UHPC-RC composite assembly type subway station and construction method thereof

Abstract

The invention provides a UHPC-RC composite assembly type subway station and a construction method thereof, and the construction method comprises the following steps: after the construction of a station foundation pit is completed, performing sequential construction from bottom to top, and using an ultra-high performance reinforced concrete structure formwork as a permanent formwork to form a bearing structure together with cast-in-place common concrete. Wherein the formworks of the middle longitudinal beams, the top longitudinal beams, the stand columns, the side walls, the middle plates and the top plates are prefabricated through ultra-high-performance concrete, and the bearing structure of the station is formed by the formworks and a cast-in-place common concrete structure; a truss steel bar part structure is designed to be pre-embedded in a formwork, and the other part structure is in cast-in-place common concrete after the common concrete is poured. According to the UHPC-RC composite assembly type subway station and the construction method thereof, the ultra-high performance reinforced concrete structure formwork serves as a permanent formwork to jointly bear and resist seepage with a cast-in-place common concrete structure, the use amount of common concrete can be reduced, the structure size is reduced, and the structural durability is improved while a larger available building space is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of underground engineering, and more specifically, relates to a UHPC-RC composite assembled subway station and a construction method thereof. Background Art

[0002] As the construction of urban rail transit slows down, the concept of urban rail transit construction has gradually shifted from the pursuit of construction scale to the pursuit of quality and efficiency. The poor impermeability of traditional concrete leads to serious groundwater leakage, and the internal steel bars are very prone to corrosion, which seriously affects the life of underground stations. Ultra-high performance concrete distributes particle size and is based on the principle of maximum density. It adds silica fume, water reducer and steel fiber to cement-based materials, avoiding the use of coarse aggregate in traditional concrete, and achieving excellent properties such as ultra-high strength, high toughness, low permeability and high volume stability. The high strength and low permeability characteristics of ultra-high performance concrete are very consistent with the demand for building materials in subway stations. However, while ultra-high performance concrete has high performance, its price is very expensive. If ultra-high performance concrete is used entirely for the casting of station structures, the cost is too expensive and does not conform to the concept of green construction. Summary of the invention

[0003] The purpose of the present invention is to provide a UHPC-RC composite assembled subway station and a construction method thereof, aiming to solve the above-mentioned technical problems existing in the prior art.

[0004] To achieve the above object, the technical solution adopted by the present invention is: to provide a UHPC-RC composite prefabricated subway station construction method, comprising: After the construction of the station foundation pit is completed, work is carried out from bottom to top, using truss steel bars as structural measures, and using ultra-high performance reinforced concrete structural formwork as permanent formwork to form a load-bearing structure together with cast-in-place ordinary concrete; among them, ultra-high performance concrete is used to prefabricate the middle longitudinal beams, top longitudinal beams and columns, as well as the formwork for the side walls, middle plates and top plates, and the formwork and cast-in-place ordinary concrete structure form the load-bearing structure of the station; part of the truss steel bar structure is pre-buried in the formwork, and after pouring ordinary concrete, the other part of the structure is in the cast-in-place ordinary concrete.

[0005] Preferably, the steps include: After the station foundation pit construction is completed, the station's cast-in-place bottom longitudinal beams and cast-in-place bottom slabs will be constructed; Install precast side wall formwork for the second underground floor and pour ordinary concrete side walls within the formwork; Install the prefabricated columns of the second underground floor, and use the connection nodes of the cast-in-place concrete prefabricated columns with the cast-in-place bottom longitudinal beams and cast-in-place bottom slabs; then install the corbels on the prefabricated columns, and hoist the prefabricated middle longitudinal beams onto the prefabricated columns; Temporary supports are set up on the inner side of the prefabricated side wall formwork on both sides of the second underground floor, and then the prefabricated middle plate formwork is hoisted, and the prefabricated middle plate formwork is supported by the prefabricated assembled middle longitudinal beam and temporary supports; Constructing cast-in-place ordinary concrete middle slab on the prefabricated middle slab formwork; Install the prefabricated side wall formwork for the first underground floor, and then cast the ordinary concrete side wall in the formwork. Then install the prefabricated assembled columns for the first underground floor, and use ultra-high performance concrete to cast the nodes; then, install the brackets and hoist the prefabricated assembled top longitudinal beams onto the prefabricated assembled columns for the first underground floor; Temporary supports are set up on the inner side of the prefabricated side wall formwork on both sides of the underground first floor, and the prefabricated top plate formwork is hoisted. The two ends of the prefabricated top plate formwork are supported by prefabricated assembled top longitudinal beams and temporary supports; The cast-in-place ordinary concrete top slab in the composite top slab is cast on the installed prefabricated top slab formwork, and the connection node between the side wall and the top slab of the underground floor is cast together with the cast-in-place ordinary concrete top slab.

