Prestress assembly type road structure and construction method thereof

Abstract

The invention relates to the technical field of highway engineering, discloses a prestressed fabricated road structure and a construction mode, and aims to promote industrial development and scientific and technological progress in China at a high level, innovate structural design and optimize a process method. According to the overall technical scheme, a prefabricated component is deeply designed, inverted-T-shaped prefabricated curbstone beams and middle supporting T beams are in place and positioned, distributed multi-point ground piles are reinforced, stiffening rib plates are connected in a reinforced mode, a single reinforcing mesh is subjected to an anti-arch effect, unbonded prestressed tendons are arranged through an inner anchoring method, fine aggregate concrete is poured and formed at a time, segmented construction is conducted, and line production is conducted. According to the design concept of'comprehensive pavement of asphalt surface layers', engineering practice is combined, research, development and application of a new technology are enhanced, a technical system is formed, and industry transformation development is boosted with high quality for industry reference.

Description

Technical Field

[0001] The present invention relates to the technical field of highway engineering, and particularly to a prestressed assembled road structure and a construction method thereof. Background Technique

[0002] The assembled construction technology has become a key planned construction method. To broaden the application field of the assembled construction technology, aiming at the problems existing in the precast components and parts of the current precast concrete structure, such as low integration degree, many production processes, low construction efficiency, etc., innovative research is carried out from aspects such as the production of assembled road components, the detailed design of precast components, the control of structural elevation, the application of prestress, integrated drainage, efficient construction, construction period optimization, cost control, and environmental protection, so as to improve the integration degree of design and construction of the precast concrete structure in the technical field of road engineering, and establish an innovative product system based on integrated technology, an efficient production and installation control management system, efficient supporting production equipment, and a construction technology system.

[0003] The research on the complete set of key technologies for assembled roads has also become one of the important topics in the current industry development. In order to solve the industry pain points in assembled roads, such as road alignment problems, large installation errors, many construction processes, difficult installation adjustment, high construction costs, construction quality, environmental protection, etc., on the premise of deeply studying the technologies of relevant scholars, our team proposed "a prestressed assembled road structure and a construction method thereof". This technology is the research and application result of the 2023 Nantong Science and Technology Plan project undertaken by the team: the complete set of key technologies for the construction of assembled roads (PFR technology system). It is hoped that through school-enterprise cooperation, a relatively mature new structure, new process, and new method for the construction of assembled roads can be formed, and joint efforts can be made for the application of new assembled construction technologies in the field of assembled roads in China, innovate the structural design, optimize the construction process, and make certain contributions to the high-quality development of the construction field of assembled road structures in China. Summary of the Invention

[0004] The purpose of the present invention is to provide a prestressed assembled road structure and a construction method thereof to solve the problems proposed in the background technique.

[0005] To achieve the above object, the present invention provides the following technical solution: A prestressed prefabricated road structure, including a roadbed, a roadbed reinforcement layer, ground piles, inverted T-shaped precast curb beams, middle support T beams, extended steel bars, connecting steel bars, unbonded prestressed tendons and an asphalt surface layer; a roadbed reinforcement layer is provided above the roadbed, ground piles are provided inside the roadbed reinforcement layer, additional steel bars are provided inside the ground piles, inverted T-shaped precast curb beams and middle support T beams are provided above the roadbed reinforcement layer, extended steel bars are provided at the ends of the inverted T-shaped precast curb beams and middle support T beams, and the opposite extended steel bars are butt-jointed by the connecting steel bar welding method; prestressed tendon ducts are provided inside both the inverted T-shaped precast curb beams and middle support T beams, a reserved notch is provided on the outer side of the inverted T-shaped precast curb beam, the unbonded prestressed tendons pass through the prestressed tendon ducts inside the inverted T-shaped precast curb beams and middle support T beams, and the unbonded prestressed tendons are tensioned and fixed by anchors in the reserved notches on the inverted T-shaped precast curb beams at both ends of the road; longitudinal distribution steel bars are also provided above the extended steel bars and connecting steel bars, the cavities inside the overall installation structure are filled with concrete to form a molded shape, and an asphalt surface layer is further provided above the entire road structure.

[0006] Preferably, the inverted T-shaped precast curb beams and middle support T beams are in a precast form, and both are precast and formed in a PC factory. Prestressed ducts are formed inside the inverted T-shaped precast curb beams and middle support T beams in the form of embedded steel sleeves. The inner diameter of the prestressed ducts is 2 mm to 3 mm larger than the diameter of the unbonded prestressed tendons. A reserved notch is formed inside the outer end of the inverted T-shaped precast curb beam in the form of an embedded square groove. The side length of the reserved notch is not less than 100 mm, the depth is not less than 80 mm and 10 mm larger than the size of the anchor in the same direction. The reserved notch inside the inverted T-shaped precast curb beam is connected and communicated with the prestressed tendon; the specific dimensions of the ends of the inverted T-shaped precast curb beams and middle support T beams are determined comprehensively according to factors such as the treatment elevation of the roadbed soil layer, soil quality conditions, and the layout requirements of the prestressed tendons, and are flexibly designed. The cutting length of the extended steel bars provided on the sides of the inverted T-shaped precast curb beams and middle support T beams is not less than 1000 mm, and the length of the extended steel bars anchored into the inverted T-shaped precast curb beams is not less than 35d and not less than 450 mm, where d is the diameter of the extended steel bars; the extended steel bars embedded in the middle support T beams are designed with a full-length cutting length. Each end of the extended steel bars protrudes from each end face of the middle support T beam by not less than 500 mm, that is, the cutting length of the extended steel bars embedded in the middle support T beam is greater than or equal to the designed flange width of the middle support T beam + 1000 mm, and the diameter of the extended steel bars is not less than 12 mm.

[0007] Preferably, the subgrade reinforcement layer is filled and compacted with crushed stones and coarse sand laid. The thickness of the subgrade reinforcement layer is not less than 300 mm. The ground piles inside the subgrade reinforcement layer can be formed by the static pressure method of precast ground piles or by the method of post-grouting with mechanical hole expansion and then inserting steel bars. The diameter of the ground piles is not less than 60 mm, the length of the ground piles is not less than 450 mm, the spacing is not more than 350 mm, and they are evenly arranged on the entire subgrade reinforcement layer. The distance between the end ground piles and the side of the inverted T-shaped precast curb beam and the middle support T beam is not more than 150 mm. The diameter of the additional steel bars inside each ground pile is not less than 16 mm, and the length of the inserted steel bars inside is not less than 650 mm.

[0008] Preferably, the extended steel bars at the ends of the inverted T-shaped precast curb beam and the middle support T beam are butt-jointed by welding connecting steel bars. The extended steel bars are arranged along the length direction of the inverted T-shaped precast curb beam and the middle support T beam. The spacing between adjacent extended steel bars is not more than 300 mm; the diameter of the longitudinal distribution steel bars is equal to the diameter of the extended steel bars, and the spacing between the longitudinal distribution steel bars is not more than 200 mm, forming a single-layer steel bar mesh to resist the reverse arch force of the foundation soil.

[0009] Preferably, a fine aggregate concrete layer is poured in the internal cavity after the overall structure is installed. The fine aggregate concrete layer is arranged between the subgrade reinforcement layer and the top asphalt surface layer. The strength of the fine aggregate concrete is not lower than C25. The top surface of the poured fine aggregate concrete layer is flush with the top surface of the middle support T beam after being installed in place, which is the design elevation of the road main structure.

