Urban hollow slab type main line bridge demolition construction method

Abstract

The invention relates to the technical field of constructional engineering, in particular to an urban hollow slab type main line bridge demolition construction method, which comprises the following steps of: cutting hollow slab girder pavement layers and hinge joints along the longitudinal bridge direction by adopting coiled saw, and cutting the connection of hollow slab girder end pavement layers along the transverse bridge direction to relieve the constraint of the pavement layers between hollow slab girders; the 8-shaped grooves are formed in the solid sections of the two end corners of the hollow slab beams, the jacks are installed in the grooves in parallel, the jacks conduct synchronous pushing operation to separate gaps between the adjacent hollow slab beams, on one hand, the grooves are formed in the solid sections of the beam ends to replace hoisting holes drilled in the beam bodies, and damage to the beam bodies of the hollow slab beams of an old bridge can be avoided; on the other hand, the jack is used for synchronously pushing out the gap at the beam end, steel wire ropes can conveniently carry the bottom for hoisting, the stability of the beam body structure is guaranteed, and meanwhile it is guaranteed that hinging between two adjacent hollow slab beams is completely relieved. And after the hollow slab girder blocks are separated, a lifting appliance is adopted for lifting and removing operation, so that the construction progress is accelerated, and the construction operation safety is effectively guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of construction engineering, and particularly to a construction method for demolishing an urban hollow slab main bridge. Background Art

[0002] With the continuous development of China's national economy and the continuous improvement of people's living standards, people's requirements for urban transportation are also gradually increasing. However, more and more urban elevated bridges have problems that are difficult to meet the current usage requirements. The reasons for this problem are manifold: 1. Low design standards. Many in-service elevated bridges have been in service for many years. The standard specifications referred to in the bridge design are relatively low. At present, the traffic flow is large and the tonnage of motor vehicles is large. The original design standards are no longer applicable to the current usage requirements of the bridges; 2. Complex usage conditions. Most urban elevated bridges have high traffic pressure and are greatly affected by the environment. Adverse environmental factors such as vehicle loads, high temperature, rainfall, freeze-thaw, and erosion seriously threaten the safety of bridge use; 3. Insufficient traffic capacity. With the rapid development of China's economy and the continuous increase in people's disposable income, the urban motor vehicle ownership has increased by 23 times in 20 years, and the shortage of road traffic capacity has become increasingly prominent; 4. Conflict with urban planning. With the continuous deepening of China's urbanization process, the urban boundary is also constantly expanding. While the relevant planning departments adjust and update the urban planning, some existing urban elevated bridges do not meet the urban planning requirements. Therefore, it is necessary to demolish the existing bridges and renovate and reconstruct the bridges at the original sites.

[0003] Different from highway bridges, urban elevated bridges are usually located in busy urban areas, with high traffic pressure, dense residential areas, and complex surrounding environments. In addition, the demolition operation space of urban elevated bridges is limited, and the requirements for maintaining traffic on the operating roads, environmental protection, and safety are high during the demolition process, which further increases the difficulty of bridge demolition work.

