基于软土加固区跟随下卧层变形的高速铁路刚性桩复合地基计算方法

Calculation Method of Rigid Pile Composite Foundation for High-speed Railway Based on Soft Soil Reinforcement Zone Following Deformation of Underlying Layer

根据刚性桩复合地基主要受力区与潜在工后变形土体在深度上的相对位置关系,提出刚性桩跨越中浅部潜在工后变形土体,使加固区跟随深部土体变形,是刚性桩复合地基控制工后变形的两个关键。刚性桩跨越中浅部潜在变形土体后,工后沉降变形将主要来源于下卧层。此时,加固区跟随下卧层变形成为深部变形向上传递的主要特征。建立桩间土单元模型,分析桩顶结构及桩间距、桩径等参数对刚性桩跨越中浅部工后变形土体的调节机制,指出桩底选择良好的承载地层,并且穿过潜在工后变形土体足够的长度是跨越中浅部潜在变形土体的重要保证;建立深部变形向上传递时,加固区桩、土相互作用及其变形效应的简化分析模型,阐述加固区跟随下卧层变形的力学机制与计算方法。

According to the relative position relationship between the potential post construction deformed soil mass and the main bearing area of the rigid pile composite foundation in depth,two key steps were proposed to control the post-construction deformation of the rigid pile composite foundation,including the use of rigid piles to cross the potential post construction deformed soil mass in the middle and shallow depth,and causing the reinforcement area to follow the deformation of the deep deformed soil mass.After the rigid piles crossing the potential deformed soil mass in the middle and shallow depth,the underlying layer will become the source of the post construction settlement deformation,and the reinforcement area will deform with the underlying layer when the deep deformation of the rigid pile composite foundation is transmitted from bottom to top.The element model of soil between piles was established to analyze the effect of pile top structure,pile spacing,pile diameter and other parameters of rigid pile composite foundation on the adjustment mechanism of pile top and pile bottom crossing the middle and shallow depth of the deformation soil.A good bearing stratum should be selected for pile bottom and sufficient length of rigid piles should be ensured to pass through potential post-construction deformed soil.A simplified analytical model was established to calculate the pile-soil interaction and deformation effects when the deep deformation was transmitted upward through the reinforcement area of rigid pile composite foundation.The mechanical mechanism and calculation method of the reinforcement area following the deformation of the underlying layer were described.