Research On Influence Characteristics Of Pits In Deep Soft Soil Area

With the introduction of the construction planning plan for the Dawan District of Guangdong,Hong Kong and Macao,the construction scale of the Dawan District urban agglomeration has to enter a new stage,especially the development of economic free trade zones such as Guangzhou Nansha,Shenzhen Qianhai and Zhuhai Hengqin.Promote regional infrastructure construction.In the actual project construction,due to the characteristics of the building and structure and the requirements of the use function,it is necessary to carry out secondary excavation or multiple excavation inside the large excavation of the existing excavation to form a pit in the pit.Due to the rheological and thixotropy of soft soil such as deep silt which is generally developed in the Dawan area,the secondary excavation of the pit in the pit in the deep soft soil site has a great influence on the deformation and internal force of the surrounding large foundation pit,and even threatens The overall stability of the foundation pit is safe and stable.Although the engineering case of the pit in the pit is very common,the theoretical research pays attention to the lack of research.There are few researches on the pit type in the pit,and the literature is insufficient.The principles of pit design and construction in the pit have not been unified,and there is no correlation.There are clear methods for specifications or procedures that can cause significant problems for designers.This paper mainly analyzes and discusses the force mechanism of the pit-type foundation pit in the pit,and uses the finite element software Mdias GTS NX as the analysis tool to select the constitutive model most suitable for soft soil foundation pit excavation through engineering examples,and study the deep soft.The depth and width of the pits in different pits of the soil site,the pit spacing between the large pit and the pit in the pit,the support method,the nature of the soil and the soil reinforcement in the passive zone at the bottom of the pit.The deformation and internal force influence finally took the project of pit pit mode of Huafa Venture Building project in Xihu District,Jinwan,Zhuhai City,Guangdong Province as the research object,and analyzed the large pit and pit pit by the combination of field measurement and numerical simulation.Deformation and interaction of the support structure.The main research contents and results are as follows:(1)Introduce the basic theory related to foundation pit engineering,study the formation process and composition of active earth pressure of pit in pit pit mode,and analyze the force of foundation pit support under pit mode based on elastic method.The calculation formula of the passive soil strength reduction method for the large foundation pit affected by the pit in the pit is derived,which provides a new idea for the support calculation of the pit pattern in the pit.(2)The characteristics of several common geotechnical constitutive models and the contact unit constitutive theory of Midas GTS software are summarized and summarized.The numerical model based on different constitutive models is established by analyzing the actual foundation pit engineering in deep soft soil area.It is concluded that the modified Mohr Coulomb constitutive model is more suitable for the simulation of foundation pit excavation in deep soft soil areas.(3)The main influencing factors of the design parameters of pits in pits(depth,width,pit spacing and supporting methods of pits in pits)are studied.The deformation of large pits in the pits under various influencing factors is analyzed.And the degree of influence of internal forces,and propose corresponding engineering design methods.(4)The main influencing factors of the soil properties of the foundation pit(the soil reinforcement method between the pits and the soil properties of the foundation pit)are studied,and the reasonable optimization suggestions for the soil reinforcement in the passive pit area of the pit in the deep soft soil area are proposed.And analyze the influence range of the pits in the pits on the large external pits under the conditions of different stratum properties,and provide reference suggestions for similar project construction.(5)Based on the finite element analysis of the pit-pit foundation pit project of Huafa Venture Building in Xihu District,Zhuhai City,Guangdong Province,the comparative analysis of monitoring data and simulated numerical results verified the pit support mode of the project.Rationality and the influence of pit excavation on the deformation of the surrounding foundation pit.