基于滑移线理论的支盘成型过程对桩周土的扰动分析

Impact analysis of the forming process of the squeezed branch pile on the soil around the pile based on the theory of slip line

为研究支盘桩桩型优化设计,就支盘桩单向成型过程对桩周土的扰动进行分析。以滑移线理论为基础,对挤土臂与土体作用进行力学化,建立单向挤压成型过程盘下土体的滑移线场模型,推导不同挤扩角盘下土体的应力场、速度场、土体极限荷载和塑性区分布,探讨成型过程对桩周土体的塑性区影响范围和盘下土体流动规律。结果表明,该模型计算的盘下土体影响深度与周明芳现场试验吻合较好,盘下土体的影响深度为0.47~0.49m;距离挤土臂越远,土体塑性流动速度越小,靠近挤土臂的土体挤密效果更好;土体极限荷载随挤扩过程的进行不断增大。研究结果具有工程应用价值,可为支盘桩桩型优化设计提供参考。

To obtain the optimal design of the squeezed branch pile,the disturbance of the soil around piles in the process of unidirectional extrusion and expansion of the squeezed branch pile is analyzed.Using the slip line field theory,the interaction force between the soil and the extruded arm is analyzed and simplified.To derive soil stress field,velocity field,soil ultimate load and the distribution of plastic zone under different extruding angles,the slip line field model of soil the unidirectional extrusion process of extruding the squeezed branch piles is established.Furthermore,the effects of forming process on the plastic zone of the soil around piles and soil flow under the tray are discussed.The results show that the depth of the affected soil under the tray calculated from the theoretical model matches well with the experimental results and the depth is between 0.47~0.49 m.As the distance from the extruded arm goes larger,the plastic flow velocity of soil becomes smaller and then the compacting effect of soil around the extruded arm is better.Moreover,the ultimate load of soil increases with the extrusion process.This paper has engineering values and can provide reference for the optimization design of branch piles.