Research On The Mechanical Properties Of Asphalt-stabilized Elastic Ballast Bed

Under the cyclic external load and vibration,the traditional ballasted track bed will suffer from breakage,abrasion and other forms of deterioration,which leads to the non-uniform cumulative deformation of the track bed and affects the long-term stability of the track structure.Polyurethanestabilized ballast track bed,as a kind of elastic stabilized track bed structure that combines the advantages of ballasted track and ballastless track,can effectively delay the breakage and abrasion of ballast particles,thereby reducing the cumulative deformation of track bed.However,due to the high cost of polyurethane-stabilized ballast track bed and the strict curing conditions and process requirements,the further promotion and application of polyurethane-stabilized ballast track bed are restricted.Therefore,based on economic and technical feasibility considerations,asphalt materials are used to stabilize the traditional ballasted track bed structure,thereby forming the asphaltstabilized elastic ballast bed structure.Asphalt-stabilized elastic ballast bed structure is considered as the main research object in this thesis.Its kinematic response under the effect of train load is analyzed,and its long-term creep behavior is estimated,which provides a reference for the design and engineering application of the asphalt-stabilized elastic ballast bed structure.Firstly the viscoelastic constitutive model of asphalt-stabilized elastic ballast bed structure is determined.The generalized Maxwell model is selected and dynamic modulus tests are carried out to determine viscoelastic parameters.Based on the structure form of double prefabricated block under rail,the finite element analysis model of the asphalt-stabilized elastic ballast bed structure is established.According to the actual dynamic response data,the reliability and effectiveness of the model are verified.It is found that compared with the traditional ballasted track bed structure,the asphaltstabilized elastic ballast bed structure can effectively reduce the dynamic vertical deformation of the subgrade bed and reduce the cumulative deformation of the track bed.In addition,the influence of different influencing factors such as the thickness and width of the asphalt-stabilized module,train speed,temperature environment and asphalt materials on the kinematic response of the structure is analyzed,and a reasonable dimension of the asphalt-stabilized module is determined.The short-term creep behavior simulation analysis at different temperatures is peformed for two different load modes.The static and dynamic creep compliance master curve results are obtained through nonlinear fitting based on the time-temperature equivalent principle.Combined with the annual temperature change data of the asphalt concrete upper roadbed,the cumulative deformation under the long-term action of the superstructure weight and the train dynamic load during the 60-year design service life is calculated,thereby estimating the long-term creep behavior of the asphalt-stabilized elastic ballast bed structure.