[0010] Preferably, the unbonded prestressed tendons are arranged inside the structure by the perforation method. After the unbonded prestressed tendons are anchored, the inside of the reserved notch should be filled and sealed with high-strength low-shrinkage mortar; the unbonded prestressed tendons are arranged longitudinally along the entire cross-section of the road, with a spacing not exceeding 1500 mm, and are evenly arranged longitudinally along the road. The cut length of the unbonded prestressed tendons should meet the requirements of tensioning and anchoring.

[0011] Preferably, to improve the bearing effect of the overall structure, several ground piles are provided in the foundation reinforcement layer. Longitudinal and transverse stiffening rib plates are positioned above the additional steel bars inside the ground piles through nuts. The length of the stiffening rib plates is the maximum distance of the ground piles in the same direction + 600 mm, the width of the stiffening rib plates is 30 mm - 50 mm, and the plate thickness is 8 mm - 12 mm. There are several reserved holes on the stiffening rib plates. The reserved holes on the stiffening rib plates correspond to the positions of the ground piles in the foundation reinforcement layer one by one. The top ends of the additional steel bars inside the ground piles are inserted into the reserved holes on the stiffening rib plates and fixed by spot welding. The diameter of the reserved holes on the stiffening rib plates is 1 mm - 2 mm larger than the diameter of the inserted steel bars in the designed ground piles; after the installation of the stiffening rib plates, longitudinal and transverse grid members will be formed in the post-cast concrete between the foundation reinforcement layer and the asphalt surface layer, strengthening the bearing effect of the overall structure.

[0012] The present invention also discloses a construction method for a prestressed prefabricated road structure, which adopts the core technical solutions of "deepening the design of prefabricated components, positioning and installing inverted T-shaped precast curb beams and middle support T-beams, strengthening the ground piles in a distributed and multi-point manner, strengthening the connection with stiffening rib plates, the arching effect of single-layer steel bar mesh, the internal anchoring method for laying unbonded prestressed tendons, one-time casting and forming of fine aggregate concrete, segmental construction, flow operation, and overall paving of the asphalt surface course". The construction process flow is as follows: measuring and setting out the road alignment, subgrade treatment --- driving ground piles, installing stiffening rib plates --- excavating trenches, hoisting inverted T-shaped precast curb beams and middle support T-beams --- perforating unbonded prestressed tendons, temporarily fixing the anchorages in the reserved slots --- butt-jointing the extended steel bars and connecting steel bars to form a single-layer steel bar mesh --- concrete pouring, vibration and curing --- tensioning and anchoring of unbonded prestressed tendons --- flow construction, repeating the above process flow until the construction of the overall structure is completed, and finally, overall paving of the asphalt surface course.

[0013] Preferably, the specific technical solutions are as follows:

[0014] Step S1: Measuring and setting out the road alignment, subgrade treatment:

[0015] According to the construction plan, use a total station to conduct on-site survey and setting out of the entire road plane position and elevation, and focus on surveying and setting out the positions of the inverted T-shaped precast curb beams and middle support T-beams in the road design. Use the method of driving stiff precast hollow pipe piles to position the road alignment. The diameter of the stiff precast hollow pipe piles is not less than 150 mm, the length is not less than 450 mm, and the spacing between adjacent stiff precast hollow pipe piles is preferably 2500 mm - 3000 mm. On the one hand, the stiff precast hollow pipe piles position the plane positions of the designed inverted T-shaped precast curb beams and middle support T-beams. On the other hand, the top elevation of the stiff precast hollow pipe piles is the bottom elevation for the on-site hoisting and installation of the T-shaped precast curb beams and middle support T-beams in the subsequent process, which is convenient for trench excavation, beneficial to component hoisting, accurately determines the trench excavation depth, and can also play a certain role in strengthening the foundation. During the on-site construction process, while measuring and setting out the road on-site alignment, mechanical equipment can be used to level the site, compact the subgrade, and construct the subgrade reinforcement layer. The soil in the local areas of the inverted T-shaped precast curb beams and middle support T-beams can be appropriately reinforced, and the on-site positioning work and foundation soil layer reinforcement are organized in stages, processes, and flows. The organization and arrangement are strictly carried out in accordance with the requirements of the construction organization design, and acceptance records are made.

[0016] Step S2: Driving ground piles, installing stiffening rib plates:

[0017] According to the technical solution, draw the plan distribution diagram of the ground piles, and accurately measure and set the plane positions of the ground piles by using a total station; on-site, the plum blossom-shaped driving of ground piles is adopted for the treatment of the roadbed to reinforce the foundation, forming a distributed multi-point ground pile reinforcement group; for the ground piles in the roadbed reinforcement layer, they can be formed by the static pressing method of precast ground piles or by the method of inserting steel bars after mechanical hole expansion and grouting. Under complex working conditions such as rich groundwater and soft soil, the static pressing method of precast ground piles can be selected to play the role of squeezing soil depth to strengthen the foundation; when the soil condition is relatively good, the method of inserting steel bars after mechanical hole expansion and grouting can be selected to form; in order to strengthen the effect of the ground piles forming a common bearing and reinforcing the foundation, the ends of the extended steel bars above each ground pile are provided with perforated stiffening rib plates, and each ground pile is connected by setting the perforated stiffening rib plates, forming a connecting beam between the foundation reinforcement layer and the post-cast concrete layer, so as to achieve the purpose of improving the bearing capacity of the overall road structure;

[0018] Step S3: Excavate the trench and hoist the inverted T-shaped precast road curb beam and the middle support T beam:

[0019] After organizing on-site positioning work and foundation soil layer reinforcement treatment in stages, processes, and in a flowing water manner, the trench excavation work before hoisting is carried out in the way of "first excavating the inverted T-shaped precast curb beam trench, and then excavating the middle support T-beam trench"; the on-site trench excavation is based on the top elevation of the rigid precast hollow pipe piles driven into the foundation soil layer in the above-mentioned process. Appropriately continue to excavate 100 mm downward from the top of the rigid precast hollow pipe piles for the need of on-site cushion construction. Pour the cushion concrete to the top of the rigid precast hollow pipe piles. The cushion concrete wraps the upper part of the rigid precast hollow pipe piles. The pouring of the cushion concrete can connect several rigid precast hollow pipe piles to form a common load-bearing body, which is conducive to foundation reinforcement and improvement of road construction quality, and improves the durability of the road structure; before on-site hoisting, first plug the reserved holes inside the inverted T-shaped precast curb beam and the middle support T-beam with rubber plugs. Adopt the technical scheme of "sectional, sectional area, and modular flowing water operation, first hoist the inverted T-shaped precast curb beam to control the overall size of the road, and then hoist the middle support T-beam to improve the road bearing system". During the hoisting of the inverted T-shaped precast curb beam and the middle support T-beam, the paving mortar method can be used to adjust the top elevation of the cushion to achieve the efficient hoisting and positioning of the inverted T-shaped precast curb beam and the middle support T-beam. During the hoisting process, the top elevations of the inverted T-shaped precast curb beam and the middle support T-beam hoisted should be key checked. Adjust the outer extended steel bars on both sides of the inverted T-shaped precast curb beam and the middle support T-beam after positioning. To improve the integrity of the road structure, the inverted T-shaped precast curb beams and the middle support T-beams in each section are connected in the form of cast-in-place segments left. The width of the cast-in-place segment is 300 mm. Along the height of the precast component, at least 3 bolt rods are set in the cast-in-place segment. The bolt rods are butt-connected with high-strength nuts. The cast-in-place segment is poured and completed with slightly expanded fine aggregate concrete, and the concrete strength is not less than C35; after the inverted T-shaped precast curb beam and the middle support T-beam are hoisted and positioned, the trench soil backfilling is immediately carried out in sections, and it shall not be exposed for too long. Try to avoid construction in the rainy season and do a good job in on-site drainage measures;

