A prefabricated roof slab connection structure for prefabricated subway stations

Abstract

This invention discloses a prefabricated roof slab connection structure for assembled subway stations, belonging to the field of subway station construction technology. It includes two semi-arched prefabricated roof slabs, which are joined at the arch crown using tenons and mortises to form an arched roof slab. A pressure cap component covers the joint. The tenon and mortise joint surface forms a locking hole extending along the arch thickness direction. Corresponding locking holes, larger at the top and smaller at the bottom, are provided within the pressure cap component. Metal anchor rods are inserted into the locking holes. The threaded grooves on the outer surface of the anchor rods form a grouting channel with the wall of the locking hole. The insertion end of the anchor rod has a deployable barb structure, which unfolds after penetrating the locking hole to form a one-way locking. High-strength, non-shrink grout is injected under high pressure, and after curing, a wedge-shaped body, smaller at the top and larger at the bottom, forms at the end of the anchor rod, tightly engaging with the inner wall of the locking hole. The pressure cap component connects adjacent arched roof slabs longitudinally along the tunnel to form a continuous whole. This invention improves the assembly strength, joint load-bearing reliability, waterproof durability, and longitudinal structural integrity of the prefabricated arched roof.

Description

Technical Field

[0001] This invention relates to the field of subway station construction technology, and specifically to a prefabricated roof slab connection structure for prefabricated subway stations. Background Technology

[0002] Traditional subway stations are mostly constructed using the open-cut and cast-in-place method, which suffers from long construction cycles, numerous on-site wet operations, and large variations in quality control. Prefabricated subway stations, on the other hand, employ a construction model of factory prefabrication and on-site assembly, which can significantly improve construction efficiency and structural quality stability, and has become an important development direction for underground engineering construction technology.

[0003] In existing precast roof slab connection schemes for prefabricated subway stations, a common practice is to join two semi-arched precast roof slabs together at the arch top, then insert circumferential tie bars or prestressed steel strands into pre-embedded tie bar holes or tensioning grooves on both sides of the joint, and finally anchor and lock them together after tensioning. This connection method has the following significant drawbacks: 1. The connection method is simplistic and lacks a permanent consolidation mechanism. Tie bar tensioning is a purely mechanical fastening connection, relying solely on the pre-tension of the tie bar to maintain contact and compression between the splice surfaces. There is no chemical bonding or grouting to form a unified consolidation between the splice surfaces. Under the coupled effects of long-term surrounding rock pressure, water pressure, and cyclic vibration loads from trains, the prestress of the tie bar will gradually decrease due to steel relaxation and concrete creep. The splice surfaces degenerate from an initial compressed state to a loose contact, the joint stiffness continuously decreases, leading to joint opening and weakening of the overall structural integrity.

[0004] 2. The waterproofing at the joints is weak, posing a high risk of leakage. In the tie-bar tensioning scheme, the waterproofing of the joints mainly relies on a single water-swellable sealing strip or elastic gasket embedded within the joint. This type of waterproofing is a "passive bonding" type, and its sealing effect highly depends on the joint surfaces remaining continuously compressed. Once the pre-tension of the tie bar loosens, causing the joint surfaces to open, the sealing strip will be unable to compensate for the increased gap, forming a seepage channel. In addition, the arch joints are subjected to repeated bending and shear deformation during long-term operation. The single-layer waterproofing structure lacks redundant protection, and once it fails, direct leakage will occur, affecting the operational safety of the station.

[0005] 3. Lack of longitudinal structural connections and insufficient overall integrity. The tie rods only address the circumferential connection of individual arched roof slabs. Adjacent arched roof slabs along the longitudinal direction of the station are typically assembled independently, lacking effective force transfer and connection structures. This results in the arched roof exhibiting a "parallel simply supported" state in the longitudinal direction, with low overall longitudinal stiffness. This makes it poorly adaptable to adverse conditions such as uneven ground settlement and seismic forces, and prone to misalignment and leakage at longitudinal joints.

[0006] 4. The coupling of structural stress and waterproofing function can easily lead to a chain reaction of failures. In the tie-bar tensioning scheme, the splice joint is both the main stress interface and the only waterproofing interface. The relative displacement and corner deformation of the joint caused by structural stress will directly affect the waterproofing layer. Under long-term repeated action, it is easy to cause the waterstop strip to tear and peel off, resulting in a chain reaction of "structural deformation → waterproofing failure → increased leakage", which is difficult to meet the durability requirements of the 100-year service life of subway projects.

[0007] Therefore, there is an urgent need to develop a precast roof slab connection structure that combines high load-bearing capacity, long-term waterproofing, and structural longitudinal integrity to overcome the shortcomings of existing tie rod tightening schemes. Summary of the Invention

[0008] The purpose of this invention is to provide a prefabricated roof slab connection structure for prefabricated subway stations. By adopting a tenon and mortise self-guided pre-compression joint, a composite anchoring of barbed metal anchor rods and grouting wedges, and an integrated structure with waterproofing and longitudinal connection of the top cover, the assembly strength, node bearing reliability, waterproofing durability and longitudinal integrity of the prefabricated roof slab of the prefabricated subway station are improved simultaneously. This effectively makes up for the technical shortcomings of existing connection schemes, such as insufficient force redundancy, weak waterproofing, and poor controllability of construction quality.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A prefabricated roof slab connection structure for a prefabricated subway station includes two semi-arched prefabricated roof slabs. The two semi-arched prefabricated roof slabs are joined together at the arch top to form an arched roof slab. A cover member is placed over the joint between the two semi-arched prefabricated roof slabs, and the cover member completely covers the joint. Multiple adjacent arched roof slabs along the longitudinal direction of the tunnel are connected by the cover member to form a continuous prefabricated arched roof. The two semi-arched precast roof slabs are respectively provided with matching tenons and mortises at their joint ends. After the tenons and mortises are spliced ​​together, a locking hole extending along the arch thickness direction is formed on their splicing surface. The cover component is provided with a locking hole that is larger at the top and smaller at the bottom corresponding to each locking hole position. A metal anchor rod is inserted into the lock hole. The outer surface of the metal anchor rod is provided with a threaded section. The threaded valley and the wall of the lock hole together form a grouting channel for high-pressure injection of non-shrink, high-strength grout into the lock hole to enhance the bonding force between the cured grout and the metal anchor rod. The upper end of the metal anchor rod is provided with an expandable barb structure. The upper end of the metal anchor rod passes through the locking hole, and the barb structure expands in the locking hole to form a one-way locking. After the grout has cured, a wedge-shaped body is formed on the upper end and around the metal anchor rod, which tightly engages with the inner wall of the locking hole. The cross-section of the wedge-shaped body is larger at the top and smaller at the bottom.

