Numerical Analysis Of Foundation Pit Precipitation Caused Land Subsidence

With the increasing scale of construction, development and utilization of aerial and underground space resources, more and more large-scale, large pit depth is gradually becoming an inevitable trend. Rainfall during excavation work throughout the entire excavation, but also in basic and upper construction process should maintain a certain level.At present, many engineering construction environment is more complex, the settlement only to meet the requirements of the control of the project, but also be done in compliance with specifications, while effects on neighboring buildings, structures minimized. Therefore,the study of land subsidence caused by excavation precipitation has important theoretical and practical significance.Pit precipitation caused land subsidence are essentially three-dimensional fluid-structure interaction. This paper compares the commonly used numerical analysis methods, the process of establishing a foundation pit dewatering coupling relationship stress field and seepage field. With finite difference software FLAC3 D, FISH using its built-in programming language, build a three-dimensional model of land subsidence,Beijing Datang Telecom Beijing Research Center project as an example of numerical analysis. The main results of this paper have achieved:(1) describes the common pit precipitation way, a comparative analysis of the advantages and disadvantages and conditions, points out well dewatering suitable for large area, drop deep pit.(2) commonly used in geotechnical engineering numerical analysis methods are summarized and made a comparison and analysis of the basic principles and use of different methods. Focuses on the finite difference method, finite difference method widely noted in the Rock and Soil Mechanics calculations for solving nonlinear large deformation,can be used to deal with fluid-structure interaction.(3) made a systematic study of the software FLAC3 D summary, by simulating the preparatory work and the model development process, recognizing the meshing to consider the actual situation and the calculation speed dual factors, in order to converge to obtain more rapid in the case Good simulation results.(4) to excavation Datang Telecom Beijing Research Center project, for example, has been drawdown 6m, 9m, 12 m and assumptions horizontal ground movements(X, Y in both directions) and when the drawdown 15 m settlement cloud. Analysis of the horizontaldisplacement of the displacement and because the overall trend showing asymmetry pit,horizontal displacement situation is similar to the north and south sides of the horizontal displacement of the east and west sides of the clear differences between the features in pit inside.(5) gives the maximum settlement point X, Y to the horizontal and vertical displacement curve gradual settlement with the excavation and pumping, noting that this excavation horizontal displacement occurs mainly in the excavation stage 0-6m subsequent stage floor in the horizontal direction gradually reach a new equilibrium.(6) The maximum subsidence resulting model is 49.816 mm. Compare the difference between 1-1 profile maximum value and monitor analog values Pit largest settlement and the settlement is given absolute error and relative error, and analyzes the causes of errors generated, indicating that the analog value and the value of having a more substantial monitoring goodness of fit, to verify the feasibility of the use of FLAC3 D solve ground subsidence caused by excavation precipitation this class solid coupling problem.