[0004] At present, the commonly used bridge demolition methods in China can be divided into blasting demolition method and mechanical demolition method. The blasting demolition method is represented by the collapse method. It is difficult to control indicators such as the blasting damage range, the bridge collapse range after blasting, the flying distance of flying objects, the impact breaking strength and noise intensity, the blasting seismic effect, and the dust splash. Therefore, the blasting demolition method is mainly used for the demolition of field bridges in relatively open environments. The commonly used mechanical demolition methods mainly include support demolition method, cable hoisting method, cantilever demolition method, jacking method, floating transportation method, large segment lowering method, etc. Among them, in response to the urban operation conditions, for hollow slab beams, mechanical separation of the hollow slab beam body can be carried out using a circular saw, etc., and then hoisted and demolished. Due to its advantages such as simple construction and clear force, this method is widely used in the demolition operation of urban elevated hollow slab bridges. At present, the existing construction methods require drilling hoisting holes on the beam body, which will cause secondary damage to the original old beam body. At the same time, the hollow slab beam body is generally thick, and drilling holes for hoisting is time-consuming and laborious. Moreover, when hoisting and demolishing, the articulated joints between the beam plates are adhered, affecting the operation safety and easily causing safety accidents. Based on this, it is necessary to study a construction method for demolishing urban hollow slab main line bridges. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a construction method for demolishing urban hollow slab main line bridges, which effectively solves the problems that the existing construction methods require drilling hoisting holes on the beam body, which will cause secondary damage to the original old beam body, and at the same time, the hollow slab beam body is generally thick, drilling holes for hoisting is time-consuming and laborious, and when hoisting and demolishing, the articulated joints between the beam plates are adhered, affecting the operation safety and easily causing safety accidents.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a construction method for demolishing urban hollow slab main line bridges, including the following steps; Step 1, three-dimensional real-scene model making Use the combined method of oblique photography and unmanned aerial vehicle to photograph the space of the complex construction area of the interchange ramp, and make an equilateral three-dimensional real-scene model; Step 2, determine the lifting points and demolition sequence Collect the spatial data of the existing bridge through the three-dimensional real-scene model, set the crane station position, select the crane model according to the effective operation radius and lifting capacity of the crane, and determine the bridge demolition sequence; Step 3, surface layer demolition and joint cutting Use a milling machine to locally mill the asphalt surface layer of the bridge pavement; then cut the pavement concrete at the longitudinal hinge joint and transverse beam joint positions, and transport it to the designated off-site location by a transport vehicle; Step 4, cutting of the hollow slab beam pavement layer According to the characteristics of the bridge structure, first determine the position of the hinge joints between the hollow slab beams, and mark them by snapping lines on the paving layer. Then, hang lines at the marked positions and use a dust-free circular saw to cut along the snapped lines to separate the bridge deck paving layer between adjacent slab beams. Step Five, grooving at the ends of the hollow slab beams Open grooves at the solid sections at both ends of the slab beam. During the construction process of the groove, first use a drilling tool to drill a first round hole on one side of the longitudinal cutting seam, then drill a second round hole on the opposite side of the longitudinal cutting seam, and then use a tool to cut off the connecting part between the first round hole and the second round hole to connect the first round hole and the second round hole, forming an inner groove body with a circular arc structure on both sides. Step Six, place the jacking device The jacking device includes a jack, a first pushing top and a second pushing top. The outer sides of the first pushing top and the second pushing top are in an arc structure and can be respectively adapted to the first round hole and the second round hole. The jack is connected between the first pushing top and the second pushing top; adjust the length of the jack so that the first pushing top and the second pushing top can be correspondingly placed in the first round hole and the second round hole, and then synchronously start the jacks at both ends of the slab beam for synchronous jacking to separate a gap between the hollow slab beams. Step Seven, hoisting Pass the steel wire rope through the gap to the bottom, then connect the steel wire rope to the lifting tool, and use the hoisting equipment to lift the hollow slab onto the transport vehicle. Step Eight, demolition of the capping beam, pier column and foundation The capping beam is cut in segments by the support method in cooperation with a wire saw, the pier column is cut in segments by a wire saw, and the enlarged foundation is demolished by a hydraulic breaker and gas cutting. The demolished structures are transported to the designated storage area by flatbed trucks along the construction access road.

[0007] Furthermore, the lifting tool includes a lifting body, an upper lifting ear and a lower lifting ear. The upper lifting ear and the lower lifting ear are respectively arranged at the upper and lower parts of the lifting body. There are two lower lifting ears. The steel wire rope is led out from one lifting ear, and then loops around the bottom of the hollow slab and is fixed on the other lifting ear. The upper lifting ear is connected to the hoisting equipment.

[0008] Furthermore, during the construction process of the groove, determine the groove opening points according to the structure of the hollow slab, then draw lines, and the drilling tool constructs according to the drawn lines.

[0009] Furthermore, the first round hole and the second round hole are of the same size and are symmetrical about the longitudinal cutting seam.

[0010] Furthermore, the first pushing top and the second pushing top have the same structure, both are steel partial ring structures, and a connecting block is arranged inside the ring structure. The jack is connected between the two connecting blocks.

[0011] Further, both ends of the jack are hinged between the connecting blocks on both sides, and a positioning component is arranged between the connecting blocks. The positioning component includes a positioning rod and a positioning sleeve. The inner ends of the positioning rod and the positioning sleeve are fitted together, and their outer ends are fixed on the connecting blocks.