[0010] Furthermore, the mating surface of the tenon and the mortise is a trapezoidal cross section, and the tenon has a gradually changing thickness along the arch axis, so that when the two semi-arched precast top plates are spliced ​​under gravity, the tenon will generate a pre-compression displacement along the thickness increasing direction.

[0011] Furthermore, the inner wall of the keyhole is provided with a groove or rough surface structure for mechanically engaging with the cured grout, so that the wedge-shaped body formed after the grout has cured has pull-out and shear resistance between it and the keyhole wall.

[0012] Furthermore, the grouting channel is connected to the joint of the tenon and mortise, and the high-pressure injected grout simultaneously fills the lock hole and the tenon-mortise joint. After curing, the two semi-arched precast top plates form a continuous integral solid body in the lock hole area and the tenon-mortise joint area.

[0013] Furthermore, a sealing gasket is bonded to the mating surface of the tenon and mortise. The sealing gasket is made of nitrile cork rubber and is bonded to the mating surface with chloroprene phenolic resin adhesive. The sealing gasket covers the entire mating surface except for the keyhole area. One of the sealing gaskets is bonded to each mating surface of the tenon and mortise. When the two semi-arched precast roof panels are spliced, the two sealing gaskets are fitted together. The two semi-arched precast roof panels are provided with a water-swellable grout-stopping strip at the outer edge of the tenon and mortise joint. The sealing gasket extends to the outer edge of the tenon and mortise joint, and the water-swellable grout-stopping strip is located at the edge of the sealing gasket.

[0014] Furthermore, the sealing gasket has pre-formed grout passage holes, and the grouting channel is connected to the tenon and mortise joint through the grout passage holes. The grout injected under high pressure fills the tenon and mortise joint through the grout passage holes. The surface of the sealing gasket is provided with a roughening treatment layer to enhance the interfacial adhesion between the sealing gasket and the cured grout.

[0015] Furthermore, an arc-shaped anchoring pad is fitted onto the metal anchor rod, and an elastic sealing gasket is provided between the arc-shaped anchoring pad and the inner arc surface of the arch.

[0016] Furthermore, the pressure cap component includes a lower structural plate and an upper waterproof plate. The lower structural plate is made of metal or fiber-reinforced composite material, and the upper waterproof plate is made of rubber or modified bitumen roll material with water guiding grooves at its edges.

[0017] Furthermore, the cover component is an integral component extending longitudinally along the tunnel. The bottom surface of the cover component is provided with a snap-fit ​​groove along the longitudinal direction. The top of each arched top plate is provided with a protrusion that mates with the snap-fit ​​groove. The snap-fit ​​groove and the protrusion are fitted together. At least two downwardly protruding positioning blocks are provided at intervals along the longitudinal direction in the snap-fit ​​groove. The top protrusion of the arched top plate is provided with a positioning groove that mates with the positioning block. When the cover component is lowered for installation, the positioning block is embedded in the positioning groove to form a longitudinal limit, so that the locking hole is aligned with the locking hole, covering the splice seam of the continuously arranged arched top plates, and connecting and fixing multiple arched top plates into one unit.

[0018] Furthermore, a grout-stopping sealing gasket is provided around the splice joint between the pressure cap component and the outer arc surface of the semi-arched precast top slab to prevent grout leakage during grouting construction.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention constructs a three-level load-bearing system of "pre-compression positioning - mechanical locking - permanent consolidation" through the synergistic cooperation of mortise and tenon joint structure with barbed metal anchor rods and grouting wedges. The mortise and tenon structure enables self-guided assembly of large-sized semi-arch components, and the gradual thickness design forms active pre-compression of the splice surface, which reduces the difficulty of on-site alignment, eliminates the initial gap of the joint, and ensures the initial force transmission stiffness of the node. The barbed structure at the upper end of the metal anchor rod can unfold in the locking hole of the pressure cap to form a one-way locking, which can provide temporary anchoring force before grouting curing. After curing, it forms a two-way mechanical embedding with the grouting wedge with a smaller upper part and a larger lower part. With the interlocking effect of the rough surface of the inner wall of the locking hole, the tensile strength, shear strength and fatigue resistance of the node are greatly improved, breaking through the limitations of traditional pure bond grouting connection with low load-bearing redundancy and easy degradation after long-term service.

[0020] 2. This invention, through an integrated capping component design, simultaneously achieves multiple functions including anchoring support, waterproofing protection, and longitudinal connection, solving the problems of waterproofing and stress coupling failure and weak longitudinal integrity in traditional solutions. The capping completely covers the arch splice joint, serving as both a reaction force bearing foundation for anchor bolt locking and a surface waterproof barrier formed by the surface waterproofing membrane and water-guiding groove. Together with the grouting filling body and waterstop strip inside the joint, it forms multiple waterproof defense lines. The capping adopts a layered structure to decouple the functions of the load-bearing layer and the waterproofing layer, avoiding structural deformation that could strain the waterproofing structure. At the same time, the locking groove at its end can longitudinally connect adjacent arched top plates into a continuous whole, significantly improving the longitudinal integrity of the structure and its resistance to uneven settlement.

