Research And Engineering Application Of The Constitutive Model Of Qianhai Soft Soil In Shenzhen

Due to the capital investment and lack of land resources,there will be large numbers of tall buildings appear along the subway and so as the deep foundation pit.Shenzhen city is widely distributed with deep and soft soil,More and more engineering problems will arise due to excavation foundation pit in the soft soil.The mainly problems encountered are easy occur collapse,overturning accidents,etc at the foundation pit,and have a significant impact on the social economy.The another serious problem is the subway tunnel deformation is too large due to the movement of the surrounding soil,Which poses a threat to the safe operation and structural safety of the subway tunnel.So if we can predict the foundation pit and subway tunnel deformation before construction and there will be have an important significance.The finite element numerical simulation is a common and effective ways to analysis the influence of foundation pit excavation on neighboring subway tunnel.But one of problem facing the designer is how to choose a right one constitutive model of soil and reasonable parameters of constitutive model in the process of using the method.Based on the actual needs,this dissertation are mainly focuses on the following works:(1)Taking the soft soil of Shenzhen city as the test object and carry out a large numbers of indoor tests to research the mechanical properties of soft soil and reasonable parameters of constitutive model of Hardening Soil.Further more,establish mathematical relationships between different parameters so as to easily to get the parameters based on simple test or geotechnical investigation report.(2)Using the finite element numerical simulation to analysis the influence of foundation pit excavation on neighboring subway tunnel based on the constitutive model of Hardening Soil and reasonable parameters.And emphasizing the deformation law on the enclosure,ground outside the pit and subway tunnel.(3)In order to study the influence of different influencing factors on tunnel def ormation by changing the parameters of support structure's stiffness,thickness and dept h of underground continuous wall,the spacing between the tunnel and the foundation pit,depth of burial of subway tunnel.(4)To make design and construction more reasonable by proposing measures to control the influence of foundation pit excavation on tunnels from three aspects of control the deformation of the foundation pit,block the way of deformation transfer,subway tunnel protection...