Research Of The Influence Of Geogrid On Ballast Mechanics

Ballast bed has the advantages of good elasticity,low noise and easy maintenance,and is widely used in our country.The most important part of the ballast track structure is the ballast bed,the ballast bed in the long-term operation of the line will produce a series of diseases such as ballast abrasion,crushing,uneven settlement of the ballast bed,and then affect the smooth and safe operation of the train.The Railway Section for the ballast bed disease maintenance operations cost a lot of manpower and material resources,while the line shutdown seriously affected the regional economy and people travel.Therefore,increase the stability of the ballast bed,slow down the uneven settlement,prolong the maintenance cycle and service life of ballast bed has become the focus of scholars at home and abroad.At present,there are many ways to increase the mechanical properties of ballast bed,improve the stability of ballast bed and extend the maintenance cycle of the line.Geogrid in civil engineering as a reinforcement material,improve the mechanical properties of granular materials obvious effect,at the same time the geogrid cost is low,transportation,storage is easier,so the study of geogrid in the field of ballast bed application has important practical significance.The accuracy of the existing numerical analysis model needs to be improved,the research content of geogrid reinforcement effect is not comprehensive,and the geogrid laying parameters need to be further optimized.In this paper,the coupling algorithm was used to solve the problem that the traditional discrete element model can’t truly reflect the interaction between geogrid and ballast particles,the influence of geogrid on mechanical properties of ballast bed was studied by combining theoretical analysis with simulation test.The main research work of this paper was summarized as follows:1.A refined model of geogrid-ballast bed was constructed.Based on the discrete element method,a fine particle model of ballast particles was established,and a fine geogrid flexible body model was established based on multi-body dynamics;on this basis,a coupling model which can accurately reflect the interaction between geogrid and ballast particles was constructed by combining discrete element and multi-body dynamics.Based on the literature data,the accuracy of geogrid-ballast bed model was verified.2.Study on the influence mechanism of geogrid on mechanical properties of ballast bed.The change of mechanical properties of ballast bed was analyzed from the macro and meso point of view after setting up the geogrid in the ballast bed.The influence rules of geogrid on the settlement of ballast,the change of the voidage of ballast under sleeper,the movement speed of sleeper,the contact force,the angular velocity and the velocity of ballast particles were studied,and the influence mechanism of geogrid on the mechanical properties of ballast bed was revealed.3.Influence of geogrid laying parameters on mechanical properties of ballast bed and optimization of related parameters.Based on the coupling model of geogrid-ballast bed,the effects of geogrid-laying depth,laying aperture and laying width on the mechanical properties of ballast bed were studied.Through the mechanical properties of ballast bed in the macroscopic and mesoscopic two angles of the change,the different laying parameters of geogrid were optimized and selected to determine the optimal laying parameters of geogrid which can be directly applied to the actual line project.4.The influence of operation conditions on the reinforcement effect of geogrid.The variation law of mechanical properties of geogrid ballast bed under different train axle load and train speed was analyzed,and the suitable line operation conditions of geogrid ballast bed were determined.