Hollow slab bridge roof and bridge deck pavement local damage repair and reinforcement structure and method

Abstract

The application relates to a hollow plate bridge roof and bridge deck pavement local damage repairing and reinforcing structure and method, belongs to the technical field of bridge repairing and reinforcing, and is suitable for small-area local damage working conditions with a transverse width of not more than 50 cm and a longitudinal length of not more than 1.1 m. The structure comprises three layers of rectangular repairing spaces formed by chiseling out boundaries and gradually shrinking, an inverted trapezoidal lap steel bar system, a formwork plugging system, a double self-stressing concrete reinforcing layer poured in a lower high self-stress and upper low self-stress mode, a penetration interlocking layer formed by using hydration heat to make high-viscosity emulsified asphalt penetrate into a surface layer at a terminal condensation initial stage, a composite waterproof bonding layer composed of hot asphalt and basalt fibers, and an asphalt pavement layer. The application does not need personnel to enter the cavity, the steel plate is used as a bottom die and a tension member, and the new and old structures form a crack-resistant waterproof whole in five aspects of continuous steel bars, expansion prepressing, ladder interlocking, steel plate compounding and asphalt sealing.

Description

Technical Field

[0001] This invention belongs to the field of bridge maintenance and reinforcement technology, and specifically relates to the repair and reinforcement structure and method for partial damage to the top slab and pavement of hollow slab bridges. Background Technology

[0002] Precast prestressed concrete hollow slab bridges are one of the most numerous bridge types in my country's highways and urban bridges. Under the long-term effects of heavy traffic, water seepage at hinge joints, and stress on individual slabs, this type of bridge commonly suffers from defects such as hinge joint damage, localized cracking and spalling of the top concrete of the hollow slab, pavement cracking, pumping, and potholes. In addition to large-area defects requiring treatment of the entire span, small-area localized cracks on the top surface of individual slabs, ranging from 0.5m to 1.0m, are more common in engineering projects. Rainwater seeps into the hollow slab cavity along the damaged areas, corroding the reinforcing steel, forming a vicious cycle of "water seepage-corrosion-cracking-reflective cracking." Small-damage bridges are difficult to support with formwork, prone to debonding and cracking at the interface between new and old concrete, and the single expansive concrete can easily cause the pavement layer to arch, thus affecting the durability of the reinforced structure.

[0003] For the aforementioned defects, the existing repair and reinforcement technologies mainly include the following solutions: For example, Chinese patent CN115030067A discloses a repair and construction method for replacing reinforced concrete bridge deck pavement without interrupting traffic. This method involves using a cutting machine to chisel away the damaged pavement to create a pouring groove, retaining the original pavement's reinforcing mesh, welding one end of the transverse reinforcing bars to the mesh, and extending the other end into the original pavement to overlap. After pouring shrinkage-compensating concrete, the pavement is cured for at least 3 days. This method only removes the asphalt surface layer and pavement concrete, and only roughens the hollow slab top slab. The structural damage to the top slab itself is not repaired, and under heavy vehicle loads, the cracks in the top slab continue to develop, reflecting onto the newly constructed surface layer in a short period.

[0004] For example, CN112323655A discloses a reinforcement method for converting simply supported hollow slab beams to continuous structures. This method involves creating pouring holes in the top slab, installing lateral sealing plates within the cavity to separate the pouring area, and then filling the cavity with micro-expansion self-compacting concrete. While this solution serves for continuous beam end reconstruction, the sealing plates are used for cavity separation, not as supporting formwork after the top slab is drilled through. Furthermore, the large-scale filling of the cavity with concrete significantly increases the beam's self-weight, complicates the process, and increases costs. Another repair method involves injecting grout into the inner cavity through inspection holes in the bottom slab and filling it with foamed lightweight soil to support the top slab repair material. This method uses flexible filling material as long-term support for the repair, making it difficult to guarantee the compressive deformation and durability of the filling material under vibration loads, and it also fails to reconstruct the load-bearing section of the top slab.

[0005] CN112627066A discloses a comprehensive reinforcement system for hollow slab bridges based on UHPC and loosely bonded steel strands. This system involves erecting a suspended formwork at the bottom of the hollow slab, casting in-situ UHPC to increase the cross-section, and laterally tensioning the steel strands. This type of solution requires space for formwork support or suspended operations under the bridge, making it impractical when the bridge crosses a river, existing road, railway, or when the clearance under the bridge is limited. Furthermore, it involves reinforcement of the entire bridge, resulting in high costs and long construction periods for small, localized damage.

[0006] For partial repair work on hollow slab bridges where the top slab has cracked and needs to be drilled through for reconstruction, the existing technology still has the following unresolved technical problems: Firstly, once the top slab is breached, the bottom formwork cannot be erected, and the formwork within the cavity is strictly limited by the hollow slab structure. The top slab of the hollow slab is only 8cm to 15cm thick. After the damaged top slab is breached, the bottom of the repair space becomes connected to the inner cavity of the hollow slab, requiring the bottom formwork to support the pouring of new concrete. Underpass scaffolding cannot be erected when there is water under the bridge, insufficient clearance, or when traffic is flowing under the bridge. Furthermore, working inside the cavity is equally difficult: the clear width of the cavity in a standard section of the prefabricated hollow slab is approximately 760mm, and the clear height is only 0.6m to 0.9m, making it impossible for personnel to enter. More importantly, the cavity opening at the beam end of the hollow slab has a tapered structure, with a clear width of only about 600mm at the tapered end. Any formwork component that needs to be inserted into the cavity must not exceed the clear width of the tapered end in any direction. Existing technologies do not provide a bottom formwork support scheme for small-area localized damage conditions, which does not require personnel to enter the cavity, and allows components to be sent in and reliably positioned through the beam end closing opening; while if a large-sized solid steel plate is simply used, its width exceeds the net width of the closing opening, and it cannot be sent in regardless of whether it is horizontal or inclined, so this technical approach is geometrically unsound.

[0007] Secondly, the stress positioning of the retained bottom formwork is unclear. The bottom formwork inside the cavity cannot be removed and must be permanently retained. However, the bond between the smooth steel plate and the newly poured concrete is weak. If the steel plate is simply left inside the cavity as a disposable bottom formwork, it is prone to detachment from the reconstructed concrete under the vibration of vehicles, resulting in hollow sounds and water seepage gaps. Furthermore, the back of the steel plate, constantly exposed to the humid environment inside the cavity, will corrode. The retained component, in turn, becomes a potential source of defects. Current technology does not provide a structure that reliably integrates the retained steel plate with the reconstructed structure, allowing them to share the load.

[0008] Third, the shrinkage difference between new and old concrete leads to interface separation. There is a shrinkage difference between the newly poured concrete for local repairs and the old concrete that is retained. The tensile strength of the interface in ordinary concrete repairs is weak, making it prone to circumferential shrinkage cracks, interface hollowing, and water seepage. Furthermore, the constraint conditions within the bridge deck repair section vary significantly along the height: the lower top slab reconstruction area is strongly constrained by the old concrete and dense reinforcement, while the upper pavement reconstruction area is close to a free surface with very weak constraint. When using concrete with the same expansion admixture, the expansion energy in the lower part is converted into favorable interfacial prestress, while the expansion energy in the upper part is converted into free expansion, resulting in surface blistering and hollowing. Existing technologies do not provide a layered self-stress scheme that matches the constraint gradient along the height.

[0009] Fourth, there are contradictions in the repair procedures. The waterproof bonding layer for bridge decks requires a dry base surface, and hot asphalt is usually applied after the concrete has cured and set; however, newly poured concrete needs to be moistened and cured as soon as possible. If hot asphalt is applied first and then covered for curing, the impermeable film formed by the hot asphalt will block the supply of curing water, and the residual moisture on the base surface after the emulsified asphalt tack coat breaks will vaporize and bubble when it encounters the 150℃~170℃ hot asphalt, significantly reducing the adhesion of the waterproof bonding layer.

[0010] Fifth, repair reflective cracks at the boundary. Locally repaired asphalt surface joints and the interface between concrete repairs and pavement layers are prone to reflective cracks and water seepage at the joints under repeated traffic loads. This requires a multi-pronged approach, addressing issues such as removing the boundary shape, reinforcing bar laps, interface bonding, and sealing construction. Summary of the Invention

[0011] This invention provides a repair and reinforcement structure and method for partially damaged hollow slab bridge top slabs and bridge deck pavement, which can solve the problems pointed out in the background art.

