Study On Design For Retaining System In Deep Foundation Pit Of The Subway Station

With the implementation of economic development and the growing urbanization in China, people pay more and more attention to the exploitation of the higher space and underground space. Large-scale foundation pit engineering is the important element of the high-rise buildings and urban underground engineering. In the construction process of the deep foundation pit, the stability is one of the problems which pay most close attention. In the issue of the foundation pit stability, the stability of the retaining system is the chief part. Based on this, the author intensifies research on these aspects:analyzing of the formality of retaining formality and the currently research state of the calculate theory, and integrating them organically, the result indicates that, the deformation of deep excavation consists of pile-wall's deformation, swelling of pit bottom and the subsidence of the earth and buildings around the excavation. The main factors affecting the stability of deep excavation are hydro-geologic condition, the soil press and the scale of the excavation, the design plan and the construction method. The reasonable support style and scheme and the information construction method should be taken to protect the safety of deep foundation pit and adjacent structure; The retaining scheme and the monitoring plan of the foundation pit of DaTun Road station are given in this paper. After distilling and collation the data of the pile-wall's deformation, cable stress and the axis force of the steeled support. The result find out the deformation curve and the variation laws of the steeled support axis force, and the result indicates that the x-displacement of the pile-wall could be the important evaluation index which shows the safety state of the retaining construction; Using the FDM software FLAC 3dto simulate the retaining state of the deep excavation to the foundation pit, gave the rule of the influence laws to the stability of the foundation pit. The influence include excavation space effect, interval of each steeled support in one layer, relation between the x-steeled support and oblique steeled support and the stiffness of the steeled support et cetera. Then in corresponding, bring up the measures for retaining system's optimization design on the basis of deformation control.Through the research, deepened the understanding to the retaining system in deep foundation pit of the subway station, and the research findings provided some theoretical basis for theoretical analysis, optimization design and calculation of the retaining in deep foundation pit.