Analysis Of Deformation Mechanism Of Deep Foundation Pit Excavation Based On Space-time Effect

Nowadays,the rapid development of urbanization has resulted in a shortage of urban space and a series of traffic congestion problems.However,it is obviously not a long-term plan to continue to build more roads on saturated ground.Therefore,an environmentally friendly and fast underground mode of transportation,the subway,is in full swing.This paper takes the deep foundation pit engineering of a station on Changchun Metro Line 2 as the research object,combines the methods of theoretical analysis,field monitoring and FLAC3 D numerical simulation,and discusses the deformation characteristics of four parts of the surrounding ground settlement,internal support axial force,deep wall lateral displacement and pit bottom soil uplift under the space-time effect.The following are the contents and conclusions of the research and analysis:(1)The deformation mechanism of foundation pit and the characteristics of soil change under space-time effect are systematically analyzed.The main factors affecting the deformation of foundation pit are summarized.The deformation control measures of foundation pit are given,which lay a solid theoretical foundation for the follow-up simulation research.(2)The monitoring instrument and working principle of foundation pit are introduced comprehensively.According to the monitoring data analysis,the deformation characteristics under four working conditions of foundation pit excavation are analyzed.It is found that the deformation of different parts of foundation pit has certain correlation and is formed by interaction.(3)The model of deep foundation pit of railway station is established by FLAC3 D numerical simulation software,and the deformation characteristics of ground settlement,internal support axial force,lateral displacement of deep wall and soil uplift at the bottom of the pit are analyzed.The similarities and differences between the simulated and monitored values are discussed.(4)On the basis of this model,the deformation law caused by space-time effect in the excavation process of foundation pit is further discussed.The influenceof different construction schemes,such as the time of bracing erection,the sequence of excavation and bracing,the vertical position of bracing and the transverse spacing of bracing,on the deformation of foundation pit is simulated and analyzed successively.It is confirmed that there is space-time effect in the excavation process of foundation pit and the simulation results are given.More scientific and reasonable construction scheme.