[0012] Further, in step three, the asphalt pavement layer is demolished in a crosswise manner, and the separation sequence is to advance from one end to the other end along the transverse direction of the hollow slabs of each span of the bridge.

[0013] The beneficial effects of the above technical solution are as follows: In view of the situation that the GPS signal is weak under the overpass and cannot be measured, the present invention uses the oblique photography + UAV technology to photograph the space of the complex construction area of the overpass ramp, and makes an equilateral three-dimensional real scene model, and the accuracy can reach millimeters. The spatial data of the existing bridge is collected through the three-dimensional real scene model, the crane station is set, and the working radius and lifting capacity of the crane are calculated, providing data support for the bridge demolition construction.

[0014] During construction, the paving layer and hinge joints of the hollow slab beams are cut along the longitudinal bridge direction in a coiled manner, and the connection of the paving layer at the ends of the hollow slab beams in the transverse bridge direction is cut to separate the connection constraints between each hollow slab, so that the hollow slab beams form single independent individuals, and at the same time, the structure of the bridge hollow slab body is not damaged. The construction machinery is conventional equipment, with simple operation, little damage to the bridge structure, and ensuring the safety of construction operations.

[0015] At the same time, the present invention opens an 8-shaped groove at both ends of the hollow slab beam, and two jacks of the same specification and model are installed in parallel in the groove. The adjacent hollow slab beams are separated by synchronous jacking. On the one hand, it ensures that the hinge joint constraints between adjacent beam bodies are completely released. On the other hand, it is convenient for the sling wire rope to carry out the bottoming operation. The 8-shaped groove structure cooperates with the pushing top to have good limit, and the jacks are started synchronously to ensure that the hollow slabs move parallel and steadily, and always remain in the stable stress state of simply supported beams, avoiding inconsistent translation during the pushing process and ensuring construction safety.

[0016] Therefore, the present invention uses a coiled method to cut the deck paving layer and the hinge joints between the slab beams of the hollow slab beam, separates each hollow slab beam body, and uses a special sling to hoist and demolish the beam body. Compared with the demolition construction, it has low noise, less dust, no damage to the stress of the bridge structure, is safe and reliable, and meets the environmental protection construction requirements for the demolition of old bridges in the city. Description of the Drawings

[0017] Figure 1 It is a cross-sectional structure diagram of a hollow slab beam bridge; Figure 2 It is a structural schematic diagram of the end slot of the hollow slab beam; Figure 3 It is a structural schematic diagram of the groove; Figure 4 It is a structural schematic diagram of the pushing device; Figure 5Another schematic structural diagram of the pushing device; Figure 6 is Figure 4 front view; Figure 7 Schematic structural diagram of the lifting appliance; Figure 8 is Figure 7 front view.

[0018] Figure 9 Example diagram of the 3D model; Figure 10 Construction step diagram of the present invention; Figure 11 Schematic structural diagram of the on-site construction of the present invention; Figure 12 Vertical elevation view of the demolition and lifting of the hollow slab.

[0019] Reference numerals: 1 is the asphalt surface course, 2 is the paved concrete, 3 is the hollow slab layer, 4 is the capping beam, 5 is the pier column, 6 is the foundation, 7 is the hollow slab, 8 is the groove, 9 is the first pushing part, 10 is the second pushing part, 11 is the jack, 12 is the connecting block, 13 is the hinge seat, 14 is the positioning assembly, 15 is the upper lifting ear, 16 is the lifting body, 17 is the lower lifting ear, 18 is the green belt. Detailed implementation manners

[0020] The present invention will be further described in detail below in conjunction with the drawings and the specific implementation manners: Example 1, this example aims to provide a construction method for demolishing the main-line bridge of urban hollow slab type, which is applicable to the demolition construction of hollow slab beams under the same type and similar conditions. Aiming at the problem that the existing construction method needs to drill lifting holes on the beam body, which will cause secondary damage to the original old beam body. At the same time, the hollow slab beam body is generally thick, and drilling holes for lifting is time-consuming and laborious. Moreover, when hoisting and demolishing, the separation of the beam slab is not complete, resulting in adhesion of the hinge joints between the slabs, affecting the operation safety and easily causing safety accidents. This example provides a construction method for demolishing the hollow slab beam of the overpass existing viaduct.