[0021] 3. This invention achieves a balance between streamlined construction procedures and quality control through optimized design of the grouting system and construction process, while also ensuring long-term service durability and ease of maintenance. The grouting channel connects to the tenon-and-mortise joint, allowing for simultaneous completion of keyhole anchoring, joint filling, and joint sealing with a single high-pressure grouting operation, reducing on-site wet work procedures. Combined with a flow-limiting structure, graded grouting process, and multi-point venting system, the grout filling sequence can be precisely controlled, effectively preventing incomplete filling and air pockets in the anchoring area. Pre-embedded testing points enable traceable verification of the quality of concealed works. The core components are equipped with anti-corrosion treatment and a post-grouting repair channel design, which not only extends service life in underground corrosive environments but also allows for internal leak repair during operation, significantly reducing long-term maintenance costs.

[0022] 4. This invention constructs a novel connection scheme with assembly buffering and elastic waterproofing by setting a nitrile cork rubber sealing gasket on the tenon-and-mortise mating surface. The sealing gasket acts as a buffer layer during the assembly process of inserting the tenon into the mortise, avoiding edge damage and concrete spalling caused by direct hard friction and impact on the mating surfaces of large-sized concrete components, thus reducing the difficulty of assembly alignment and the component scrap rate. After assembly, the sealing gasket is compressed and fills the joint under the pre-compression force of the tenon and mortise, forming a double waterproof line with the water-swellable grout-stopping strip on the outer edge. The elastic sealing gasket can adapt to long-term micro-deformation and vibration loads of the structure, avoiding the problem of cracking and interface peeling of rigid grout filling bodies under repeated bending and shearing. This scheme eliminates the need to inject grout into the joint, simplifying the on-site construction process. At the same time, nitrile cork rubber has excellent water resistance, aging resistance, and elastic recovery properties, meeting the durability requirements for long-term service in underground engineering.

[0023] 5. This invention further provides a composite connection scheme combining a sealing gasket and grouting. By pre-drilling grout passage holes on the sealing gasket, the grout can enter the tenon joint through the lock hole and grout passage holes, achieving a composite consolidation of the elastic sealing gasket and the rigid grout. The roughened treatment layer on the surface of the sealing gasket enhances the interfacial adhesion between the nitrile cork rubber and the cement-based grout, avoiding the risk of delamination between the two dissimilar materials. The two work together to form a composite interface of "elastic sealing + rigid consolidation." The sealing gasket provides buffer protection and initial grout stopping during construction, while the grout provides structural consolidation strength and additional waterproofing after curing. This achieves a balance between construction convenience and structural reliability, further improving the load-bearing redundancy and waterproof durability of the joint. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the prefabricated roof slab connection structure of the prefabricated subway station of the present invention; Figure 2 This is a schematic diagram of the semi-arched prefabricated roof slab structure with tenons of the present invention; Figure 3This is a schematic diagram of the semi-arched prefabricated roof slab structure with mortises of the present invention; Figure 4 This is a sectional view of the mortise and tenon joint of the semi-arched precast roof slab of the present invention; Figure 5 This is a schematic diagram of the metal anchor structure of the present invention; Figure 6 This is a schematic diagram of the sealing gasket bonding in Embodiment 2 of the present invention.

[0025] The markings in the diagram are as follows: 1-Semi-arched precast roof slab, 2-Covering component, 21-Lower structural slab, 22-Upper waterproof slab, 23-Snap-fit ​​groove, 3-Tongue, 4-Rivet, 5-Lock hole, 6-Locking hole, 7-Metal anchor rod, 8-Grouting channel, 9-Barbed structure, 10-Plug-in protrusion, 11-Arched anchoring pad, 12-Elastic sealing gasket, 13-Exhaust pipe, 14-Exhaust channel, 15-Water guide groove, 16-Sealing gasket. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0027] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "horizontal," "inner," "outer," and "one side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] Example 1

[0029] like Figure 1-5 As shown, this embodiment provides a prefabricated roof slab connection structure for prefabricated subway stations, applied to the splicing of prefabricated arch roofs in single-arch prefabricated subway stations. A single arched roof slab is formed by joining two symmetrical semi-arched prefabricated roof slabs 1 together at the arch top, with its bottom overlapping the station's cast-in-place sidewalls. Multiple arched roof slabs are arranged sequentially along the tunnel's longitudinal direction, and their tops are connected longitudinally via a capping member 2, forming a continuous and integrated prefabricated arch roof system.

[0030] Specifically, in this embodiment, the mating ends of the two semi-arched precast roof slabs 1 are respectively machined with mutually compatible tenons 3 and mortises 4. The mating surfaces of the tenons 3 and mortises 4 adopt a trapezoidal cross-section design, and the tenons 3 have a gradually changing thickness distribution along the arch axis, with the thickness increasing from the inner side of the arch to the outer side. During assembly, the two semi-arched precast roof slabs 1 are aligned and moved closer to the arch top from both sides. The tenons 3 are inserted into the mortises 4 to achieve self-guiding positioning. Under the action of the component's gravity, the tenons undergo slight slippage along the thickness increasing direction, achieving pre-compression of the splicing surface.

[0031] To optimize the pre-compaction effect and reduce the risk of concrete splitting, this embodiment is implemented in the following detailed manner: A 2-5mm installation gap is reserved on the side of the tenon 3 and the mortise 4 to reduce the difficulty of aligning large-sized components. The gap is eventually filled with grout to achieve uniform force transmission. The inclination angle of the trapezoidal mating surface is controlled at 1:10 to 1:15 to ensure guidance while reducing the lateral splitting force generated by the arch axis pressure.

