嵌岩桩锚支护基坑变形特性分析

Analysis of deformation characteristics of foundation pit supported by rock-socketed pile and anchor

以南昌某桩锚支护的深基坑工程为例,建立基坑开挖支护的二维有限元模型,分析渗流-应力耦合作用下孔隙水压力分布,并从位移、内力变化等方面进一步分析各工况下坑外地表土体与支护构件的变形趋势。研究结果表明:支护构件在风化岩中变形较小,其侧移主要产生于砂土层中,围护结构变形沿坑底分界面处表现出较大差异;坑外地表土体沿距离坑边1~12 m范围内出现明显沉降槽,土体沉降的主要影响范围约为0.6倍的基坑设计深度;随着锚索侧向变形增大,锚索的侧向拉力、注浆段锚索与临近土体摩阻力也随之增大,导致锚索轴力持续增长。

Taking for example a deep foundation pit project supported by piles and anchors in Nanchang,a two-dimensional finite element model of foundation pit excavation and support is established to analyze the pore water pressure distribution under seepage-stress coupling action,and the deformation trend of ground surface soil and support components outside the pit under various working conditions are also discussed from the aspects of displacement and internal force change.The research conclusions indicate that,the supporting members are less deformed in weathered rocks,and their lateral displacement is mainly generated in sandy soil stratum,the deformation of the surrounding structure is quite different along the interface at the bottom of the pit;the obvious settlement groove appears on the ground surface soil outside the pit within the range of 1~12 m away from the pit edge,and the main influence range of soil settlement is about 0.6 times of the design depth of the foundation pit;with the increase of lateral deformation of anchor cables,the lateral tension of anchor cables,the friction between anchor cables in grouting section and adjacent rock and soil mass increases,which leads to the continuous increase of the axial force of anchor cables.