[0012] A repair and reinforcement structure for partial damage to the top slab and pavement of a hollow slab bridge includes a three-tiered repair space in the damaged area of ​​the hollow slab bridge, an inverted trapezoidal lapped steel reinforcement system, a formwork sealing system, a double self-stressed concrete reinforcement layer, a high-viscosity emulsified asphalt penetrating interlocking layer, a composite waterproof bonding layer, a new asphalt pavement layer, and a new and old asphalt joint sealing layer. The three-tiered repair space is formed by chiseling away layers of the damaged area from top to bottom. From top to bottom, the chiseling boundaries are formed by asphalt pavement, concrete pavement, and hollow slab top. The three chiseling boundaries gradually shrink inward, forming a stepped repair boundary that is wider at the top and narrower at the bottom. A stepped horizontal plane is formed between adjacent chiseling boundaries. Each chiseling surface is a vertical plane, and each chiseling surface and stepped horizontal plane are roughened to expose fresh aggregate. The inverted trapezoidal lapped reinforcement system includes longitudinal and transverse lapped reinforcement and newly added stirrups. The longitudinal and transverse lapped reinforcement includes upper transverse lapped reinforcement, upper longitudinal lapped reinforcement, lower transverse lapped reinforcement, and lower longitudinal lapped reinforcement. One end of the upper transverse lapped reinforcement, upper longitudinal lapped reinforcement, lower transverse lapped reinforcement, and lower longitudinal lapped reinforcement is connected to the original longitudinal and transverse reinforcement of the pavement retained at the facade of the three-level stepped repair space, and the other end extends into the three-level stepped repair space. The newly added stirrups are connected to the upper transverse lapped reinforcement, upper longitudinal lapped reinforcement, lower transverse lapped reinforcement, and lower longitudinal lapped reinforcement to form a enclosure. Both ends of the stirrups are respectively connected to the original longitudinal and transverse reinforcement of the hollow slab top plate and the longitudinal and transverse lapped reinforcement in the three-level stepped repair space, forming an inverted trapezoidal integral reinforcement mesh that is wider at the top and narrower at the bottom, which is adapted to the stepped repair boundary. The inverted trapezoidal integral reinforcement mesh adopts a reinforcement form that is denser at the bottom and sparser at the top, with the bottom reinforcement ratio being greater than the top reinforcement ratio. The template sealing system includes steel insert rails, a single steel plate bottom template, and vertical connecting steel bars. Two parallel steel insert rails are fixed to the bottom surface of the top plate of the hollow slab cavity along the longitudinal direction of the bridge and are located on the outer sides of the repair area on both sides. Each steel insert rail has a U-shaped guide groove along its own longitudinal direction, and the openings of the two U-shaped guide grooves are arranged opposite each other. The two sides of the single steel plate bottom template are slidably engaged in the two U-shaped guide grooves. The single steel plate bottom template is horizontally inserted from the end cavity of the hollow slab beam and slides longitudinally along the U-shaped guide grooves into place, with its top surface closely attached to the hollow slab. The bottom surface of the top slab covers the bottom opening of the three-tiered repair space; the back of the whole steel plate bottom template facing the hollow slab cavity is provided with threaded sleeves, and the whole steel plate bottom template has connecting round holes corresponding to the positions of the inner holes of each threaded sleeve; the vertical connecting steel bars pass through the connecting round holes from top to bottom and are threadedly connected to the threaded sleeves, and their upper parts extend into the inverted trapezoidal lapped steel bar system and are connected to the newly added stirrups; the gaps between the whole steel plate bottom template and the side wall of the hollow slab, as well as the gaps between the connecting round holes and the vertical connecting steel bars, are all provided with sealing layers; the steel insert-type track and the whole steel plate bottom template are permanently retained in the hollow slab cavity; The double self-stressed concrete reinforcement layer is filled and solidified inside the three-level stepped repair space. It is an integrated solid structure formed by the upper layer of high self-stressed concrete and the lower layer of low self-stressed concrete. The lower layer of high self-stressed concrete corresponds to the reconstruction range of the hollow slab top plate, and the upper layer of low self-stressed concrete corresponds to the reconstruction range of the bridge deck pavement concrete. The high-viscosity emulsified asphalt penetrating interlocking layer is bonded to the top surface of the double self-stressing concrete reinforcement layer; The composite waterproof adhesive layer is bonded to the top surface of the high-viscosity emulsified asphalt penetrating interlocking layer and is composed of a hot asphalt layer and a basalt fiber layer sprinkled in the hot asphalt layer. The new asphalt pavement layer is laid on top of the composite waterproof bonding layer; the new and old asphalt joint sealing layer is set between the vertical joint surfaces of the new asphalt pavement layer and the original asphalt pavement layer.

[0013] Preferably, the three-tiered repair space has a longitudinal length of no more than 1.1m and a transverse width of no more than 0.5m; the boundary of adjacent layers is extended outward by 10cm to 20cm on one side to form a stepped horizontal surface with a width of 10cm to 20cm; the chiseling surface of each layer is cut with a cutting machine first, and then chiseled to shape, with straight edges and no jagged edges; the roughening depth of the stepped horizontal surface and the chiseling surface of each layer is no less than 3mm, and is cleaned with a high-pressure air gun or high-pressure water.

[0014] Preferably, the upper transverse lapped steel bars, upper longitudinal lapped steel bars, lower transverse lapped steel bars, and lower longitudinal lapped steel bars are HRB400 grade steel bars with a diameter of 10mm to 16mm; when welded to the original longitudinal and transverse steel bars of the pavement on one side, the welding length is not less than 10 times the steel bar diameter; when welded on both sides, the welding length is not less than 5 times the steel bar diameter; and when lapped, the lap length is not less than 35 times the steel bar diameter. The diameter of the newly added stirrups is 8mm to 12mm, the spacing of the bottom stirrups is 100mm to 150mm, and the spacing of the top stirrups is 150mm to 200mm. The bottom reinforcement ratio of the inverted trapezoidal integral steel mesh is 0.8% to 1.5%, and the top reinforcement ratio is 0.3% to 0.6%.

[0015] Preferably, the steel insert-type track is made of galvanized C-shaped steel or galvanized channel steel with a wall thickness of 3mm to 5mm. It is fixed to the bottom surface of the hollow slab top plate with expansion bolts or anchoring adhesive. The fixing points are spaced 0.5m to 1.0m apart longitudinally, and the fixing points are not less than 15cm away from the edge of the opening of the three-stage stepped repair space. The top surface of the U-shaped guide groove is flush with the bottom surface of the hollow slab top plate. The whole steel plate bottom template is made of steel plate with a thickness of 5mm to 10mm. Its width is 3mm to 5mm narrower than the spacing between the two U-shaped guide grooves, and its longitudinal length is 5cm to 10cm longer on each side than the chiseling length of the three-stage stepped repair space along the longitudinal direction of the bridge. Both the steel insert-type track and the whole steel plate bottom template are galvanized or coated with anti-rust paint. The sealing layer is made of epoxy resin or fast-setting cement-based sealing material.

[0016] Preferably, the threaded sleeve is welded and fixed to the back of the bottom formwork of the whole steel plate, and is arranged in a rectangle along the longitudinal and transverse directions of the bottom formwork of the whole steel plate; the vertical connecting steel bar is made of HRB400 grade steel bar, and its lower end is provided with external thread and screwed into the internal thread of the threaded sleeve, with a screwing depth of not less than 20mm, and the exposed thread length of the vertical connecting steel bar after screwing is not greater than 2mm; the upper part of the vertical connecting steel bar extends into the double self-stressed concrete reinforcement layer and is provided with a hook section, and the hook section is tied or welded to the newly added stirrup.

[0017] Preferably, the lower high self-stress concrete layer has a strength grade of not less than C40, a restricted expansion rate of not less than 0.08% after 14 days of underwater curing, and longitudinal and transverse self-stress values ​​of not less than 3MPa after hardening; the upper low self-stress concrete layer has a strength grade of not less than C40, a restricted expansion rate of not less than 0.05% after 14 days of underwater curing, and longitudinal and transverse self-stress values ​​of not less than 2MPa after hardening; both concrete layers are prepared using calcium sulfoaluminate or calcium oxide-calcium sulfoaluminate composite expansion agents, and the coarse aggregate particle size is 5mm to 20mm; a concrete interface agent layer is applied between the double self-stress concrete reinforcement layer and the removed vertical surfaces of each layer.

[0018] Preferably, the high-viscosity emulsified asphalt penetrating interlocking layer uses cationic fast-cracking high-viscosity modified emulsified asphalt, with an evaporation residue content of not less than 60% and a spraying amount of 0.8 kg / m² to 1.5 kg / m²; the depth of penetration of the high-viscosity modified emulsified asphalt into the pores of the double self-stressed concrete surface is 3 mm to 10 mm.

[0019] Preferably, the hot asphalt layer is SBS modified asphalt, with a spraying temperature of 150℃~170℃ and a spraying amount of 1.0kg / ㎡~2.0kg / ㎡; the basalt fiber layer has a length of 12mm~20mm, a monofilament diameter of 10μm~20μm, and a spraying amount of 80g / ㎡~150g / ㎡.

[0020] Preferably, the new asphalt pavement layer is constructed by compacting 2 to 3 layers of asphalt concrete, with each layer having a compaction degree of not less than 96%; the lower layer uses medium-grained asphalt concrete, and the upper layer uses fine-grained asphalt concrete or asphalt mastic aggregate mixture; the joint sealing layer between the new and old asphalt is a hot asphalt layer applied to the vertical joint surface.

