斜坡地基PHC管桩加固参数研究的数值模拟结果分析

Improved Numerical Simulation and Parameter Analysis in Slope Foundation Reinforced by PHC Pile Under the Loading of High Fill Embankment

高填路堤荷载作用下斜坡地基PHC管桩在不同设计参数下的工作性状及其处理效果是工程实践关注的重要问题。结合工程实际特点,本文应用有限差分数值模拟方法,通过在垫层中设置过渡网格,提出了路堤填土和垫层之间传力分析方法;结合FLAC3D建模分析,采用先地应力平衡再建立接触面的方法,解决了山区陡坡路段采用管桩加固路基时接触面影响初始地应力场的求解和平衡问题。以此为基础,重点研究了路基变形分布、PHC管桩受力和桩土荷载分担特性等随格栅模量、桩长、桩间距和桩帽尺寸等设计参数的变化关系。计算结果表明:PHC管桩加固高填路堤斜坡地基,可以有效地减小路基沉降以及路基深层水平位移;桩长对斜坡高填路堤PHC管桩复合地基的变形、管桩受力和桩土荷载特征的影响显著。在一定桩间距范围内,桩间距对于工程的总沉降和路堤边坡的稳定影响不大,但对于路堤不均匀沉降和桩土荷载分担特性影响较大。

The working characteristics and reinforcement effects of PHC pile under different design parameters is the most important for the reinforcement of soft soil foundation under the loading of high fill embankment.Taking a case study,a finite difference method was utilized to analyze the disadvantage in calculation of interface loading if meshes cannot be continuous and consistent.Thus,a new idea was proposed to rationally analyze the loading transfer from embankment fill to cushion in piles,in which transition meshes was set up to keep grids as continuous.As for a steep slope reinforced by piles,a proposed method was also presented in the solution to geo-stress field and balance,in which the stress was firstly balanced,and then the interface was set up in the Three Dimensional Fast Lagrangian Analysis of Continua.The factors were selected to analyze the deformation distribution of the subgrade,the pile stress and load sharing characteristics of piles after a series of numerical simulations,including the design parameters of geogrid modulus,pile spacing,pile length and pile cap size,etc.The impact of geogrids on deformation of subgrade can be neglected when the height of embankment soil is much larger than that of soil arch.From the simulations,it was shown that pile lengths have obvious effect on the settlement and horizontal displacement of reinforced slope,PHC axial force and bending moment,and loading sharing ration of pile-soil.Effective pile spacing influence the difference settlement ol high embankment and loading sharing ration ol pile and soil,but the change ol pile spacing have no influence to the total settlement and stability ol high embankment.