杭州某软土基坑工程开挖对地铁的影响研究

Research on the influence of excavation of a soft soil foundation pit in Hangzhou on subway

随着我国的城市化建设进程不断加快,对于城市地下空间的开发规模也逐步增加,涉及到的基坑工程也逐步向着更深更大的方向发展,针对基坑支护设计的要求也越来越高。为了研究软土地区深基坑开挖施工对邻近或上盖地铁隧道的影响,本文以杭州市滨江区某地铁上盖项目为例,详细介绍了其基坑特点及基坑支护设计方案,并采用了Plaxis有限元软件建立三维模型,模拟基坑施工全过程,最后结合基坑开挖引起的既有隧道的水平位移、竖向位移和水平径向收敛现场监测数据,分析了基坑开挖过程中对邻近地铁隧道的影响,并总结归纳了施工过程中造成地铁隧道变形报警的原因。研究分析表明,本项目保护区范围地铁设施变形与模型计算结果相比存在差异,基坑开挖应分层分段分块对称开挖,附属设施两侧土方需平衡开挖。

With urbanization construction process is accelerating unceasingly,the development scale of urban underground space has gradually increased,and the foundation pit engineering involved has gradually developed in a deeper and larger direction,and the requirements for foundation pit support design are getting higher and higher.In order to study the influence of deep foundation pit excavation construction on adjacent or overlying subway tunnels in soft soil areas,this paper takes an overlying subway project in Binjiang District of Hangzhou City as an example,introduces its characteristics of foundation pit and its support design scheme in detail,and uses Plaxis finite element numerical software to establish a three-dimensional model to simulate the whole construction process of foundation pit.Finally,combined with the monitoring data of horizontal displacement,vertical displacement and horizontal radial convergence of existing tunnels caused by foundation pit excavation,this paper analyzes the influence of foundation pit excavation on adjacent subway tunnels,and summarizes the causes of subway tunnel deformation alarm during construction.The research and analysis show that the deformation of subway facilities in the protected area of this project is different from the model calculation results.The excavation of foundation pit should be stratified,segmented and symmetrical,and the soil excavation on both sides of the ancillary facilities should be balanced.