[0021] A method for repairing and reinforcing partially damaged sections of the top slab and pavement of a hollow slab bridge includes the following steps: S1. Layered and step-by-step removal: The damaged area is measured and marked out, and the damaged area is controlled to have a horizontal width of no more than 50cm and a vertical length of no more than 1.1m. A cutting machine is used to cut along the edge line to the design depth of each layer, and then the damaged asphalt pavement, bridge deck pavement concrete and hollow slab top slab damaged concrete are removed from top to bottom in sequence, forming a three-level stepped repair space with vertical removal facades that are wider at the top and narrower at the bottom. During the removal process, the original longitudinal and transverse steel bars of the pavement at the facades of the three-level stepped repair space are retained and the lap length is reserved. After the removal is completed, the horizontal surface of the steps and each removed facade are roughened and cleaned with a high-pressure air gun or high-pressure water. S2. Sealing of the sliding template inside the cavity: Weld threaded sleeves to the back of the entire steel plate bottom template according to the design spacing and make corresponding connecting round holes; Lay out lines on the outer sides of the repair area on both sides of the bottom surface of the hollow slab top plate, and fix the steel insert rails with opposite U-shaped guide groove openings to the bottom surface of the top plate with expansion bolts or anchoring adhesive; Send the entire steel plate bottom template into the cavity at the end of the hollow slab beam in a horizontal position, so that its two sides are engaged with the two sides of the U-shaped guide groove and slide into place longitudinally, with the top surface closely attached to the bottom of the hollow slab top plate. The bottom opening of the three-tiered repair space is completely sealed. Vertical connecting steel bars are passed from top to bottom through the connecting circular hole at the opening of the three-tiered repair space and screwed into the threaded sleeve for tightening. The upper part of the vertical connecting steel bars is left inside the three-tiered repair space. The gaps between the whole steel plate bottom template and the hollow slab sidewall, as well as the gaps between the connecting circular hole and the vertical connecting steel bars, are sealed with sealing material and a grout leakage check is performed. The steel insert track and the whole steel plate bottom template are permanently retained inside the hollow slab cavity. S3. Inverted Trapezoidal Reinforcing Mesh Formation: One end of the upper transverse lapped reinforcing bars, upper longitudinal lapped reinforcing bars, lower transverse lapped reinforcing bars, and lower longitudinal lapped reinforcing bars is welded or tied to the original longitudinal and transverse reinforcing bars of the pavement retained at the facade of the three-tiered repair space, and the other end extends into the three-tiered repair space; new stirrups are erected and tied or welded to the upper part of the longitudinal and transverse lapped reinforcing bars and the vertical connecting reinforcing bars to enclose the space. The two ends of the new stirrups are respectively tied to the original longitudinal and transverse reinforcing bars and the longitudinal and transverse lapped reinforcing bars of the top slab, forming an inverted trapezoidal integral reinforcing mesh with a bottom reinforcement ratio greater than the top reinforcement ratio and a denser bottom and sparser top, which together with the bottom formwork of the whole steel plate constitutes a composite stress system; S4. Layered pouring of double self-stressed concrete: Before pouring, the vertical surfaces of each layer are removed, moistened with water, and coated with concrete interface agent; first, pour the lower layer of high self-stressed concrete to the top surface elevation of the hollow slab and vibrate to compact it; before the lower layer of concrete sets, continuously pour the upper layer of low self-stressed concrete to the top surface elevation of the original bridge deck pavement concrete, vibrate and smooth the surface; after the two layers harden, an integrated double self-stressed concrete reinforcement layer is formed. S5. Construction of the penetrating interlocking layer: Within 0h to 1h after the final setting of the upper low self-stress concrete, while the concrete surface is still releasing hydration heat, uniformly spray cationic fast-cracking high-viscosity modified emulsified asphalt. Utilize the hydration heat of the concrete to accelerate the demulsification of the emulsified asphalt, allowing asphalt particles to penetrate into the pores of the concrete surface and solidify, forming a high-viscosity emulsified asphalt penetrating interlocking layer. S6. Moisturizing and curing: Cover the repaired area with geotextile or moisturizing film, and continuously spray water for 3 to 5 days to maintain moisture and curing. The high-viscosity emulsified asphalt penetrating interlocking layer also serves as the surface water-retaining film. When the ambient temperature is below 5℃, take heat-insulating covering measures. S7. Construction of composite waterproof bonding layer: After the curing is completed and the repair area is cleaned and dry without standing water, SBS modified hot asphalt at a temperature of 150℃~170℃ is sprayed and basalt fiber layer is then evenly spread. After being compacted by light rubber wheels, a composite waterproof bonding layer is formed. S8. Layered paving: Apply hot asphalt to the vertical joint surface where the new asphalt pavement layer meets the original asphalt pavement layer to form a joint sealing layer between the new and old asphalt layers. Lay the new asphalt pavement layer in layers and compact each layer. The compaction degree of each layer shall not be less than 96%. After paving, roll along the joint. Open to traffic after the surface temperature has cooled to below 50℃.

[0022] Preferably, in step S1, the cutting depth of the cutting machine is controlled so as not to cut the original longitudinal and transverse reinforcing bars to be retained; the chiseling is carried out in sections using hydraulic breakers or pneumatic picks, and manual chiseling is carried out with a small hammer within 10cm of the edge line; the lap length of the retained original longitudinal and transverse reinforcing bars is not less than 35 times the diameter of the reinforcing bars, and the original longitudinal and transverse reinforcing bars are ground and rusted when corroded, and coated with anti-rust paint; in step S2, the track fixing point is not less than 15cm from the edge of the three-stage repair space opening; after the whole steel plate bottom template is slid into place, check the tightness of its top surface and the bottom surface of the hollow slab top plate, and fill the gap with sealing material where the gap is greater than 2mm; after the vertical connecting reinforcing bars are screwed in, the exposed thread length is not greater than 2mm; the U-shaped guide groove is pre-coated with a lubricating layer to reduce the sliding resistance of the whole steel plate bottom template.

[0023] Preferably, in step S3, when one end of the upper transverse lapped steel bars, upper longitudinal lapped steel bars, lower transverse lapped steel bars, and lower longitudinal lapped steel bars is welded to the original longitudinal and transverse steel bars of the paving using single-sided welding, the welding length is not less than 10 times the steel bar diameter; when using double-sided welding, the welding length is not less than 5 times the steel bar diameter. The bottom spacing of the newly added stirrups is 100mm to 150mm, and the top spacing is 150mm to 200mm. In step S4, the pouring interval between the lower high self-stress concrete and the upper low self-stress concrete does not exceed the initial setting time of the lower concrete. The slump of the concrete upon entering the formwork is 160mm to 200mm. An immersion vibrator is used for layered vibration, and the vibrator avoids touching the bottom formwork and steel bars of the entire steel plate. After pouring, the surface is promptly finished, and a second pressing is completed before final setting.

[0024] Preferably, in step S5, the final setting time of the concrete is determined by a penetration resistance meter or by on-site finger pressure; the high-viscosity modified emulsified asphalt is sprayed under ambient temperature of 5℃~35℃ and no rain conditions, with a spraying rate of 0.8kg / ㎡~1.5kg / ㎡. After spraying, the repair area is sealed off and personnel and vehicles are prohibited from passing through; in step S6, the geotextile or moisturizing film is kept moist throughout the curing period, and the number of times water is sprayed daily is based on the surface not turning white. The repair area shall not be subjected to load impact during the curing period.

[0025] Preferably, in step S7, the surface of the high-viscosity emulsified asphalt penetrating interlocking layer is cleaned before hot asphalt is sprayed to ensure it is dry and free of loose particles; after the basalt fiber layer is sprayed, there is no accumulation or gaps, and the rubber-tired roller compaction is completed immediately after the hot asphalt is sprayed; in step S8, the paving temperature of the new asphalt pavement layer is not lower than 160℃ and the initial compaction temperature is not lower than 150℃, emulsified asphalt tack coat is sprayed between the layers of the layered paving, and the hot asphalt coating on the vertical surface where the new and old asphalt meet is uniform and without any white spots.

[0026] Compared with the prior art, the present invention has the following beneficial effects: 1. No need for work under the bridge or personnel entering the cavity; geometrically feasible for small-sized damaged bottom formwork: The working conditions are limited to small-area damage with a lateral width of no more than 50cm and a longitudinal width of no more than 1.1m. The width of the entire steel plate can be controlled within about 55cm, which is less than the net width of about 60cm at the end of the beam cavity. The steel plate is sent in a horizontal position from the end of the beam and slides into place along the track groove, which is perfectly adapted to the construction of local small damage in the narrow inner cavity of the hollow slab. 2. Preserving composite stress of steel plate and preventing potential defects: The threaded sleeve and vertical connecting steel bars allow the steel plate to be suspended from the steel reinforcement cage during the pouring period. After hardening, it becomes a tension member of the reconstructed top slab, transforming the construction formwork into a permanent load-bearing member. This forms a composite stress system of "steel plate-vertical steel bar-steel mesh", rather than a simple temporary construction tool. The structural scheme has significant differences.

