At present, China's high-speed rail bridge project has the characteristics of large construction difficulty coefficient, large investment and long period. Once an accident happens, the loss is very huge. Therefore, it is of great significance for the far-reaching development of China's high-speed rail industry to improve the construction technology of high-speed rail bridges and strengthen the construction quality management.
1 current situation of high-speed railway construction
1. 1 Characteristics of China high-speed railway
At present, the total mileage of high-speed rail projects under construction in China exceeds 1 10,000 kilometers, and the construction scale is relatively large, of which high-speed rail bridges account for more than half, especially in cities with more rivers and lakes. Faced with higher and higher industry requirements and more and more problems, improving the construction technology of high-speed rail bridges, strengthening the design and research of bridges and strengthening the management of bridge projects have become the top priority of high-speed rail bridge construction. In recent years, based on the advanced technology and successful experience of high-speed rail bridge construction in Japan, Germany and other countries, combined with the development of high-speed rail in China, through continuous modernization and scientific development, China has successfully realized the innovation and breakthrough of high-speed rail bridge construction technology and achieved good results in many related fields.
1.2 China's high-speed railway construction requirements
Bridge is an extremely important part of high-speed railway civil engineering. Its function is to save the occupied area, stabilize the route on the bridge and make the high-speed train run smoothly, thus ensuring the comfort of passengers and the safety of operation. Therefore, it is necessary to strengthen the stiffness and strength of the overall design of high-speed rail bridges. The vertical and lateral stiffness requirements of the superstructure and the overall structure requirements are very high, so the design of high-speed rail bridges usually adopts prestressed parallel T-beams or box girders. However, special parts such as arch bridges and continuous beams still need special design. In practical engineering, the construction of long-span bridges often adopts various design methods, as well as various erection methods, such as the common precast whole-hole box girder method and the method of pouring concrete beams on movable supports one by one. Because the train usually runs at high speed on the high-speed rail, it will produce a very strong structural dynamic response, which will affect the comfort of passengers and the safety of operation. In addition, the long-term operation of the train will produce running noise and load impact on the bridge. These problems require high-speed rail bridges not only to have the provisions of ordinary bridges, but also to have stricter quality management requirements.
1.3 The construction safety situation is complicated.
The construction of high-speed rail bridge is a complex project, which must be integrated, integrated and combined. Construction safety is not the business of the construction unit or the railway management unit, but involves many related units, many departments, a wide range and a high degree of difficulty. Therefore, it must be emphasized that the main leaders need to be personally responsible, need to make overall arrangements, and need all departments to work together, strengthen the implementation of responsibilities, give play to the advantages of the system, and form an overall synergy. In particular, it is necessary to strengthen the management of joint departments, put an end to the phenomenon of out-of-control and disconnection, firmly grasp the initiative of safety production, and improve the level of comprehensive safety management.
2 High-speed rail bridge construction quality management strategy
2. 1 management strategy of high-speed railway bridge construction team
It is necessary to strengthen the education of high-speed rail bridge construction team, instill new safety construction concepts into them, and strengthen the change of safety concepts of leaders and employees, so that everyone can fully realize that high-speed rail bridge construction is not only related to the safety of railway operation, but also to the safety of people's lives, and enhance the sense of responsibility of construction team. Let them know that only by ensuring safety can they create maximum profits for the enterprise. The construction unit should set up a construction team headed by the main leaders, and ask the main leaders to ensure on-site security, coordinate and solve the problems existing in the construction, and ensure that the bridge construction can be completed safely on schedule. Moreover, in the process of high-speed rail bridge construction, it is necessary to analyze and summarize the long-term accumulated practical experience of engineers and technicians, so as to scientifically determine the various processes of high-speed rail bridge construction. Only in this way can we improve the management level of high-speed rail bridge construction team and promote the further promotion and development of high-speed rail bridge construction technology in China. In order to effectively improve the construction quality of high-speed rail bridge project, we must give full play to the role of high-quality and experienced designers and strengthen the management of construction team. In the specific bridge construction stage, we should choose excellent and experienced construction teams, so as to ensure the quality of high-speed rail bridges in essence. Of course, for the construction personnel, pre-job training is needed to familiarize them with the work flow, so as to ensure that the expected efficiency and effect can be achieved in the construction process, especially for the more important skilled positions such as carpentry, welding and steel reinforcement, it is necessary to ensure that the personnel's ability meets the specified requirements or even higher.
