Common problems and solutions in subway track construction?

With the rapid development of cities and the gradual increase of urban population, traffic congestion has become an urgent problem in the construction of subway tracks, and the large-scale construction of subways has alleviated the pressure on subway tracks to some extent. In subway construction, track construction is an important link, and it is also one of the important factors that affect the construction period of subway project. As the infrastructure for the normal operation of subway, track plays the role of bearing and guiding trains. However, there are still some problems in the current subway track construction, which need relevant personnel to attach great importance to and actively explore reasonable solutions to effectively improve the quality level of subway construction projects.

First, the common problems in subway track construction

(1), the quality of managers is not high.

The low quality of managers is an important factor leading to problems in subway track engineering construction. In the construction of subway track project, many managers lack good technical literacy and fail to control and grasp the quality, progress and cost of the project well. At the same time, the lack of on-site construction experience leads to low management level, which will have a great impact on the quality of the project.

(2) The emergency plan is insufficient.

In the process of construction management, the relaxation of safety management is due to the nonstandard construction materials about safety production in many projects, the construction organization does not involve the emergency plan for emergencies, or there is no unified safety education after designing the emergency plan, or the design scheme does not meet the actual requirements on site. In this case, it is difficult to improve the safety level of the site through macro and micro construction management methods. Some site workers lack self-discipline awareness, do not understand the habitual violations on the site now, turn a blind eye to some safety hazards, and the related management functions are out of touch, which leads to the failure to implement safety management measures. In the event of a safety accident, the scene is flustered and cannot be repaired in time.

(3), the construction quality inspection is lax

There are many small links in the construction management of subway track engineering, which occur at different times and in different parts. In the process of construction, quality inspection is generally carried out by spot check, which makes it impossible to take into account every part of the subway track. If every part is inspected, it will be impossible to complete the construction within the specified subway track period. Therefore, there must be some unqualified places in the project, and the quality of the whole subway track project will be affected, so it is difficult to meet the prescribed standards.

Second, the subway track construction problems and countermeasures

(1), change the thinking of engineering construction and respect objective laws.

To do a good job in subway track construction and effectively ensure its construction quality, firstly, under the premise of environmental protection, we should reasonably control the construction scale and slow down the construction speed, and we should not blindly pursue the GDP effect brought by major projects; Secondly, the implementation of time limit quota or reasonable arrangement of time limit for a project, consolidate the foundation of engineering quality and safety management. It is suggested that the time limit for each major of track construction be determined. If the time limit specified in the quota cannot be reached, the acceptance shall not be organized or the warranty period shall be appropriately extended. From the system, the time and manpower that must be invested in track construction are clearly defined, which consolidates the foundation of project quality and safety management, effectively avoids the huge economic waste caused by blindly compressing the construction period, and is also a powerful guarantee to avoid quality and safety accidents.

(2) Improve the resilience and safety awareness of construction management personnel.

The management of subway track construction is a long-term work. In this process, the construction conditions and environment are constantly changing, which requires the construction personnel to adjust their management skills and working methods in time according to the actual situation. The members of the project team work together to direct the project operation, so it is particularly important to have a high-quality management team. Safety awareness should run through the whole project, and should also be rooted in every manager's mind, taking safety management as the top priority, which is not only related to the economic benefits of the project, but also related to the safety of life and property of construction personnel. It should and must be accomplished as an arduous task, and it should be done well.

(3) Strengthen education and training.

Management personnel are an important part of subway track engineering management. Only managers with high professional quality can carry out strict and reasonable management activities in the whole construction process, and the whole project can develop in an orderly and standardized direction. Therefore, the establishment of a high-level and high-quality management team should be the premise of subway track engineering management. The subway track department should organize regular training to improve the technical level of relevant personnel, and can also use overseas exchange and study to let managers gain more management experience.

Third, measures and methods to improve the quality of subway track construction

(1), using rails with higher performance.

