Analysis Of Pile-anchor Support Structure With Fulcrum Method And Parameter Backcalculation Based On Monitoring Data

Pile-anchor support structure is widely used for the construction larger space of the internal place in foundation pit and gains more attention. Deformation as a control condition for supporting structure design in foundation pit is a very complex engineering problem, but fulcrum method is accepted by lots of engineers for its clear computing model and simple procedure. However, the choice of the resistance factor of soils is a problem in engineering, the approximate range of m-value is given in general specifications. For the large different geological conditions, the m-value has great arbitrary. In fulcrum method calculation, the accuracy of the m-value effects the displacement and internal force results of supporting structure directly, so, inversion analysis of the m-value is necessary depending on project site measured deformation. The m-value can supply reference and basis for engineering design in foundation pit in similar stratum or near the region, forecasting the deformation of supporting structure.Firstly this paper gives brief overview of pile-anchor support structure about its features and the range of application, working mechanism and failure modes, analyzing the main factors of design, etc; introduces the inversion analysis theory of foundation pit engineering, shows the necessity of soil parameter obtained from dynamic inversion, comparing with kinds of inversion analysis method. Secondly, it sets up finite element analysis model for pile-anchor support system, handling the monitoring data from foundation pit excavation process. In the analysis process, supporting piles are dispersed by beam element and in excavation process consides supporting deformation nonlinear. It develops FORTRAN program executing inversion calculating for supporting structure. Finally, put the fulcrum method modeling inversion analysis used in actual project, getting m-value through inversion analysis and forecasting the deformation of supporting structure, realizing dynamic design and information construction, examining practical application.The results show that deformation inversion analysis obtains good results during parameter inversion and displacement prediction of deep foundation pit engineering, proving that the method is reasonable on inversion analysis and prediction during deep foundation pit excavation.