Mechanics Response Of Heavy-haul Railway Tunnel With Cracks

Because of its large capacity, high efficiency, low cost, etc. heavy-haul railway plays a more and more important role in the development of the national economy. At the same time, the increase of train axle load will inevitably make the impact load increase, affect the bearing capacity of the tunnel structure. In addition, most area of our country located in earthquake-prone areas, the natural disasters such as earthquake will cause huge damage to tunnel structure, seriously affect the driving safety. Lining crack will inevitably produce during the process of the construction and operation of the tunnel. Under the impact of the heavy-haul train axle load and earthquake load, the existence of crack may cause stress concentration and tunnel diseases. So the static and dynamic analysis of tunnel with cracks under heavy-haul trains and seismic loading is very necessary.In this article, research on the heavy-haul railway tunnel with cracks is carried out by the method of FEM numerical simulation. Firstly, adopt a plane strain model to simulate the heavy-haul tunnel, the modal analysis is carried out on the tunnel structure to get the natural frequency and vibration mode. The dynamic response of lining in frequency domain was observed under the load changing with frequency of nodal force and acceleration. The heavy-haul train loading and earthquake acceleration were simulated by means of sine wave superposition and United States EL-Centro data, the lining and surrounding rock displacement, stress, velocity and acceleration were compared under two kinds of different loads. Different models with different crack length on the location of tunnel vault, tunnel spandrel, and tunnel waist were established to get the stress intensity factor at the crack tip under the seismic and heavy-haul loading. Safety coefficient of the lining is obtained under different kinds of loading in order to determine the most dangerous working condition and the weak position of lining. The results showed that the train’s load have more influence on lining inverted arch while seismic load effect on the upper lining is larger. The work condition under seismic load is more dangerous than that undertrain’s load.