[0020] Step S4: Pass the unbonded prestressed tendon through the hole, and temporarily fix the anchor in the reserved notch:

[0021] After the inverted T-shaped prefabricated curb beam and the middle supporting T-beam are hoisted in sections, the unbonded prestressed tendons can be laid out. First, the rubber plugs at the reserved holes inside the inverted T-shaped prefabricated curb beam and the middle supporting T-beam are pulled out, and the unbonded prestressed tendons are punched on site by the traction method. During the punching process of the unbonded prestressed tendons, it should be ensured that there are no debris in the reserved holes in the inverted T-shaped prefabricated curb beam and the middle supporting T-beam. If necessary, a high-pressure air gun should be used for flushing. After the unbonded prestressed tendons are punched, they are temporarily fixed in the reserved notches at the ends of the inverted T-shaped prefabricated curb beams on both sides of the road. While waiting for the subsequent prestressing force to be applied, in order to improve the local compressive strength of the prestressed tendons to be applied later, the reserved notches of the inverted T-shaped prefabricated curb beam are arranged in a three-step shape, and compression spiral tendons are arranged inside the pressure-bearing surface. The compression spiral tendons are designed and produced in an integrated manner during the prefabrication and forming of the inverted T-shaped prefabricated curb beam PC factory. The on-site unbonded prestressed tendons are temporarily fixed and arranged using anchors. During the operation, the on-site arrangement position of the formed ground piles or stiffening rib plates at the bottom must not be affected. The on-site unbonded prestressed tendons are pierced one by one, anchored as they are pierced, and temporarily fixed. A dedicated person is assigned to inspect and accept the situation on site, and good records of the process are kept.

[0022] Step S5: Butt-join the extended steel bars and the connecting steel bars to form a single steel mesh:

[0023] After the unbonded prestressed reinforcement is punched, the upper steel mesh is installed in sections according to the modules. That is, between the protruding steel bars at both ends of the inverted T-shaped prefabricated curb beam and the middle supporting T-beam, the protruding steel bars at both ends are connected by welding additional connecting steel bars. The longitudinal distribution steel bars are arranged on the upper part of the protruding steel bars that have been connected one by one according to the design requirements to form a single steel mesh that connects the protruding steel bars and the connecting steel bars. During the on-site steel mesh installation process, the longitudinal distribution steel bars should be installed from the middle to both ends of the road. The longitudinal distribution steel bars within 500mm of the welding point of the protruding steel bars and the connecting steel bars should be appropriately increased. The ends of the longitudinal distribution steel bars are provided with 90-degree hooks and anchored into their lower parts. The anchoring length is not less than 350mm. Before pouring concrete in each section, the aforementioned hidden engineering acceptance is completed and the acceptance records are kept.

[0024] Step S6: Concrete pouring, vibration and curing:

[0025] According to the technical solution, adopt flow operation, check and review the positional relationship between the inverted T-shaped precast curb beam and the middle support T beam. After verification, carry out the on-site concrete pouring work; the concrete pouring is carried out in one go for each section with fine aggregate concrete. The pouring height of the concrete is flush with the top surfaces of the in-place inverted T-shaped precast curb beam and the middle support T beam. The strength of the fine aggregate concrete is not less than C25. Strictly follow the design drawings and technical solutions, strengthen vibration and curing, and enhance the quality of the concrete pouring and forming around the inverted T-shaped precast curb beam and the middle support T beam. Problems such as incomplete vibration, deformation of the stiffening rib plate caused by collision, and structural hollowing are not allowed; the concrete pouring above the on-site roadbed can be carried out together with the concrete in the post-cast section between adjacent inverted T-shaped precast curb beams to improve the integrity and bearing capacity of the road structure.

[0026] Step S7: Unbonded prestressed tendon tensioning and anchoring:

[0027] After the concrete pouring is completed, the curing time shall not be less than 14 days. Use a jack to tension each unbonded prestressed tendon one by one. The on-site prestressed tendon tensioning can be carried out after all the works are completed. Adopt over-tensioning with 1.03σcon and symmetric tensioning, and tension from the middle of the road to both ends respectively; during the on-site construction process, first, for the temporary fixation of the unbonded prestressed tendon in the reserved notch on the side of the inverted T-shaped precast curb beam in the aforementioned process, loosen the anchor, tension with a jack, and carry out final anchoring after reaching the preset stress; if the designed road width is less than 8m, a one-end fixed and one-end tensioning scheme can be adopted; if the designed road width is 8m or more, a two-end symmetric tensioning scheme should be adopted; after the on-site prestressed tendon tensioning and anchoring are completed, carry out grouting sealing treatment on the anchor fixed in the reserved notch, and fill the cavity in the anchor and the reserved notch with slightly expanding high-strength mortar tightly. The grouting sealing work is organized simultaneously with the prestressed tendon tensioning and anchoring, that is, follow the principle of "tensioning and anchoring simultaneously, grouting and sealing simultaneously", complete one by one without omission, and do a good job in the process acceptance records;

[0028] Step S8: Flow construction, repeat steps S1 to S7 until the overall structure construction is completed, and finally carry out the full paving of the asphalt surface layer:

[0029] After all the above processes are completed, adopt the flow operation organization method. The on-site flow construction organization form runs through the entire project construction period. Repeat steps S1 to S7, carry out flow operation in sections, intervals, and modules, combine the hoisting of precast components with concrete pouring, and carry out wet and dry mixed operations until the overall structure construction is completely completed. Finally, carry out the full paving of the asphalt surface layer; organize the completion acceptance and do a good job in material filing.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: The overall technical solution of the present invention follows the design concept of "deepening the design of prefabricated components, positioning and installing the inverted T-shaped precast curb beam and the middle support T beam, strengthening the ground piles at distributed multi-points, strengthening the connection with stiffening rib plates, the arching effect of single-layer steel bar mesh, arranging the unbonded prestressed tendons by internal anchoring method, pouring the fine aggregate concrete in one go, constructing in sections, and carrying out flow operation, and fully paving the asphalt surface course". The structure has strong anti-vibration ability, can be quickly installed in an assembled manner, can save nearly 40% of the construction period compared with the traditional wet operation method, reduce the construction cost by about 25%, meet the requirements of green construction, and is convenient for later maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of the road structure of the present invention;

[0032] Figure 2 is a flow chart of the construction process of the present invention;

