Risk analysis and control measures for traversing process
When a steel structure truss girder traverses the construction process, a risk accident occurs, which may result in casualties and poor social influence. Therefore, the potential risks in the construction process must be analyzed before construction. It is necessary not only to ensure the safety of the steel truss girder traversing the construction itself, but also to avoid adverse effects of the construction on the existing business lines. Before the formal construction, according to the construction technology plan adopted, identify and evaluate the possible risks in the construction, make correct assessment and judgment of the construction risks, and formulate control measures to actively control the construction risks to ensure construction safety. Through construction risk analysis and taking corresponding measures to ensure the smooth completion of the construction of the steel truss girder and the normal operation of the existing lines.
Risk Source Identification
The construction of steel truss girder bridges across the existing railway line due to its special construction difficulties, construction risks need to be combined with on-site investigations and construction plans for risk source identification. Before the construction, the potential sources of risk in the construction process were screened through the expert survey method, and the major potential risks in all construction processes were classified and classified.
Steel Truss Beam Risk
Due to the characteristics of the steel truss girder itself and the construction process, there are some potential risks in the construction of the steel girder during the process. 1) As the traversing movement continues, the risk of distorting the steel truss girder due to unsynchronized traction may occur on the left and right sides of the steel truss girder. Therefore, the traction equipment on both sides must be adjusted at any time to ensure simultaneous traction. 2) During the traverse process, if the failure of one side longitudinal restraining device may cause the longitudinal deflection of the steel beam to be too large, longitudinal correction shall be implemented during the traverse. 3) In the process of falling beams, there may be excessive force at the top branch of a certain pier, resulting in local buckling of the steel structure truss. When the beams are dropped, it is necessary to ensure that the progress of the falling of the jacks is consistent. The construction personnel must pay close attention to the deformation of the beam bottom.
Existing cable risk
The traverse of steel truss girders crossing over existing railway lines due to their particular construction will inevitably affect the operation lines, and therefore there are also some potential risks. 1) During the construction of steel truss girders, debris may fall on existing lines, causing serious consequences. The construction party should install guardrails on both sides of the bridge before the steel truss girder enters the existing line to prevent debris from falling and to clean up the debris on the deck. 2) The deflection of slide girders during construction of steel truss girders is too large, which will affect the normal operation of existing lines. The slide beam deflection must be monitored in real time during construction. 3) During the construction of steel truss girders, the effects of train operation command signals may inadvertently be generated, and the normal operation of existing railway trains may be disturbed. Therefore, before the construction, the construction personnel should be made aware of the relevant knowledge and avoid using equipment that may cause interference.
Facility risk
There are various types of facilities for steel truss girder traversing construction, and the safety of construction facilities is a necessary condition for completing the traverse. Therefore, it is necessary to carry out risk analysis on various important construction facilities. 1) As the most important temporary structure in the construction process, the construction platform must be checked for the deformation and overall stability of the support under the most unfavorable conditions, and the foundation settlement should be observed regularly. 2) The slideway beam is an important temporary structure of the truss girder of the steel structure. The design requirements such as strength, stiffness and stability should be met during the traverse. The surface friction coefficient of the slideway beam should meet the traction design requirements, otherwise it may cause difficulty in traversing. Lubricants should be applied repeatedly before each stage of traverse operation. 3) If two oil pumps are not synchronized during construction, they will also cause a large longitudinal displacement of the steel truss girder. Before the construction, a comprehensive inspection of the traction equipment is required, and 2 to 3 trial tractions are performed. After ensuring that the equipment is operating properly, formal traverse begins. During the traversing operation, a special person must control the jack brake and report the current hydraulic pressure in real time. The person in charge of the traverse site is in control of the information in the current construction and gives further instructions for construction.
Other risks
During the construction, due to force majeure and human factors, some uncontrollable risk factors will be generated. These risks may also have serious consequences for construction, resulting in bad social impact and becoming a type of construction risk that cannot be ignored in the construction of steel bridges. This requires the construction unit to make relevant risk plans and properly handle the conflicts and conflicts. At the same time, it requires the construction personnel to strictly abide by the relevant construction regulations, reasonably arrange related issues, and properly handle the construction emergency.
The steel structure truss girder bridge has high construction difficulty and risk across the construction of the existing railway. A reasonable construction plan and a perfect risk response plan are the necessary conditions for the successful construction. The analysis of the risk of traverse construction of the railway steel truss girder bridge across high-speed trains can provide some references for such projects.
1) The construction of steel truss girders is gradually adopted in order to reduce the interference with high-speed rails due to the particularity and high risk of construction across the existing lines. The construction technology and techniques for the transverse movement of steel truss girders across high-speed railways for operation need to be further analyzed.
2) For the steel truss girder bridges with transverse construction, it is important to pay attention to and monitor the location of the localized buckling of the bottom slab of the slideway girder and the temporary pier of the slideway girder during the traverse. At the same time, the design unit must not only consider the structural safety of the bridged state but also consider the force requirements of the temporary structure during the construction phase.
3) Construction risk analysis of steel frame truss girders is an important part of construction safety. The construction preparatory stage should identify the potential construction risks. By selecting a reasonable construction plan and formulating a sound construction organization design, construction risks can be effectively avoided.