Research On Ground Settlement Of Cut And Cover Method Appllied In Construction Of Subway Station In Soft Soil Area

In recent years, as the development of our country booming fast, there areplenty of metropolises constructing subways, which are the signs of the moderncivilization. However, deep foundation pit excavation also brings negativeinfluence on the surrounding buildings, especially in the southeast coastal area ofour country, where soft soil is widely distributed. In order to implement excavationof specific projects steadily, diaphragm wall supporting system, which is regardedas an relatively mature method, has been used generally both at home and abroadto assure the safety of the deep foundation pit and adjacent environment. But thephenomena are very common that subside of the soil and apophasis of thefoundation pit are too large, exceeding allowable value.This paper is mainly based on real project to study the influence of theexcavation of the subway station on the ground settlement in the soft soil area.Firstly, apply finite element analysis method and discuss several parameters whichhave significant effects on soft soil, and analyze the diaphragm wall supportingsystem in detail. Secondly, build up2D and3D finite element model of therepresentative deep foundation pit excavation of the Fuming Road subway station inNingbo City, Zhejiang Province, analyze the influence of the excavation on thesubside of soil, deformation of diaphragm wall and the strut axial forces，andcompare results of numerical simulation with observed data to validate the model.Finally, establish3D model of a deep foundation pit of specific project in Hangzhou,analyze the same items against project of Fuming Road, compare them with theresults of Fuming Road to analyze their generalities and specialties, and summarizethe law of ground subsidence between deep foundation pit excavations in soft soilarea.Main ideas of this paper are as follows：(1) Obtain laws of ground settlement, the apophasis, diaphragm wall deformati-on, strut axial forces in the foundation pit excavation.(2) Compare the results of ground settlement, the apophasis, diaphragm wall d-eformation, strut axial forces of2D and3D model.(3) Analyze the mutation of the first layer strut axial forces in the diaphragm w-all corners and put forward suggestions to the construction.(4) Analyze the influence on the deep foundation pit excavation by comparingthe differences of the soft soil parameters in Ningbo and Hangzhou.This paper provide new ideas and methods for the impacts of the main soft soilparameters on the deep foundation pit excavation in this paper, and discuss new ways and references for the design and construction of the diaphragm wallsupporting system.