What are the technical requirements for bridge support installation and expansion joint construction?

Bridge bearings and expansion joints are the core auxiliary components of bridge structures, directly related to the load-bearing stability, driving comfort, and structural durability of the bridge. Bridge bearings play an important role in transmitting the load of the upper structure of the bridge and adapting to structural deformation, while expansion joints are used to absorb the expansion deformation of the bridge caused by temperature changes and load effects, preventing rainwater and debris from infiltrating the interior of the bridge structure. The quality of the construction of both directly affects the service life and operational safety of the bridge. If the construction is not standardized, problems such as bearing detachment, displacement, expansion joint leakage, and damage are prone to occur, which can cause hidden dangers such as bridge structure cracking and bridge head jumping, affecting the traffic experience and engineering safety. Based on industry standards and engineering practices such as the "Technical Specification for Construction of Highway Bridges and Culverts" (JTG/T 3650-2020) and "Highway Bridge Bearings" (GB/T 19735-2019), the technical requirements for bridge bearing installation and expansion joint construction revolve around five core stages: pre construction preparation, bearing installation, expansion joint construction, quality inspection, and post maintenance. The technical requirements of each stage are coordinated and connected to ensure that the construction quality meets the design and specification requirements, and to guarantee the long-term stable operation of the bridge.
The installation of bridge bearings and the construction of expansion joints follow the core principles of "precise positioning, standardized operation, collaborative adaptation, and long-term stability". The core goal is to ensure that the bearings are installed firmly and evenly, the expansion joints are installed flat and tightly sealed, and can effectively adapt to the deformation of the bridge structure, resist external environmental influences, and balance construction accuracy and engineering economy. The implementation of technical requirements should be based on the type of bridge (beam bridge, arch bridge, cable-stayed bridge, etc.), span size, load level, and operating environment. Targeted optimization of construction plans should be carried out to avoid blindly applying processes and ensure that technical measures are scientifically feasible and effective.

Pre construction preparation is the foundation for ensuring the quality of support installation and expansion joint construction. The core is to avoid quality hazards from the source through measures such as material control, equipment debugging, and grassroots treatment, laying the foundation for subsequent construction. The focus covers three key aspects: material control, equipment debugging, and grassroots treatment.

Material control requires strict control over the quality of bridge bearings, expansion joints, and auxiliary materials to ensure they meet design requirements and industry standards. Bridge bearings need to be selected according to the load, span, and deformation requirements of the bridge, using suitable types (such as plate rubber bearings, bowl bearings, ball bearings, etc.). The bearing capacity, stiffness, displacement, and other indicators of the bearings need to be tested and qualified. After entering the site, sampling and re inspection are required to verify the specifications, models, quality certificates, and inspection reports. Unqualified products are strictly prohibited from being put into use. The expansion joints shall be made of materials with good wear resistance, aging resistance and sealing performance. The common types include modular expansion joints, comb plate expansion joints, caulking expansion joints, etc. The expansion amount of the expansion joints shall match the design expansion amount of the bridge. After mobilization, the appearance quality of the expansion joints shall be checked to avoid cracks, damage, deformation and other defects. Auxiliary materials (such as anchor bolts, sealants, grouting materials, etc.) need to be compatible with the support and expansion joint materials to ensure a firm connection and tight seal. Grouting materials need to have good bonding strength and strength to meet construction and usage requirements.

Equipment debugging requires comprehensive inspection and calibration of specialized equipment used in construction to ensure stable equipment performance and guarantee construction accuracy. The lifting equipment, level, total station, etc. required for the installation of supports need to be accurately calibrated to ensure smooth lifting and accurate measurement data; The cutting equipment, vibration equipment, compaction equipment, etc. used in the construction of expansion joints need to be adjusted for operating parameters to ensure smooth cutting, compact vibration, and proper compaction. At the same time, it is necessary to prepare the necessary instruments and equipment for quality testing, such as displacement sensors, pressure sensors, etc., to ensure accurate and reliable testing data and provide support for construction quality control.