[0032] During prefabrication, anti-splitting steel mesh is pre-embedded in the area of ​​the tenon root and the mortise sidewall. The steel mesh adopts... The 6@100mm bidirectional arrangement, with a protective layer thickness of not less than 20mm, improves the local crack resistance of the nodes.

[0033] To address the issue of insufficient pre-compression force due to the self-weight of large-span arches, a temporary tensioning fixture is provided: temporary tensioning jacks are installed at the arch feet of the two semi-arches. After alignment, a lateral tension force is applied, driving the tenon to slide along the gradient surface to the designed pre-compression amount. The pre-compression force can be quantitatively controlled according to the span and load requirements of the components to ensure that the splicing surfaces are tightly and evenly fitted.

[0034] Along the longitudinal direction of the tunnel, the semi-arched precast roof slab 1 adopts an interlaced splicing method to improve the overall stress performance. Insertion grooves and insertion protrusions 10 are respectively set on both sides of the component. Adjacent components are positioned by interlocking through the insertion grooves and insertion protrusions 10. In this embodiment, the semi-arched precast roof slab 1 also has a reserved hole at the same position in the longitudinal direction. A longitudinal relay steel bar is inserted into the reserved hole and tightened ring by ring. For projects with higher priority of construction difficulty, a through-joint splicing scheme can also be adopted to unify the component mold specifications and reduce the complexity of assembly and waterproofing treatment.

[0035] A water-swellable grout-stopping strip is installed along the circumferential length of the outer edge of the mortise and tenon joint. In this embodiment, the grout-stopping strip adopts a composite structure of "rubber elastomer + water-swellable rubber". It relies on the elasticity of the rubber itself to achieve initial sealing in the dry state and avoid grout leakage in the early stage of grouting. When it comes into contact with groundwater, the rubber expands in volume and further fills the gap, enhancing the water-stopping and grout-stopping effects.

[0036] In a preferred embodiment of the present invention, after the tenon 3 and the mortise 4 are joined, their joint surfaces together form a through-hole 5 along the arch thickness direction. The pressure cap component 2, corresponding to the position of each through-hole 5, has a pre-formed tapered locking hole 6 that is larger at the top and smaller at the bottom. The locking hole 6 is a truncated cone structure that is larger at the top and smaller at the bottom, and is coaxially corresponding to the through-hole 5.

[0037] To ensure the forming accuracy of the lock hole 5 and the smooth installation of the anchor bolt, while enhancing the mechanical interlocking and anchoring effect in the locking area, this embodiment refines the hole structure and anchoring forming mechanism as follows: The keyhole 5 is a straight hole structure with equal diameter. During the prefabrication stage, high-strength metal sleeves are pre-embedded in the straight holes of the tenon 3 and mortise 4 respectively. After the components are assembled and positioned, the sleeves are precisely aligned to form a complete and continuous metal channel.

[0038] A metal anchor rod 7 is inserted into the lock hole 5. Specifically, the metal anchor rod 7 is inserted upward from the inside of the arch. The surface of the rod is provided with a continuous thread section, and the gap between the thread valley and the inner wall of the lock hole forms a grouting channel 8. The upper end of the metal anchor rod 7 is provided with an expandable barb structure 9. In this embodiment, the barb structure 9 adopts a multi-lobed elastic barb. During the insertion process, the barb is constrained by the hole wall and retracts into the corresponding receiving groove of the anchor rod. When the upper end of the anchor rod enters the locking hole 6, which is larger at the top and smaller at the bottom, the barb expands outward by its own elasticity and abuts against the conical inner wall of the locking hole, forming a one-way lock and preventing the anchor rod from sliding down.

[0039] The metal sleeve and the metal anchor rod 7 are fitted with a clearance fit. On the one hand, this ensures the coaxiality accuracy of the locking hole from the production source, preventing concrete debris from clogging the grouting channel and reducing the resistance during on-site installation of the anchor rod, thus improving assembly efficiency. On the other hand, the metal sleeve significantly improves the local bearing capacity and shear resistance of the hole wall, forming a synergistic force-bearing system with the internal anchor rod and cured grout, effectively strengthening the connection stiffness and overall connection strength of the joint. To further improve the interfacial bonding performance, the inner wall of the metal sleeve is pre-grooved with annular grooves or roughened by sandblasting. The grooves are 3-5mm deep and spaced 15-25mm apart. After the grout cures, it can be embedded in the grooves to form a multi-level mechanical interlock, preventing interface slippage failure.

[0040] To verify the effectiveness of the barb locking, the lower end of the metal anchor rod 7 is marked with a positioning scale line. When the anchor rod is inserted until the scale line is aligned with the inner arc surface of the arch, it is determined that the barb has reached the unfolded position of the locking hole. Then, a pre-pulling force of a set value is applied for verification. If the anchor rod does not slip, the locking is confirmed to be effective, ensuring the locking reliability of the concealed parts.

[0041] During high-pressure grouting, the grout fills the grouting channel 8 from bottom to top. After filling the circumferential gap of the locking hole 5, it continues to rise into the locking hole 6 area, completely encasing the upper end of the metal anchor rod 7 and the barbed structure 9. After the grout has cured, a wedge-shaped body naturally forms on the upper end and around the metal anchor rod 7, tightly fitting the inner wall of the locking hole 6. The cross-section of this wedge-shaped body is larger at the top and smaller at the bottom, forming an enlarged-bottom mechanical interlocking with the truncated cone-shaped locking hole, ensuring the pull-out resistance of the joint from a structural perspective. This mechanical interlocking structure is independent of the adhesive anchoring effect. Even if stress relaxation occurs at the bonding interface of the grout later, the structural interlocking between the wedge-shaped body and the locking hole can still provide a stable pull-out safety reserve, significantly improving the long-term service reliability of the joint.