[0033] Reference numerals in the drawings: 1 - subgrade reinforcement layer, 2 - fine aggregate concrete layer, 3 - asphalt surface course, 4 - ground pile, 5 - inverted T-shaped precast curb beam, 6 - middle support T beam, 7 - extended steel bar, 8 - connecting steel bar, 9 - stiffening rib plate, 10 - prestressed tendon duct, 11 - reserved notch, 12 - unbonded prestressed tendon, 13 - anchor, 14 - additional steel bar. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] Please refer to Figure 1 , in the embodiment of the present invention, a prestressed assembled road structure is disclosed, which includes a subgrade, a subgrade reinforcement layer 1, a ground pile 4, an inverted T-shaped precast curb beam 5, a middle support T beam 6, an extended steel bar 7, a connecting steel bar 8, an unbonded prestressed tendon 12 and an asphalt surface course 3. A subgrade reinforcement layer 1 is provided above the subgrade. Ground piles 4 are provided inside the subgrade reinforcement layer 1. Additional steel bars 14 are provided inside the ground piles 4. An inverted T-shaped precast curb beam 5 and a middle support T beam 6 are provided above the subgrade reinforcement layer 1. Extended steel bars 7 are provided at the ends of the inverted T-shaped precast curb beam 5 and the middle support T beam 6. The opposite extended steel bars 7 are butt-jointed by welding with a connecting steel bar 8. Prestressed tendon ducts 10 are provided inside both the inverted T-shaped precast curb beam 5 and the middle support T beam 6. A reserved notch 11 is provided on the outer side of the inverted T-shaped precast curb beam 5. The unbonded prestressed tendon 12 passes through the prestressed tendon ducts 10 inside the inverted T-shaped precast curb beam 5 and the middle support T beam 6, and the unbonded prestressed tendon 12 is tensioned and fixed by an anchor 13 in the reserved notch 11 on the inverted T-shaped precast curb beam 5 at both ends of the road. Longitudinal distribution steel bars are also provided above the extended steel bars 7 and the connecting steel bar 8. The cavity inside the overall installation structure is poured and formed with concrete, and an asphalt surface course 3 is further provided above the entire road structure.

[0035] The inverted T-shaped prefabricated curb beam 5 and the central supporting T-beam 6 are prefabricated and are prefabricated in a PC factory. Prestressed channels are formed inside the inverted T-shaped prefabricated curb beam 5 and the central supporting T-beam 6 by pre-buried steel casing. The inner diameter of the prestressed channel is 2mm to 3mm larger than the diameter of the unbonded prestressed tendons 12. A reserved notch 11 is formed inside the outer end of the inverted T-shaped prefabricated curb beam 5 by pre-buried square grooves. The side length of the reserved notch 11 is not less than 100mm, the depth is not less than 80mm and is 10mm larger than the size of the anchor 13 in the same direction. The reserved notch 11 inside the inverted T-shaped prefabricated curb beam 5 is connected to the unbonded prestressed tendons. The specific dimensions of the ends of the inverted T-shaped prefabricated curb beam 5 and the central supporting T-beam 6 are determined comprehensively based on the roadbed soil treatment elevation, soil conditions, prestressed reinforcement layout requirements, etc., and are flexibly designed. The cutting length of the protruding steel bars 7 provided on the sides of the inverted T-shaped prefabricated curb beam 5 and the central supporting T-beam 6 is not less than 1000mm, and the length of the protruding steel bars 7 anchored in the inverted T-shaped prefabricated curb beam 5 is not less than 35d (d is the diameter of the protruding steel bars 7) and not less than 450mm. The protruding steel bars 7 at both ends embedded in the central supporting T-beam 6 should be designed to be full-length, and each end of the protruding steel bars 7 should be exposed to the end faces of the central supporting T-beam 6 by not less than 500mm, that is, the cutting length of the protruding steel bars 7 embedded in the central supporting T-beam 6 should be greater than or equal to the designed flange width of the central supporting T-beam 6 + 1000mm, and the diameter of the protruding steel bars 7 is not less than 12mm.

[0036] The roadbed reinforcement layer 1 is compacted by laying crushed stone and coarse sand. The thickness of the roadbed reinforcement layer 1 is not less than 300 mm. The ground piles 4 inside the roadbed reinforcement layer 1 can be formed by the static pressure method of prefabricated ground piles 4 or by the method of inserting reinforcement after mechanical hole expansion and grouting. The diameter of the ground piles 4 is not less than 60 mm, the length of the ground piles 4 is not less than 450 mm, the spacing is not more than 350 mm, and they are evenly distributed on the entire roadbed reinforcement layer 1. The end ground piles 4 are not more than 150 mm away from the side of the inverted T-shaped prefabricated curb beam 5 and the middle supporting T-beam 6. The diameter of each additional steel bar 14 inside the ground pile 4 is not less than 16 mm, and the length is not less than 650 mm.

[0037] The extended steel bars 7 at the ends of the inverted T-shaped prefabricated curb beam 5 and the central support T-beam 6 are butt-jointed using welded connecting bars 8. The extended steel bars 7 are arranged along the length of the inverted T-shaped prefabricated curb beam 5 and the central support T-beam 6, with the spacing between adjacent extended steel bars 7 no greater than 300mm. The diameter of the longitudinally distributed steel bars is equal to that of the extended steel bars 7, and the spacing between the longitudinally distributed steel bars is no greater than 200mm, forming a single-layer steel mesh to resist the reverse arching force of the foundation soil.

[0038] After the overall structure is installed, a fine aggregate concrete layer 2 is cast in the internal cavity. The fine aggregate concrete layer 2 is arranged between the subgrade reinforcement layer 1 and the top asphalt surface layer 3. The strength of the fine aggregate concrete is not less than C25. The top surface of the cast fine aggregate concrete layer 2 is flush with the top surface of the middle support T-beam 6 after being installed in place, which is the design elevation of the road main structure.

[0039] The unbonded prestressed tendons 12 are arranged inside the structure by the perforation method. The unbonded prestressed tendons 12 pass through the prestressed tendon ducts 10 reserved inside the inverted T-shaped precast curb beam 5 and the middle support T-beam 6, and are tensioned and anchored at the reserved notch 11 inside the inverted T-shaped precast curb beam 5 at both ends. After the unbonded prestressed tendons 12 are anchored, the inside of the reserved notch 11 shall be filled and sealed with high-strength and low-shrinkage mortar. The unbonded prestressed tendons 12 are arranged longitudinally along the entire cross-section of the road, with a spacing not exceeding 1500 mm, and are uniformly arranged longitudinally along the road. The cutting length of the unbonded prestressed tendons 12 shall meet the requirements of tensioning and anchoring.

[0040] To improve the load-bearing effect of the overall structure, several ground piles 4 are provided in the foundation reinforcement layer. Above the additional steel bars 14 inside the ground piles 4, longitudinal and transverse stiffening rib plates 9 are positioned by nuts. The length of the longitudinal and transverse stiffening rib plates 9 is the maximum distance of the ground piles 4 in the same direction + 600 mm, the width is 30 mm - 50 mm, and the plate thickness is 8 mm - 12 mm. Several reserved holes are provided on the longitudinal and transverse stiffening rib plates 9. The reserved holes on the longitudinal and transverse stiffening rib plates 9 correspond to the positions of the ground piles 4 in the foundation reinforcement layer one by one. The top ends of the additional steel bars 14 are inserted into the reserved holes on the longitudinal and transverse stiffening rib plates 9 and fixed by spot welding. The diameter of the reserved holes on the longitudinal and transverse stiffening rib plates 9 is 1 mm - 2 mm larger than the diameter of the inserted steel bars in the designed ground piles 4. After the longitudinal and transverse stiffening rib plates 9 are installed, longitudinal and transverse grid members will be formed in the post-cast concrete between the foundation reinforcement layer and the asphalt surface layer 3, strengthening the load-bearing effect of the overall structure.

