Underground excavation metro station full-prefabricated assembly structure and construction method thereof

Abstract

The invention provides a fully-prefabricated assembly structure of an underground excavation subway station and a construction method of the fully-prefabricated assembly structure, and belongs to the technical field of urban rail transit engineering design and construction. The subway station prefabricated assembly structure comprises an underground diaphragm wall, a top beam, a secondary lining arch cover, an inverted arch / bottom plate, a double-bracket side wall, a middle plate, a shielding door vertical beam, a wall separating wall and a platform plate, the top beam is arranged at the top end of the underground diaphragm wall, the secondary lining arch cover is connected with the top beam through a high-strength bent bolt, and the double-bracket side wall is connected with the middle plate through a high-strength straight bolt. The inverted arch / bottom plate is connected with the double-bracket side wall through high-strength bent bolts, the screen door vertical beam and the middle plate are integrally prefabricated, the upper end and the lower end of the wall separation wall are connected with the second lining arch cover and the double-bracket side wall in an anchoring mode respectively, and the platform plate is installed on the inverted arch / bottom plate. According to the method, the purpose of thorough template removal of underground excavation station structure building is achieved, the construction method matched with the method is not limited by station site hydrogeological conditions at all, and the method has very considerable engineering application and popularization value.

Description

Technical Field

[0001] The invention belongs to the technical field of urban rail transit engineering design and construction, and in particular relates to a fully prefabricated assembly structure of a dark-excavated subway station and a construction method thereof. Background Art

[0002] At present, underground subway stations generally adopt the in-situ cast-in-place method to build the main structure. The structural construction is carried out according to the process of building scaffolding → laying waterproofing → tying steel bars → erecting formwork → pouring commercial concrete. The formwork can only be removed after it has been maintained to reach the designed strength. Usually, a large number of people, materials, objects, and machines are required, and it is difficult to form a longitudinal extension flow organization operation. At the same time, it is restricted by the narrow construction site in the tunnel. It often faces difficulties such as difficult material stacking, long construction period, low construction efficiency, high investment cost, high engineering risk, and difficulty in corporate profitability. In addition, raw material construction is seriously polluted, the quality of finished products is difficult to guarantee, the steel skeleton collapses, and the formwork scaffold overturns. These phenomena are common. There are engineering quality problems and safety hazards, which seriously threaten the driving safety and operation stability of the station. Summary of the invention

[0003] The purpose of the present invention is to overcome the difficulties existing in the prior art and propose a fully prefabricated assembly structure for a dark-cut subway station and a construction method thereof, so as to achieve the purpose of factory prefabrication and on-site assembly of all structures, eliminate complex construction links such as in-situ steel bar binding, bracket formwork installation, concrete pouring and maintenance, and successfully solve the above-mentioned technical problems.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect, the present invention provides a construction method for a fully prefabricated assembly structure of a dark-excavated subway station, wherein the prefabricated components used in the method include: an underground continuous wall, a secondary lining arch cover, an inverted arch / bottom plate, a double-corbel side wall, a middle plate with a screen door vertical beam, an off-wall wall and a platform plate, wherein the middle plate has branch structures on both sides in the horizontal direction, and is overlapped with the double-corbel side wall to form a track top air duct, and each prefabricated component is provided with a reserved high-strength bolt hole according to the assembly connection relationship, and a pre-buried grouting pipe, a reserved grouting hole and a reserved reinforcing bar hole are arranged according to the force safety requirements;

[0006] The construction steps are as follows:

[0007] Step S1: The ground machinery forms a trench and constructs a guide wall, and the prefabricated underground continuous wall is hoisted vertically downward in sections. Two adjacent prefabricated components are firmly connected by using corrugated joints and filled with slurry. A safe gap for assembly with the double-corbel side wall is reserved on the inner side of the underground continuous wall. The top elevation of the underground continuous wall is higher than the bottom height of the arch guide pit, and the bottom of the underground continuous wall is lower than the bottom elevation of the invert arch / bottom plate, and sufficient embedding depth is ensured to prevent overturning and instability;