[0042] The lower end of the metal anchor bolt 7 is fitted with an arc-shaped anchoring pad 11. The curvature of the arc-shaped anchoring pad 11 matches the inner arc surface of the arch. An elastic sealing gasket 12 is installed between the pad and the concrete surface to ensure uniform transmission of the anchoring force and to seal the gaps in the anchor bolt installation, preventing grout leakage during grouting. To address the risk of corrosion in the underground environment, the metal anchor bolt 7 is treated with an epoxy coating for corrosion protection. For projects with higher durability requirements, fiber-reinforced composite (FRP) anchor bolts can be used to fundamentally eliminate the risk of corrosion, while also possessing higher specific strength.

[0043] In a preferred embodiment of the present invention, the grouting channel 8 is connected to the mortise and tenon joint (the grouting channel 8 passes through the mortise and tenon joint). The high-pressure injected non-shrinkage high-strength grout can simultaneously fill the lock hole 5 and the mortise and tenon joint, and after curing, form a continuous integral solid body, which firmly connects the two semi-arched precast top plates.

[0044] To address the issues of uncontrollable grout flow and insufficient venting leading to incomplete filling, this embodiment employs both structural optimization and process control to ensure grout quality: Flow channel limiting design: A flow limiting groove with a width of 3~5mm is set at the connection position between the lock hole 5 and the splice joint to increase the resistance of the grout flowing into the splice joint and ensure that the grout fills the lock hole from bottom to top first during the grouting process. After the lock hole is filled, it overflows into the splice joint to avoid the formation of cavities at the top of the lock hole.

[0045] The graded grouting process adopts a low-pressure-high-pressure graded grouting method: The first step is to grout at a low pressure of 0.2~0.3MPa, with the grout rising along the grouting channel to fill the lock hole until continuous, bubble-free grout overflows from the top vent. The second step is to seal the vent of the lock hole 6, increase the pressure to 0.5~0.8MPa, and fill the tenon and mortise joint with grout. After stabilizing the pressure for 2~3 minutes, the grouting is completed, achieving orderly and full filling of the two areas.

[0046] Multi-point venting system: Vent pipe 13 is pre-embedded inside the pressure cap component 2, and venting channel 14 is provided to connect the locking hole 6 and the vent pipe 13. An openable overflow valve is installed at the end of the vent pipe 13. At the same time, a micro venting groove is set at the highest point of the tenon joint. The venting groove is connected to the main venting system to eliminate the dead corner of air stagnation in the narrow joint. During the grouting process, the valve is closed after the overflow valve flows out a continuous and uniform amount of grout to ensure full grouting.

[0047] Grout sealing reinforcement: A grout sealing gasket is installed along the perimeter of the splice joint between the gland member 2 and the outer arc surface of the semi-arched precast top slab 1. In this embodiment, the grout sealing gasket adopts a multi-lip rubber structure. The greater the grouting pressure, the tighter the lip structure is pressed against the concrete surface, forming a self-sealing effect. Before grouting, a pre-pressure is applied to the gland by temporary tightening bolts to ensure the initial sealing state and avoid grout leakage during high-pressure grouting.

[0048] After the grout has cured, a wedge-shaped body is formed on the upper end and around the metal anchor rod 7, tightly engaging with the inner wall of the locking hole 6. The wedge-shaped body is smaller at the top and larger at the bottom, forming a triple mechanical engagement with the inner wall of the locking hole and the threaded section of the anchor rod, jointly providing strong pull-out resistance. At the same time, the grout in the joint is tightly bonded to the tenon and mortise surface, making the locking hole area and the tenon and mortise area a continuous stress-bearing whole.

[0049] To ensure controllable quality of concealed works, this embodiment includes a quality inspection scheme: ultrasonic sensors are pre-embedded around the keyholes, and the fullness and defect location of the grout are detected by ultrasonic transmission after the grout has cured; at the same time, a grouting parameter traceability system is established to record the grouting volume, grouting pressure, and overflow time of each keyhole, and compare them with the theoretical filling volume. Abnormal data points are verified using a borehole endoscope to ensure that the quality of the nodes meets the standards.

[0050] In a preferred embodiment of the present invention, the pressure cap component 2 covers the top of the arch splice joint, completely covering the splice area circumferentially, and simultaneously undertaking multiple functions such as longitudinal connection, structural stress, and waterproof protection. The pressure cap component 2 adopts a layered composite structure, including a lower structural plate 21 and an upper waterproof plate 22. The lower structural slab 21 is made of high-strength steel or fiber-reinforced composite material (FRP) and serves as the main load-bearing layer, bearing the anchor bolt locking reaction force and longitudinal force transmission. The surface of the metal structural slab is treated with hot-dip galvanizing and heavy-duty anti-corrosion coating to improve its durability in underground environments.

[0051] The upper waterproof membrane 22 is made of rubber or modified bitumen waterproof membrane and is bonded to the structural plate. Water guide grooves 15 are set at the edge of the waterproof membrane to guide the seepage groundwater to drain away along the water guide grooves 15 and prevent it from seeping into the splice joint.

[0052] To avoid the failure of the coupling between stress and waterproofing function, this embodiment adopts a functional decoupling design: a buffer isolation layer is set between the lower structural plate 21 and the upper waterproof plate 22. The structural stress deformation is borne by the lower structural plate and will not be transmitted to the upper waterproof plate, thus ensuring the long-term integrity of the waterproofing system.

