Analysis Of Soil Deformation And Deformation Mechanism Of Adjacent Foundation Pit Excavation

The construction and excavation of adjacent foundation pit projects not only need to consider the disturbance and deformation effects of their own foundation pit excavation,but also need to pay attention to a series of mutual effects caused by adjacent foundation pit excavation.Compared to single foundation pit excavation,the excavation situation of adjacent foundation pit projects is more complex,with stricter control over the surrounding environment,construction impact,and deformation,and more sensitive to the stress and deformation of its soil.Therefore,conducting an analysis of the influence of stress and deformation on the soil and structure during the excavation process of adjacent foundation pits is currently one of the research focuses in the field of foundation pit engineering.Taking the adjacent foundation pit project of Hainan Twin Towers as the background,the finite element numerical analysis method was used to study the influence of soil deformation under adjacent foundation pit excavation.The deformation laws of adjacent foundation pits under different influencing factors were analyzed,in order to provide reference and reference for the design and construction of subsequent related foundation pit projects.The main work content and achievements are as follows:(1)Based on the actual situation of adjacent foundation pit projects and combined with on-site monitoring data,the surface settlement outside the pit,horizontal deformation,vertical deformation at the top of the underground continuous wall,and axial force of the anchor rod during the excavation process of the foundation pit were analyzed,and compared with the simulation results.The analysis results showed that the simulation results can well reflect the actual excavation situation.(2)Using finite element analysis method to study the characteristics of soil stress and deformation in adjacent foundation pits under synchronous and sequential excavation processes,simulating and analyzing the influence laws of soil stress,surface settlement,structural stress and deformation,and pit bottom uplift under different processes of adjacent foundation pits;The research results indicate that during the excavation process,due to the influence of adjacent foundation pit construction and support,there are significant differences in the stress and deformation characteristics of the soil and structure between the pits compared to the far end of the foundation pit.(3)Based on the deformation results of adjacent foundation pits under synchronous excavation and sequential excavation processes,a comparative analysis was conducted with the deformation of individual foundation pits.Due to the mutual influence between adjacent foundation pits,the deformation of individual excavation pits was greater than that of adjacent foundation pit processes,while the deformation of adjacent foundation pit synchronous excavation processes was smaller than that of sequential excavation processes.Based on the comprehensive analysis,it is concluded that: considering deformation control,The deformation control effect of adjacent foundation pits in synchronous excavation process is good.(4)Based on the synchronous excavation process of adjacent foundation pits,a study was conducted on the deformation characteristics of foundation pits.The study showed that the spacing between foundation pits,the depth ratio of foundation pits,the depth of underground continuous walls,and the inclination angle of anchor rods have a significant impact on the deformation of foundation pits.As the spacing between foundation pits increases,the deformation of the foundation pit gradually increases,and the coupling influence area of adjacent foundation pits gradually decreases,gradually developing towards the deformation law of a single foundation pit.An increase in the depth ratio of the foundation pit is beneficial for reducing the deformation of the foundation pit.When there is a difference in the depth of adjacent foundation pits,it can cause shallow pits to tilt towards deep pits.The change in depth of the underground continuous wall only within a certain limit value has a significant positive effect on the deformation control of the foundation pit,while an increase in depth beyond the limit value has a relatively small impact on the deformation of the foundation pit.The change in the inclination angle of the anchor rod has a strong impact on the position where the maximum deformation occurs,and there is a reasonable range of values.When the inclination angle of the anchor rod is less than this range,the deformation of the foundation pit decreases with the increase of the inclination angle of the anchor rod.