[0008] Step S2: excavating the arch pilot pit, and applying the outer initial support and temporary span reduction support;

[0009] Step S3: After the arch is penetrated, an inner layer initial support is set, a safe gap for assembly with the second lining arch cover is reserved, the reserved reinforcement hole at the top of the underground continuous wall is cleaned, anchor bars are inserted, the crown beam steel bars are tied and the crown beam is cast. The crown beam is provided with a reserved high-strength bolt hole corresponding to the second lining arch cover, a track is laid at the top of the crown beam, and the second lining arch cover is provided with a groove corresponding to the track; the crown beam gives priority to the cast-in-place scheme to ensure the integrity, continuity and smoothness of the track, ensure the smooth longitudinal sliding of the second lining arch cover and the precise alignment of the high-strength bent bolt holes, and the prefabrication scheme can also be used to directly assemble the crown beam prefabricated components at the top of the underground continuous wall;

[0010] Step S4: remove the temporary span reduction support, and lay a waterproof layer close to the initial support until the bottom of the lateral outer side of the crown beam;

[0011] Step S5: using a pushing mechanical device to push and slide the secondary lining arch cover longitudinally along the track to an assembly position, and connecting and fixing the secondary lining arch cover and the crown beam by high-strength bent bolts;

[0012] Step S6: After all the secondary lining arch covers are assembled, grouting is performed to backfill the reserved assembly safety gap between the secondary lining arch cover and the inner initial support and the vertical gap between the secondary lining arch cover and the crown beam on the outer side of the track;

[0013] Step S7: excavate the rock and soil mass below the station in layers until the tunnel is through, lay a fine-level cushion layer at the bottom of the tunnel, and transport the invert / bottom plate components to the assembly location for assembly;

[0014] Step S8: assemble the double-corbel side wall components on both sides piece by piece, and use high-strength bent bolts to firmly connect them with the inverted arch / bottom plate components. In order to ensure the vertical accuracy and overall stability of the double-corbel side wall when assembling the middle plate components in the next step, use temporary steel braces to support the double-corbel side wall on the inverted arch / bottom plate, and ensure that the high-strength straight bolt holes of the double-corbel side wall and the middle plate are fully aligned and accurately assembled;

[0015] Step S9: Use jacking and transportation equipment to transport the middle plate component to its position along the longitudinal direction of the station, vertically lower it and place it on the double brackets of the side walls on both sides, and fasten the two together with high-strength straight bolts;

[0016] Step S10: Grouting is performed from the top of the double-corbel side walls on both sides to backfill the reserved safety assembly gap between the side walls and the underground continuous wall. After the grouting is completed and the grouting strength reaches the requirement, the temporary steel bracing is removed;

[0017] Step S11: cleaning the reserved reinforcement holes of the secondary lining arch cover and the double-corbel side wall, inserting anchor bars and vertically and continuously building the wall away from the wall, and forming anchor connections with the secondary lining arch cover and the double-corbel side wall at the upper and lower ends respectively;

[0018] Step S12: Using the free-standing wall as the outer formwork, using fine stone concrete to fill the horizontal space between the free-standing wall and the arch foot of the secondary lining arch cover, the crown beam, and the upper part of the underground continuous wall, and the vertical gap between the secondary lining arch cover and the crown beam on the inner side of the track in layers;

[0019] Step S13: Assembling the platform plate on the invert / base plate;

[0020] Step S14: construct an invert backfill to limit the lateral displacement of the wall under the platform slab, thus completing the construction of the entire prefabricated assembly structure of the underground excavation station.

[0021] Furthermore, the double-corbel side walls, inverted arch / bottom plate, middle plate, screen door vertical beam, platform plate and away wall have equal longitudinal widths. If the crown beam is a prefabricated component, its longitudinal width is equal to the longitudinal width of the secondary lining arch cover, ensuring reliable force transmission and coordinated deformation. The longitudinal adjacent rings of the prefabricated components are firmly connected by the high-strength bent bolts.

