Technical Scheme Research And Mechanical Property Analysis Of Repair Beam For High Speed Railway

China is the country which with the longest high-speed railway and the largest construction scale in the world at present. High-speed rail trains has high requirements to the comfort of the line and the settlement of the post-construction, so it generally uses the way of building bridges instead of roads, which has a large proportion in high-speed railway. Bridge structure is easy to damage but difficult to repair in wartime, and damage may also occur in earthquakes, landslides, mudslides and other natural disasters. The fracture of high-speed railway will cause huge economic losses, but there are no special repair technology and repair equipment reserved for high-speed railway bridge. The repair equipment, technical and tactical performance of the existed ordinary railway bridge can not meet the repair needs of high-speed railway. Has been put into operation, a large number of high-speed railway bridges facing a dilemma that there are no repair technology supported and repair equipment reserved after damage. Therefore, it is urgent to study a kind of beam repair structure which is suitable for high-speed railway bridges, and which has important economic significance and social benefits.In this paper, a new type of high-speed railway steel beam is proposed, which is based on the review of the existed railway steel beam, the mechanical properties of the new beam is analyzed and studied. The main work and conclusions are as follows:(1)In this paper, a new repair technique scheme of high-speed railway bridge beam is proposed. Unlike traditional ordinary railway bridge repair methods,the beam structure of the new repair scheme for temporary repair is no longer removed, by the transformation of the structure can form a permanent bridge structure, to avoid the secondary change of damaged bridges.(2)The new emergency repair beam scheme which can meet the needs of high-speed railway is designed, the structural form of the beam is determined and the connection between the section of the beam is studied. By using steel pins- shear connections and arranging prestressed tendons at the bottom of repair beams, which can make repair beam become prestressed steel structure, effectively improve the repair beam field spell frame rate, improve the longitudinal, lateral stiffness of temporary repair beam.Compared with ordinary railway repair steel beams,it will be significantly improved the temporary traffic speed.(3)The technical scheme of temporary repair beam to permanent bridge structure is studied. By placing concrete on the top of the steel beam flange, arranging and tensioning the external prestressed tendons, and the prestressed steel concrete composite beams are formed. By connecting the uplink and downlink of the beam, arranging and tensioning the transverse prestressed tendons, make the emergency repair beam to form a double line integrated prestressed composite beam.(4)The mechanical performance analysis results of the temporary repair beam with the single traffic state show that under the action of high-speed rail load, the strength, stiffness, natural vibration frequency of repair beam can meet the requirements of <Fundamental code for design on railway bridge and culvert >. Because of the connection mode of the steel pin-shear bond between the section of the beam, the beam can not transmit the tension, the strength and stiffness of the repair beam are lower than which has the same beam section. The vertical stiffness of the repair beam can be significantly improved by setting longitudinal prestressed tendon, and the overall stress level of the beam is reduced.(5)The results of mechanical performance analysis of the permanent beam with double track under normal operation condition show that under the action of high-speed rail load, the strength, stiffness and natural vibration frequency of the permanent beam meet the requirements of <Code for design of high speed railway>. The overall performance is comparable to that of original prestressed concrete box girder with double line. Compared with the temporary repair beam, the stress level of the permanent beam is lower and the longitudinal and lateral stiffness is higher improved.In this paper, the technical scheme of high-speed railway bridge is proposed, repair speed is fast and temporary traffic speed is higher. By the transformation of the structure can form a permanent bridge structure, to avoid the secondary change of damaged bridges. Providing equipment and technical support for the repair of high-speed railway bridges in our country, the economic and social benefits are significant.