[0021] During the construction of this embodiment, a saw is used to cut the paving layer and hinge joints of the hollow slab beams longitudinally along the bridge, and the connection of the paving layer at the ends of the hollow slab beams is cut transversely to release the constraint of the paving layer between the hollow slab beams. To avoid damaging the hollow slab beams of the old bridge by opening lifting holes, this construction method uses 8-shaped grooves at the solid sections at both ends of the hollow slab beams. Two electric jacks of the same specification and model are installed in parallel in the grooves, and the jacks are synchronously pushed to separate the adjacent hollow slab beams by a 10-cm gap. On the one hand, opening grooves at the solid sections at the beam ends instead of drilling lifting holes in the beam body can avoid damaging the beam body of the old bridge hollow slab beams. On the other hand, using jacks to synchronously push out a 10-cm gap at the beam ends facilitates lifting with a wire rope sling, ensures the stability of the beam structure, and at the same time ensures that the hinges between adjacent hollow slab beams are completely released. After the hollow slab beams are separated in blocks, a lifting tool is used for lifting and removing operations, thereby accelerating the construction progress and effectively ensuring the safety of construction operations.

[0022] During the specific construction process, such as Figure 10 shown in the construction step flow chart, this embodiment provides a method for demolishing a urban hollow slab main bridge, including the following steps; Step 1, three-dimensional real-scene model making Use the combined method of oblique photography and unmanned aerial vehicle (UAV) to photograph the space of the complex construction area of the interchange ramp, and make an equal-proportion three-dimensional real-scene model; before construction, use the oblique photography + UAV technology to collect complex spatial data in the interchange area and make an equal-proportion three-dimensional real-scene model.

[0023] Before construction, use the oblique photography + UAV technology to photograph the construction area and establish an equal-proportion three-dimensional real-scene model. Specifically, as an example, the model instance is shown in Figure 9 shown. Collect the spatial data of the existing bridges on the interchange ramp. According to the collected effective working space data, select a reasonable crane standing position, measure the effective working radius of the crane in the oblique photography + UAV model, check the lifting capacity of the crane through the weight of a single hollow slab beam and the limited working radius of the crane, select the crane model, determine the demolition sequence of the hollow slab beams, and determine the operation plan.

[0024] Step 2, determine the lifting points and demolition sequence Collect the spatial data of the existing bridges through the three-dimensional real-scene model, set the crane standing position, select the crane model according to the effective working radius and lifting capacity of the crane, and determine the bridge demolition sequence.

[0025] Step 3, surface layer demolition and gap cutting Use a milling machine to perform local milling on the asphalt surface layer 1 of the bridge pavement; then cut the paving concrete 2 at the longitudinal hinge joint and transverse beam joint, and use a transport vehicle to transport it to a designated location outside the site; before the bridge load-bearing structure is formally dismantled, first use a milling machine to perform local milling on the asphalt surface layer 1 of the existing bridge pavement (subject to the actual situation on site), cut the paving concrete 2 at the longitudinal hinge joint and transverse beam joint, and use a transport vehicle to transport it to a designated location outside the site. During the cutting process of the milling machine, a fog cannon truck is used to continuously spray water to reduce dust.

[0026] At the same time, during construction, the auxiliary parts will be dismantled. For example, when dismantling street lights, make sure the power is disconnected before dismantling. Then use a crane to lift them. The lifting rope must be kept close to the street light pole to prevent it from tipping over during the loosening of the bolts. Finally, use a transport vehicle to transport them off-site.

[0027] On the bridge deck, a truck crane is used to dismantle the bridge signboards, sidewalk slabs, and anti-collision guardrails, etc., and transport them to the designated location. The sidewalk cover is removed according to the actual situation. If the sidewalk cover is a precast concrete cover, during the removal process, a cutting machine is used to cut the wet joint position, and then a crane is used to lift it to the transport vehicle and transport it to the designated location outside the site; the guardrail is cut by a cutting machine, cut into sections of 4 meters, and then the base is crushed and dismantled, and finally lifted by a crane to a temporary storage area, and then transported to the designated location outside the site.

[0028] In addition, in this embodiment, the asphalt pavement layer is removed in sections during construction, and the separation order is from one end to the other end along the horizontal direction of the hollow slab of each span of the bridge. During the cutting and disassembly of the bridge deck accessories, damage to the beam body should be avoided as much as possible, and protective measures should be taken to ensure that debris during the construction process does not splash outside the beam body.

