土拱效应及土工格栅拉膜效应数值分析

为了更为清楚的认识桩网结构支承路堤土拱效应,建立了单桩简化模型。从沉降、竖向应力、主应力变化等方面研究了土拱效应产生的机理及变化特征,同时对土工格栅拉膜效应进行了研究。研究结果表明:路堤等沉面高度约为1.7倍桩净间距;路堤可分为土拱影响区和土拱未影响区,土拱影响区桩间土中心位置路堤竖向应力呈"S"形变化,土拱未影响区呈直线变化;桩顶应力分布不均匀,桩净间距小于1 m时,桩中心所受应力最小,桩边缘所受应力最大,桩净间距大于等于1 m时,桩边缘所受应力最小,靠近桩边缘处应力最大;路堤大、小主应力方向发生旋转,大主应力流线近似椭圆弧;土工格栅应力近似"M"形分布,靠近桩边缘的桩间土位置应力最大,桩间土中心和桩中心位置应力最小。

Numerical Analysis of Soil Arching Effect and Tensioned Membrane Effect of Geogrid

In order to have a better understanding of the soil arching effect in those pile-net supports embankments,a simplified model for single pile is established.From the angle of settlement,vertical stress and principal stress,the mechanism and the changing characteristics of soil arching effect are studied;and the tensioned membrane effect of geogrid is also studied at the same time.The research results indicate that the height of equal settlement section is about 1.7 times length of pile net spacing;the embankment can be divided into soil arch affected zone and non-affected zone.In soil arch affected zone,the vertical stress of the embankment in the center of the soil among piles changes with "S" shape.In soil arch non-affected zone,the stress varies linearly.The stress on the top of pile distributes unevenly.When pile net spacing is less than one metre,the stress in the center of pile is the minimum and the stress on the edge of pile is the maximum.When pile net spacing is more than or equal to 1 metre,stress on the edge of pile is minimum and the stress near the edge of pile is maximum.The direction of major and minor principal stress is rotated and the flow lines of the major principal stress are approximate to elliptical arc.The distribution of geogrid stress is approximate to "M" shape,the stress close to the edge of pile is maximum and the stress in the center of the pile and soil among piles is minimum.