Grassroots treatment is a prerequisite for the installation of supports and the construction of expansion joints. It is necessary to ensure that the installation surface is flat, solid, and clean, and to avoid construction quality hazards caused by uneven and unstable grassroots. The installation base of the support needs to clean up surface debris, floating slurry, and oil stains. The uneven parts of the base surface should be polished and repaired to ensure that the flatness of the base meets the specification requirements. The flatness deviation of the installation surface of the plate rubber support should not exceed 2mm/m, and the flatness deviation of the installation surface of the pot type support should not exceed 1mm/m. The base layer of expansion joint construction needs to be cleaned thoroughly, and aging and damaged road structures should be removed to ensure a solid base layer. At the same time, expansion joint installation slots should be reserved, and the slot size and depth should meet the design requirements. The slot wall should be flat and vertical to avoid problems such as tilting and loosening. After the grassroots treatment is completed, it needs to be inspected and qualified before entering the next process.

The technical requirements for the installation of bridge bearings are the core to ensure that the bearings function properly. The focus is on four major aspects: positioning and laying out, bearing installation, anchoring and fixing, and gap adjustment, to ensure that the bearing installation is accurate, firm, and evenly stressed.

High precision measuring equipment is required for positioning and laying out. Based on the bridge design drawings, the installation position, elevation, and levelness of the supports should be accurately determined. After laying out, a review should be conducted to ensure that the positioning deviation meets the specification requirements. The center position deviation of the supports should not exceed 5mm, and the elevation deviation should not exceed ± 3mm. For basin and spherical supports, the center axis of the supports should be accurately positioned to ensure alignment with the axis of the upper and lower structures of the bridge, avoiding offset and affecting load transmission.

The installation of bearings requires the selection of appropriate construction techniques based on the type of bearings. When installing plate type rubber bearings, a layer of cement mortar should be laid on the base layer first, with a thickness controlled between 20-30mm to ensure a tight connection between the bearings and the base layer. During the installation process, the levelness of the bearings should be adjusted to avoid tilting or loosening, and the height difference of the four corners of the bearings should not exceed 1mm. When installing pot type bearings, the lower cushion plate of the bearings should be installed first, and the levelness of the cushion plate should be adjusted before lifting the bearing body to ensure that the upper and lower cushion plates of the bearings are aligned and the bolt connection is firm. Clean lubricating materials should be filled inside the bearings to ensure that they can rotate and move flexibly. When installing ball bearings, it is necessary to ensure that the contact surface of the ball joint is clean and smooth. After installation, the rotational flexibility of the bearing should be checked to avoid jamming.

Anchor fixation must strictly follow the requirements of the specifications, and the anchor bolts of the support must be implanted at the design depth. The bolts should be installed firmly, and the tightening torque should meet the design standards to avoid displacement of the support due to loose bolts. For large supports, grouting anchoring method should be used, and the grouting material should be full, dense, without voids or cracks, to ensure that the anchoring strength meets the requirements. After anchoring is completed, it is necessary to check the fixing condition of the support to avoid problems such as looseness and displacement.

Gap adjustment should be based on the deformation requirements of the bridge structure, and the gap between the supports should be reasonably adjusted to ensure that the supports can freely expand and rotate, meeting the deformation requirements of the bridge structure under temperature changes and loads. Reasonable expansion and contraction gaps should be reserved for plate rubber bearings to avoid excessive or insufficient gaps affecting their use; Basin type and ball type bearings need to adjust the displacement of the bearings to ensure that the displacement range meets the design requirements. At the same time, the sealing performance of the bearings needs to be checked to avoid rainwater and debris entering the interior of the bearings, which may affect their service life.

The core technical requirements for the construction of bridge expansion joints are to ensure that the installation of expansion joints is smooth, tightly sealed, and flexible. The focus is on the four major links of slot treatment, expansion joint installation, anchoring and fixing, and sealing treatment to avoid problems such as water leakage, loosening, and damage.

The groove treatment should be carried out after the grassroots acceptance is qualified. The debris and floating soil inside the groove should be cleaned to ensure that the groove is clean and dry. For the loose parts of the groove wall, reinforcement treatment should be carried out to avoid collapse during the construction process. A layer of waterproof membrane or waterproof coating should be laid at the bottom of the groove to enhance its waterproof performance and prevent rainwater from seeping into the interior of the bridge structure, corroding the steel bars and concrete.

