Dynamic Response And Fatigue Life Analysis Of Heavy-haul Railway Tunnel Structure

With the development of science and technology economy,the development of heavy haul railway has become a major direction of railway development in China.The axle of heavy haul railway is heavy.Under the action of train load,the vibration of the foundation under rail is large,and the requirement of the foundation under rail is higher for heavy haul railway.For Heavy-haul Railway tunnels,the greater the axle load of the train,the stronger the vibration of the tunnel bottom structure will be.In order to ensure the safety of Heavy-haul Railway transportation,the structure of Heavy-haul Railway Tunnel should meet the design service life.With the increase of axle load of heavy haul railway,under the excitation of train load,the bottom structure of tunnel is more likely to suffer from diseases.The damage of bottom structure of heavy haul railway tunnel directly affects the safety of heavy haul transportation.In this paper,the dynamic response and fatigue life of Heavy-haul Railway tunnel structure are analyzed by numerical simulation.The main contents and analysis results are as follows:(1)The model of heavy-duty C80 truck with axle load of 25 t is established by using multi-body dynamics software UM,and the vehicle-track coupling dynamic model is established in UM software.At the same time,the tunnel model established in ABAQUS software is imported into UM software,and the tunnel model and the Track-Vehicle model are connected by force element to establish the tunnel-track-vehicle coupling model.The time-history curve of vertical wheel-rail force of heavy haul truck is simulated and calculated by UM software.(2)The structural model of CRTS III slab ballastless track is established by finite element software ABAQUS,and the coupling dynamic model of surrounding rock-tunnel-track is established.(3)Vertical wheel-rail force is applied to the coupled dynamic model of surrounding rock-tunnel-track to analyze the dynamic characteristics of the bottom structure of single-track Heavy-haul Railway Tunnel under the condition of grade III surrounding rock.(4)Based on the dynamic analysis results of Heavy-haul Railway Tunnel structure,the fatigue life of the bottom structure of Heavy-haul Railway Tunnel is calculated by combining the cumulative fatigue damage theory and the calculation method of fatigue life.Combined with the annual traffic volume of heavy haul railway,the service life of the bottom structure of heavy haul railway tunnel is calculated.Taking the design and service life of heavy haul railway as the evaluation index,the paper judges whether the tunnel structure meets the service life requirement.(5)The dynamic characteristics of the bottom structure of Heavy-haul Railway tunnels,such as acceleration and principal stress,change roughly the same.When the train passes by,the dynamic characteristics reach the maximum when it reaches the analysis section.(6)By calculating the cumulative fatigue life of the bottom structure of heavy haul railway tunnel,it is concluded that under the condition of grade III surrounding rock,the tunnel is 20 meters deep and the train travels at 80 km/h.The fatigue life of inverted arch center,under rail,inverted arch and side wall joints of tunnel lining structure are 77,84 and 96 years,respectively.The fatigue life of track slab in central position is 106 years,and that of track slab under rail is 103 years.The fatigue life of the compact layer at different analysis positions is 79 years at the center of the compact layer and 74 years at the bottom of the rail.