[0041] The present invention also discloses the construction method of the above road structure, adopting the core technical solutions of "deepening the design of prefabricated components, positioning and fixing the inverted T-shaped precast curb beam and the middle support T-beam, distributed multi-point ground pile reinforcement, strengthening the connection with stiffening rib plates, the reverse arch effect of single-layer steel bar mesh, the internal anchoring method of unbonded prestressed tendons, one-time casting and forming of fine aggregate concrete, sectional construction, flow operation, and overall paving of the asphalt surface layer", as Figure 2 shown, and its construction process flow is as follows:

[0042] Measure and set out the alignment of the road, subgrade treatment --- drive in ground piles, install stiffening rib strips --- excavate trenches, hoist inverted T-shaped precast curb beams and middle support T-beams --- perforate unbonded prestressed tendons, temporarily fix the anchorages in the reserved notches --- butt the extended reinforcement bars and connecting reinforcement bars to form a single-layer steel bar mesh --- concrete pouring, vibration and curing --- unbonded prestressed tendon tensioning and anchoring --- carry out flow construction, repeat the above technological processes until the overall structure construction is completed, and finally fully pave the asphalt surface course.

[0043] The specific technical solution of the construction method is as follows:

[0044] Step S1: Measure and set out the alignment of the road, subgrade treatment

[0045] According to the construction plan, use a total station to conduct on-site surveying and setting out of the entire road plane position and elevation, with a focus on surveying and setting out the positions of the inverted T-shaped precast curb beams and middle support T-beams in the road design. Use the method of driving in stiffening precast hollow pipe piles to position the road alignment. The diameter of the stiffening precast hollow pipe piles is not less than 150 mm, the length is not less than 450 mm, and the spacing between adjacent stiffening precast hollow pipe piles is preferably 2,500 mm to 3,000 mm. On the one hand, the stiffening precast hollow pipe piles position the plane positions of the designed inverted T-shaped precast curb beams and middle support T-beams. On the other hand, the top elevation of the stiffening precast hollow pipe piles is the bottom elevation for the on-site hoisting and placement of the T-shaped precast curb beams and middle support T-beams in the subsequent processes, which is convenient for trench excavation, beneficial for component hoisting, accurately locates the trench excavation depth, and can also play a certain role in strengthening the foundation. During the on-site construction process, while measuring and setting out the on-site alignment of the road, mechanical equipment can be used to level the site, compact the subgrade, and construct the subgrade reinforcement layer. The soil in the local areas of the inverted T-shaped precast curb beams and middle support T-beams can be appropriately reinforced. Organize on-site positioning work and foundation soil layer reinforcement in stages, processes, and flows, and strictly implement the organization and arrangement in accordance with the requirements of the construction organization design, and do a good job in acceptance records.

[0046] Step S2: Drive in ground piles, install stiffening rib strips

[0047] According to the technical solution, draw the plan distribution diagram of the ground piles, and accurately measure and set the plane positions of the ground piles by using a total station. On-site, for the treatment of the roadbed, the ground piles are driven in a plum blossom pattern to reinforce the foundation, forming a distributed multi-point ground pile reinforcement group. For the ground piles in the roadbed reinforcement layer, they can be formed by the static pressing method of precast ground piles or by the method of inserting steel bars after mechanical hole expansion and grouting. Under complex working conditions such as rich groundwater and soft soil, the static pressing method of precast ground piles can be selected to play the role of strengthening the foundation by the depth of soil compaction. When the soil condition is relatively good, the method of inserting steel bars after mechanical hole expansion and grouting can be selected. In order to strengthen the effect of the ground piles jointly bearing and reinforcing the foundation, the ends of the extended steel bars above each ground pile are provided with perforated stiffening rib plates. By setting the perforated stiffening rib plates to connect each ground pile, a connecting beam is formed between the foundation reinforcement layer and the post-cast concrete layer to achieve the purpose of improving the bearing capacity of the overall road structure.

[0048] Step S3: Excavate the trench and hoist the inverted T-shaped precast road curb beam and the middle support T beam

[0049] After organizing on-site positioning work and foundation soil layer reinforcement treatment in stages, processes, and in a flowing water manner, the trench excavation work before hoisting is carried out in the way of "first excavating the groove of the inverted T-shaped precast curb beam and then excavating the groove of the middle support T beam". The on-site trench excavation is based on the top elevation of the stiffened precast hollow pipe piles driven into the foundation soil layer in the above-mentioned process. Appropriately continue to excavate 100 mm downward from the top surface of the stiffened precast hollow pipe piles for the construction needs of the on-site cushion layer. Pour the cushion layer concrete to the top surface of the stiffened precast hollow pipe piles. The cushion layer concrete wraps the upper part of the stiffened precast hollow pipe piles. The pouring of the cushion layer concrete can connect several stiffened precast hollow pipe piles to form a common load-bearing body, which is conducive to foundation reinforcement and improving the construction quality of the road and enhancing the durability of the road structure. Before on-site hoisting, first plug the reserved holes inside the inverted T-shaped precast curb beam and the middle support T beam with rubber plugs. Adopt the technical scheme of "segmented, sectionalized, and modular flowing water operation, first hoisting the inverted T-shaped precast curb beam to control the overall dimensions of the road, and then hoisting the middle support T beam to improve the road bearing system". During the hoisting process of the inverted T-shaped precast curb beam and the middle support T beam, the paving mortar method can be used to adjust the top elevation of the cushion layer to achieve the efficient hoisting and positioning of the inverted T-shaped precast curb beam and the middle support T beam. During the hoisting process, the top elevations of the hoisted inverted T-shaped precast curb beam and the middle support T beam should be key-rechecked, and the outstretched steel bars on both sides of the inverted T-shaped precast curb beam and the middle support T beam after positioning should be adjusted. To improve the integrity of the road structure, the inverted T-shaped precast curb beams and the middle support T beams in each section are connected in the form of cast-in-place post-cast sections. The width of the post-cast section is 300 mm. Along the height of the precast components, at least 3 bolt rods are arranged inside the post-cast section. The bolt rods are connected by high-strength nuts. The post-cast section is poured and completed with slightly expanded fine aggregate concrete, and the concrete strength is not less than C35. After the inverted T-shaped precast curb beam and the middle support T beam are hoisted and positioned, the trench soil backfilling is immediately carried out in sections, and it shall not be exposed for too long. Try to avoid construction during the rainy season and do a good job in on-site drainage measures.

[0050] Step S4: The unbonded prestressed tendon penetrates through the hole, and the anchor in the reserved notch is temporarily fixed

[0051] After the segmented hoisting of the inverted T-shaped precast curb beam and the middle support T beam is completed, the work of laying unbonded prestressed tendons can be carried out. First, pull out the rubber plugs at the reserved holes inside the inverted T-shaped precast curb beam and the middle support T beam in place, and use the traction method to perforate the on-site unbonded prestressed tendons after cutting. During the perforation process of the unbonded prestressed tendons, it should be ensured that there is no debris in each reserved hole of the inverted T-shaped precast curb beam and the middle support T beam. When necessary, use a high-pressure air gun for flushing. After the unbonded prestressed tendons are perforated, they are temporarily fixed in the reserved grooves at the ends of the inverted T-shaped precast curb beams on both sides of the road, waiting for the subsequent prestress application. To improve the local compressive capacity of the prestressed tendons during subsequent application, the reserved grooves of the inverted T-shaped precast curb beams are arranged in a three-step shape, and compressive spiral bars are arranged inside the bearing surface. The compressive spiral bars are integrally designed and produced when the inverted T-shaped precast curb beams are prefabricated and formed in the PC factory. The on-site unbonded prestressed tendons are temporarily fixed and arranged with anchor devices, and the on-site layout positions of the already formed ground piles or stiffening rib plates below should not be affected during the operation. The on-site unbonded prestressed tendons are perforated one by one, anchored and temporarily fixed as they are perforated. Special personnel are arranged for on-site inspection and acceptance, and process acceptance records are made.

