桩承式路堤土拱效应颗粒流分析

土拱效应是桩承式路堤中荷载传递机制中的关键因素。参照前人室内模型试验,采用颗粒流软件PFC2D建立离散元(DEM)数值模型,对桩承式路堤中的接触力分布、主应力偏转、竖向位移和侧向位移等进行深入分析。模拟中,路堤填料和桩间土采用Disk单元模拟,桩和模型箱采用Wall单元模拟,路堤DEM模型采用分层压实法生成;路堤填料细观参数通过建立数值双轴试验进行标定,桩间土细观参数通过建立数值压缩试验进行标定。模拟结果表明:桩承式路堤中土拱由多个不同圆心的半球形拱共同组成,拱的高度约为5(s-a)/6;在该高度内路堤中的主应力发生明显偏转,竖向位移量和侧向位移量较大。

DEM Analysis of Soil Arching of Pile Supported Embankment

Pile supported embankment has been widely used in road, airport and dam engineering due to effective construction and economic advantages which can effectively control the settlement and differential settlement. The soil aching effect is a key factor in the load transfer mechanism of pile supported embankment. Based on the current laboratory model test, a series of numerical simulations were conducted with the particle flow code PFC2D to study the contact force, principal stress, vertical and lateral displacements in embankment. The embankment fill and subsoil were simulated by the Disk,andthe pile and model box were simulated by the WallThe multi-layer compaction method was used to establish the Discrete Element Method models. The micromechanical properties of the embankment fill and subsoil were obtained from numerical biaxial compression test and simple compression test, respectively. The simulation results indicated that the soil arching in pile supported embankment was composed by multiple hemispherical arches with different centers, and the height of arching was about 5(s-a)/6. Within the soil aching height, the deflection of principal stresswas obvious, and the vertical and lateral displacements were significant.