[0006] The cast-in-place ordinary concrete top slab reserves a space of a certain height at the top above the prefabricated assembled top longitudinal beam.

[0007] Preferably, the construction of the cast-in-place ordinary concrete middle plate on the prefabricated middle plate formwork includes: the connection node between the underground second floor side wall and the middle plate is cast together with the cast-in-place ordinary concrete middle plate, and a space of a certain height is reserved at the top of the cast-in-place ordinary concrete middle plate above the prefabricated assembled middle longitudinal beam; and the height of the space is 80-120mm.

[0008] Preferably, the cast-in-place ordinary concrete top slab in the composite top slab is cast on the installed prefabricated top slab formwork, and the connection node between the underground first floor side wall and the top slab is cast together with the cast-in-place ordinary concrete top slab, including: reserving a space of a certain height at the top of the cast-in-place ordinary concrete top slab above the prefabricated assembled top longitudinal beam, wherein the height of the space is 80-120mm; and then after the initial setting of the top slab concrete meets the construction requirements, pouring ultra-high performance concrete into the space.

[0009] Preferably, for the node positions where columns are set, ordinary concrete is used to cast the center longitudinal beam and top plate to 100 mm below the top elevation of the composite center plate, steel bars are laid in the recess of the prefabricated assembled center longitudinal beam within 1000 mm outside the axial direction of the column node, and concrete is poured to 100 mm below the top elevation of the composite center plate; for non-column node positions, ordinary concrete is poured above the prefabricated assembled center longitudinal beam to 100 mm below the top elevation of the composite center plate.

[0010] Preferably, for the node positions where columns are set, ordinary concrete cast-in-place top longitudinal beams and top plates are used to 100 mm below the top elevation of the composite top plate, and steel bars should be laid and concrete should be poured in the hollow cavity of the prefabricated assembled top longitudinal beams within 1000 mm outside the column node along the axial direction; for non-column node positions, ordinary concrete is poured above the prefabricated assembled top longitudinal beams to 100 mm below the top elevation of the composite top plate.

[0011] Preferably, after the construction of the station foundation pit is completed, the cast-in-place bottom longitudinal beams and cast-in-place bottom slabs of the station are constructed, including pre-embedding of steel bars of prefabricated assembled columns before the pouring work is carried out.

[0012] The UHPC-RC composite prefabricated subway station is characterized in that it is manufactured based on the steps in the UHPC-RC composite prefabricated subway station construction method as described in any one of the above items; the structure is an open-cut rectangular double-layer two-span station, including an underground two-layer structure and an underground one-layer structure, wherein the underground two-layer structure includes; Cast-in-place bottom longitudinal beams; A cast-in-place bottom plate is located on the top of the cast-in-place bottom longitudinal beam; the cast-in-place bottom plate is connected and fixed to the cast-in-place bottom longitudinal beam; Prefabricated assembled columns located on the second underground floor are connected to the cast-in-place base plate; There are multiple superimposed side walls located on the second underground floor, and each of the superimposed side walls is respectively connected and fixed to the side of the cast-in-place bottom plate; A prefabricated middle longitudinal beam connected to the prefabricated columns located on the second underground floor; The composite middle plate is connected to the end of the composite side wall located on the second underground floor away from the cast-in-place bottom plate, and is connected to the prefabricated assembled columns and the prefabricated assembled middle longitudinal beam located on the second underground floor; The underground structure includes: A plurality of laminated side walls are provided on the first underground floor, each of which is respectively connected and fixed to the side edge of the laminated middle plate; Prefabricated assembled columns located on the first underground floor are connected to the composite middle plate; Prefabricated and assembled top longitudinal beams, and the prefabricated and assembled columns located on the first underground floor; The composite top plate is connected to the end of the composite side wall located on the first underground floor away from the composite middle plate, and is connected to the prefabricated assembled columns and the prefabricated assembled top longitudinal beams located on the first underground floor. Preferably, the laminated side wall comprises: Prefabricated side wall formwork is provided with accommodation space so as to avoid dismantling the formwork; Truss reinforcement is arranged in the accommodation space; The cast-in-place ordinary concrete side wall is filled in the accommodation space and is connected with the prefabricated side wall formwork and the truss steel bars.