[0053] Along the longitudinal direction of the tunnel, the bottom surfaces of the capping component 2 are respectively provided with locking grooves 23 at both ends. Corresponding to the locking grooves, the arched top plates have protrusions. The locking grooves 23 and protrusions are fitted together, covering the joints of the continuously arranged arched top plates, thus connecting and fixing multiple arched top plates into a single unit, achieving longitudinal series connection. To achieve initial longitudinal positioning during the hoisting and lowering stage and prevent the capping component from slipping along the tunnel longitudinal direction, this embodiment provides downwardly protruding positioning blocks at intervals along the longitudinal direction at the bottom of the locking grooves 23. Positioning grooves are provided at corresponding positions of the protrusions on the top of the arched top plates. When the capping component 2 is lowered for installation, the positioning blocks first fully engage with the protrusions in the locking grooves and then embed into the positioning grooves, forming front and rear limiting positions, allowing the locking holes 6 on the capping component to quickly align with the locking holes 5 on the arched top plates. A 2-3mm assembly gap is reserved between the positioning blocks and the positioning grooves to avoid jamming. After tightening, the blocks are fixed by anchor bolts and grout sealing gaskets. In this embodiment, the snap-fit ​​groove adopts a tongue-and-groove structure, and a water-swellable sealing strip is pre-installed in the groove. The sealing is completed simultaneously during the insertion process, which not only improves the integrity of the longitudinal structure, but also ensures the waterproof performance of the longitudinal joint.

[0054] To address maintenance needs during operation, a grouting channel is pre-embedded within the pressure cap component 2. The lower end of the grouting channel connects to the splice joint area, while the upper end has a reserved grouting interface. If leakage occurs at the splice joint after long-term service, grouting repair can be performed from inside the structure through the grouting channel, eliminating the need for excavation and top covering, significantly reducing maintenance difficulty and costs.

[0055] The construction process of this invention is as follows: Factory prefabrication: Prefabricate semi-arched prefabricated top slabs and cover components according to design requirements, and simultaneously embed auxiliary components such as metal sleeves, anti-splitting steel mesh, vent pipes, waterstop strips and grouting channels. After acceptance, transport them to the site.

[0056] On-site hoisting and positioning: Using three-dimensional adjustable hoisting tools in conjunction with a laser positioning system, the two semi-arched precast roof slabs are hoisted into place. The tenons are inserted into the mortises to achieve initial positioning, and the elevation and axis deviation of the components are adjusted to within the allowable range.

[0057] Pre-tightening construction: Install temporary tensioning fixtures, apply the designed pre-pressure, and let the tenon slide along the gradient surface to the set pre-tightening amount to temporarily fix the position of the component.

[0058] Installation of the gland component: Hoist the gland component above the splice joint, align the locking holes and lock holes, install temporary tightening bolts, compact the grout sealing gasket, and complete the longitudinal snap-fit ​​splicing of the gland.

[0059] Anchor bolt installation and locking: Insert the metal anchor bolt upwards from the inside of the arch, observe the scale on the bolt body to confirm that it is in place, apply pre-pull-out force to verify the effectiveness of the barb locking, and install the elastic sealing gasket and the arc-shaped anchor plate in sequence.

[0060] Graded grouting construction: Connect the grouting equipment and carry out grouting according to the graded process of "low-pressure filling of key holes - high-pressure filling of joints - pressure stabilization and grouting". Monitor the grouting pressure and overflow status throughout the process to ensure full filling.

[0061] Final quality inspection: After the grouting material reaches the strength standard, ultrasonic testing is used to check the grouting fullness. If it passes the test, the temporary fixtures are removed and the single arch splicing is completed. The above process is repeated, and longitudinal continuous assembly is achieved by clamping the cap.

[0062] Example 2

[0063] like Figure 6 As shown, the precast roof slab connection structure provided in this embodiment is basically the same as that in Embodiment 1, except that a sealing gasket 16 is provided on the mating surface of the tenon 3 and the mortise 4, and the sealing gasket 16 fills the tenon-mortise joint. The specific implementation scheme of this embodiment is as follows: In this embodiment, a sealing gasket 16 is bonded to each mating surface of the tenon 3 and the mortise 4. The sealing gasket 16 is made of nitrile cork rubber and is bonded to the concrete mating surface using chloroprene phenolic resin adhesive. The sealing gasket 16 is prefabricated in the factory into an irregularly shaped sheet that perfectly matches the shape of the tenon and mortise mating surface, covering the entire mating surface except for the area of ​​the lock hole 5. At the position corresponding to the lock hole 5, the sealing gasket 16 is pre-drilled with a clearance hole so that the lock hole 5 remains open after the components are assembled.

[0064] The single-sided adhesive application process for the sealing gasket 16 is as follows: During the factory prefabrication stage, the concrete mating surfaces are first cleaned and dried, and a chloroprene phenolic adhesive primer is applied. After the primer is surface dry, the prefabricated sealing gasket 16 is adhered to the mating surfaces and pressure is applied to ensure that the adhesive evenly wets the interface between the sealing gasket and the concrete. After curing at room temperature, the bonding is complete. The adhesive is only applied between the sealing gasket 16 and the concrete mating surfaces; the exposed surfaces of the sealing gasket 16 (i.e., the surfaces where the two sealing gaskets are placed) are not coated with adhesive.

[0065] The sealing gasket 16 is designed with a thickness of 3.2mm in its free state (before compression) and 2mm after assembly and compression. During assembly, the two semi-arched precast roof panels 1 align and approach the arch from both sides, and the tenons 3 are inserted into the mortises 4. The two sealing gaskets 16 first come into contact and fit together. As the tenons slide along the gradually thickening direction for pre-compression, the sealing gasket 16 is gradually compressed to 2mm, completely filling the tenon and mortise joint. Nitrile cork rubber has excellent elastic recovery properties and resistance to compression set, and can maintain a stable sealing contact pressure even under long-term pre-compression.

