粉质黏土开挖引起的单桩沉降及荷载传递机理

Single Pile Settlement and Load Transfer Mechanism Caused by Silty clay Excavation

为进一步研究饱和粉质黏土中相邻开挖条件下单桩的沉降和荷载传递机制,采用三维耦合固结数值分析方法分析开挖土壤附近的桩土相互作用,土的本构模型采用改进的低应变刚度亚塑性模型。由于开挖引起应力释放,桩身沉降呈线性增加,同时开挖引起的地面位移使部分桩处于主影响域边界。按沉降准则计算,桩承载力表观损失为14%。桩中最大弯矩约为350kN·m,最大挠度为28mm。此外,桩-土界面处抗剪强度的调动是控制桩-土-开挖相互作用的关键因素,桩中荷载向下传递的机制可在开挖过程中确定。

In order to further study the settlement and load transfer mechanism of single pile under adjacent excavation in saturated silty clay,the three-dimensional coupled consolidation numerical analysis method was used to analyze the pilesoil interaction near excavation.An improved low strain stiffness sub plastic(clay)constitutive model is adopted.Due to the stress release caused by excavation,the pile settlement increases linearly.This is because some piles are at the boundary of the main influence area and the ground displacement caused by excavation.According to the settlement criterion,the apparent loss of pile bearing capacity is 14%.The maximum bending moment generated in the pile is about 350kN·m and the maximum deflection is 28mm.In addition,the adjustment of shear strength at the pile-soil interface is the key factor to control the pile-soil-excavation interaction.During the excavation process,the mechanism of load transfer downward in the pile can be determined.