倾斜基底软土桩网复合地基工作机理分析

Analysis of Working Mechanism of Pile-geogrid Composite Foundation for Reinforcing Inclined Soft Soil Base

以杭深高速铁路一典型工点为例,采用FLAC 3D建立有限元模型对路堤荷载作用下倾斜基底软土桩网复合地基的受力变形特性进行分析。结果表明:路堤顶部发生明显的沉降和横向位移,在路堤同一高度处,路堤中部沉降最大,路堤右侧沉降次之,路堤左侧沉降最小;桩顶沉降和地基土表面沉降、土工格栅的沉降和拉力均关于路堤中心不对称,表现为右侧大于左侧,最大值出现在路堤中心偏向右侧约2倍桩间距处;斜坡桩和悬浮桩的桩间土发生明显的绕桩流动而平台桩的桩间土并未发生绕桩流动现象;桩身弯矩分布与桩的位置和桩端嵌固条件密切相关。

In this paper,an engineering project in Hangzou-Shenzhen High Speed Railway is case-studied.A finite element model is built using FLAC 3D.The behavior of the pile-geogrid composite foundation with an inclined base due to the embankment load is studied.The numerical analysis shows significant settlement and a lateral movement at the embankment top.At the same level inside the embankment,the settlement at the inner part is the largest,and the settlement at the right side is larger than that at the left side.Also,the behavior is not symmetric to the embankment,such as the settlements of the pile head and the ground surface,and the settlement and the tension of the geogrid.The settlement or the tension at the right side is greater than that at the left side,and the maximum is located at the spot where is double pile spacing away from the embankment center.As for the slope piles and the floating piles,significant soil flow around the pile occurs.However,this is not detected for the platform piles.The moment distribution along the pile is dependent of the pile location and the embedding condition at the pile tip.