Study On Reinforcement Mechanism Of Geogrid Under Static And Dynamic Loads

With the rapid development of traffic engineering,reinforced soil structure is widely used in roadbed,retaining wall,slope and other structures because of its performance and cost advantages.The study of geogrid reinforcement mechanism can provide an important basis for the safety design of reinforced soil structure.In this paper,HDPE unidirectional geogrid and coarse sand were selected as test materials.The pull-out test under static and dynamic loads was carried out,and the discrete element model of the pull-out test was established.The geogrid reinforcement mechanism was analyzed from the perspective of macroscopic mechanical properties and mesoscopic parameters.The main work and achievements of this paper are as follows :(1)The pull-out test under static and dynamic load conditions was carried out.The development process of the pull-out force of the grid in the test was studied.The effects of transverse rib spacing,normal stress and load frequency on the pull-out characteristics were quantitatively analyzed.Based on Mohr-Coulomb theory,the evaluation method of shear performance of reinforced soil was established.The changes of interface strength parameters were analyzed,and the effects of different factors on the macroscopic mechanical properties of reinforced soil interface were explored.(2)Through direct shear test and tensile test,the physical and mechanical properties such as friction angle of sand and tensile strength of geogrid were obtained.Based on this,the two-dimensional porosity of sand was deter mined by iterative method,and the discrete element model of direct shear test was established.The discrete element model of tensile test was established by piecewise linear model,and then the discrete element model of drawing test was established and its model parameters were calibrated.(3)The discrete element simulation of the pull-out test under static and dynamic load conditions was carried out.The changes of sand porosity and particle coordination number,the evolution process of displacement field,contact force chain and fabric anisotropy during the pull-out process were analyzed.The effects of transverse rib spacing,normal stress,load frequency and other factors on the microscopic parameters were revealed.Combined with the changes of macroscopic mechanical properties,the response of microscopic parameters to macroscopic mechanical properties was revealed.The formation and change process of shear bands during the pull-out process was explored,and the reinforcement mechanism of geogrid was studied in depth.