某工程对撑道数对支护桩变形影响的研究

Research on the Influence of the Number of Support Channels on the Deformation of Supporting Piles in a Certain Project

基坑开挖卸荷将导致基坑侧壁出现水平位移与沉降现象,进而诱发基坑垮塌、周围管道破裂及局部渗漏等灾害。本文以某一内支撑深基坑工程为例,通过构建三维有限元模型,使用Midas GTS NX数值模拟软件进行建模,对比分析对撑数量不同的内支撑系统工程中应力响应及围护结构的变形状况,探究运用对撑数量不同的内支撑系统进行深基坑开挖对基坑周围支护结构变形的影响。结果表明:相较于单对撑的内支撑系统,使用双对撑的内支撑系统受力更加合理,不仅减少了围护桩的变形,而且降低了内支撑梁构件上的最大轴力,从而使得内支撑杆件更加安全。同时也可以满足控制基坑变形的要求。其中,内支撑系统中最大的轴力出现在对撑梁上,而围护桩背后的主动土压力则由基坑周边的桁架梁进行传递。监测结果表明基坑开挖对周围围护结构的影响主要表现为水平位移和沉降,最大变形均满足现行隧道结构保护规范控制值要求。

Unloading during excavation of foundation pit will cause horizontal displacement and settlement of the side wall of the pit,leading to disasters such as pit,collapse,the surrounding pipeline rupture,and local leakage.This article takes a deep foundation pit project with internal support as an example,by constructing a three-dimensional finite element model was constructed and Midas GTS NX numerical simulation software was used for modeling.The stress response and deformation of the retaining structure in the engineering of internal support systems with different numbers of supports are compared and analyzed.The influence of using internal support systems with different numbers of supports on the deformation of the surrounding support structure during the excavation of the deep foundation pit excavation is explored.The results indicate that compared to the internal support system using a single pair of braces,the internal support system using a double pair of braces has a more reasonable stress distribution.It not only reduces the deformation of the retaining pile,but also lowers the maximum axial force on the internal support beam components,making the internal support members safer.At the same time,it can also meet the requirements of controlling the deformation of the foundation pit.Among them,the maximum axial force in the internal support system occurs on the supporting beams,while the active soil pressure behind the retaining piles is transmitted by the truss beams around the foundation pit.The monitoring results indicate that the impact of foundation pit excavation on the surrounding retaining structure is mainly manifested as horizontal displacement and settlement,and the maximum deformation meets the control value requirements of the current tunnel structure protection specification.