[0022] Furthermore, a plurality of water-swellable waterproof stop adhesives are arranged between the end of the waterproof layer and the crown beam to achieve waterproof sealing.

[0023] Furthermore, the middle plate adopts an arch bridge type curved middle plate, and a shield door vertical beam is arranged on the curved surface below the arch bridge type curved middle plate. The arch bridge type curved middle plate and the shield door vertical beam are prefabricated as a whole and bear force together. The curved triangle area enclosed by the double corbel side wall and the arch bridge type curved middle plate serves as the rail top piston air duct, and the ventilation area is adjusted by changing the radius of the curved middle plate.

[0024] Furthermore, the middle plate adopts a flat plate structure, and an "L"-shaped branch structure is provided near the double-corbel side wall, wherein the shield door vertical beam is formed by extending downward from the vertical wall of the "L"-shaped branch structure.

[0025] Furthermore, when there are more than two tracks arranged at the top end of the crown beam, the second lining arch cover is provided with reserved grouting channels between adjacent tracks, and after the second lining arch cover is fully assembled, the gaps between adjacent tracks are backfilled by grouting through the reserved grouting channels.

[0026] Furthermore, the inverted arch / bottom plate is provided with a reserved cup opening for inserting the platform board support legs. The inverted arch / bottom plate is arranged on a finely leveled cushion layer, and both ends are fastened to the double corbel side walls by the high-strength bent bolts. A cup opening is provided on the upper surface for inserting the platform board, and the width of the cup opening is slightly larger than the thickness of the platform board wall.

[0027] Furthermore, the groove at the bottom end of the second lining arch cover is pre-embedded with an arc-shaped pressure-bearing steel plate that matches the geometric shape of the track, and the contact interface between the arc-shaped pressure-bearing steel plate and the track is coated with a lubricating drag-reducing agent to reduce the friction resistance encountered during the pushing and sliding process of the second lining arch cover, thereby ensuring the pushing efficiency and assembly accuracy.

[0028] Furthermore, the exposed surfaces of the high-strength bent bolts and the high-strength straight bolts are coated with an antiseptic.

[0029] On the other hand, the present invention also provides a prefabricated assembly structure of a concealed excavation subway station constructed using the above-mentioned construction method.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) Completely realize the purpose of removing formwork from underground excavation station structure construction, and completely avoid construction material pollution, steel frame collapse, support formwork overturning and other engineering quality defects and safety hazards;

[0032] (2) The fully prefabricated assembly technology replaces the traditional in-situ cast-in-place process, significantly shortening the construction period, improving the construction effect, reducing costs and increasing efficiency for enterprises, and the quality of the finished product is fully controllable. It has many advantages such as green environmental protection, emission reduction and carbon reduction, energy saving and consumption reduction;

[0033] (3) The prefabricated component assembly technology is completely unrestricted by the hydrogeological environment of the project and can be applied to all strata, with engineering universality and promotion;

[0034] (4) Expand the application boundary conditions of existing prefabrication and assembly technology, effectively fill in and make up for the deficiencies and gaps in the construction methods of underground excavation station structures, and promote the standardization and industrialization of prefabricated component production;

[0035] (5) Promote the revision, improvement, implementation and enforcement of technical documents such as design standards, construction specifications and acceptance standards for prefabricated assembly structures in the field of urban rail transit underground excavation projects, and form a package of coordinated and systematic prefabrication and assembly technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0037] Figure 1 This is a cross-sectional view of the prefabricated assembly structure of a dark-excavated subway station according to an embodiment of the present invention;

[0038] Figure 2 This is a construction sequence diagram of a prefabricated assembly structure of a dark-excavated subway station according to an embodiment of the present invention;

[0039] Figure 3 This is a large-scale drawing of the connection node between the double-corbel side wall and the arch bridge type curved middle plate in an embodiment of the present invention;

[0040] Figure 4 This is a large-scale drawing of the connection node between the crown beam and the secondary lining arch cover according to an embodiment of the present invention;

[0041] Figure 5 This is a large-scale drawing of the connection node between the invert and the double-corbel side wall according to an embodiment of the present invention.

