this paper has a higher applicability in the analysis of soil compaction.The traditional theory is extended from plane strain problem to three-dimensional space analysis,which can provide more scientific theoretical guidance for pile driving design.