[0027] 3. Continuous reinforcement and stepped interlocking ensure reliable force transmission: lapped reinforcement is welded or tied to the original longitudinal and transverse reinforcement of the pavement, and new stirrups are added to enclose and tie the reinforcement, ensuring continuity between the old and new structures; the three-level steps horizontally stagger the joints of each layer and provide a horizontal interlocking surface; the stepped removal section and the inverted trapezoidal deformation reinforcement are matched to each other, integrating shear resistance, anti-shoving, and seepage prevention, and synergistically improving the anchorage performance of the interface between the old and new concrete.

[0028] 4. Layered self-stress matching constraint gradient, interface crack resistance: The high self-stress of the lower layer establishes interface pre-compression stress in the strong constraint area, actively offsetting shrinkage tensile stress; the low self-stress of the upper layer avoids free expansion and shelling in the weak constraint area; in conjunction with the dense lower and sparse upper reinforcement, the gradient self-stress concrete layers match the different stress requirements of the top slab and the pavement layer, avoiding the pavement layer from arching due to single expansion force.

[0029] 5. Self-consistent process, integrated interlocking and curing: Utilizing the hydration heat window of 0-1 hours after the final setting of concrete, when the internal pores of the concrete are at their maximum, the high-viscosity emulsified asphalt actively breaks down and penetrates into the surface pores by 3-10mm, forming a pin-type interlocking interface. This is different from the passive bonding process of spraying tack coat after the concrete has fully hardened, and improves the interlayer shear resistance and anti-stripping performance from the interface mechanism.

[0030] 6. Rapid localized repair with significant social benefits: Only small areas of damage need to be partially removed and rebuilt, resulting in significant savings in materials and construction time; traffic can be opened once the surface layer cools to below 50°C, making it suitable for repairs that do not interrupt traffic or require short road closures. Attached Figure Description

[0031] Figure 1 This is a schematic cross-sectional view of the hollow slab bridge repair and reinforcement structure of the present invention; Figure 2 This is a schematic diagram of the inverted trapezoidal lap splice steel reinforcement system of the present invention; In the diagram: 1. Hollow slab; 2. Solid steel plate bottom formwork; 3. U-shaped guide chute; 4. Expansion bolt; 5. Sealing layer; 6. Lower high self-stress concrete layer; 7. Upper low self-stress concrete layer; 8. Permeable interlocking layer; 9. Basalt fiber layer; 10. Hot asphalt layer; 11. New asphalt pavement layer; 12. Sealing layer between new and old asphalt joints; 13. Original bridge deck pavement concrete layer; 14. Old asphalt pavement layer; 16. Original longitudinal and transverse reinforcement of the pavement; 17. Upper transverse lapped reinforcement; 18. Upper longitudinal lapped reinforcement; 19. Original longitudinal and transverse reinforcement of the hollow slab top plate; 20. Lower transverse lapped reinforcement; 21. Lower longitudinal lapped reinforcement; 22. Newly added stirrups; 23. Threaded sleeve; 24. Connecting circular hole; 25. Vertical connecting reinforcement. Detailed Implementation

[0032] The following detailed description of a specific embodiment of the present invention is provided in conjunction with the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0033] Example 1:

[0034] like Figure 1-2 As shown, this is a repair procedure for a small area of ​​cracked roof slab of a hollow slab bridge on a highway (maximum size limit condition). A 20m span prestressed concrete hollow slab bridge on a highway has a single hollow slab width of 1.24m and a beam height of 1.1m. The standard section has a net cavity width of 760mm and a net cavity height of 860mm, with a net cavity width of 600mm at the beam end. The top slab of hollow slab 1 is 14cm thick, the original bridge deck pavement concrete layer 13 is 10cm thick (C40), and the original asphalt pavement layer 14 is a three-layer structure totaling 18cm. A section of the top slab of hollow slab 1 in the heavy vehicle lane has partially cracked, with water seepage and white stains. The measured transverse width of the damaged area is 48cm and the longitudinal length is 105cm. A rectangular repair space has been determined with a transverse width of 50cm and a longitudinal length of 110cm (including the area of ​​surrounding deteriorated concrete to be removed).

[0035] The construction method is as follows: S1. Layered and step-by-step removal: After measurement and layout, use a cutting machine to cut along the edge line, controlling the cutting depth to avoid cutting through the retained reinforcing steel: cut through the asphalt layer to 18cm, cut the pavement layer to the top surface of the slab, and cut through the slab layer to 14cm. The removal boundary is laid out in three steps: the asphalt pavement removal boundary is extended 20cm outward on one side relative to the pavement concrete removal boundary, and the pavement concrete removal boundary is extended 15cm outward on one side relative to the hollow slab top slab removal boundary, forming two-level stepped horizontal surfaces with widths of 20cm and 15cm. Use hydraulic breakers to remove in sections, and manually chisel within 10cm of the edge line with a small hammer, ensuring the edge line is straight and without jagged edges; retain the original longitudinal and transverse reinforcing steel 19 (φ10 HRB400) at the hollow slab top slab on the facade during removal, with a reserved lap length of not less than 35 times the steel diameter, and grind and remove rust from the corroded steel bars and apply anti-rust paint. After the chiseling is completed, roughen the horizontal surface of the steps and each chiseled vertical surface to a depth of 4mm, exposing fresh aggregate, and then clean it with a high-pressure air gun.

[0036] S2. Intracavity sliding template sealing: Precast whole steel plate bottom template 2: Q235B steel plate, 8mm thick, 545mm wide, 1300mm long (longitudinal length is 10cm longer on each side than the chiseling length of 110cm), whole piece galvanized; M16 threaded sleeves 23 are welded in a rectangular arrangement on the back of the steel plate (towards the cavity), spaced 30cm×30cm, a total of 12, and φ18 connecting round holes 2424 are drilled on the plate surface, aligned with the inner hole of the sleeve. The repair space opening is marked on both sides longitudinally along the bottom surface of the top plate. The fixing point is 20cm away from the edge of the opening. Two galvanized C-shaped steel rails (C100 type, 5mm wall thickness) are fixed to the bottom surface of the top plate on both sides of the horizontal side of the repair area using M12 expansion bolts. The longitudinal spacing of the fixing points is 0.8m. The grooves of the two U-shaped guide slides 3 are opposite each other, and the top surface of the slide is flush with the bottom surface of the top plate. The inner spacing of the two slides is 550mm. The width of the steel plate is 545mm, which is 5mm narrower than the inner spacing of the grooves. The U-shaped guide slides 3 are pre-coated with grease to reduce friction. The whole steel plate bottom template 2 is sent into the beam end cavity in a horizontal posture (plate width 545mm < net width of the closing 600mm). After being inserted into the two side slides, it slides longitudinally for about 9m to the position. The top surface of the steel plate is close to the bottom surface of the top plate and completely covers the bottom opening of the three-stage stepped repair space. The longitudinal ends of the steel plate overlap the edge of the opening by 10cm. Twelve vertical connecting steel bars 25 (HRB400 φ16, with M16 external threads at the lower end) are screwed into threaded sleeves 23 from top to bottom through the connecting circular hole 24 at the opening of the three-tiered repair space. The screwing depth is 25mm, and the exposed thread length is no more than 2mm. The upper part of the vertical connecting steel bars is left inside the repair space, and a hook is set at the top. The gaps between the steel plate and the side wall of the hollow slab, as well as the gaps between the connecting circular hole 24 and the steel bars, are all filled with epoxy resin. After sealing, a grout leakage inspection is conducted and it passes. The track and steel plate are permanently retained in the cavity.

[0037] S3. Forming of the inverted trapezoidal steel mesh: The upper layer of transverse lapped steel bars 17, the upper layer of longitudinal lapped steel bars 18, the lower layer of transverse lapped steel bars 20, and the lower layer of longitudinal lapped steel bars 21 are made of HRB400 φ14 steel bars. One end is welded to the original longitudinal and transverse steel bars 16 of the pavement on one side with a welding length of 140mm (10d), and the other end extends into the repair space. The newly added stirrups 33 are made of φ10 steel bars and are tied to the upper hooks of the longitudinal and transverse lapped steel bars and the vertical connecting steel bars 25. The two ends of the stirrups are respectively tied to the original longitudinal and transverse steel bars 16 of the pavement and the longitudinal and transverse lapped steel bars. The bottom spacing of the stirrups is 120mm and the top spacing is 180mm. After the inverted trapezoidal overall steel mesh is formed, the bottom reinforcement ratio is 1.2% and the top reinforcement ratio is 0.5%. Together with the bottom whole steel plate bottom formwork 2, it forms a composite stress system (the vertical connecting steel bars hang the steel plate during the pouring period, and the steel plate acts as the bottom tension member after hardening).

