Numerical Simulation Of Geogrid Reinforcement Based On Discrete Element Method

With the rapid development of China’s economy,reinforced soil technology has been widely used in civil engineering construction.As an important reinforced material,geogrid is widely used in the engineering practice of reinforced soil because of its excellent engineering characteristics.Now the research on the interface between Geogrid and soil has gradually become a hot topic in the field of geotechnical engineering.Although scholars at home and abroad have done a lot of research on the interaction mechanism of reinforced soil interface,the interface mechanism of reinforced soil is more complex because there are many factors affecting the interface characteristics of reinforced soil,especially the interaction mechanism between coarse-grained soil and geogrid is still lack of research,so it is still necessary to further study the characteristics of reinforced soil interface.This paper mainly uses numerical simulation methods to carry out the following studies on geogrid-reinforced rock and soil:Firstly,based on the triaxial test of coarse-grained soil,the triaxial discrete element numerical model of gravel is established by PFC3D program.The results are compared with the test to calibrate the meso parameters.During the calibration process,it is found that the linear contact model can not simulate the irregular triaxial test of large-grained gravel,and the rolling resistance model is more suitable.Then the influence of meso parameters(friction coefficient,rolling resistance coefficient,loading rate and gradation)on the macro and micro properties of triaxial test is analyzed.Secondly,based on the gravel triaxial test,the reinforced gravel triaxial test numerical simulation is carried out to compare the changes of reinforced soil interface characteristics before and after reinforcement.It is found that the deformation constraint of the reinforced triaxial specimen increases,the rolling resistance between particles increases,and the macro strength increases.The spherical element of rolling resistance model is used to simulate the triaxial test of reinforced macadam,and good simulation results can be obtained.Compared with the non reinforced macadam,the softening phenomenon of stress-strain curve is weakened after adding geogrid,and the addition of geogrid can delay the failure of the test sample.Finally,according to the existing indoor slope model test,the PFC3D particle flow program is used for numerical simulation analysis.The comparison between the numerical simulation results and the test results verifies the rationality and effectiveness of the model.By using the discrete element method,we can calculate the large deformation and force transfer changes of the slope,study the force transfer path changes and the accumulation after instability of the reinforced slope,and then explore themeso mechanism of geogrid reinforcement of rock and soil.By analyzing the average contact force of Geogrid and the average angle between the contact force and the horizontal plane,it is found that the increase of geogrid will change the path of load downward transmission,and the constraint of Geogrid on rock and soil will be enhanced,which will change the path of force transmission.Under the condition of multi-layer grid,the grids work together,and the force transfer path shifts to the slope.Geogrid reinforcement plays a role in enhancing the shear strength of soil.With the increase of geogrid layers,the reinforcement effect on the slope is stronger.