The installation of expansion joints requires precise positioning. The expansion joint should be lifted into the slot, and the elevation and levelness of the expansion joint should be adjusted to ensure that the top surface of the expansion joint is level with the bridge deck pavement, with a deviation of no more than 2mm. The centerline of the expansion joint should be aligned with the bridge axis, with a deviation of no more than 3mm. During the installation process, it is necessary to ensure that the expansion device of the expansion joint is flexible, without any jamming, and that the expansion amount meets the design requirements. For modular expansion joints, it is necessary to ensure that each expansion unit is firmly connected and the gap is uniform; For comb plate expansion joints, it is necessary to ensure that the comb plates are tightly connected without looseness or warping.

Anchor fixation requires the use of anchor bolts to fix the expansion joint in the slot. The depth and spacing of bolt implantation should meet the design requirements, and the tightening torque should be uniform to ensure that the expansion joint is installed firmly and avoid loosening and displacement during vehicle operation. After anchoring is completed, grouting material needs to be filled in the gap between the expansion joint and the groove wall. The grouting material should be full, dense, and tightly combined with the groove wall and expansion joint to enhance overall stability.

Sealing treatment is the key to the construction of expansion joints, and high-quality sealant should be selected to fill the gaps of the expansion joints, ensuring a tight seal and preventing rainwater and debris from infiltrating. Before filling the sealant, it is necessary to clean the debris and dust in the gap to ensure that the gap is clean and dry. The filling should be full, without bubbles or gaps. After filling, the surface of the sealant should be trimmed to be level with the expansion joint and bridge deck pavement, enhancing its aesthetics and waterproof effect.

Quality inspection is a key link in ensuring the installation of bearings and the construction quality of expansion joints. It needs to be carried out throughout the entire construction process, with a focus on testing installation accuracy, anchoring strength, sealing performance, and other indicators, in order to promptly identify and rectify quality hazards. The installation inspection of supports requires checking the positioning deviation, levelness, anchoring firmness, and flexibility of rotation and expansion of the supports to ensure compliance with regulatory requirements; The construction inspection of expansion joints requires checking the installation elevation, levelness, anchoring strength, and sealing performance of the expansion joints, as well as conducting waterproof tests to ensure no water leakage. The parts that fail the inspection need to be repaired and rectified in a timely manner until they pass the inspection.

Post maintenance is an important guarantee for maintaining the long-term stable operation of bearings and expansion joints. Technical requirements revolve around bearing maintenance, expansion joint maintenance, and regular inspections. The maintenance of bearings requires regular cleaning of debris and dust on the surface of the bearings, inspection of the sealing performance and lubrication of the bearings, and timely replenishment of lubricating materials. If corrosion, damage, displacement, or other problems are found in the bearings, they need to be repaired or replaced in a timely manner. The maintenance of expansion joints requires regular cleaning of debris inside the joints to avoid blockage and affecting the expansion function. The integrity of the sealant should be checked, and if cracks or detachment are found, they should be repaired or replaced in a timely manner; At the same time, it is necessary to check the anchoring condition of the expansion joint to avoid looseness and damage. Regular inspections require comprehensive checks on bearings and expansion joints, with a focus on identifying potential hazards and taking timely measures to ensure they are always in good working condition.

The implementation of technical requirements for bridge support installation and expansion joint construction should be carried out throughout the entire construction process, with coordinated control at all stages, strict adherence to industry standards, and optimization of construction plans based on the actual situation of bridge engineering. With the application of intelligent construction equipment and new materials, the level of refinement and standardization of support installation and expansion joint construction continues to improve. Through scientific preliminary preparation, standardized construction operations, accurate quality inspection, and comprehensive post maintenance, the construction quality of supports and expansion joints can be effectively guaranteed, avoiding various quality hazards, extending the service life of bridges, ensuring the safety of bridge operation and driving comfort, and providing strong support for high-quality construction of bridge engineering.