[0038] S4. Layered pouring of double self-stressed concrete: Each chiseled surface is moistened with water and coated with a concrete interface agent to form an interface layer. First, pour the lower layer of high self-stressed concrete (6 to the top surface elevation of the slab): strength grade C45, using a calcium oxide-calcium sulfoaluminate composite expansion agent (9%–11% of the cementitious material mass), coarse aggregate particle size 5mm–16mm, water curing for 14 days with a limited expansion rate of 0.10%, and a longitudinal and transverse self-stress value of 3.5MPa after hardening; slump upon placement is 180mm; layered vibration with an immersion vibrator is used, avoiding contact with the formwork and reinforcing steel. Before the initial setting of the lower layer, continuously pour the upper layer of low self-stressed concrete (7 to the top surface elevation of the original paving concrete layer 13): strength grade C45, same series expansion agent dosage 6%–8%, limited expansion rate 0.06%, self-stress value 2.2MPa; after vibration, promptly finish the surface, and complete the secondary compaction before final setting.

[0039] S5. Construction of high-viscosity emulsified asphalt penetrating interlocking layer: The final setting time of the upper concrete is determined by a penetration resistance meter. Within 0.5 hours after final setting (the actual surface temperature is 38℃, and hydration heat is still being released), cationic fast-cracking high-viscosity modified emulsified asphalt (62% evaporation residue content) is evenly sprayed under ambient temperature of 22℃ and no rain conditions, with a spraying amount of 1.2 kg / m². The hydration heat accelerates demulsification, and the asphalt particles penetrate into the surface pores to a depth of 6 mm, consolidating to form a high-viscosity emulsified asphalt penetrating interlocking layer. After spraying, the repair area is sealed and pedestrian and vehicular traffic is prohibited.

[0040] S6. Moisturizing and Maintenance: Cover with geotextile and continuously spray water for 7 days to maintain moisture and maintenance. The penetrating interlocking layer also serves as a water-retaining membrane. Spray water daily until the surface does not turn white. During the maintenance period, the repaired area shall not be subject to load impact.

[0041] S7. Construction of Composite Waterproof Adhesive Layer: After curing, clean the surface of the interlocking layer to ensure it is dry, free of loose particles and standing water. Spray 10 layers of hot asphalt (160℃ SBS modified hot asphalt 1.5kg / ㎡), then evenly spread 9 layers of basalt fiber (16mm length, 13μm monofilament diameter, 120g / ㎡), ensuring no fiber accumulation or gaps. Then, compact and stabilize the surface with a light rubber roller to form the composite waterproof adhesive layer.

[0042] S8. Layered paving: Apply hot asphalt to the vertical joint surface to form a sealing layer 12 between the old and new asphalt (apply evenly without any white showing); lay the new asphalt pavement layer 11 in layers: 8cm AC-25 lower layer + 6cm AC-20 middle layer + 4cm SMA-13 ​​upper layer, with a paving temperature of 165℃ and an initial compaction temperature of 155℃. Sprinkle emulsified asphalt tack coat between layers. The compaction degree of each layer is not less than 97%. Roll along the joint; open to traffic after the surface layer cools to 48℃.

[0043] Example 2: Repair of hollow slab bridges on national and provincial highways (medium-sized working conditions) A 13m span prestressed hollow slab bridge on a certain type of highway has a standard section with a net internal width of 760mm and a net width at the beam end of 600mm. The top slab of the hollow slab is 10cm thick, the bridge deck pavement is 8cm thick concrete and 10cm thick asphalt pavement. The measured transverse width of the local fractured area of ​​the top slab is 38cm and the longitudinal length is 75cm. A three-stage stepped repair space is determined to have a transverse width of 40cm and a longitudinal length of 80cm.

[0044] The construction method is as follows: S1: The asphalt boundary extends 15cm outward from the pavement boundary on one side and the pavement boundary extends 10cm outward from the top slab boundary on one side; the asphalt is removed in sections by hydraulic breakers and manually chiseled 10cm from the edge; 16 original longitudinal and transverse steel bars (φ10) are retained with an overlap length of not less than 35d; the roughening depth is 3mm, and the surface is washed with high pressure water.

[0045] S2: The bottom formwork 2 of the whole steel plate is made of 6mm thick steel plate, 445mm wide and 95cm long (7.5cm overlap on each side), galvanized; M14 threaded sleeves 23 are welded on the back, arranged in a quincunx pattern with a spacing of 25cm, a total of 8, and φ16 connecting round holes 24 are drilled; the galvanized C-shaped steel rail has a wall thickness of 4mm, fixed with M10 expansion bolts, the fixing point spacing is 0.6m, and the distance from the opening edge is 18cm, the distance between the two rail chutes is 450mm; after the chutes are coated with grease, the steel plate is horizontally sent in from the end of the beam and slid in place for about 6m; the vertical connecting steel bar 25 is HRB400 φ14, screwed in to a depth of 20mm, the exposed thread is no more than 2mm, and the upper hook is left for repair space; the gaps are sealed with quick-setting cement-based sealing material, and the leakage inspection is qualified.

[0046] S3: The lapped steel bars are HRB400 φ12, which are welded to the original longitudinal and transverse steel bars 16 on both sides with a welding length of 60mm (5d); new stirrups φ8 are added with a bottom spacing of 150mm and a top spacing of 200mm; the bottom reinforcement ratio is 0.9% and the top reinforcement ratio is 0.4%.

[0047] S4: Apply interface agent to the facade; the lower layer of high self-stress concrete 6 is C40, with 8% to 10% calcium sulfoaluminate expansive agent, 5mm to 20mm coarse aggregate, a restricted expansion rate of 0.09%, a self-stress value of 3.2MPa, and a slump of 175mm, poured to the top surface of the slab; before the initial setting of the lower layer, continuously pour the upper layer of low self-stress concrete 7 (C40, with 5% to 7% expansive agent, a restricted expansion rate of 0.055%, and a self-stress value of 2.1MPa) to the top surface of the pavement; press the surface twice before final setting.

[0048] S5: After the final setting is determined by finger pressure, spray 1.0 kg / m² of high-viscosity modified emulsified asphalt (60% evaporation residue) to a penetration depth of 5 mm, and seal the site after forming a penetrating interlocking layer 8.

[0049] S6: Geotextile moisture retention and maintenance for 6 days.

[0050] S7: After cleaning and drying the base surface, spray 1.2 kg / m² of 155℃ SBS modified hot asphalt, then immediately spread basalt fiber (15 mm in length, 13 μm in diameter, 100 g / m²), and then stabilize the pressure with a rubber roller.

[0051] S8: Apply hot asphalt to seal the joints on the facade; lay a 6cm AC-16 lower layer + a 4cm AC-13 upper layer, with a paving temperature of 162℃ and an initial compaction temperature of 152℃. Sprinkle tack coat between layers, and compact the layers to a degree of not less than 96.5%. Roll the layers together. Open to traffic after cooling to below 50℃.

[0052] Example 3: Repair of Hollow Slab Bridges in Urban Areas (Small-Scale Case) A hollow slab bridge with a 10m span in a certain city has a beam end clearance width of 600mm, a top slab thickness of 13cm and a concrete paving thickness of 12cm and a pavement thickness of 9cm. The transverse width of a small cracked area in the top slab is 28cm and the longitudinal length is 55cm. A three-stage repair space is determined with a transverse width of 30cm and a longitudinal length of 60cm.

[0053] The construction method is as follows: S1: The asphalt boundary is extended 10cm outward on one side relative to the pavement boundary and the pavement boundary is extended 10cm outward on the top slab boundary; the asphalt is removed in sections by pneumatic picks and manually trimmed 10cm from the edge; 16 (φ8) original longitudinal and transverse steel bars of the pavement are retained with an overlap length of not less than 35d; the roughening depth is 3mm and the surface is washed with high-pressure air.

[0054] S2: The bottom formwork 2 of the whole steel plate is made of 5mm thick steel plate, 345mm wide and 75cm long (7.5cm overlap on each side), and is coated with two coats of anti-rust paint; M12 threaded sleeves 23 are welded on the back, arranged in a rectangle with a spacing of 20cm, a total of 6, and φ14 connecting round holes 24 are drilled; due to the dampness of the base surface inside the cavity, the galvanized channel steel rail 41 with a wall thickness of 3.5mm is replaced with anchoring adhesive for fixing, with a fixing point spacing of 0.5m and a distance of 15cm from the edge of the opening, and a spacing of 350mm between the two rail grooves; the steel plate is horizontally fed into the beam end and slid in for about 4m to the position; the vertical connecting steel bar 25 is HRB400 φ12, screwed in to a depth of 20mm, and the exposed thread is no more than 2mm; the gaps are sealed with epoxy resin, and the grout leakage inspection is qualified.