[0029] Step 4: Cutting of hollow slab beam pavement layer According to the characteristics of the bridge structure, the position of the hinge joint between the hollow slab beams is first determined, and a line is drawn on the pavement layer to mark it. Then a line is hung at the marked position, and a dust-free disk saw is used to cut along the line position to separate the bridge deck pavement layer between adjacent slab beams. Step 5: Slotting the hollow slab beam ends Grooves 8 are opened at the solid sections at both ends of the slab beam. During the construction process of the grooves 8, the positions for opening the grooves are determined according to the structure of the hollow slab 7, and then lines are drawn. The drilling tool constructs according to the drawn lines. First, a first round hole is drilled on one side of the longitudinal cut using a drilling tool, then a second round hole is drilled on the opposite side of the longitudinal cut, and then the connecting part between the first round hole and the second round hole is cut off with a tool, so that the first round hole communicates with the second round hole, forming an inner groove body with an arc-shaped structure on both sides; in this embodiment, an 8-shaped groove structure is used to separate the hollow slab, and the embedded holes at both ends restrain each other, thereby ensuring that the hollow slab can be pushed synchronously, making the gaps uniform and avoiding the situation of uneven gaps and partial adhesion of the hollow slab.

[0030] Step Six, Place the Jacking Device The jacking device includes a jack 11, a first pushing top 9, and a second pushing top 10. The outer sides of the first pushing top 9 and the second pushing top 10 are arc-shaped structures and can be respectively adapted to the first round hole and the second round hole. The jack 11 is connected between the first pushing top 9 and the second pushing top 10; adjust the length of the jack 11 so that the first pushing top 9 and the second pushing top 10 can be correspondingly placed in the first round hole and the second round hole, and then synchronously start the jacks at both ends of the slab beam for synchronous jacking to separate a gap between the hollow slab beams; during implementation, the first round hole and the second round hole are of the same size and are symmetric about the longitudinal cut. During construction, the round hole drill bit is closely attached to the gap to construct the first round hole, and then the second round hole is constructed in the same way, and then the connecting part in the middle of the two is cut off with a cutter to form an 8-shaped groove structure.

[0031] In terms of structure, the first pushing top 9 and the second pushing top 10 have the same structure, both are steel partial ring structures, and a connecting block 12 is arranged inside the ring structure. The jack 11 is connected between the two connecting blocks 12. This structure can receive the load of the jack through the connecting block and transfer it to the pushing top. Preferably, the connecting block is arranged in the middle of the pushing top, and then the pushing top is forced from the middle to separate the hollow slab.

[0032] In this embodiment, the 8-shaped groove structure is used in cooperation with the pushing top to have good limiting, and the jacks are started synchronously to ensure that the hollow slab moves parallel and steadily and is always in a stable stress state of a simply supported beam, avoiding inconsistent translation during the jacking process and ensuring construction safety.

[0033] Step Seven, Hoisting Pass the steel wire rope through the gap to lift from the bottom, and then connect the steel wire rope to the lifting tool. Use the hoisting equipment to lift the hollow slab onto the transport vehicle; the lifting tool includes a lifting body 16, an upper lifting ear 15, and a lower lifting ear 17. The upper lifting ear 15 and the lower lifting ear 17 are respectively arranged at the upper and lower parts of the lifting body. There are two lower lifting ears. The steel wire rope is led out from one lifting ear, and after surrounding the hollow slab from the bottom, it is fixed to the other lifting ear. The upper lifting ear is connected to the hoisting equipment.

[0034] Step 8, demolition of capping beams, piers and foundations For the capping beam, the support method is used in combination with segmental cutting by a rope saw. For the pier column, segmental cutting is carried out using a rope saw. For the enlarged foundation, it is demolished using a hydraulic breaker and gas cutting. The demolished structure is transported to the designated storage area by flatbed truck along the construction access road.

[0035] As Figure 11-12 shown in the construction flow chart, all lifting equipment uses truck cranes. The demolished structure is transported to the designated storage area by flatbed truck along the construction access road. Drilling is carried out 2 meters from the beam end, and the horizontal distance between the two holes is 1 meter. Lifting is carried out using steel wire ropes, and the steel wire ropes are wound around rubber belts for protection. The waste after bridge demolition is transported to the designated location for centralized treatment, and the beam is firmly tied with ropes during external transportation.

