| In recent years,with the rapid growth of national economy,the process of urbanization is gradually accelerating,the supply of urban land is tight,and the use of underground space is getting more and more attention.At present,the theoretical research and engineering practice of foundation pit support in pure soil layer have become more and more mature,but the research on deformation characteristics of super-deep foundation pit in soil-rock composite stratum is not perfect.Based on the super-deep foundation pit project of Science Museum Station of Shenzhen Metro Line 6,this paper analyzes the deformation characteristics of the diaphragm wall in the process of excavation of the super-deep foundation pit supported by the diaphragm wall of the subway station in the soil-rock composite stratum,such as the settlement of the top of the diaphragm wall,the deformation of the wall body and the settlement of the surface outside the pit.The main research contents and results of this paper are as follows:(1)By arranging monitoring elements in the background project,this article has carried out detailed monitoring of the excavation deformation characteristics of the foundation pit in the soil-rock composite stratum,focusing on the settlement of the top wall of the underground diaphragm wall,wall deformation and the surface outside the pit.The change law and deformation characteristics of main deformation indexes such as settlement are described in detail,and the typical deformation characteristics of foundation pits in soil-rock composite stratum are summarized in combination with engineering geological conditions.(2)Based on the actual engineering geological conditions and the excavation scheme,this article uses the finite element numerical calculation software ABAQUS to establish a model of an super-deep foundation pit supported by an underground diaphragm wall of a subway station in the soil-rock composite stratum.The calculated results are compared with the actual monitoring data,and the reliability of the constitutive model and various contact models of rock and soil in the finite element numerical model is verified.(3)Using the numerical model of background engineering,this paper studies the shear strength of the rock layer,the stiffness of the underground diaphragm wall,and the support stiffhess on the soil-rock composite stratum.The impact will provide a reference for the optimization of the design scheme and construction scheme of the super-deep foundation pit for a subway station supported by underground diaphragm wall under similar soil-rock composite stratum. |
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