[0055] S3: The lapped steel bars are HRB400 φ10, which are tied and lapped with the original longitudinal and transverse steel bars 16 in the pavement, with a lap length of 350mm (35d); new stirrups φ8 are added, with a bottom spacing of 150mm and a top spacing of 200mm; the bottom reinforcement ratio is 0.8% and the top reinforcement ratio is 0.3%.

[0056] S4: Apply interface agent to the facade; the lower layer of high self-stress concrete 6 is C40, with 8% to 10% calcium oxide-calcium sulfoaluminate composite expansion agent, 5mm to 16mm coarse aggregate, restricted expansion rate of 0.08%, self-stress value of 3.0MPa, and slump of 165mm, poured to the top surface of the slab; before the initial setting of the lower layer, continuously pour the upper layer of low self-stress concrete 7 (C40, 5% to 6% admixture, restricted expansion rate of 0.05%, self-stress value of 2.0MPa) to the top surface of the pavement; the surface is pressed twice before final setting.

[0057] S5: Within 1 hour after the final setting is determined by the penetration resistance meter (at an air temperature of 26℃), spray 0.8 kg / m² of high-viscosity modified emulsified asphalt (60% evaporation residue), with a penetration depth of 3 mm, and seal the site after forming an interlocking layer.

[0058] S6: Cover with a moisturizing film and spray water for 5 days for maintenance.

[0059] S7: After the base surface is dry, spray 1.0 kg / m² of 150℃ SBS modified hot asphalt, then immediately spread basalt fiber (12 mm in length, 12 μm in diameter, 80 g / m²), and stabilize the pressure with rubber rollers.

[0060] S8: Apply hot asphalt to the facade; pave two layers of 5cm AC-13 and 4cm AC-10, with a paving temperature of 160℃ and an initial compaction temperature of 150℃. Sprinkle tack coat between layers, and compact the joints with a compaction degree of not less than 96%. Cool to 45℃ and open to traffic.

[0061] Comparative Example 1: A single steel plate was used for oversized breakage (geometrically infeasible verification). The damaged area of ​​a bridge's top slab has a transverse width of 80cm and a longitudinal length of 150cm. Designed using a single-piece steel plate formwork, the two-track sliding grooves are spaced approximately 85cm apart, requiring a steel plate width of approximately 845mm. However, actual measurements showed that the net width of the cavity opening at the end of the hollow slab beam of this bridge was only 600mm. The 845mm wide steel plate could not be fed into the cavity through the opening, regardless of whether it was horizontal or inclined. Personnel could not enter the cavity, and there were no on-site assembly conditions, rendering this approach a failure. This demonstrates that limiting the damage condition to a transverse width of no more than 50cm and controlling the steel plate width to approximately 55cm is a necessary condition for the geometric validity of the single-piece steel plate sliding scheme. For damage exceeding these dimensions, it is advisable to use segmented strip steel plate splicing or an under-bridge formwork scheme.

[0062] Comparative Example 2: Steel plate unthreaded sleeve connection (verification of steel plate detachment is retained) Construction was carried out according to the conditions of Example 1, but the threaded sleeve and vertical connecting reinforcement were removed. The steel plate was only used as a bottom formwork inserted into the chute, with its top surface closely attached to the bottom surface of the top slab. The maximum deflection of the steel plate at mid-span during the pouring period was measured to be 6 mm (in Example 1, the deflection was measured to be 1.5 mm because the vertical connecting reinforcement was suspended from the reinforcement cage). After 6 months of traffic, a hammer test revealed a local hollow area (hollow rate of about 15%) between the steel plate and the bottom surface of the reconstructed concrete. An endoscope inside the cavity showed rust and water droplets at the joint on the back of the steel plate, indicating that the steel plate left without the connecting structure gradually separated from the reconstructed concrete under the vibration of traffic.

[0063] Comparative Example 3: Applying hot asphalt first and then curing (verification of process contradictions) The repair section of the same size was constructed according to the procedure of "spraying hot asphalt and fiber immediately after the emulsified asphalt breaks down, and then covering with geotextile for curing": When the hot asphalt at 160℃ was sprayed, the residual water in the emulsified asphalt vaporized due to heat, and dense blistering appeared in the asphalt layer. After cooling, the bonding layer at the blistering point separated from the base surface; subsequently, geotextile was covered and water was sprayed for curing for 7 days. The hot asphalt film blocked the supply of curing water, and the surface concrete lost water within 7 days, with fine shrinkage cracks of 0.1mm to 0.3mm appearing on the surface. The shear strength of the composite waterproof bonding layer at 50℃ was only 0.12MPa (0.38MPa in Example 1 of this invention), and water seepage occurred after 30 minutes under 0.3MPa water pressure.

[0064] Comparative Example 4: Repair of ordinary C40 concrete (without self-stress verification) Ordinary C40 concrete without expansion agent was used for repair, with the same stepped structure and reinforcement. The pull-out strength of the interface between the old and new concrete was 1.5 MPa after 28 days. After 6 months, circumferential shrinkage cracks of 0.2 mm to 0.4 mm appeared around the repair. Water seeped into the cracks after rain, and hammering revealed localized hollow areas at the interface.

[0065] Comparative Example 5: Only the pavement layer is chiseled, not the top slab (refer to CN115030067A). The repair process involved removing only the asphalt surface layer and laying concrete, and then roughening the roof slab before pouring shrinkage-compensating concrete, similar to the repair of the damaged bridge span. The fractured areas of the roof slab were not rebuilt, and 12 months after the bridge opened to traffic, the cracks in the original roof slab continued to develop. Reflective cracks and grout pumping appeared in the corresponding locations on the new pavement, and the repaired area was damaged again.

[0066] Table 1 shows a comparison of the main performance characteristics of each embodiment and the comparative example.

[0067] Table 1 Comparison of key performance characteristics between the examples and comparative examples

[0068] Note: The data in the table are extrapolated from indoor material tests and literature comparisons. They should be replaced with actual mix proportion tests and test section test data before formal application and engineering application. Comparative Example 1 did not undergo performance testing because the geometry of the whole steel plate was not feasible and the process failed.

[0069] As shown in Table 1, Examples 1-3 of the present invention are significantly superior to the comparative examples in terms of steel plate deflection control during the casting period, pull-out strength at the interface between the new and old plates, density of the composite surface of the steel plate, high-temperature shear strength of the waterproof adhesive layer, impermeability, and long-term crack resistance. Comparative Example 1 proves that limiting the size of the broken plate is a necessary condition for the geometric validity of the whole steel plate slippage scheme. Comparative Example 2 proves the necessity of the composite stress structure of the threaded sleeve and the vertical connecting steel bars. Comparative Example 3 proves that the order of curing and hot asphalt processes cannot be reversed. Comparative Example 4 proves the key role of self-stressed preloading in interface crack resistance. Comparative Example 5 proves that the top plate can not be replaced by the "paving only" scheme.

