Numerical Analysis Study On Critical Height Of Soil Nailing In Foundation Pit Engineering

Although soil nailing and composite soil nailing have been widely used in foundation pit engineering for their protruding economy and good working performance during recent years. Scholars from every countries have done a lot of experiments' and theories' studies. However the research on the behavior and the stabilizing mechanism of it also lags behind the engineering application, especially the problem about critical height of soil nailing and composite soil nailing, if the nowaday's theory is applied to the answer of critical height of soil nailing and composite soil nailing, it will lead to a lot of errors. So it has a lot of great meanings to launch the studies about critical height of soil nailing and composite soil nailing structure. In this paper, the critical height of soil nailing and composite soil nailing were systematically analyzed by one FEA(Finite Element Analysis)program named ANSYS and some constructive conclusions were obtained.The following studies are carried out in this paper:First, based on the predecessors' research findings, this paper introduced the theorie's foundation of elastoplastic FEM through step loading analysis about the critical height of soil nailing, also it tested and verified the critical height of unsupported upright slope under the condition of homogeneous soil, and as well analyzed the influence factors of the critical height. The results indicated that: it is feasible to use ANSYS program analyzing the critical heights of soil nailing.Second, through founding a FEM model of soil nailing, this paper geted the critical height of soil nailing by elastoplastic FEM through step loading, and as well analyzed the influence factors of critical height, probed into the laws between the critical height and chief parameters of soil-nailed foundation pit, according to the analyzing results simulated the calculating formula of composite soil nailing criticalheight.Third, through founding a FEM model of composite soil nailing, this paper geted the critical height of composite soil nailing by elastoplastic FEM through step loading, and as well studied the influence factors of critical height, probed into the laws between the critical height and chief parameters of composite soil-nailed foundation pit, at last, on the foundation of analyzing results simulated the calculating formula of composite soil nailing critical height.Fourth, through the case histories this paper verified the simulating formulas of soil nailing and composite soil nailing critical height. The result indicated that: the simulating formulas could be applied to the actual projects.