[0036] The lifting appliance is fabricated from steel sections with a thickness of 2 cm. Taking the example of a 16 m long hollow slab beam in a certain project, a 16 m long lifting appliance is set according to the length of the hollow slab beam section for use in the demolition and lifting operation of the hollow slab beam. To ensure the safety and reliability during the lifting operation, the upper lifting lugs of the lifting appliance are respectively set 2 meters from the end, facilitating a 60° safety angle between the upper steel wire rope and the lifting appliance. The lower lifting lugs of the lifting appliance are set 1 m from the beam end. When the length of the hollow slab beam changes, the position of the lower lifting lugs can be changed (so that the position where the steel wire rope holds the hollow slab at the bottom is 1 m from the beam end).

[0037] In this embodiment, due to the limited operation space and complex surrounding environment of urban elevated bridges, the crane lifting and demolition method is generally adopted. This embodiment overcomes the problem that the currently commonly used method of opening lifting holes causes secondary damage to the old bridge body, and the problem that it is time-consuming and laborious to drill holes in relatively thick hollow slab beams. At the same time, the use of jacks to synchronously push and separate the hollow slabs can effectively release the adhesion constraints between the beam bodies and ensure the safety of the lifting operation. Through the independently developed lifting appliance, the construction efficiency, material turnover efficiency and mechanized operation level of the demolition of hollow slab beams in a limited space are improved, and considerable economic benefits are achieved.

[0038] Taking the comparison of drilling lifting holes as an example, when using drilling lifting holes to lift and transport hollow slab beams, a professional drilling operation team is required. Two lifting holes are drilled at the hinge joints at both ends of every two hollow slab beams. The whole bridge has a total of 38 spans, and an average of 24 hollow slab beams per span. Calculated in total, 38×23×2 = 1748 lifting holes need to be drilled. The construction of a single lifting hole using a water drill costs 400 yuan, and the total cost for drilling lifting holes in hollow slab beams is 1748×400 = 699,200 yuan. By using the method of opening grooves in the solid sections at both ends of the beam body and synchronously pushing and separating adjacent beam bodies using electric jacks, the cost of drilling lifting holes can be saved, and economic benefits of 699,200 yuan can be generated.

[0039] This embodiment is applicable to bridge demolition projects of various heights and slopes in confined spaces due to the characteristics of limited operation space for urban elevated bridge demolition, complex surrounding environment, high requirements for maintaining traffic on the operating road, and high requirements for environmental protection. It has wide applicability and can improve the speed of project construction and ensure the construction quality of the project. This construction technology improves work efficiency, reduces labor, saves costs, and has achieved good economic and social benefits, showing good application prospects in bridge demolition construction.

[0040] Embodiment 2 further describes the pushing structure.

[0041] In this embodiment, both ends of the jack 11 are hinged between the connecting blocks 12 on both sides, and a positioning component 14 is arranged between the connecting blocks 12. In a specific structure, the positioning component 14 includes a positioning rod and a positioning sleeve. The inner ends of the positioning rod and the positioning sleeve are fitted together and can slide relative to each other, and their outer ends are fixed to the connecting blocks. During implementation, hinge seats 13 are correspondingly arranged on the two connecting blocks, and both ends of the jack are connected to the hinge seats 13.

[0042] In order to reduce the load on the jack in this embodiment, during the pushing process, the adhesion strength between the hollow slabs is inconsistent. Even if the jacks apply force synchronously, the situation of inconsistent translation inside the hollow slabs will still occur. In this case, the hollow slabs on both sides of a plane will tilt, thereby causing the pushing structure to bear this external force, that is, applying a force to the first pushing part through the first round hole, and applying a force to the second pushing part through the second round hole in the sleeve, and forcing the jack connecting the two pushing parts to deflect, which easily damages the jack. In order to reduce the load on the jack, in this embodiment, the jack is hinged between the two connecting blocks in a hinged manner and is limited by the positioning component. Even if deflection occurs, the positioning component bears the load. At the same time, the positioning component is used to position the two pushing parts and protect the jack when necessary.

