Optimize Design Of The Pile Type Of Collapible Loess Foundation Treament And Numerical Analysis

In this paper, taking Henan area of Sanmenxia Zhongyuan Gold Smelter relocation upgrading project in collapsible loess foundation for engineering background, through the analysis of the collapse load of lime soil pile composite foundation test, exploratory sampling indoor soil test and conventional three axis test, the settlement mechanism of loess, the reinforcement mechanism of lime soil compaction pile, the influence radius of compaction, the value and deformation analysis of the bearing capacity of composite foundation, the stress ration of pile and soil, and the optimization design of collapsible loess foundation are systematically analyzed. The main work was as follows:(1) The theoretical research and engineering application of single pile of lime soil compaction pile in collapsible loess foundation treatment are made.According to the mechanism of loess collapsibility, this paper makes theoretical analysis of the reinforcement mechanism of lime soil compacted pile. By area ratio formula and the stress ratio formula, the calculation formula of bearing capacity of lime soil pile composite foundation is obtained. Based on the unified strength theory, the influence of soil compaction pile radius is studied, and the calculating formula of soil compaction pile radius can also obtain by theoretical analysis and formula derivation. With the load test of lime soil compaction pile composite foundation in raw material area, the characteristic value of bearing capacity of lime soil pile composite foundation is made an analysis, and the compaction radius of lime soil compaction pile is calculated. At the last, we make a comparative analysis of the physical and mechanical properties of the soil around the pile before and after the reinforcement.(2) The optimization design and engineering application of composite pile in collapsible loess foundation treatment was studied.The foundation reinforcement of multi type pile consists of tamping soil cement pile and soil compaction pile. This paper makes a study of the reinforcement mechanism of the optimization of multi type in collapsible loess foundation treatment from eliminating foundation collapsibility by soil discharging hole Sutu compaction pile and improving the bearing capacity of composite foundation. The calculating formula of the bearing capacity and deformation of combined pile composite foundation can also obtain by theoretical analysis and formula derivation. With the load test of combined pile composite foundation in the comprehensive area, the characteristic value of bearing capacity and deformation of combined pile composite foundation is made an analysis, and we make a comparative analysis of the physical and mechanical properties of the soil around the pile before and after the reinforcement.(3) The numerical analysis of the collapsible loess composite foundation is made.The Kulun Moore model in FLAC3 D is an ideal elastoplastic constitutive model, this model proposed the friction angle and cohesion in soil damage to reflect soil shear strength. The Kulun Moore model is difficult to fully reflect the complex stress-strain constitutive relation of collapsible loess, while the Duncan Chang model can be a very good reaction of nonlinear stress-strain relationship of loess. This paper introduces the Duncan Chang model into FLAC3 D to make the analysis results more in line with the actual situation of the project.The contents of numerical analysis conclude the solution of the Duncan Chang model parameters, the static loading numerical test of the bearing capacity of single pile, the numerical analysis of single pile axial force and lateral friction force, the optimization design of lime soil pile, the analysis of composite foundation settlement, the analysis of the effect of spacing of composite foundation on the pile axial force, and the comparative analysis between single pile and combined pile composite foundation.