[0042] Reference numerals in the figure: 1-underground continuous wall, 2-crown beam, 3-second lining arch cover, 4-inverted arch, 5-double corbel side wall, 6-arch bridge type curved middle plate, 7-shielding door vertical beam, 8-off-wall wall, 9-platform slab, 10-inverted arch backfill, 11-outer initial support, 12-temporary span reduction support, 13-inner initial support, 14-bottom of arch guide pit, 15-waterproof layer, 16-grouting pipe, 17-fine leveling cushion layer, 18-temporary steel diagonal brace, 19-water-swelling water-stop adhesive, 20-double-strand track, 21-high-strength bent bolts, 22-grouting channels, 23-high-strength straight bolts. DETAILED DESCRIPTION

[0043] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to be able to fully convey the scope of the present invention to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0044] This embodiment provides a fully prefabricated assembly structure and construction method for a dark-excavated subway station. Figures 1 to 5 As shown, the prefabricated assembly structure of the subway station includes an underground continuous wall 1, a crown beam 2, a secondary lining arch cover 3, an inverted arch 4, a double-corbel side wall 5, an arch bridge type curved middle plate 6, a screen door vertical beam 7, an off-wall wall 8, a platform slab 9, high-strength bent bolts 21, and high-strength straight bolts 23. The underground continuous wall 1, the secondary lining arch cover 3, the inverted arch 4, the double-corbel side wall 5, the arch bridge type curved middle plate 6 with a screen door vertical beam 7, the off-wall wall 8, and the platform slab 9 are prefabricated components. According to the connection relationship between each prefabricated component and other assembly parts (cast crown beam), high-strength bolt holes are reserved in advance, and pre-buried grouting pipes, reserved grouting holes and reserved reinforcing bar holes are arranged according to the force safety requirements.

[0045] The prefabricated components of the underground continuous wall 1 are designed as permanent structures with a service life of 100 years. The wall thickness is 1000mm and the component width is 3000mm. A crown beam 2 is set on the top of the wall with a width equal to the wall thickness of the underground continuous wall 1 and a height of 1000mm. The two are rigidly connected by inserting anchor bars in the reserved dowel bars holes. A double-strand track 20 is installed on the top of the crown beam 2, with high-strength bent bolt holes reserved inside, and a waterproof layer 15 is laid on the outside. Four water-swelling waterstop strips 19 are set at the end of the waterproof layer 15 to enhance the waterstop effect at weak locations.

[0046] A safe assembly gap of 100 mm is reserved between the secondary lining arch cover 3 and the inner initial support 13 to ensure assembly accuracy; a grouting pipe 16 with a diameter of 25 mm is embedded in the center of the arch crown, fixed reinforcing bars 8 are embedded in the arch shoulders on both sides, and two high-strength bent bolt holes and grouting holes 22 are embedded in the arch feet on both sides. A matching groove for a double-strand track 20 is reserved at the bottom, which is fastened to the crown beam 2 by high-strength bent bolts 21, and an arc-shaped pressure-bearing steel plate matching the track geometry is embedded in the groove.

[0047] The vertical gap between the second lining arch cover 3 and the crown beam 2 on the outer rail side of the double-track 20 is filled with grouting through the grouting pipe 16, and the vertical gap between the second lining arch cover 3 and the crown beam 2 on the inner rail side and the horizontal space between the wall 8 and the arch foot of the second lining arch cover 3, the crown beam 2, and the upper part of the underground continuous wall 1 are backfilled synchronously, and the gap between the double tracks is filled densely using the grouting channel 22 to ensure that the second lining arch cover 3 and the crown beam 2 are completely close.