Claims

1. A construction method for demolishing the main girder of an urban hollow slab bridge, characterized in that, It includes the following steps; Step 1, three-dimensional real-scene model making Photograph the space of the complex construction area of the interchange ramp by combining oblique photography and unmanned aerial vehicle, and make an equi-scale three-dimensional real-scene model; Step 2, determine the lifting points and demolition sequence Collect the spatial data of the existing bridge through the three-dimensional real-scene model, set the crane positions, select the crane model according to the effective operation radius and lifting capacity of the crane, and determine the bridge demolition sequence; Step 3, surface layer demolition and joint cutting Use a milling machine to locally mill the asphalt surface layer of the bridge pavement; then cut the pavement concrete at the longitudinal hinge joints and transverse beam joints, and transport it to the designated off-site location by a transport vehicle; Step 4, cutting of the paving layer of the hollow slab beam According to the structural characteristics of the bridge, first determine the position of the hinge joints between the hollow slab beams, and mark them by snapping lines on the paving layer. Then hang lines at the marked positions, and use a dust-free circular saw to cut along the snapped lines to separate the bridge pavement between adjacent slab beams; Step 5, grooving at the ends of the hollow slab beams Open grooves at the solid sections at both ends of the slab beam. During the construction process of the grooves, first use a drilling tool to drill a first round hole on one side of the longitudinal cut, then drill a second round hole on the opposite side of the longitudinal cut, and then use a tool to cut off the connecting part between the first round hole and the second round hole to make the first round hole communicate with the second round hole, forming an inner groove body with a circular arc structure on both sides; Step 6, place the jacking device The jacking device includes a jack, a first pushing part and a second pushing part. The outer sides of the first pushing part and the second pushing part are in an arc structure and can be respectively adapted to the first round hole and the second round hole. The jack is connected between the first pushing part and the second pushing part; adjust the length of the jack so that the first pushing part and the second pushing part can be correspondingly placed in the first round hole and the second round hole, and then synchronously start the jacks at both ends of the slab beam to perform synchronous jacking to separate a gap between the hollow slab beams; Step 7, hoisting Pass the steel wire rope through the gap to the bottom, then connect the steel wire rope to the lifting tool, and use the hoisting equipment to lift the hollow slab onto the transport vehicle; Step 8, demolition of the capping beam, pier column and foundation The capping beam is cut in segments by the support method in cooperation with a wire saw, the pier column is cut in segments by a wire saw, the enlarged foundation is demolished by a hydraulic breaker and gas cutting, and the demolished structure is transported to the designated storage area by a flatbed truck along the construction access road.

2. The construction method for demolishing the main urban hollow slab bridge according to claim 1, wherein: The lifting tool includes a lifting body, an upper lifting ear and a lower lifting ear. The upper lifting ear and the lower lifting ear are respectively arranged at the upper and lower parts of the lifting body. There are two lower lifting ears. The steel wire rope is led out from one lifting ear, and is fixed to the other lifting ear after surrounding the hollow slab at the bottom. The upper lifting ear is connected to the hoisting equipment.

3. The construction method for demolishing the main urban hollow slab bridge according to claim 1, characterized in that: During the construction process of the groove, determine the groove opening points according to the structure of the hollow slab, then draw lines, and the drilling tool constructs according to the drawn lines.

4. The construction method for demolishing the main urban hollow slab bridge according to claim 1, characterized in that: The first round hole and the second round hole are of the same size and are symmetric about the longitudinal cut.

5. The construction method for demolishing the main urban hollow slab bridge according to claim 1 is characterized in that: The first pushing part and the second pushing part have the same structure, both are steel partial ring structures, and a connecting block is arranged inside the ring structure. The jack is connected between the two connecting blocks.

6. The construction method for demolishing the main urban hollow slab bridge according to claim 5, characterized in that: Both ends of the jack are hinged between the connecting blocks on both sides, and a positioning component is arranged between the connecting blocks. The positioning component includes a positioning rod and a positioning sleeve. The inner ends of the positioning rod and the positioning sleeve are fitted together, and their outer ends are fixed on the connecting blocks.

7. The construction method for demolishing the main urban hollow slab bridge according to claim 1, characterized in that: In step three, the asphalt pavement layer is demolished in sections across the spans, and the separation sequence is to advance from one end to the other end along the transverse direction of the hollow slabs of each span of the bridge.

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