1. The whole installation process of precast beam is as follows (see Figure 2): 1. After the precast beam is hoisted out from the prefabrication yard, the gantry crane travels to the outermost side of the bridge, from the outer side of the span back in turn until the span is installed; 2. Install the level crossing device in the inner half of the span, and put the beam carrier on the level crossing device; 3. Install the bridge erecting machine on the installed span, and directly install the precast beam on the outer half span of the two spans of the gantry crane with the bridge erecting machine, but not the inner half span for the time being, so that the precast beam can be hoisted by the gantry crane on the beam carrier; 4. The bridge erecting machine uses its own hoisting mechanism and hoisting mechanism to move forward step by step, and the bridge deck track moves forward synchronously, and so on, until it is completely installed. Fig. 2 Schematic diagram of installation process II. The compilation and implementation of the safety technical scheme requires the close cooperation of several large-scale equipment for the installation of each beam in this project, and any omission will lead to serious accidents. Therefore, the formulation of safety technical scheme must be reasonable, effective and highly operable. The basic content is as follows: 1. The large-scale equipment in this project is different from other general equipment and has particularity. Therefore, in the training of operators, in addition to the explanation of general mechanical operation knowledge, manufacturers are also invited to explain the particularity of equipment, and engineers and technicians are also invited to explain the whole installation process, so that mechanics can understand the relationship between equipment and cooperate with each other in their work. After passing the examination in all aspects, an operation certificate shall be issued before taking up the post. 2. The release agent on the prefabrication platform of the prefabrication yard should be evenly coated and full, so as to avoid adhesion during component hoisting. 3. The gantry crane has a span of 35m, and the walking devices are driven by two motors respectively, so the walking on both sides must be synchronized, otherwise the top beam will be distorted, resulting in serious consequences; In addition, the working interval of the gantry crane on the bridge is only a few meters, the front end of the gantry crane is an installed bridge deck, and dozens of tons of prefabricated beams are required to be very stable in the air. If the gantry crane collides with the bridge deck during walking, the hoisting wire rope may break, and the consequences are unimaginable. Therefore, it is necessary to regularly check the synchronous control system and walking limit before going to work every afternoon to maintain absolute sensitivity and reliability. 4. The beam carrier on the bridge deck moves to the beam connection position in advance through the grade crossing device, and waits for the gantry crane to lower the beam. It is forbidden for all personnel to operate and stay under lifting load; When the operator firmly fixes the precast beam on the beam carrier, the hook can be unhooked. 5. Because the precast beam is long and pulled by the left and right steel ropes at the same time, it is necessary to observe whether the two sides are synchronized at any time during the translation of the grade crossing device, that is, the precast beam should always move parallel to the bridge axis and not skew. 6. The beam carrier is in a state of vibration during walking, so it is necessary to pay attention to whether the locking device of precast beam is loose. If it is found loose, stop and lock it in time. 7. The bridge erecting machine shall traverse to the center line of the track before the girder carrier arrives. When traversing, pre-tighten the wire rope of the hoist, pause for a moment when the wire rope of the net begins to bear force, and then start the motor to move. Avoid instantaneous stress of wire rope. After the beam carrier enters the proper position, the rear parts of two trusses of the bridge erecting machine are supported by supporting rods, and the precast beam is lifted by the beam carrier and moved forward to the previous span; Take down the support rod, and the beam carrier will return to its original road. The bridge erecting machine starts to move laterally, and when it reaches a certain position, the beam will be put in place by the beam lifting trolley, and fixed measures will be taken. 8. After completing one span, the bridge erecting machine will move forward to prepare for the next span, and the operation steps of moving forward will be carried out in strict accordance with the requirements of the manual. Three. Safety measures 1. When lifting the precast beam from the beam platform, it is forbidden to pull it hard, and the strength should be gradually increased before lifting it. 2. Every process from lifting the mould to putting it in place should be commanded by a special person, with a clear division of labor and smooth cooperation. For example, the formwork lifting of precast beams is commanded by the signalman in the prefabrication yard, and the final lifting height and walking position are commanded by the signalman on the bridge deck. 3. All mechanical equipment shall strictly implement the pre-shift inspection system and regular maintenance system, and make records. 4. After the first beam of each span is installed in place, reliable temporary fixing measures must be taken, such as splay welding with steel bars, and then each beam can be temporarily connected with the first beam. 5. The moving forward of the bridge erecting machine is a multi-party cooperative process, especially in the downhill direction of the bridge deck. Because at this time, the bridge erecting machine will automatically slide forward, and if it is not well controlled, it is easy to have an accident. During construction, two winches are used, with the back gently lowered and the front gently pulled, step by step and gradually put in place. 6. The special protection scheme for crossing bridges and railways shall be implemented after being reported to Hangzhou Branch of Shanghai Railway Bureau for approval. In case of emergency, the railway department specifies several time periods, and the train stops, allowing construction above the railway; Because the railway is the main traffic line from Hangzhou to Ningbo, passenger and cargo transportation is busy; The time period specified by the railway department is only 30 minutes at a time. However, the construction party must obey unconditionally, and make all preparations in advance every time, and then quickly frame the beam.
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