基坑开挖对地下管线工作性状影响的数值分析

Numerical Analysis on the Influence of Foundation Pit Excavations on the Working Behavior of Underground Pipelines

为研究基坑开挖对于地下管线工作性状的影响,进而为管道安全评估与防护提供参考依据,利用Plaxis 3D Tunnel建立基坑开挖中的土体与地下管线相互作用的有限元模拟模型。对土体采用Hardening-Soil模型,对管线及基坑支护结构与土之间均采用接触面单元,对不同管道数量和位置以及施工步骤、基坑尺寸对地下管线水平位移、竖向位移和内力的影响进行了大量的参数分析。结果表明在基坑支护结构、管线与土体相互作用下,墙背管线位移随基坑尺寸增大而增大,但其分布形态不变;管道距离地下连续墙越近,管道的位移则越大,而地面位移越小;管道数量越多,管道位移与墙背土体位移均越小;管线内力与变形与基坑开挖特性参数之间的关系是非线性的。

To investigate the influence of the excavation of foundation pit on the working behaviour of buried pipelines and to provide general references for safety assessment and protection of pipelines, a 3D finite element model for simulating the interaction of soil-pipeline during foundation pit excavation was set up by using the software Plaxis 3 D Tunnel. A Hardening-Soil model was adopted to simulate the stress-strain behavior of soil, while a contact surface model was used for simulating the interactions between pipelines, retaining structures and soil. The horizontal displacement, vertical displacement and internal forces of the underground pipelines were studied through a large a- mount of parametric analysis of the influential factors such as different number of pipes, pipe location, construction procedures, and foundation pit dimensions. The results of the analyses show that, under the interaction between retai- ning structures, pipelines and soil, the larger are the excavation dimensions, the larger are the displacements of the buried pipelines behind the retaining wall, but the pattern of deformation distribution remain unchanged; the deformation of a pipeline increases, but the deformation at ground surface decreases, with the decrease of the distance between the pipeline and retaining wall; both deformations of pipelines and soil will decrease with the increase in the number of pipes ; the relations between the internal forces and deformation of the pipelines and the factors are generally nonlinear.