The Displacement Analysis Of Soil Outside The Foundation Pit Based On The Reduction Method

With the rapid development of city modernization and town construction, the constructionland is shrinking in urban area, the development and utilization of underground space hasbeen more and more widely and the excavation of large-scale and deep foundation pit in thedowntown area has become an inevitable trend of the new era. The excavation of foundationpit in the downtown area not only involves the stability problem, but also involves the impacton the surrounding environment. Based on the above, it’s significant to study thedisplacement of soil outside the foundation pit.Firstly, this article introduces the development and the present situation of foundation pitengineering, the research of soil displacement outside the foundation pit, advantage anddisadvantage and suitable area of bottom-up foundation pit excavation method.Secondly, this article elaborates on the shear strength reduction method and it’s lack ofdevelopment, then introduces the reduction method of deformation parameters to completereduction method’s theory, base on the constitutive relationship of soil.Thirdly, taking Futian Station of Guangzhou-Shenzhen-Hongkong passenger dedicatedline as project background, this paper gives a brief introduction of the project overview,including the following: the basic situation of the station, engineering geology, hydrogeology,segmentation and enclosing structure scheme, dewatering and excavaton, etc.Fourthly, focusing on the soil displacement outside the foundation pit, this article uses thefinite element software ABAQUS to build two-dimensional models of the segmentation usingthe bottom-up excavation method, and studies the vertical and horizontal displacement of soil,and safety factor base on the reduction method. Besides, in order to optimize the enclosingstructure design, this article analysis a few factors to study it’s influence of soil displacementoutside the foundation pit, such as the elastic modulus and Poisson ratio of soil, the internalfriction angle and cohesive strength, the thickness and embedded depth of undergroundcontinuous wall, the soil scope of consolidation and the brace stiffness.Finally, the third party has conducted a comprehensive and systematic monitoring, andestablished a five levels pre-warning system during the construction process. An analysis andcomparison is made between the finite element numerical simulation results and monitoringdata to find their difference and the causes for it. The research in this article has somepractical value, which can provide a reference for similar projects and research work in thefuture.