[0048] The inverted arch 4 is arranged on the fine leveling cushion layer 17, and its two ends are fastened to the double corbel side walls 5 by high-strength bent bolts 21. A cup mouth is arranged on the top for the platform plate 9 to be inserted. The width of the cup mouth is 20 mm greater than the thickness of the platform plate 9 wall, and the depth of the cup mouth is 200 mm.

[0049] The double-corbel side wall 5 is provided with two rows of parallel corbels, with a reserved top for fixing dowel bars away from the wall wall 8. A safe assembly gap of 100 mm is reserved between the back and the underground continuous wall 1 to ensure assembly accuracy. After assembly, temporary steel diagonal braces 18 are used to support and stabilize the double-corbel side wall 5 on the inverted arch 4 to prevent it from tilting or even collapsing. The temporary steel diagonal braces 18 are made of double-piece steel 25a, with the double-corbel side wall 5 and the inverted arch 4 connected at both ends respectively. The double-corbel side wall 5 is firmly connected to the arch bridge type curved middle plate 6 by high-strength straight bolts 23, and then the temporary steel diagonal braces 18 are removed.

[0050] The arch bridge type curved middle plate 6 and the shield door vertical beam 7 are integrally prefabricated and bear force together; the arch bridge type curved middle plate 6 is overlapped on the two rows of brackets of the double bracket side wall 5, and is connected and fixed by high-strength straight bolts 23. The branch structure of the arch bridge type curved middle plate 6 and the double bracket side wall 5 form a track top air duct, and the ventilation area can be adjusted by changing the radius of the curved middle plate. The part of the high-strength straight bolt 23 protruding from the upper edge of the arch bridge type curved middle plate is buried in the building decoration layer, the protruding height is 100mm, and the thickness of the building decoration layer is 150mm. The timing for laying the building decoration layer closely on the upper part of the arch bridge type curved middle plate 6 is when all the station structures are assembled to ensure the continuity and integrity of the laying.

[0051] The away wall 8 is constructed continuously along the longitudinal direction by masonry, and its two ends are connected to the secondary lining arch cover 3 and the double corbel side wall 5 by inserting anchor bars in the reserved reinforcement holes, followed by layered backfilling of the horizontal space between the away wall 8 and the arch foot of the secondary lining arch cover 3, the crown beam 2, and the upper part of the underground continuous wall 1 with fine stone concrete.

[0052] The longitudinal width of the secondary lining arch cover 3 is equal to the width of the underground continuous wall 1 component, which is 3000mm; the longitudinal widths of the double-corbel side walls, inverted arches, arch bridge-type arc-shaped middle plates, shield door vertical beams, platform plates and off-wall walls are completely equal, which is 2000mm, to ensure reliable force transmission and coordinated deformation; the longitudinal adjacent rings of the prefabricated components are firmly connected by high-strength bent bolts 21.

[0053] The waterproof layer 15 is pre-paved with reverse-adhesive waterproof membrane, which is closely attached to the inner base surface of the inner initial support 13 and fully laid.

[0054] The exposed surfaces of the high-strength bent bolts 21 and high-strength straight bolts 23 are coated with antiseptic to prevent rust from weakening the joint's stress-bearing performance and the seam's water-stopping effect. Filling is strictly prohibited to prevent vibration and falling off.

[0055] The purpose of setting the reserved safe assembly gap in the second lining arch cover 3 is to eliminate the friction resistance encountered during the sliding process and ensure that the waterproof layer 15 is not damaged.

[0056] The purpose of setting the reserved safe assembly gap for the double-corbel side wall 5 is to avoid the hidden danger of limited installation space of the double-corbel side wall 5 due to insufficient assembly accuracy of the underground continuous wall 1 components.

[0057] In the above-mentioned fully prefabricated structure of the underground subway station, the inverted arch can adopt a horizontal bottom plate without an arch, the arch bridge type curved middle plate can also adopt other forms of middle plates, and the cast crown beam can be replaced by prefabricated components. When prefabricated crown beam components are used, the longitudinal width of the crown beam is equal to the longitudinal width of the secondary lining arch cover.

