浅基坑开挖对既有车站的安全影响分析

Analysis of Safety Influence of Shallow Foundation Pit Excavation on Existing Station

针对基坑开挖引起土体自重应力卸载,进而导致周边土体应力结构发生变化,使既有车站结构受力发生变化,从而改变既有车站安全性问题,采用midas GTS数值模拟和现场监测的研究方法,建立浅基坑和既有车站二维有限元计算模型,并结合现场对边坡竖向位移、水平位移、地表沉降、既有地铁结构水平位移、竖向位移的监测数据,分析现场安全控制情况。结果表明:在浅基坑分三层开挖,并及时控制边坡稳定的前提下,既有车站竖向位移为4.01 mm,水平位移为0.335 mm,均小于地铁安全控制标准20 mm,确认既有地铁结构安全可控。

In view of the excavation of foundation pit causes the soil self-weight stress unloading,which change the stress structure of surrounding soil and the stress structure of the existing station,which will cause the safety problems of the existing station,the two-dimensional finite element calculation model of shallow foundation pit and the existing station is established by using the research method of midas GTS numerical simulation and field monitoring.Combined with the monitoring data of slope vertical displacement,horizontal displacement,surface settlement,horizontal displacement and vertical displacement of existing subway structure,the safety situation of site control is analyzed.The results show that the shallow foundation excavation is divided into three layers,and the vertical displacement of the existing station is 4.01 mm and the horizontal displacement is 0.335 mm under the timely control of the slope stability,both of which are less than 20 mm below the safety control standard of the subway,indicating that the existing subway structure is safe and controllable.