Rail is the main construction material of subway track, and its performance and quality directly affect the construction quality of subway track. In subway track construction, rails are divided into two types: heavy rail and light rail. Either way, it is necessary to test its performance, use rails with relatively good performance as track construction materials, and strengthen welding construction management to improve rail welding quality. All welders are required to hold relevant certificates, have certain welding experience and do pre-job training to ensure that each welder can weld rails in strict accordance with the requirements, so as to avoid reducing the overall performance of rails due to welding quality problems.

(2) Layout and quality control of sleepers

Except turnout, there are three kinds of fasteners on the main line, and each fastener should be used in conjunction with the corresponding sleeper. Fasteners along the whole line must be strictly controlled according to the location of fastener type mileage in the track-laying comprehensive map. It is particularly important to note that it can be arranged according to the design requirements according to the needs of the front and rear slope pads of the turnout. To determine the sleeper spacing according to the comprehensive track-laying diagram, it is necessary to pay attention to the position of turnout and the position of the boundary point between jointless track and slotted track. Sleeper spacing can be determined according to slope and curve radius.

In the process of construction, when the sleeper can directly contact the track floor and cannot connect the sleeper with the concrete ballast bed in some areas because the tunnel is too high or the deviation data between the center line and the design height center line is large, the solutions are as follows: First, adjust the line and slope, which can be mainly aimed at the sections with conditional slope adjustment, tunnel height and center line exceeding the allowable range; Second, dig the bottom of the tunnel. Mainly in individual construction sites, the tunnel is out of range at high speed, and the cutting range is relatively small. For the bed without pillow, it can be mainly aimed at unconditional alignment and slope adjustment before and after the car and the tunnel ground height exceeding a certain range.

(3) Strengthen the quality control of ballast bed laying.

Ballast bed laying is also one of the basic projects of track construction, which has great influence on the quality of track construction. Therefore, in the process of track construction, construction personnel are required to strictly abide by the relevant requirements in all aspects of measurement, design and construction. First of all, surveyors should do a good job in subgrade elevation measurement, minimize the measurement error and ensure the measurement accuracy. Secondly, in order to ensure the accuracy of laying, guide piles and steel strings shall not be touched during survey construction, so as to avoid errors. Third, when transporting ballast, we should do a good job in organizational design to ensure that ballast transportation can achieve continuous operation and ensure the construction progress. Fourth, do a good job in performance testing of pavers. When the paver fails or is abnormal, it should be removed in time, and the paver and other mechanical equipment shall not be operated in spite of illness. Fifth, the fallen ballast should be cleared in time during the ballast transportation, and the transportation route should not be designed in bed surface to avoid damaging the subgrade.

(4) Layout of auxiliary track-laying base

Usually, the track base is laid on the track of vehicle parking lot or traffic section. These two places have enough space for large-scale operations such as assembling track rows and storing track materials, and the geographical environment is convenient, so it is more flexible and convenient to set up track auxiliary bases. This project includes the elevated construction section. When setting the auxiliary track, the elevated section should be set synchronously. The whole process is an underground subway. The auxiliary track is generally set in the open-cut station section, and the specific location can be selected in its middle, starting point and end point. When setting, ensure that it is in a relatively flat environment, so that some equipment can work normally, ensure the smoothness of surrounding roads, ensure that materials vehicles can work efficiently and accurately, and ensure that hydropower systems can be effectively connected and used. (5) Improve rail welding.

Flash contact welding and gas pressure welding are basically used for primary welding, standard rails are welded into long rails in factories or bases, and thermite welding, forced arc welding and gas pressure welding are used for secondary welding and tertiary welding, that is, the rails are welded into super-long seamless rails at the track laying site. At present, the "short-time preheating rapid thermite welding method" widely used in this field has great application advantages. Its biggest feature is the improvement of preheating accelerator, which greatly shortens the welding time of aluminothermic welding joint, improves the material properties of the joint and makes the welding joint more reliable.

Four. conclusion

In a word, the track is the infrastructure for the normal operation of the subway, and its construction quality directly affects the total construction period and construction quality of the subway construction project. Therefore, it is necessary to strengthen the improvement and innovation of subway construction technology, improve the quality of subway construction, and solve various problems existing in subway construction at present, so as to ensure the smooth implementation of subway track construction and effectively improve the quality level of subway construction projects.

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