[0058] The construction method of the above-mentioned fully prefabricated structure of the underground excavation subway station is as follows:

[0059] Step S1: The ground machine forms a groove and constructs a guide wall, and the prefabricated underground continuous wall 1 is hoisted vertically downward in sections. Two adjacent prefabricated components are firmly connected by using corrugated joints and filled with slurry. A safe gap for assembly with the double-corbel side wall 5 is reserved on the inner side of the underground continuous wall 1. The wall top elevation is 0.5m higher than the bottom 14 of the arch guide pit, and the wall bottom is placed 3.5m below the inverted arch 4;

[0060] Step S2: excavating the arch pilot pit, and constructing the outer initial support 11 and the temporary span reduction support 12;

[0061] Step S3: After the arch is penetrated, the inner initial support 13 is set, a safe gap for assembly with the secondary lining arch cover 3 is reserved, the reserved reinforcement hole at the top of the underground continuous wall 1 is cleaned, the anchor bars are inserted, the crown beam steel bars are tied and the crown beam 2 is cast, the double-strand track 20 is laid and the high-strength bolt holes are reserved;

[0062] Step S4: remove the temporary span reduction support 12, lay the waterproof layer 15 until the bottom of the crown beam 2, and set 4 water-swellable waterproof adhesives 19 at the end to waterproof the joint;

[0063] Step S5: Use a pushing mechanical device to push the secondary lining arch cover 3 along the double-track 20 to the assembly position, fasten it to the crown beam 2 through the high-strength bent bolts 21, fill the gap between the double tracks with the grouting channel 22, and apply a lubricating drag reducing agent on the contact interface between the track and the groove during pushing;

[0064] Step S6: After the secondary lining arch cover 3 is fully assembled, grouting is performed through the grouting pipe 16 to backfill the reserved assembly safety gap between the secondary lining arch cover 3 and the inner initial support 13 and the vertical gap between the secondary lining arch cover 3 and the crown beam 2 on one side of the outer rail of the double track 20;

[0065] Step S7: excavate the soil below the station in layers until the tunnel is through, lay a fine-level cushion layer 17 at the bottom of the tunnel, transport the invert 4 to the assembly position, lift, lower, and assemble;

[0066] Step S8: Assemble the double-corbel side walls 5 on both sides one by one, and fix them firmly with temporary steel diagonal braces 18;

[0067] Step S9: using a lifting device to lift the arch bridge type curved middle plate 6 up to 200 mm above the upper surface of the double-corbel side wall 5, transporting the arch bridge type curved middle plate 6 to the assembly position along the longitudinal direction, vertically dropping it into place, and fastening it to the double-corbel side wall 5 by high-strength straight bolts 23;

[0068] Step S10: Grouting is performed from the top of the double-corbel side walls 5 on both sides to backfill the reserved safe assembly gap behind them, followed by removal of the temporary steel braces 18;

[0069] Step S11: vertically and continuously build the wall 8, and connect the upper and lower ends with the second lining arch cover 3 and the double-corbel side wall 5 by inserting reinforcement in the reserved reinforcement holes;

[0070] Step S12: Using the free-standing wall 8 as the outer formwork, using fine stone concrete to fill the free-standing wall 8 and the arch foot of the secondary lining arch cover 3, the crown beam 2, the horizontal space between the upper part of the underground continuous wall 1, and the vertical gap between the secondary lining arch cover 3 and the crown beam 2 on the inner side of the double-strand track 20 in layers;

[0071] Step S13: The platform slab 9 is vertically inserted into the reserved cup of the invert 4 in sections, and the remaining space between the two is compacted and firmly embedded by grouting;

[0072] Step S14: constructing an invert backfill 10 to further limit the lateral displacement of the wall under the platform slab, thus completing the construction of the entire prefabricated assembly structure of the underground excavation station.

