Study On Spatial Analysis Method Of Retaining Structures Considering Earth Pressure Horizontal Redistribution

Deep foundation pit with complex plane shape and small length depth ratio has obvious spatial effect.The deformation and internal force of the retaining structures are often different along the direction of the foundation pit.At present,the deformation and internal force of the retaining structures are usually simplified as plane strain problems in the design of foundation pit,which can’t reflect the influence of spatial effect and the staged construction process on the overall characteristics of the spatial retaining structures.Conventional analysis methods of the retaining structures based on load-structure method are usually based on the assumption of plane earth pressure and cannot consider the horizontal redistribution effect of earth pressure caused by the different deformation of the retaining structures.Therefore two aspects are involved in this study:(1)the horizontal redistribution law of earth pressure caused by the non-uniform deformation of retaining structures;(2)a spatial analysis method for the retaining structures considering horizontal redistribution of earth pressure.The main work and innovative achievements are as follows:1.The movable plates testing chest device has been independently developed,which can accurately measure the displacement of the movable plates and the earth pressure.The device provides an effective test method for studying the horizontal redistribution of earth pressure.2.With the increase of the displacement and the width of the movable plates,and with the increase of the vertical load,the absolute value of the increment of the resultant force of earth pressure on the movable plates and on the stationary plates both increase.When the displacement of the movable plates reaches 0.005 times the width of the movable plates,it is approximately considered that the soil in the relaxation zone enters a plastic yielding state,and the increase of the displacement of the movable plates no longer causes the horizontal redistribution of the earth pressure.The resultant force of earth pressure on the movable plates and on the stationary plates both remain the same.3.Based on the laboratory test results,the mechanism of the horizontal redistribution of earth pressure has been analyzed.The standard calculation model of the horizontal redistribution of the earth pressure on the stationary plates and the standard calculation model of the earth pressure increment on the movable plates have been put forward.The area which distance to the movable plates is 0～6.0 times the width of the movable plates is the main influence range of horizontal redistribution of earth pressure.4.Based on the proposed standard calculation model of the horizontal redistribution of earth pressure,a spatial analysis method of the retaining structures considering horizontal redistribution of earth pressure was developed.A "spring-beam" boundary model has been established to realize the spatial calculation of the retaining structures considering the influence of horizontal redistribution of earth pressure,which is caused by the non-uniform deformation of the retaining structures.For special engineering problems in which the interaction of the retaining structures need to be considered,this method can obtain more realistic results than the simplified method of plane calculation under the condition that the total earth pressure remains unchanged.5.The 3D finite element software 3D-RSFES with independent intellectual property rights was developed by Visual C++.The software 3D-RSFES takes the retaining structures as the analysis object and takes the earth pressure as the external load.3D-RSFES has realized the 3D finite element analysis of the whole construction process of the foundation pit using the "air element method" and the "total method".3D-RSFES provides a variety of earth pressure calculation modes,in which the "spring-beam" boundary model is adopted to realize the spatial calculation of the retaining structures considering the horizontal redistribution of earth pressure.