[0066] The buffering effect of the sealing gasket 16 during the assembly process is manifested in the fact that when the tenon 3 is inserted into the mortise 4, the two concrete mating surfaces do not directly contact each other, but are guided and slid through the elastic contact of the two sealing gaskets 16. This effectively avoids damage to the concrete edges and corners and surface chipping caused by hard friction and collision during the alignment of large-sized precast components, and reduces the requirements for assembly alignment accuracy and component scrap rate.

[0067] In terms of waterproofing construction, the sealing gasket 16 extends to the outer edge of the tenon joint, and the water-swellable sealing strip is placed at the edge of the sealing gasket 16 (i.e., the outermost edge of the joint), forming a double waterproofing line of "internal elastic sealing gasket and outer edge water-swellable sealing strip". When compressed, the sealing gasket 16 fits tightly against the mating surface, providing primary elastic sealing and waterproofing; the water-swellable sealing strip expands in volume when groundwater seeps in, further sealing the tiny gaps at the outer edge of the joint, providing additional expansion-based waterproofing protection. The two waterproofing lines complement each other: the sealing gasket adapts to minor structural deformations, maintaining continuous contact pressure, while the sealing strip provides expansion compensation when gaps unexpectedly increase, jointly ensuring the long-term waterproof reliability of the joint.

[0068] In the area surrounding the keyhole 5, since the sealing gasket 16 avoids the keyhole, the splice joint in this area is sealed by the grout injected under high pressure and cured within the keyhole 5 (i.e., the solidified body of the anchor bolt anchoring zone). Under high pressure, the grout in the keyhole 5 penetrates into the micro-gap of the splice joint around the keyhole, and after curing, forms a sealing ring, reliably sealing the splice joint around the keyhole. It seamlessly connects with the waterproof area of ​​the sealing gasket 16, forming a complete waterproof sealing system for the splice joint.

[0069] In this scheme, the grouting channel 8 is only used for high-pressure grouting into the lock hole 5 to anchor the metal anchor rod 7, and the grout does not enter the tenon and mortise joint. During grouting, since the joint is completely filled by the sealing gasket 16, there is no need to set up a flow restriction groove and a joint venting system. The grouting process is simplified to single-stage grouting: grout is injected into the lock hole at a pressure of 0.2~0.3MPa until continuous, bubble-free grout overflows from the top vent, and the grouting is closed after pressure stabilization.

[0070] Example 3

[0071] Based on Example 2, this embodiment further pre-fabricates grout passage holes on the sealing gasket 16, allowing the grout to enter the tenon and mortise joint, forming a composite bonding connection between the sealing gasket and the grout.

[0072] Specifically, during the prefabrication stage, the sealing gasket 16 has several grout passage holes prefabricated around the corresponding lock hole 5. The grout passage holes are evenly distributed along the circumference of the lock hole, and the hole diameter is determined according to the grouting flow requirements. The grout passage holes connect the inner cavity of the lock hole 5 with the cavity of the tenon and mortise joint, so that the grout can enter the joint from the lock hole through the grout passage holes during high-pressure grouting.

[0073] The surface of the sealing gasket 16 (including the surface in contact with the grout) is roughened, specifically by sandblasting or prefabricating micro-grooves / protrusions to form a roughened layer, increasing the contact area and mechanical interlocking force between the nitrile cork rubber and the cement-based grout, and preventing the two dissimilar materials from peeling off due to poor adhesion.

[0074] After assembly, the sealing gasket 16 is compressed to 2mm. The sealing gasket occupies the main space in the joint, and the remaining small gaps are filled by grout. The grouting construction adopts a staged process: the first step is to grout at a low pressure of 0.2~0.3MPa. The grout rises along the grouting channel 8 to fill the lock hole 5. After the lock hole is filled, the grout enters the tenon joint through the grout passage hole on the sealing gasket and fills the remaining gap between the sealing gasket and the joint; the second step is to increase the pressure to 0.5~0.8MPa, so that the grout fully fills the joint and penetrates into the rough treatment layer on the surface of the sealing gasket. After stabilizing the pressure for 2~3 minutes, the grouting is completed.

[0075] After the grout has cured, a composite solidified body of "sealing gasket-grout" is formed within the joint: the sealing gasket 16 provides elastic sealing and buffering deformation capacity, while the cured grout provides rigid structural strength and additional waterproofing; the roughened surface layer of the sealing gasket forms a mechanical interlock with the grout, ensuring that the two materials work together under stress and that the interface does not peel off. This composite structure combines the deformation adaptability of the elastic sealing gasket with the structural strength of the grout solidified body, achieving a unity of buffer protection during construction and structural consolidation during operation.

[0076] In the area surrounding the keyhole 5, similar to Example 2, the splicing seam around the keyhole is sealed by the grout material that has solidified inside the keyhole, and is continuously connected with the composite solidified body inside the splicing seam.

[0077] The waterproofing scheme in this embodiment is as follows: the internal "sealing gasket and grout" composite solidified body provides the main waterproofing, the outer edge water-swellable grout-stopping strip provides additional expansion waterproofing, and the upper waterproofing plate 22 and water guide groove 15 of the pressure cap component 2 provide surface drainage waterproofing, forming a multi-layer redundant waterproofing system.

[0078] The construction process in this embodiment is basically the same as that in embodiment 1, except that: Factory prefabrication stage: When prefabricating the semi-arched prefabricated roof slab, the prefabrication and pasting of the sealing gasket 16 are completed simultaneously (including the prefabrication of the grout passage and surface roughening treatment). After the sealing gasket is pasted in the factory, it is transported to the site and no on-site pasting work is required.