[0052] Step S5: Connect the extended steel bars and the connecting steel bars to form a single-layer steel bar mesh

[0053] After the perforation of the unbonded prestressed tendons is completed, install the upper steel bar mesh in modules by segments, that is, between the extended steel bars provided at both ends of the inverted T-shaped precast curb beam and the middle support T beam, use the additional connecting steel bars to weld and connect the extended steel bars at both ends, and arrange the longitudinal distribution steel bars according to the design requirements above the extended steel bars that have been connected one by one, so as to form a single-layer steel bar mesh of the connected extended steel bars and the connecting steel bars. During the installation process of the on-site steel bar mesh, the longitudinal distribution steel bars should be installed from the middle to both ends of the road. The longitudinal distribution steel bars within 500 mm of the welding points of the extended steel bars and the connecting steel bars should be appropriately densified. The end of the longitudinal distribution steel bar is provided with a 90-degree hook and anchored into the lower part, and the anchorage length is not less than 350 mm. Before the concrete pouring in each section, the acceptance of the aforementioned process concealed works is carried out, and acceptance records are made.

[0054] Step S6: Concrete pouring, vibration and curing

[0055] According to the technical solution, adopt flow operation, check and review the positional relationship between the inverted T-shaped precast curb beam and the middle support T-beam. After verification, carry out the on-site concrete pouring work. The concrete pouring is carried out in one go for each section with fine aggregate concrete. The pouring height of the concrete is flush with the top surfaces of the already positioned inverted T-shaped precast curb beam and the middle support T-beam. The strength of the fine aggregate concrete is not less than C25. Strictly execute in accordance with the design drawings and technical solutions, strengthen vibration and curing, and strengthen the quality of the concrete pouring and forming around the inverted T-shaped precast curb beam and the middle support T-beam. There shall be no problems such as incomplete vibration, deformation of the stiffening rib plates caused by collision, and structural hollowing. The concrete pouring above the on-site roadbed can be carried out together with the concrete of the post-cast section between adjacent inverted T-shaped precast curb beams to improve the integrity and bearing capacity of the road structure.

[0056] Step S7: Unbonded prestressed tendon tensioning and anchoring

[0057] After the concrete pouring is completed, the curing time shall be not less than 14 days. Use a jack to tension each unbonded prestressed tendon one by one. The on-site prestressed tendon tensioning can be carried out after all the works are completed. Adopt 1.03σcon over-tensioning and symmetric tensioning, and tension from the middle of the road to both ends respectively. During the on-site construction process, first, for the temporary fixation of the unbonded prestressed tendon in the reserved notch on the side of the inverted T-shaped precast curb beam in the foregoing process, loosen the anchor, tension with the jack, and carry out the final anchoring after reaching the preset stress. If the designed road width is less than 8m, a one-end fixed and one-end tensioning scheme can be adopted; if the designed road width is 8m or more (including 8m), a two-end symmetric tensioning scheme shall be adopted. After the on-site prestressed tendon tensioning and anchoring are completed, carry out the sealing of the anchor fixed in the reserved notch. Use slightly expanding high-strength mortar to fill the cavity in the anchor and the reserved notch tightly. The sealing work of the anchor is organized simultaneously with the prestressed tendon tensioning and anchoring, that is, follow the principle of "tensioning and anchoring simultaneously, sealing the anchor immediately after anchoring", complete one by one without omission, and do a good job in the process acceptance records.

[0058] Step S8: Flow construction, repeat steps S1 to S7 until the overall structure construction is completed, and finally fully pave the asphalt surface course

[0059] After all the above processes are completed, adopt the flow operation organization method. The on-site flow construction organization form runs through the entire project construction period. Repeat steps 2.2.1 to 2.2.7, carry out flow operation in sections, intervals, and modules, combine the hoisting of precast components with concrete pouring, and carry out wet and dry mixed operations until the overall structure construction is completely completed. Finally, fully pave the asphalt surface course. Organize the completion acceptance and do a good job in material filing.

[0060] In summary, the structure of the present invention has strong anti-vibration ability, can be quickly installed in an assembled manner, saves nearly 40% of the construction period compared with the traditional wet operation method, reduces the construction cost by about 25%, meets the requirements of green construction, and is convenient for later maintenance.

[0061] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A prestressed prefabricated road structure, characterized in that: The roadbed comprises a roadbed, a roadbed reinforcement layer, ground piles, an inverted T-shaped prefabricated curb beam, a middle supporting T-beam, extended steel bars, connecting steel bars, unbonded prestressed bars and an asphalt surface layer; a roadbed reinforcement layer is provided above the roadbed, ground piles are provided inside the roadbed reinforcement layer, additional steel bars are provided inside the ground piles, an inverted T-shaped prefabricated curb beam and a middle supporting T-beam are provided on the upper part of the roadbed reinforcement layer, and extended steel bars are provided at the ends of the inverted T-shaped prefabricated curb beam and the middle supporting T-beam, and the opposite extended steel bars are butted together by connecting steel bar welding; the inverted T-shaped prefabricated curb beam and the middle supporting T-beam are provided with extended steel bars. Prestressed tendon channels are provided inside the supporting T-beams. A reserved notch is left on the outer side of the inverted T-shaped prefabricated curb beam. The unbonded prestressed tendons pass through the prestressed tendon channels inside the inverted T-shaped prefabricated curb beam and the middle supporting T-beam. The unbonded prestressed tendons are tensioned in the reserved notches on the inverted T-shaped prefabricated curb beams at both ends of the road and fixed with anchors. Longitudinal distribution steel bars are also provided on the upper part of the protruding steel bars and the connecting steel bars. The cavity inside the overall installation structure is cast and formed with concrete. An asphalt surface layer is also provided on the upper part of the entire road structure.

2. A prestressed prefabricated road structure according to claim 1, characterized in that: The inverted T-shaped prefabricated curb beam and the central supporting T-beam are prefabricated and are formed in a PC factory. Prestressed channels are formed inside the inverted T-shaped prefabricated curb beam and the central supporting T-beam through embedded steel casing. The inner diameter of the prestressed channel is 2mm to 3mm larger than the diameter of the unbonded prestressed tendons. A reserved notch is formed inside the outer end of the inverted T-shaped prefabricated curb beam through embedded square grooves. The side length of the reserved notch is not less than 100mm, the depth is not less than 80mm and is 10mm larger than the size of the anchor in the same direction. The reserved notch inside the inverted T-shaped prefabricated curb beam is butt-jointed with the unbonded prestressed tendons. The specific dimensions of the ends of the inverted T-shaped prefabricated curb beam and the central supporting T-beam are determined according to the roadbed soil. The layer treatment elevation, soil conditions, prestressed reinforcement layout requirements, etc. are comprehensively determined and flexibly designed. The cutting length of the protruding steel bars on the sides of the inverted T-shaped prefabricated curb beam and the central supporting T-beam is not less than 1000mm, and the length of the protruding steel bars anchored in the inverted T-shaped prefabricated curb beam is not less than 35d and not less than 450mm, where d is the diameter of the protruding steel bars. The protruding steel bars at both ends embedded in the central supporting T-beam are designed to be full-length, and each end of the protruding steel bars is exposed to not less than 500mm of each end face of the central supporting T-beam, that is, the cutting length of the protruding steel bars embedded in the central supporting T-beam is greater than or equal to the designed central supporting T-beam flange width + 1000mm, and the diameter of the protruding steel bars is not less than 12mm.

