Research And Application Of Deformation Law And Control Of Deep Foundation Pit In Changchun Area

In recent years,the construction of the Changchun area has developed rapidly,but most of the foundation pits in urban construction are located in densely populated areas.There are problems such as building encirclement,dense underground pipe network,narrow construction site,complicated construction environment and tight construction period.It is likely to have an adverse effect on adjacent buildings,underground traffic lines and municipal lines.When an accident occurs,the deformation caused by the excavation of the foundation pit will not only cause damage to facilities such as surrounding buildings,but also seriously endanger personal safety.Therefore,the design of foundation pit engineering under complex conditions should be changed from traditional strength control to deformation control based on strength.It is also important to study the law of deformation caused by foundation pit excavation to ensure surrounding buildings and equipment.Safety and normal use,and reduce the adverse effects during construction.Based on the measured data of several typical foundation pit engineering cases in Changchun area,this paper analyzes the deformation characteristics of foundation pit engineering under different conditions,in order to find common characteristics;reveal the deformation law of foundation pit and retaining structure,and study the relevant Changchun The formula of the foundation pit deformation and the practical law chart,the research results of the deformation characteristics and deformation law are formed;the overall risk classification standard of the foundation pit in Changchun area is formulated,and the foundation pit deformation control index is proposed;the foundation pit deformation control index is applied to the actual foundation pit engineering.The deformation control design was carried out,and the deep foundation pit model was established by GTS NX for numerical simulation to verify the deformation control design.The specific research contents and conclusions are as follows:Firstly,the stratigraphic conditions,geotechnical parameters,supporting forms and design and deformation measured data of typical foundation pits in Changchun area are statistically analyzed.The stratum-weighted active earth pressure coefficient,foundation pit insertion ratio and foundation pit in Changchun area are obtained.The displacement and settlement range and average value are compared with the statistical data of foundation pits in other parts of the country to locate the design and practice level of the deep foundation pit deformation control in Changchun.Secondly,based on the practice of foundation pit in Changchun area,the analysis samples of foundation pit examples are established,and a large number of measured data of foundation pit deformation are statistically analyzed,and the deformation characteristics of foundation pit surface deformation and foundation pit retaining structure deformation characteristics are systematically revealed.The formulas and practical rules for the deformation of deep foundation pits in Changchun area are obtained to guide the design and construction of foundation pit engineering in Changchun.Thirdly,according to the research results of deformation characteristics and deformation laws,the classification criteria of the overall risk level of foundation pits in Changchun area are studied and formulated,and the scientific and reasonable foundation pit deformation control index suitable for Changchun area is proposed.Finally,using the deformation control index of foundation pit,the deformation control design of the complex foundation pit adjacent to the surrounding structure(structure)is carried out,and the deep foundation pit model is established by GTS NX to simulate the deformation.Feasibility and correctness in pit engineering design.The research results of the thesis can be used to guide the design and construction of foundation pit engineering in Changchun,and provide an important reference for the design and construction of deep foundation pit deformation control.