基于结构扰动下模袋桩柱孔扩张模型研究  

Research on cylindrical cavity expansion model of bag pile based on structural disturbance

作　　者：杜永龙 张崇厚[2] 胡雨村[1] Du Yonglong;Zhang Chonghou;Hu Yucun(Department of Civil Engineering,School of Soil and Water Conservation,Beijing Forestry University,100083,Beijing,China;Department of Civil Engineering,Tsinghua University,100084,Beijing,China)

机构地区：[1]北京林业大学水土保持学院土木工程系,北京100083 [2]清华大学土木工程系,北京100084

出　　处：《应用力学学报》2021年第3期1185-1195,共11页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(31700637)。

摘　　要：基于考虑土体结构扰动及初始应力影响的柱孔扩张理论分析模袋桩的挤土效应,将桩体扩张时周围土体分为弹性区和塑性区,考虑到施工扰动导致原位土强度降低的特征,提出对数式的原位强度扰动函数,引入土体灵敏度参数描述扰动影响。基于摩尔库伦强度准则、非关联流动准则,推导出柱形孔扩张时不排水条件下土体应力场、应变场及位移场的解析解,通过Henkel水压力公式推导出超孔隙水压力表达式。通过与实测值及传统理论解的比较,验证了本文理论模型在模袋桩挤土力学分析上的适用性。参数分析结果显示:考虑扰动下的径向应力及超孔隙水压力均低于不考虑扰动情况,扰动下的环向应力会与不考虑扰动情况出现一个与土体内摩擦角有关的交叉点;扰动在r/Rp≤0.25范围内影响效果明显;柱孔扩张对低初始应力水平下的土体影响更大。Based on the cylindrical cavity expansion theory considering the structural disturbance of soil and initial stress,the squeezing effect of bag pile is analyzed.The surrounding soil mass is divided into the elastic region and plastic region during the pile expanding.Considering the reduction of the in-situ soil strength caused by construction disturbance,a logarithmic in-situ strength disturbance function was proposed,and the soil sensitivity is introduced to describe the disturbance.Based on the Mohr-Coulomb criterion and the nonassociated flow criterion,the analytical solutions of the stress field,strain field and displacement field under the undrained condition are derived,and the excess pore water pressure is derived by Henkel water pressure formula.Compared with the measured values and traditional solutions,the applicability of the theoretical model in this paper is verified.The parameter analysis shows that the radial stress and excess pore water pressure under disturbance are lower than those without disturbance,and the tangential stress under disturbance will have a cross point related to the internal friction angle of soil with that without disturbance;the effect of disturbance is obvious in the range of R/Rp≤0.25;the effect of cylindrical cavity expansion on soil under low initial stress is greater.

关 键 词：结构扰动 柱孔扩张 模袋桩 灵敏度 初始应力 

分 类 号：TU43[建筑科学—岩土工程]