2.2 Optimize the construction technical scheme
Before the construction of high-speed rail bridge, technicians need to make an easy-to-understand organizational design based on the supply of machines and tools, materials and the construction practice, and make safety technical disclosure for specific parts, especially key working procedures and projects with greater risks under bad weather conditions, and explain in detail the problems existing in the construction personnel involved in the disclosure, extending horizontally to the management personnel of relevant departments and vertically to the team. In addition, it is also necessary to check whether the safety guarantee system of the construction site is sound, and whether the project manager, team leader, technician and other production commanders and the relevant departments of production, machinery, equipment, logistics, technology, etc. perform their respective duties to ensure the safe production of the construction site and ensure the implementation of various requirements in the system. It is also necessary to check whether practical and feasible emergency rescue countermeasures have been considered in the risky construction scheme.
2.3 High-speed Railway Bridge Transition Section Settings Management Countermeasures
During the construction of high-speed rail bridge, the subgrade behind the on-site console is easy to sink and deform, which will have a very serious impact on the quality control of high-speed rail. Therefore, the construction unit needs to use special piles such as cement mixing piles as semi-rigid composite foundation to effectively control foundation settlement. In addition, plain concrete or flaky concrete should be used to backfill the foundation pit, and the foundation pit should be compacted according to the specified design. However, in the face of the situation that the transition section often adopts regular trapezoidal structure with narrow upper part and wide lower part, the choice of filler should be more suitable with higher strength and smaller deformation.
2.4 Application countermeasures of jointless track bridge design and construction
In order to meet the comfort requirements of high-speed rail passengers, the safety requirements of trains and the stability of track operation, it is necessary to carry out structural design based on the principle of people-oriented. Therefore, in order to meet the above requirements, it is particularly important to adopt the design of jointless track in the construction of high-speed rail bridges. The design of jointless track requires that the arrangement of long rails, the locking mode and the choice of track structure form should be reasonable, and the neutralization temperature should be scientific, so as to control the stress of tracks, piers and abutments and the broken joints of rails within allowable values. In addition, it is necessary to ensure that the anti-climbing ability and stability of the track meet the requirements. Because of the heavy stress on the rails of jointless track on the bridge, it is necessary to effectively control the deformation and possible displacement of the bridge itself caused by the train running on the bridge to fully ensure the safety of the train running on the bridge. At the same time, the designer should also fully consider the additional rail force caused by the interaction between beam and rail, and then control it in a safe range through effective measures.
2.5 bridge construction materials management strategy
The construction management of high-speed rail bridge is mainly responsible for the progress and quality of construction, especially for the quality problems of construction. The construction unit of high-speed rail bridge should establish corresponding supervision departments, audit the construction of high-speed rail bridge in strict accordance with the construction design scheme, carefully supervise the materials used in construction, and control the quality problems of materials to ensure that the materials used in the whole construction process meet the requirements. It is also necessary to ensure that the safety performance of the bridge can meet the standard, and the completed state of the bridge meets the design requirements and specifications, which all put forward high requirements for the regulatory authorities, and they need to do a good job in supervision during the construction of high-speed rail bridges. Moreover, it is necessary to comprehensively improve the comprehensive quality of the construction team by organizing training, so that it can establish the safety awareness of construction and solve the safety problems of construction.
2.6 High-speed Railway Bridge Maintenance Management Strategy
The construction quality management of high-speed rail bridge is very important, but the daily maintenance management should not be underestimated, because if the bridge can not be maintained in time, it will inevitably lead to the decline of bridge performance, and finally will inevitably bring various security risks. Therefore, it is necessary to establish a very professional and experienced maintenance team to carry out regular inspection and maintenance management of high-speed rail bridges, and this maintenance team needs standardized inspection and maintenance methods and procedures to ensure that engineers can keep abreast of the state of high-speed rail bridges at any time, so as to solve various sudden crisis events in time. Of course, the construction unit also needs to strengthen the training and management of this maintenance team, so that it has more professional and superb maintenance capabilities and means.
3 Conclusion
In the high-speed rail construction project, the engineering construction of high-speed rail bridge is the most important load-bearing part, and its strict quality management has important practical significance for the operation and management of high-speed rail trains in the future. Therefore, high-speed rail construction units need to strengthen the management of high-speed rail bridge construction, improve the construction technology of high-speed rail bridge, speed up innovative research, strictly control the construction quality, improve the safety of high-speed rail operation, and ensure the comfort and personal safety of passengers.
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