3. A prestressed prefabricated road structure according to claim 1, characterized in that: The roadbed reinforcement layer is compacted by laying crushed stone and coarse sand. The thickness of the roadbed reinforcement layer is not less than 300mm. The ground piles inside the roadbed reinforcement layer can be sunk by static pressure method of prefabricated ground piles or formed by mechanical hole expansion and grouting followed by reinforcement insertion. The diameter of the ground piles is not less than 60mm, the length of the ground piles is not less than 450mm, the spacing is not more than 350mm, and they are evenly distributed on the entire roadbed reinforcement layer. The distance between the end ground piles and the side of the inverted T-shaped prefabricated curb beam and the middle supporting T-beam is not more than 150mm. The diameter of the additional steel bar inside each ground pile is not less than 16mm, and the length is not less than 650mm.

4. A prestressed prefabricated road structure according to claim 1, characterized in that: The extended steel bars at the ends of the inverted T-shaped precast curb beams and the middle support T-beams are butt-connected by welded connecting steel bars. The extended steel bars are arranged along the lengths of the inverted T-shaped precast curb beams and the middle support T-beams, and the distance between adjacent extended steel bars is not greater than 300 mm. The diameter of the longitudinal distribution steel bars is equal to that of the extended steel bars, and the distance between the longitudinal distribution steel bars is not greater than 200 mm, forming a single-layer steel mesh to resist the reverse arch force of the foundation soil.

5. A prestressed prefabricated road structure according to claim 1, characterized in that: A fine aggregate concrete layer is poured in the internal cavity after the overall structure is installed. The fine aggregate concrete layer is arranged between the subgrade reinforcement layer and the top asphalt surface layer. The strength of the fine aggregate concrete is not lower than C25. The top surface of the poured fine aggregate concrete layer is flush with the top surface of the middle support T-beam after being installed in place, which is the design elevation of the road main structure.

6. The pre-stressed assembled road structure according to claim 1, wherein: The unbonded prestressed tendons are arranged inside the structure by the perforation method. After the unbonded prestressed tendons are anchored, the reserved notch inside shall be filled and sealed with high-strength and low-shrinkage mortar. The unbonded prestressed tendons are arranged longitudinally along the transverse section of the road, with a spacing not exceeding 1500 mm, and are evenly arranged longitudinally along the road. The cut length of the unbonded prestressed tendons shall meet the requirements of tensioning and anchoring.

7. A prestressed prefabricated road structure according to claim 1, characterized in that: To improve the bearing effect of the overall structure, several ground piles are provided in the subgrade reinforcement layer. Longitudinal and transverse stiffening rib plates are positioned above the additional steel bars inside the ground piles through nuts. The length of the stiffening rib plates is the maximum distance of the ground piles in the same direction + 600 mm, the width of the stiffening rib plates is 30 mm - 50 mm, and the plate thickness is 8 mm - 12 mm. Several reserved holes are provided on the stiffening rib plates. The reserved holes on the stiffening rib plates correspond to the positions of the ground piles in the subgrade reinforcement layer one by one. The top ends of the additional steel bars inside the ground piles are inserted into the reserved holes on the stiffening rib plates and fixed by spot welding. The diameter of the reserved holes on the stiffening rib plates is 1 mm - 2 mm larger than the diameter of the inserted steel bars in the designed ground piles. After the stiffening rib plates are installed, longitudinal and transverse grid members will be formed in the post-cast concrete between the subgrade reinforcement layer and the asphalt surface layer, strengthening the bearing effect of the overall structure.

8. A construction method of a prestressed prefabricated road structure, characterized in that: Adopt the core technical solution of "deepening the design of precast components, positioning and installing the inverted T-shaped precast curb beams and the middle support T-beams, distributed multi-point ground pile reinforcement, strengthening the connection with stiffening rib plates, the anti-arch effect of a single-layer steel mesh, the internal anchoring method of unbonded prestressed tendons, one-time pouring and forming of fine aggregate concrete, segmented construction, flow operation, and full paving of the asphalt surface layer". The construction process flow is as follows: measuring and setting out to determine the road alignment trend, subgrade treatment --- driving ground piles, installing stiffening rib plates --- excavating trenches, hoisting the inverted T-shaped precast curb beams and the middle support T-beams --- perforating the unbonded prestressed tendons, temporarily fixing the anchor devices in the reserved notches --- butt-connecting the extended steel bars and the connecting steel bars to form a single-layer steel mesh --- concrete pouring, vibration and curing --- tensioning and anchoring of the unbonded prestressed tendons --- flow construction, repeating the above process flow until the construction of the overall structure is completed, and finally fully paving the asphalt surface layer.

