Study On Analysis Theory Of Train Derailment And Limit Value Of Bridge Lateral Rigidity For Derailment Control

Due to the speed-up of Chinese railways, the lateral vibration amplitudes of some bridges surpass the corresponding limit value for traffic safety determined by the Code for Rating Existing Railway Bridges (abbreviated to the Code herein). To strengthen these bridges or to limit the speed of trains running on these bridges restrains the speed-up strategy. Low value of bridge lateral rigidity results in a series of derailment accidents on bridges. The problem in bridge design for high speed line to be urgently solved is whether the safety of running trains can be ensured by the lateral rigidity of the newly designed bridges. A great deal of researches on lateral rigidity of railway bridges have been made at home and abroad, and fruitful achievements have been attained. However, the analysis theory of train derailment has not been broken through, and the problem of bridge lateral rigidity remains to be solved. In this dissertation, the analysis theory of train derailment and the limit value of lateral rigidity for railway bridges have been investigated on the basis of previous researches. The main contents and contributions of the dissertation are as follows.(1) It has been testified that the mechanism of train derailment is the loss of the lateral movement stability of train-bridge (or train-track) system. The theory of energy random analysis for train derailment is put forward, and a set of analysis software for train derailment is developed.(2) Four cases of derailment on bridges are analyzed. All the calculated results conform with the actual status, so the feasibility of the theory of energy random analysis for train derailment is verified. (3) The analysis method of the limit value of bridge lateral rigidity for derailment prevention is proposed, by which the limit values of lateral rigidity of railway steel bridges on speed-raised line are determined. The limit values of width-to-span ratio for lateral rigidity of 32 m and 40 m long deck steel plate girder are determined as 1/13.6 and 1/15.7 respectively. The limit value of width-to-span ratio for lateral rigidity of 3×80 m steel truss continuous beam is determined as 1/12.1. These limit values of lateral rigidity of steel bridges can be taken as reference for the modification of the bridge design code.(4) The safety of running trains on five bridges of which lateral vibration amplitudes surpass limit value stipulated by the Code is analyzed. The calculated results show that trains on these bridges will not derail within design speed, which is consistent with the practical facts. The problem of safety analysis of train running on bridges with their lateral vibration amplitudes exceeding specifications is solved. The calculated results have been adopted by corresponding railway departments, and a great economic effect is achieved.(5) The method of establishing the limit value of bridge lateral rigidity for traffic safety is proposed. With the method, the limit value for traffic safety of T-shape prestressed concrete bridge is presented. The limit values for traffic safety of 32 m and 24 m long T-shape prestressed concrete bridge are determined as L/3980 and L/4411 respectively. Finally, L/4500 is determined to be the recommended limit value for the lateral amplitude for traffic safety of T-shape prestress.ed concrete bridge on speed-raised line.(6) The analysis method for train derailment control on bridge and the safety coefficient for resisting derailment are put forward. The finite element model for basket handle arch bridge of concrete-filled steel tube is presented. Derailment control analysis of high speed trains on five bridges of passenger special line is performed. The calculated results show that train running on these bridges will not derail, and the safety coefficients for resisting derailment are great. The study has provided an important theoretical basis for the design of these bridges, and the results have already been adopted by the Fourth Survey & Design Institute of China Railways and China Zhongtie Major Bridge Engineering Group Co.Ltd respectively.