Study On Calculation Methods And Durability Of Under-track Understructure Of Asphalt Concrete Reinforced Subgrade Bed In Seasonal Frozen Area

With the implementation of the national "The Belt and Road" strategy,China and other countries cooperate in infrastructure construction.The China Railway Eryuan Engineering and Russian companies won the bid for the Moscow-Kazan high-speed rail project,most of the road sections are seasonal frozen areas.At present,the concretewaterproof layer used in high-speed railways in China has problems such as cracking and other problems,which can cause frostbite,freeze-thaw and other hazards on the bed,affecting ride comfort and safety.Asphalt concrete has the characteristics of high strength,good flexibility,vibration reduction,waterproof,low temperature crack resistance,etc.Very early used abroad for railway bed structure but less applied in our country.In this regard,by consulting literature,laboratory tests,and numerical simulations,Analysis of Dynamic Response and Durability of Asphalt Concrete Used to Strengthen Surface Structure of Subgrade Bed.The paper firstly combines domestic and international road and railway basic design methods and related literatures to study the calculation method of the service life of the surface layer of the reinforced concrete bed of asphalt concrete,and uses this method to design the reasonable thickness of the surface structure of the reinforced bed in the Moka high-speed rail project.Secondly,using ABAQUS finite element software as a calculation tool,the dynamic response problems of the reinforced subgrade surface structure under moving loads are studied.Finally,the asphalt concrete damage theory was applied to study the damage process and mechanical properties of the asphalt layer under cyclic loading.The results of the thesis indicate that the surface structure of the reinforced concrete bed of asphalt reinforced concrete with 7cm and 12 cm thickness meets the requirements of the Moka High-speed Rail for heavy cargo and high-speed passenger car loads;the surface layer of the asphalt concrete reinforced bed can effectively improve the stress of the bed,and the thickness 7cm is an ideal thickness;the asphalt layer structure with a thickness of 7-12 cm has not been damaged after 1 million cyclic loads.When the asphalt layer thickness is thick,the initial damage at the bottom of the asphalt layer is larger,but the damage is slower.Finally,it is in a stable stage after 400,000 loads,and the thicker the asphalt layer,the better the asphalt layer’s mechanical properties such as stress and strain,and better durability.The research results of the thesis have guiding significance for the design of the surface structure of the reinforced asphalt concrete bed in the future,and provide a valuable reference for the future design of the railway bed.