9. The construction method according to claim 8, characterized in that: The specific technical solution is as follows: Step S1: Measuring and setting out to determine the road alignment trend, subgrade treatment: According to the construction plan, a total station is used to conduct on-site surveying and setting out of the entire road plane position and elevation. The key is to survey and set out the positions of the inverted T-shaped precast road curb beams and the middle support T-beams in the road design. The road alignment is positioned by driving rigid precast hollow pipe piles. The diameter of the rigid precast hollow pipe piles is not less than 150 mm, the length is not less than 450 mm, and the spacing between adjacent rigid precast hollow pipe piles is preferably 2,500 mm to 3,000 mm. On the one hand, the rigid precast hollow pipe piles are used to position the plane positions of the designed inverted T-shaped precast road curb beams and the middle support T-beams. On the other hand, the top elevation of the rigid precast hollow pipe piles is the bottom elevation for the on-site hoisting and placement of the T-shaped precast road curb beams and the middle support T-beams in the subsequent process, which is convenient for trench excavation, beneficial to component hoisting, accurately determines the trench excavation depth, and can also play a certain role in strengthening the foundation. During the on-site construction process, while measuring and setting out the on-site road alignment, machinery can be used to level the site, tamp the roadbed, and construct the roadbed reinforcement layer. The soil in the local areas of the inverted T-shaped precast road curb beams and the middle support T-beams can be appropriately reinforced. The on-site positioning work and the foundation soil layer reinforcement are organized in stages, processes, and in a flowing water manner. The organization and arrangement are strictly carried out in accordance with the requirements of the construction organization design, and acceptance records are well kept. Step S2: Drive the ground piles and install the stiffening rib plates: According to the technical plan, draw the plane distribution diagram of the ground piles, and accurately survey and set out the plane positions of the ground piles by using a total station. For the treatment of the roadbed on-site, the ground piles are driven in a plum blossom pattern to carry out the foundation reinforcement treatment, forming a distributed multi-point ground pile reinforcement group. The ground piles in the roadbed reinforcement layer can be formed by the static pressing method of precast ground piles or by the method of inserting steel bars after mechanical hole expansion and grouting. Under complex working conditions such as abundant groundwater and soft soil, the static pressing method of precast ground piles can be selected to play the role of squeezing soil depth to strengthen the foundation. When the soil condition is relatively good, the method of inserting steel bars after mechanical hole expansion and grouting can be selected. In order to strengthen the effect of the ground piles forming a common bearing and strengthening the foundation, the ends of the extended steel bars above each ground pile are provided with perforated stiffening rib plates. By setting the perforated stiffening rib plates to connect each ground pile, a connecting beam is formed between the foundation reinforcement layer and the post-cast concrete layer to achieve the purpose of improving the bearing capacity of the overall road structure. Step S3: Excavate the trench and hoist the inverted T-shaped precast road curb beam and the middle support T-beam: After organizing on-site positioning work and foundation soil layer reinforcement treatment in stages, processes, and in a flowing water manner, the trench excavation work before hoisting is carried out by the method of "first excavating the groove of the inverted T-shaped precast curb beam and then excavating the groove of the middle support T beam". The on-site trench excavation is based on the top elevation of the stiffened precast hollow pipe piles driven into the foundation soil layer in the above-mentioned process. Appropriately continue to excavate 100 mm downward from the top of the stiffened precast hollow pipe piles for the need of on-site cushion construction. The cushion concrete is poured to the top of the stiffened precast hollow pipe piles, and the cushion concrete wraps the upper part of the stiffened precast hollow pipe piles. The pouring of the cushion concrete can connect several stiffened precast hollow pipe piles to form a common load-bearing body, which is beneficial to foundation reinforcement and improving the road construction quality and enhancing the durability of the road structure. Before on-site hoisting, first plug the reserved holes inside the inverted T-shaped precast curb beam and the middle support T beam with rubber plugs. Adopt the technical scheme of "sectional, sectional area, and modular flowing water operation, first hoist the inverted T-shaped precast curb beam to control the overall size of the road, and then hoist the middle support T beam to improve the road bearing system". During the hoisting process of the inverted T-shaped precast curb beam and the middle support T beam, the paving mortar method can be used to adjust the top elevation of the cushion to achieve the efficient hoisting and positioning of the inverted T-shaped precast curb beam and the middle support T beam. During the hoisting process, the top elevations of the inverted T-shaped precast curb beam and the middle support T beam hoisted should be key checked. Adjust the external extended steel bars on both sides of the inverted T-shaped precast curb beam and the middle support T beam after positioning. To improve the integrity of the road structure, the inverted T-shaped precast curb beams and the middle support T beams in each section are connected in the form of a cast-in-place section left. The width of the cast-in-place section is 300 mm. Along the height of the precast component, no less than 3 bolt rods are arranged in the cast-in-place section. The bolt rods are connected by high-strength nuts. The cast-in-place section is poured and completed with slightly expanded fine aggregate concrete, and the concrete strength is not less than C35. After the inverted T-shaped precast curb beam and the middle support T beam are hoisted and positioned, the trench earthwork backfilling is immediately carried out in sections, and the exposure time should not be too long. Try to avoid construction during the rainy season and do a good job in on-site drainage measures; Step S4: Pass the unbonded prestressed tendon through the hole and temporarily fix the anchor in the reserved notch: After the inverted T-shaped prefabricated curb beam and the middle supporting T-beam are hoisted in sections, the unbonded prestressed tendons can be laid out. First, the rubber plugs at the reserved holes inside the inverted T-shaped prefabricated curb beam and the middle supporting T-beam are pulled out, and the unbonded prestressed tendons are punched on site by the traction method. During the punching process of the unbonded prestressed tendons, it should be ensured that there are no debris in the reserved holes in the inverted T-shaped prefabricated curb beam and the middle supporting T-beam. If necessary, a high-pressure air gun should be used for flushing. After the unbonded prestressed tendons are punched, they are temporarily fixed in the reserved notches at the ends of the inverted T-shaped prefabricated curb beams on both sides of the road. While waiting for the subsequent prestressing force to be applied, in order to improve the local compressive strength of the prestressed tendons to be applied later, the reserved notches of the inverted T-shaped prefabricated curb beam are arranged in a three-step shape, and compression spiral tendons are arranged inside the pressure-bearing surface. The compression spiral tendons are designed and produced in an integrated manner during the prefabrication and forming of the inverted T-shaped prefabricated curb beam PC factory. The on-site unbonded prestressed tendons are temporarily fixed and arranged using anchors. During the operation, the on-site arrangement position of the formed ground piles or stiffening rib plates at the bottom must not be affected. The on-site unbonded prestressed tendons are pierced one by one, anchored as they are pierced, and temporarily fixed. A dedicated person is assigned to inspect and accept the situation on site, and good records of the process are kept. Step S5: Butt-join the extended steel bars and the connecting steel bars to form a single steel mesh: After the unbonded prestressed reinforcement is punched, the upper steel mesh is installed in sections according to the modules. That is, between the protruding steel bars at both ends of the inverted T-shaped prefabricated curb beam and the middle supporting T-beam, the protruding steel bars at both ends are connected by welding additional connecting steel bars. The longitudinal distribution steel bars are arranged on the upper part of the protruding steel bars that have been connected one by one according to the design requirements to form a single steel mesh that connects the protruding steel bars and the connecting steel bars. During the on-site steel mesh installation process, the longitudinal distribution steel bars should be installed from the middle to both ends of the road. The longitudinal distribution steel bars within 500mm of the welding point of the protruding steel bars and the connecting steel bars should be appropriately increased. The ends of the longitudinal distribution steel bars are provided with 90-degree hooks and anchored into their lower parts. The anchoring length is not less than 350mm. Before pouring concrete in each section, the aforementioned hidden engineering acceptance is completed and the acceptance records are kept. Step S6: Concrete pouring, vibration and curing: According to the technical plan, adopt a flow operation to check and verify the position relationship between the inverted T-shaped prefabricated curb beam and the middle supporting T-beam. After confirming that there is no error, carry out on-site concrete pouring. Fine stone concrete is used for concrete pouring. Each section is poured at one time. The concrete pouring height is flush with the top surface of the inverted T-shaped prefabricated curb beam and the middle supporting T-beam. The strength of fine stone concrete is not less than C25. Strictly follow the design drawings and technical plans, strengthen vibration and maintenance, and improve the quality of concrete pouring and forming around the inverted T-shaped prefabricated curb beam and the middle supporting T-beam. Problems such as loose vibration, deformation of stiffening ribs due to collision, and hollowing of the structure must not occur. The concrete pouring above the on-site roadbed can be poured together with the post-cast section concrete between adjacent inverted T-shaped prefabricated curb beams to improve the integrity and bearing capacity of the road structure. Step S7: Unbonded prestressed tendon tensioning and anchoring: After the concrete is poured, the curing time shall not be less than 14 days. Each unbonded prestressed tendon shall be tensioned one by one by a jack. The on-site tensioning of the prestressed tendons can be carried out after the completion of all projects. The over-tensioning is carried out with 1.03σcon, and the symmetric tensioning is adopted, and the tensioning is carried out from the middle of the road to both ends respectively; during the on-site construction process, first, for the temporary fixation of the unbonded prestressed tendon in the reserved notch on the side of the inverted T-shaped precast curb beam in the aforementioned process, the anchor is loosened, the jack is tensioned, and the final anchoring is carried out after reaching the preset stress; if the designed road width is less than 8m, a one-end fixed and one-end tensioning scheme can be adopted; if the designed road width is 8m and above, a two-end symmetric tensioning scheme shall be adopted; after the on-site prestressed tendon is tensioned and anchored, the anchor fixed in the reserved notch shall be sealed. The cavity in the anchor and the reserved notch shall be filled tightly with slightly expanding high-strength mortar. The sealing work of the anchor is organized simultaneously with the tensioning and anchoring of the prestressed tendon, that is, following the principle of "tensioning and anchoring simultaneously, sealing immediately after anchoring", and completed one by one without omission, and the process acceptance records shall be made well; Step S8: Carry out flow construction, repeat steps S1 to S7 until the overall structure construction is completed, and finally carry out the overall paving of the asphalt surface layer: After all the above processes are completed, adopt the flow operation organization method. The on-site flow construction organization form runs through the entire project construction cycle. Repeat steps S1 to S7, and carry out flow operation in sections, intervals, and modules. Combine the hoisting of precast components with concrete pouring, and carry out wet and dry mixed operations until the overall structure construction is completed. Finally, carry out the overall paving of the asphalt surface layer; organize the completion acceptance and do a good job in material filing.

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