Research Of Disease Classification And Reinforcement Measures Of Heavy-haul Railway Concrete Bridges

Under the condition of capacity expansion of heavy-haul railway,the axle load and traffic volume of trains are further improved.Concrete bridges of heavy-haul railway show new disease characteristics,and more accurate requirements are also put forward for disease classification of concrete bridges.In the actual operation,it was found that the problems of mid-span vertical deflection and mid-span transverse amplitude exceeding the normal values of "Verification Code for Railway Bridges" occurred in the small-span bridges of heavy-haul railways,which have endangered the safety of bridges and traffic.The main research direction of this paper is the classification of concrete bridge diseases on heavy haul railway and the reinforcement measures of bridge diseases.The main research contents and conclusions are as follows:(1)Summarize the common diseases of existing railway concrete bridges,and analyze the prominent diseases of heavy haul railway and their causes in combination with the characteristics of heavy haul railway.Statistical analysis was made on the diseases of heavy-duty railway bridges with different spans and different beam types.The results show that small-span bridges are greatly affected by heavy-duty transportation,and the diseases are more prominent,especially for 12 m ordinary height reinforced concrete beams.(2)Through theoretical calculation and analysis,the vertical stiffness and lateral stiffness of 12 m ordinary height concrete beam structure under heavy haul transportation conditions are studied.The results show that the mid-span vertical deflection ratio of the bridge span exceeds the mid-span vertical deflection ratio of the bridge span under design load under the action of 30 t axle load train.When the speed of the heavy-haul train is between 60 and 75 km/h,the mid-span transverse amplitude of the bridge exceeds the normal value requirements of the "Verification Code for Railway Bridges".The results show that the vertical and transverse stiffness of the bridge structure are relatively weak.(3)Aiming at the weak vertical stiffness of 12 m ordinary height reinforced concrete beam,the vertical reinforcement measures are determined through theoretical analysis,and the mid-span deflection,vertical amplitude and vertical acceleration parameters of the bridge structure before and after reinforcement are calculated and compared by finite element analysis.The results show that the mid-span,vertical amplitude and vertical acceleration of the strengthened bridge structure are reduced by 11.5 %,26.6 % and 26.2 % respectively.The field test data verify that the vertical stiffness of the bridge structure can be significantly improved by adopting the reinforcement method.(4)Aiming at the problem of weak lateral stiffness of 12 m ordinary height reinforced concrete beam,the lateral reinforcement measures are determined through theoretical analysis.The transverse natural vibration frequency,transverse amplitude and transverse acceleration parameters of the bridge structure before and after reinforcement are compared and analyzed by finite element method.The results show that the first-order transverse natural vibration frequency of the reinforced structure is increased by 26.0 %,the transverse amplitude in the structure span is reduced by 46.5 %,and the transverse acceleration is reduced by 23.4 %.The field test data verify that the lateral stiffness of the bridge structure can be significantly improved by adopting the reinforcement method.