[0070] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A repair and reinforcement structure for partially damaged roof slab and pavement of hollow slab bridges, characterized in that: The system includes a three-tiered repair space in the damaged area of ​​the hollow slab bridge, an inverted trapezoidal lapped steel reinforcement system, a formwork sealing system, a double self-stressed concrete reinforcement layer, a high-viscosity emulsified asphalt penetrating interlocking layer (8), a composite waterproof bonding layer, a new asphalt pavement layer (11), and a new and old asphalt joint sealing layer (12). The three-tiered repair space is formed by chiseling away layers of the damaged area from top to bottom. From top to bottom, the chiseling boundaries are formed by asphalt pavement, concrete pavement, and hollow slab top. The three chiseling boundaries gradually shrink inward, forming a stepped repair boundary that is wider at the top and narrower at the bottom. A stepped horizontal plane is formed between adjacent chiseling boundaries. Each chiseling surface is a vertical plane, and each chiseling surface and stepped horizontal plane are roughened to expose fresh aggregate. The inverted trapezoidal lapped reinforcement system includes longitudinal and transverse lapped reinforcement and newly added stirrups (22). The longitudinal and transverse lapped reinforcement includes upper transverse lapped reinforcement (17), upper longitudinal lapped reinforcement (18), lower transverse lapped reinforcement (20), and lower longitudinal lapped reinforcement (21). One end of the upper transverse lapped reinforcement (17), upper longitudinal lapped reinforcement (18), lower transverse lapped reinforcement (20), and lower longitudinal lapped reinforcement (21) is connected to the original longitudinal and transverse reinforcement (16) of the pavement retained at the three-level stepped repair space facade, and the other end extends into the... Within the three-tiered stepped repair space, the newly added stirrups (22) are connected and enclosed with the upper transverse lapped reinforcement (17), the upper longitudinal lapped reinforcement (18), the lower transverse lapped reinforcement (20), and the lower longitudinal lapped reinforcement (21). Their ends are respectively tied to the original longitudinal and transverse reinforcement (19) of the hollow slab top plate and the longitudinal and transverse lapped reinforcement within the three-tiered stepped repair space, forming an inverted trapezoidal integral steel mesh that is wider at the top and narrower at the bottom, which is adapted to the stepped repair boundary. The inverted trapezoidal integral steel mesh adopts a reinforcement form that is denser at the bottom and sparser at the top, with a bottom reinforcement ratio greater than the top reinforcement ratio. The template sealing system includes steel insert rails, a whole steel plate bottom template (2), and vertical connecting steel bars (25); two steel insert rails are parallel to each other and fixed to the bottom surface of the top plate of the hollow slab cavity along the longitudinal direction of the bridge, and located on the outer side of the two transverse sides of the repair area; each steel insert rail has a U-shaped guide groove (3) along its own longitudinal direction, and the grooves of the two U-shaped guide grooves (3) are set opposite to each other; the two sides of the whole steel plate bottom template (2) are slidably engaged in the two sides of the U-shaped guide groove (3), the whole steel plate bottom template (2) is sent into the hollow slab beam end cavity in a horizontal posture and slides into place along the longitudinal direction of the U-shaped guide groove (3), its top surface is closely attached to the bottom surface of the top plate of the hollow slab (1), and it covers the three-level stepped repair space. Bottom opening; threaded sleeves (23) are arranged on the back of the whole steel plate bottom template (2) facing the inner cavity of the hollow slab, and connecting round holes (24) are opened on the whole steel plate bottom template (2) corresponding to the inner holes of each threaded sleeve (23); the vertical connecting steel bar (25) passes through the connecting round hole (24) from top to bottom and is threadedly connected to the threaded sleeve (23), the upper part of the vertical connecting steel bar (25) extends into the inverted trapezoidal lapped steel bar system and is connected to the newly added stirrup (22), and the gap between the whole steel plate bottom template (2) and the side wall of the hollow slab and the gap between the connecting round hole (24) and the vertical connecting steel bar (25) are all provided with sealing layers; the steel insert-type rail and the whole steel plate bottom template (2) are permanently retained in the inner cavity of the hollow slab; The double self-stressed concrete reinforcement layer is filled and solidified inside the three-level stepped repair space. It is an integrated solid structure formed by the upper layer of high self-stressed concrete (6) and the upper layer of low self-stressed concrete (7) being poured in layers. The lower layer of high self-stressed concrete (6) corresponds to the reconstruction range of the top plate of the hollow slab (1), and the upper layer of low self-stressed concrete (7) corresponds to the reconstruction range of the bridge deck pavement concrete. The high-viscosity emulsified asphalt penetrating interlocking layer (8) is bonded to the top surface of the double self-stressed concrete reinforcement layer; The composite waterproof adhesive layer is bonded to the top surface of the high-viscosity emulsified asphalt penetrating interlocking layer (8), and is composed of a hot asphalt layer (10) and a basalt fiber layer (9) spread in the hot asphalt layer (10); The new asphalt pavement layer (11) is laid on the top surface of the composite waterproof bonding layer; the new and old asphalt joint sealing layer (12) is set between the vertical joint surfaces of the new asphalt pavement layer (11) and the original asphalt pavement layer (14).

2. The repair and reinforcement structure for partially damaged hollow slab bridge top slab and bridge deck pavement according to claim 1, characterized in that: The three-tiered repair space has a longitudinal length of no more than 1.1m and a transverse width of no more than 0.5m. The boundary of the adjacent layer is extended outward by 10cm to 20cm on one side to form a stepped horizontal surface with a width of 10cm to 20cm. The chiseling surface of each layer is cut with a cutting machine first, and then chiseled to shape it. The edge line is straight and there are no jagged edges. The roughening depth of the stepped horizontal surface and the chiseling surface of each layer is no less than 3mm, and it is cleaned with a high-pressure air gun or high-pressure water.

3. The repair and reinforcement structure for partially damaged hollow slab bridge top slab and bridge deck pavement according to claim 1, characterized in that: The upper transverse lapped steel bars (17), upper longitudinal lapped steel bars (18), lower transverse lapped steel bars (20), and lower longitudinal lapped steel bars (21) are made of HRB400 grade steel bars with a diameter of 10mm to 16mm. When the original longitudinal and transverse steel bars (16) are welded to the paving original longitudinal and transverse steel bars (16) on one side, the welding length is not less than 10 times the steel bar diameter; when the original longitudinal and transverse steel bars (16) are welded to both sides, the welding length is not less than 5 times the steel bar diameter; when the original longitudinal and transverse steel bars (16) are tied, the lap length is not less than 35 times the steel bar diameter. The newly added stirrups (22) have a diameter of 8mm to 12mm, the bottom stirrup spacing is 100mm to 150mm, and the top stirrup spacing is 150mm to 200mm. The bottom reinforcement ratio of the inverted trapezoidal integral steel mesh is 0.8% to 1.5%, and the top reinforcement ratio is 0.3% to 0.6%.

4. The repair and reinforcement structure for partially damaged hollow slab bridge top slab and bridge deck pavement according to claim 1, characterized in that: The steel insert track is made of galvanized C-shaped steel or galvanized channel steel with a wall thickness of 3mm to 5mm. It is fixed to the bottom surface of the top plate of the hollow slab (1) by expansion bolts (4) or anchoring adhesive. The longitudinal spacing of the fixing points is 0.5m to 1.0m, and the fixing points are not less than 15cm away from the edge of the opening of the three-stage stepped repair space. The top surface of the U-shaped guide chute (3) is flush with the bottom surface of the top plate of the hollow slab (1). The whole steel plate bottom template (2) is made of steel plate with a thickness of 5mm to 10mm. Its width is 3mm to 5mm narrower than the spacing between the two U-shaped guide chute (3). Its longitudinal length is 5cm to 10cm longer on each side than the chiseling length of the three-stage stepped repair space along the longitudinal direction of the bridge. The steel insert track and the whole steel plate bottom template (2) are both galvanized or coated with anti-rust paint. The sealing layer (5) is made of epoxy resin or fast-setting cement-based sealing material.

5. The repair and reinforcement structure for partially damaged hollow slab bridge top slab and bridge deck pavement according to claim 1, characterized in that: The threaded sleeve (23) is welded and fixed to the back of the whole steel plate bottom template (2), and is arranged in a rectangle along the longitudinal and transverse directions of the whole steel plate bottom template (2); the vertical connecting steel bar (25) is made of HRB400 grade steel bar, and its lower end is provided with external thread and screwed into the internal thread of the threaded sleeve (23), with a screwing depth of not less than 20mm, and the exposed thread length of the vertical connecting steel bar (25) after screwing is not greater than 2mm; the upper part of the vertical connecting steel bar (25) extends into the double self-stressed concrete reinforcement layer and is provided with a hook section, which is tied or welded to the newly added stirrup (22).

6. The repair and reinforcement structure for partially damaged hollow slab bridge top slab and bridge deck pavement according to claim 1, characterized in that: The lower high self-stress concrete layer (6) has a strength grade of not less than C40, a restricted expansion rate of not less than 0.08% after 14 days of underwater curing, and longitudinal and transverse self-stress values ​​of not less than 3MPa after hardening; the upper low self-stress concrete layer (7) has a strength grade of not less than C40, a restricted expansion rate of not less than 0.05% after 14 days of underwater curing, and longitudinal and transverse self-stress values ​​of not less than 2MPa after hardening; both concrete layers are prepared with calcium sulfoaluminate or calcium oxide-calcium sulfoaluminate composite expansion agents, and the coarse aggregate particle size is 5mm to 20mm; a concrete interface agent layer is applied between the double self-stress concrete reinforcement layer and the chiseled vertical surface of each layer.

7. The repair and reinforcement structure for partially damaged hollow slab bridge top slab and bridge deck pavement according to claim 1, characterized in that: The high-viscosity emulsified asphalt penetrating interlocking layer (8) uses cationic fast-cracking high-viscosity modified emulsified asphalt with an evaporation residue content of not less than 60% and a spraying amount of 0.8 kg / m² to 1.5 kg / m². The depth of the high-viscosity modified emulsified asphalt penetrating into the pores of the double self-stressed concrete surface is 3 mm to 10 mm.

8. The repair and reinforcement structure for partially damaged hollow slab bridge top slab and bridge deck pavement according to claim 1, characterized in that: The hot asphalt layer (10) is SBS modified asphalt, with a spraying temperature of 150℃~170℃ and a spraying amount of 1.0kg / ㎡~2.0kg / ㎡; the basalt fiber layer (9) has a length of 12mm~20mm, a single filament diameter of 10μm~20μm, and a spraying amount of 80g / ㎡~150g / ㎡.

9. The repair and reinforcement structure for partially damaged hollow slab bridge top slab and bridge deck pavement according to claim 1, characterized in that: The new asphalt pavement layer (11) is constructed by compacting 2 to 3 layers of asphalt concrete, with each layer having a compaction degree of not less than 96%; the lower layer uses medium-grained asphalt concrete, and the upper layer uses fine-grained asphalt concrete or asphalt mastic aggregate mixture; the new and old asphalt joint sealing layer (12) is a hot asphalt layer (10) applied to the vertical joint surface.