[0079] On-site assembly stage: When the tenon is inserted into the mortise, it is stably aligned by relying on the elastic buffer of the sealing gasket. After pre-tightening, the sealing gasket is compressed to the designed thickness.

[0080] Grouting construction stage: graded grouting is adopted, and the joints are filled simultaneously through the grout holes of the sealing gasket.

[0081] The remaining construction procedures (gland installation, anchor bolt locking, quality inspection, etc.) are the same as in Example 1, and will not be repeated here.

[0082] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A prefabricated roof slab connection structure for a prefabricated subway station, characterized in that, It includes two semi-arched precast roof slabs, which are joined together at the arch crown to form an arched roof slab. A cover member covers the joint between the two semi-arched precast roof slabs, which completely covers the joint. Multiple adjacent arched roof slabs along the longitudinal direction of the tunnel are connected by the cover member to form a continuous prefabricated arched roof. The two semi-arched precast roof slabs are respectively provided with matching tenons and mortises at their joint ends. After the tenons and mortises are spliced ​​together, a locking hole extending along the arch thickness direction is formed on their splicing surface. The cover component is provided with a locking hole that is larger at the top and smaller at the bottom corresponding to each locking hole position. A metal anchor rod is inserted into the lock hole. The outer surface of the metal anchor rod is provided with a threaded section. The threaded valley and the wall of the lock hole together form a grouting channel for high-pressure injection of non-shrink, high-strength grout into the lock hole to enhance the bonding force between the cured grout and the metal anchor rod. The upper end of the metal anchor rod is provided with an expandable barb structure. The upper end of the metal anchor rod passes through the locking hole, and the barb structure expands in the locking hole to form a one-way locking. After the grout has cured, a wedge-shaped body is formed on the upper end and around the metal anchor rod, which tightly engages with the inner wall of the locking hole. The cross-section of the wedge-shaped body is larger at the top and smaller at the bottom.

2. The prefabricated roof slab connection structure for a prefabricated subway station according to claim 1, characterized in that, The mating surface of the tenon and the mortise is a trapezoidal cross section. The tenon has a gradually changing thickness along the arch axis, so that when the two semi-arched precast top plates are spliced ​​under gravity, the tenon will generate a pre-compression displacement along the thickness increasing direction.

3. The prefabricated roof slab connection structure for a prefabricated subway station according to claim 1, characterized in that, The inner wall of the keyhole is provided with a groove or rough surface structure for mechanical interlocking with the cured grout, so that the wedge-shaped body formed after the grout is cured has pull-out and shear resistance between it and the keyhole wall.

4. The prefabricated roof slab connection structure for a prefabricated subway station according to claim 1, characterized in that, The grouting channel is connected to the joint of the tenon and mortise. The high-pressure injected grout fills the lock hole and the tenon joint at the same time. After curing, the two semi-arched precast top plates form a continuous integral solid body in the lock hole area and the tenon joint area.

5. The prefabricated roof slab connection structure for a prefabricated subway station according to claim 1, characterized in that, A sealing gasket is bonded to the mating surface of the tenon and mortise. The sealing gasket is made of nitrile cork rubber and is bonded to the mating surface with chloroprene phenolic resin adhesive. The sealing gasket covers the entire mating surface except for the keyhole area. One of the sealing gaskets is bonded to each mating surface of the tenon and mortise. When the two semi-arched precast roof panels are spliced, the two sealing gaskets are placed in close contact with each other. The two semi-arched precast roof panels are provided with a water-swellable grout-stopping strip at the outer edge of the tenon and mortise joint. The sealing gasket extends to the outer edge of the tenon and mortise joint, and the water-swellable grout-stopping strip is set at the edge of the sealing gasket.

6. The prefabricated roof slab connection structure for a prefabricated subway station according to claim 5, characterized in that, The sealing gasket has pre-formed grout passage holes, and the grouting channel is connected to the tenon and mortise joint through the grout passage holes. The grout injected under high pressure fills the tenon and mortise joint through the grout passage holes. The surface of the sealing gasket is provided with a roughening treatment layer to enhance the interfacial adhesion between the sealing gasket and the cured grout.

7. The prefabricated roof slab connection structure for a prefabricated subway station according to claim 1, characterized in that, An arc-shaped anchoring pad is fitted onto the metal anchor rod, and an elastic sealing gasket is provided between the arc-shaped anchoring pad and the inner arc surface of the arch.

8. The prefabricated roof slab connection structure for a prefabricated subway station according to claim 1, characterized in that, The pressure cap component includes a lower structural plate and an upper waterproof plate. The lower structural plate is made of metal or fiber-reinforced composite material, and the upper waterproof plate is made of rubber or modified bitumen roll material with water guide grooves at its edges.

9. The prefabricated roof slab connection structure for a prefabricated subway station according to claim 1, characterized in that, The cover component is an integral component extending longitudinally along the tunnel. The bottom surface of the cover component is provided with a snap-fit ​​groove along the longitudinal direction. The top of each arched top plate is provided with a protrusion that mates with the snap-fit ​​groove. The snap-fit ​​groove and the protrusion are fitted together. At least two downwardly protruding positioning blocks are provided at intervals along the longitudinal direction in the snap-fit ​​groove. The top protrusion of the arched top plate is provided with a positioning groove that mates with the positioning block. When the cover component is lowered for installation, the positioning block is embedded in the positioning groove to form a longitudinal limit, so that the locking hole is aligned with the locking hole, covering the splice seam of the continuously arranged arched top plates, and connecting and fixing multiple arched top plates into one unit.

10. The prefabricated roof slab connection structure for a prefabricated subway station according to claim 1, characterized in that, A grout-stopping sealing gasket is provided between the pressure cap component and the outer arc surface of the semi-arched precast top slab, along the perimeter of the splice joint, to prevent grout leakage during grouting construction.

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