Research On Dynamic Response And Fatigue Life In Bottom Structure Of Heavy Haul Railway Tunnel

Abstract:Heavy haul railway has become an important direction of the development of the railway transportation with its big axle load, high transport capacity and low transport cost. The increase of the axle load will produce greater vibration load in base of tunnel which could impact the safety of bottom structure of heavy haul railway. Therefore, more reasonable in design and a longer service life of structure are required for ensuring the security and stability of its operations. The dissertation is granted from the National Natural Science Foundation of China (U1361204), the National Natural Science Foundation of China (51278494), and study on the dynamic response and fatigue life in bottom structure of heavy haul railway tunnel under different structure type and basement condition with the methods of theoretical analysis and numerical calculation. The main research contents and conclusions are as follows:(1) A three-dimensional finite element model with tunnel and surrounding rock coupling of heavy haul railway is builded to discuss the variation characteristics of dynamic response in bottom structure of heavy haul railway tunnel under different invert arch rise-span ratio, invert arch thickness and filling layer thickness, and to analyse the influence law of dynamic response from different structural design parameters quantitatively.(2) According to the forced state in bottom structure of tunnel, the appropriate fatigue life prediction method is selected. With the dynamic finite element calculation result, the fatigue calculation software is used to analysis the fatigue life distribution in bottom structure of tunnel. On this basis, the reasonable design parameter values which meet the structural durability and service life are proposed.(3) By comparative analysis of dynamic calculation and fatigue life calculation, the bottom structure of tunnel is determined as the key parts in the design of heavy haul railway tunnel, and the forced state of structure is considered as the primary factor to be considered in the design of heavy haul railway tunnel.(4) The influence law and degree of dynamic response and fatigue life in bottom structure of tunnel under different basement condition are quantitatively analysed by the method of combining dynamic calculation and fatigue life calculation. On this basis, the change trend of structure fatigue life with the change of basement condition is discussed.