[0073] Except for the underground continuous wall 1, other prefabricated components are vertically hoisted into the ventilation shafts at both ends of the station, and then transported horizontally to the intersection of the main body and the air duct commonly provided at the end of a conventional dark-cut station to expand the space. Mechanical equipment is then used to push and slide the prefabricated components longitudinally or directly transport them to the assembly position for precise assembly.

[0074] It can be seen from the above technical scheme that the present embodiment provides a fully prefabricated assembly structure of a dark-cut subway station and a construction method thereof, which achieves the purpose of completely eliminating the template in the construction of the dark-cut station structure, eliminates the operation links such as on-site steel bar binding, support template erection, concrete pouring and maintenance, and can significantly shorten the construction period, improve construction efficiency, and reduce engineering risks; moreover, the supporting construction method is almost not restricted by hydrogeological conditions, has strong engineering adaptability and high value for promotion and popularization.

[0075] The above embodiments of the present invention are described in detail through examples, but the contents described are only exemplary embodiments of the embodiments of the present invention and cannot be considered to limit the scope of implementation of the embodiments of the present invention. The protection scope of the embodiments of the present invention is defined by the claims. Anyone who utilizes the technical solutions described in the embodiments of the present invention, or who, inspired by the technical solutions of the embodiments of the present invention, designs similar technical solutions within the essence and protection scope of the embodiments of the present invention to achieve the above technical effects, or who makes equal changes and improvements to the scope of application, shall still fall within the scope of protection covered by the patent of the embodiments of the present invention.

Claims

1. A construction method for a fully prefabricated assembly structure of a dark-excavated subway station, characterized in that: The prefabricated components used in this method include: underground continuous wall, secondary lining arch cover, inverted arch / bottom plate, double-corbel side wall, middle plate with screen door vertical beam, off-wall wall and platform plate. The two sides of the middle plate are branch structures, which overlap with the double-corbel side wall to form a track top air duct. Each prefabricated component is provided with a reserved high-strength bolt hole according to the assembly connection relationship, and pre-buried grouting pipes, reserved grouting holes and reserved reinforcement holes are arranged according to the force safety requirements. The construction steps are as follows: Step S1: The ground machinery forms a trench and constructs a guide wall, and the prefabricated underground continuous wall is hoisted vertically downward in sections. Two adjacent prefabricated components are firmly connected by using corrugated joints and filled with slurry. A safe gap for assembly with the double-corbel side wall is reserved on the inner side of the underground continuous wall. The top elevation of the underground continuous wall is higher than the bottom height of the arch guide pit, and the bottom of the underground continuous wall is lower than the bottom elevation of the invert arch / bottom plate, and sufficient embedding depth is ensured to prevent overturning and instability; Step S2: excavating the arch pilot pit, and applying the outer initial support and temporary span reduction support; Step S3: After the arch is penetrated, an inner layer initial support is set, a safety gap for assembly with the secondary lining arch cover is reserved, the reserved reinforcement hole at the top of the underground continuous wall is cleaned, anchor bars are inserted, crown beam steel bars are tied and the crown beam is cast, or a prefabricated crown beam component is directly assembled at the top of the underground continuous wall; the crown beam is provided with a reserved high-strength bolt hole corresponding to the secondary lining arch cover, a track is laid at the top of the crown beam, and the secondary lining arch cover is provided with a groove corresponding to the track; Step S4: remove the temporary span reduction support, and lay a waterproof layer close to the initial support until the bottom of the lateral outer side of the crown beam; Step S5: using a pushing mechanical device to push and slide the secondary lining arch cover longitudinally along the track to an assembly position, and connecting and fixing the secondary lining arch cover and the crown beam by high-strength bent bolts; Step S6: After all the secondary lining arch covers are assembled, grouting is performed to backfill the reserved assembly safety gap between the secondary lining arch cover and the inner initial support and the vertical gap between the secondary lining arch cover and the crown beam on the outer side of the track; Step S7: excavate the rock and soil mass below the station in layers until the tunnel is through, lay a fine-level cushion layer at the bottom of the tunnel, and transport the invert / bottom plate components to the assembly location for assembly; Step S8: assemble the double-corbel side wall components on both sides piece by piece, and use high-strength bent bolts to firmly connect them with the inverted arch / bottom plate components. In order to ensure the vertical accuracy and overall stability of the double-corbel side wall when assembling the middle plate components in the next step, use temporary steel braces to support the double-corbel side wall on the inverted arch / bottom plate, and ensure that the high-strength straight bolt holes of the double-corbel side wall and the middle plate are fully aligned and accurately assembled; Step S9: Use jacking and transportation equipment to transport the middle plate component to its position along the longitudinal direction of the station, vertically lower it and place it on the double brackets of the side walls on both sides, and fasten the two together with high-strength straight bolts; Step S10: Grouting is performed from the top of the double-corbel side walls on both sides to backfill the reserved safety assembly gap between the side walls and the underground continuous wall. After the grouting is completed and the grouting strength reaches the requirement, the temporary steel bracing is removed; Step S11: cleaning the reserved reinforcement holes of the secondary lining arch cover and the double-corbel side wall, inserting anchor bars and vertically and continuously building the wall away from the wall, and forming anchor connections with the secondary lining arch cover and the double-corbel side wall at the upper and lower ends respectively; Step S12: Using the free-standing wall as the outer formwork, using fine stone concrete to fill the horizontal space between the free-standing wall and the arch foot of the secondary lining arch cover, the crown beam, and the upper part of the underground continuous wall, and the vertical gap between the secondary lining arch cover and the crown beam on the inner side of the track in layers; Step S13: Assembling the platform plate on the invert / base plate; Step S14: construct an invert backfill to limit the lateral displacement of the wall under the platform slab, thus completing the construction of the entire prefabricated assembly structure of the underground excavation station.