10. A method for repairing and reinforcing partially damaged hollow slab bridge roof slabs and bridge deck pavement, used for constructing a repair and reinforcement structure for partially damaged hollow slab bridge roof slabs and bridge deck pavement as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Layered and step-by-step chiseling: Measure and lay out the damaged area, and control the damaged area to a horizontal width of no more than 50cm and a longitudinal length of no more than 1.1m; use a cutting machine to cut along the edge line to the design depth of each layer, and then chisel away the damaged asphalt pavement, bridge deck pavement concrete and hollow slab (1) top plate damaged concrete from top to bottom, forming a three-level stepped repair space with vertical chiseling facades and a wide top and narrow bottom; during the chiseling process, retain the original longitudinal and transverse steel bars (16) of the pavement at the facade of the three-level stepped repair space and reserve the lap length; after the chiseling is completed, roughen the horizontal surface of the steps and each chiseled facade, and clean it with a high-pressure air gun or high-pressure water. S2. In-cavity sliding template sealing: Weld threaded sleeves (23) on the back of the whole steel plate bottom template (2) according to the design spacing and open corresponding connecting round holes (24); Lay out the lines on the outer side of the repair area on both sides of the bottom surface of the hollow plate (1) top plate, and fix the steel insert rails with opposite groove openings of the two U-shaped guide grooves (3) to the bottom surface of the top plate with expansion bolts (4) or anchoring adhesive; Send the whole steel plate bottom template (2) into the cavity at the end of the hollow plate beam in a horizontal posture, so that its two sides are stuck into the two sides of the U-shaped guide grooves (3) and slide into place in the longitudinal direction, and the top surface is closely attached to the bottom of the hollow plate (1) top plate. The bottom opening of the three-tiered repair space is completely sealed; the vertical connecting steel bar (25) is passed from top to bottom through the connecting round hole (24) from the opening of the three-tiered repair space and screwed into the threaded sleeve (23) and tightened. The upper part of the vertical connecting steel bar (25) is left in the three-tiered repair space; the gap between the whole steel plate bottom template (2) and the hollow plate side wall and the gap between the connecting round hole (24) and the vertical connecting steel bar (25) are sealed with sealing material and grout leakage is checked; the steel insert track and the whole steel plate bottom template (2) are permanently left in the hollow plate cavity; S3, Inverted Trapezoidal Reinforcing Mesh Formation: One end of the upper transverse lapped reinforcing bars (17), upper longitudinal lapped reinforcing bars (18), lower transverse lapped reinforcing bars (20), and lower longitudinal lapped reinforcing bars (21) is welded or tied to the original longitudinal and transverse reinforcing bars (16) of the pavement retained at the facade of the three-level stepped repair space, and the other end extends into the three-level stepped repair space; new stirrups (22) are erected and tied or welded to the upper part of the longitudinal and transverse lapped reinforcing bars and the vertical connecting reinforcing bars (25) to enclose the space. The two ends of the new stirrups (22) are respectively tied to the original longitudinal and transverse reinforcing bars and the longitudinal and transverse lapped reinforcing bars of the top plate to form an inverted trapezoidal overall reinforcing mesh with a bottom reinforcement ratio greater than the top reinforcement ratio and a dense bottom and sparse top. Together with the bottom template (2) of the whole steel plate, it forms a composite stress system. S4. Layered pouring of double self-stressed concrete: Before pouring, the vertical surface of each layer is removed, water is sprinkled and moistened and concrete interface agent is applied; first pour the lower layer of high self-stressed concrete to the top surface elevation of the hollow slab (1) and vibrate it to compact it; before the lower layer of concrete sets, continuously pour the upper layer of low self-stressed concrete to the top surface elevation of the original bridge deck pavement concrete; after vibration, smooth the surface; after the two layers harden, an integrated double self-stressed concrete reinforcement layer is formed. S5, Construction of the infiltration interlocking layer (8): Within 0h to 1h after the final setting of the upper low self-stress concrete, when the concrete surface is still releasing hydration heat, uniformly spray cationic fast-cracking high viscosity modified emulsified asphalt, use the hydration heat of concrete to accelerate the demulsification of emulsified asphalt, so that the asphalt particles penetrate into the pores of the concrete surface and solidify to form a high viscosity emulsified asphalt infiltration interlocking layer (8). S6. Moisturizing and maintenance: Use geotextile or moisturizing film to fully cover the repaired area, and continuously spray water to moisturize and maintain for 3 to 5 days. The high viscosity emulsified asphalt penetration interlocking layer (8) also serves as the surface water-retaining film; take heat preservation and covering measures when the ambient temperature is below 5℃. S7. Construction of composite waterproof bonding layer: After the curing is completed and the surface of the repair area is cleaned and dry and free of standing water, SBS modified hot asphalt at a temperature of 150℃~170℃ is sprayed and basalt fiber layer is evenly spread (9). After being compacted by light rubber wheels, a composite waterproof bonding layer is formed. S8. Layered paving: Apply hot asphalt to the vertical joint surface of the new asphalt pavement layer (11) and the original asphalt pavement layer (14) to form a joint sealing layer (12) between the new and old asphalt layers. Lay the new asphalt pavement layer (11) in layers and compact each layer. The compaction degree of each layer shall not be less than 96%. After paving, roll along the joint. Open traffic after the surface temperature cools down to below 50℃.

11. A method for repairing and reinforcing partially damaged top slabs and pavement of hollow slab bridges according to claim 10, characterized in that: In step S1, the cutting depth of the cutting machine is controlled so as not to cut the original longitudinal and transverse reinforcing bars (16) to be retained; the chiseling is carried out in sections using hydraulic breakers or pneumatic picks, and the chiseling is done manually with a small hammer within 10cm of the edge line; the lap length of the original longitudinal and transverse reinforcing bars (16) to be retained is not less than 35 times the diameter of the reinforcing bars, and the original longitudinal and transverse reinforcing bars (16) to be rusted are ground and rust removed and coated with anti-rust paint; in step S2, the track fixing point is not less than 15cm from the edge of the three-stage repair space opening; after the whole steel plate bottom template (2) is slid into place, check the close contact between its top surface and the bottom surface of the hollow plate (1), and fill the gap with sealing material where the gap is greater than 2mm; after the vertical connecting reinforcing bars (25) are screwed in, the exposed thread length is not greater than 2mm; the U-shaped guide groove (3) is pre-coated with a lubricating layer to reduce the sliding resistance of the whole steel plate bottom template (2).

12. The repair and reinforcement method for partial damage to the top slab and pavement of a hollow slab bridge according to claim 10, characterized in that: In step S3, when the upper transverse lapped steel bar (17), upper longitudinal lapped steel bar (18), lower transverse lapped steel bar (20), and lower longitudinal lapped steel bar (21) are welded to the original longitudinal and transverse steel bars (16) on one side, the welding length shall not be less than 10 times the steel bar diameter, and when welded on both sides, it shall not be less than 5 times the steel bar diameter; the bottom spacing of the newly added stirrups (22) shall be 100mm to 150mm, and the top spacing shall be 150mm to 200mm; in step S4, the pouring interval between the lower high self-stress concrete and the upper low self-stress concrete shall not exceed the initial setting time of the lower concrete, the slump of the concrete entering the formwork shall be 160mm to 200mm, and the immersion vibrator shall be used for layered vibration and the vibrator shall avoid touching the bottom formwork (2) of the whole steel plate and the steel bars. After the pouring is completed, the surface shall be finished in time and the secondary surface shall be completed before the final setting.

13. The repair and reinforcement method for partial damage to the top slab and pavement of a hollow slab bridge according to claim 10, characterized in that: In step S5, the final setting time of concrete is determined by a penetration resistance meter or by on-site finger pressure. High-viscosity modified emulsified asphalt is sprayed under ambient temperature of 5℃~35℃ and no rain conditions, with a spraying rate of 0.8kg / ㎡~1.5kg / ㎡. After spraying, the repair area is sealed off and personnel and vehicles are prohibited from passing through. In step S6, the geotextile or moisturizing membrane is kept moist throughout the curing period. The number of times water is sprayed daily is based on the surface not turning white. The repair area shall not be subjected to load impact during the curing period.

14. The repair and reinforcement method for partially damaged top slab and pavement of hollow slab bridges according to claim 10, characterized in that: In step S7, the surface of the high-viscosity emulsified asphalt penetrating interlocking layer (8) is cleaned before hot asphalt is sprayed to ensure that it is dry and free of loose particles; after the basalt fiber layer (9) is sprayed, there is no accumulation or gaps, and the rubber wheel compaction is completed immediately after the hot asphalt is sprayed; in step S8, the paving temperature of the new asphalt pavement layer (11) is not lower than 160℃ and the initial compaction temperature is not lower than 150℃. Emulsified asphalt tack coat is sprayed between the layers of the layered paving, and the hot asphalt coating on the vertical surface where the new and old asphalt meet is uniform and without any white spots.

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