Study On Shear Test And Discrete Element Numerical Simulation Method Of Reinforced Gravel Pile Composite

With the development of China’s economy,the construction of infrastructure has also become very rapid,especially the construction of roads,which has made unprecedented progress.In the coastal areas of China,especially in the large rivers,due to the poor soil quality is mostly muddy soil or silty clay,so the construction of the project will face many challenges.The reinforced gravel pile composite foundation is widely used in soft soil area because it combines the natural properties of gravel with the good strength and tensile properties of geosynthetics.At present,the research on the Composite Foundation of gravel pile is still at the initial stage,and there are few reports on its stability analysis.However,the stability analysis is just an impo rtant part of the design and calculation of composite foundation.Therefore,based on the theory of similitude,this paper studies the horizontal shear performance of the reinforced gravel pile and its shear deformation mechanism and engineering application,the main research contents and results are as follows.First,based on the principle of similarity,based on the large-scale Direct Shear test of "gravel-geosynthetics sleeve pile-circumferential filling" composite,which is formed by three different tensile strength of reinforcement,two kinds of pile-circumferential filling soil considering its relative compactness when it is sand,and the filling soil considering its water content when it is soft soil,in this paper,the shear behavior and shear deformation characteristics of the reinforced gravel pile composite under different normal stresses are studied.The area replacement method is used to calculate the shear strength index of gravel pile,and the method is applied to the composite of reinforced gravel pile.At the same time,the Shear Strength Index of the reinforced gravel pile with different strength bars is fitted,and the fitting formula of the Shear Strength Index with the change of the strength of the bars is obtained.By comparing the results of direct shear test with the results of discrete element method(Dem),the modified Coefficient of Shear Strength Index is obtained.The Shear Strength Index of the pile is modified and the shear strength index of the pile is obtained by back calculation of the formula.On this basis,the rationality of the fitting formula is verified by comparing the back-calculated shear strength index of the pile body with that calculated by the fitting formula.Finally,the application of the project examp le,after the Reinforced gravel pile treatment of highway embankment slope and gravel pile treatment of slope stability analysis.The results show that the embankment in soft soil area has high stability after treated by the technology of reinforcing bar a nd gravel pile composite foundation,at the same time,compared with the gravel pile reinforcement gravel pile after treatment of the project has a better stability.