2. The construction method according to claim 1, characterized in that: The double-corbel side walls, inverted arch / bottom plate, middle plate, screen door vertical beam, platform plate and off-wall wall in the prefabricated structure have equal longitudinal widths. If the crown beam is a prefabricated component, its longitudinal width is equal to the longitudinal width of the secondary lining arch cover.

3. The construction method according to claim 1, characterized in that: A plurality of water-swellable water-stopping adhesives are arranged between the end of the waterproof layer and the crown beam to achieve waterproof closing.

4. The construction method according to claim 1, characterized in that: The middle plate adopts an arch bridge type curved middle plate, and a shield door vertical beam is arranged on the curved surface below the arch bridge type curved middle plate.

5. The construction method according to claim 1, characterized in that: The middle plate adopts a flat plate structure, and an "L"-shaped branch structure is arranged near the double-corbel side wall, wherein the vertical beam of the shield door is formed by the vertical wall of the "L"-shaped branch structure extending downward.

6. The construction method according to claim 1, characterized in that: When there are more than two tracks arranged at the top end of the crown beam, the second lining arch cover is provided with reserved grouting channels between adjacent tracks. After all the second lining arch covers are assembled, the reserved grouting channels are used to backfill the gaps between the adjacent tracks.

7. The construction method according to claim 1, characterized in that: The inverted arch / bottom plate has a reserved cup opening for inserting the wall under the platform plate.

8. The construction method according to claim 1, characterized in that: The groove at the bottom end of the secondary lining arch cover is pre-embedded with an arc-shaped pressure-bearing steel plate that matches the geometric shape of the track, and a lubricating drag-reducing agent is applied to the contact interface with the track.

9. The construction method according to claim 1, characterized in that: The exposed surfaces of the high-strength bent bolts and the high-strength straight bolts are coated with antiseptic.

10. A fully prefabricated assembly structure of a dark-excavated subway station, characterized in that: The method is constructed by the construction method described in any one of claims 1 to 9.

Images