[0013] Preferably, the prefabricated top longitudinal beam is a hollow member.

[0014] Preferably, the prefabricated longitudinal beam is a notch-shaped component.

[0015] The beneficial effect of the UHPC-RC composite prefabricated subway station construction method provided by the present invention is that compared with the prior art, the UHPC-RC composite prefabricated subway station construction method of the present invention has the characteristics of versatility and assembly, and can realize the factory prefabrication of components, which is conducive to improving the level of building industrialization and saving construction period. The ultra-high performance reinforced concrete structure formwork has high strength and good volume stability, and the light and thin design can achieve better template function; the ultra-high performance reinforced concrete structure formwork as a permanent formwork reduces the demolding process, and the factory prefabrication of components can shorten the construction period. The ultra-high performance reinforced concrete structure formwork is used as a permanent formwork and is load-bearing and impermeable together with the cast-in-place ordinary concrete structure, which can reduce the amount of ordinary concrete, reduce the size of the structure, and improve the durability of the structure while realizing a larger usable building space. According to the stress characteristics of the structure, ultra-high performance reinforced concrete materials are only used locally to reduce the stress redundancy of high-strength materials, which can save engineering costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of the structure of a UHPC-RC composite assembled subway station provided by an embodiment of the present invention; Figure 2 A schematic diagram of structural truss reinforcement in a UHPC-RC composite assembled subway station construction method provided in an embodiment of the present invention; Figure 3 A structural diagram of the superimposed side wall in the UHPC-RC composite assembled subway station construction method provided in an embodiment of the present invention; wherein the left figure is a front view; and the right figure is a top view; Figure 4 Elevation and cross-sectional views of the laminated middle plate in the UHPC-RC composite prefabricated subway station construction method provided by the embodiment of the present invention; wherein the left side of the upper figure is the side wall side; the right side is the column side; the left figure of the lower figure is the AA cross-sectional view; the right figure is the BB cross-sectional view; Figure 5 Elevation and cross-sectional views of the superimposed top slab in the UHPC-RC composite prefabricated subway station construction method provided by an embodiment of the present invention; wherein the left side of the upper figure is the side wall side; the right side is the column side; the left figure of the lower figure is the AA cross-sectional view; and the right figure is the BB cross-sectional view; Figure 6 A cross-sectional view of a prefabricated and assembled middle longitudinal beam in a UHPC-RC composite assembled subway station construction method provided in an embodiment of the present invention; Figure 7 A cross-sectional view of a prefabricated top longitudinal beam in a UHPC-RC composite prefabricated subway station construction method provided in an embodiment of the present invention; FIG8 (a) is a construction sequence of a UHPC-RC composite prefabricated subway station provided by an embodiment of the present invention Figure 1 ; FIG8 (b) is a construction sequence of a UHPC-RC composite prefabricated subway station provided by an embodiment of the present invention Figure 2 ; FIG8 (c) is a construction sequence of a UHPC-RC composite prefabricated subway station provided by an embodiment of the present invention Figure 3 ; Wherein, A represents the ultra-high performance concrete post-casting layer; FIG8 (d) is a construction sequence of a UHPC-RC composite prefabricated subway station provided by an embodiment of the present invention Figure 4 ; FIG8 (e) is a construction sequence of a UHPC-RC composite prefabricated subway station provided by an embodiment of the present invention Figure 5 ; Wherein, A represents the ultra-high performance concrete post-casting layer; Fig. 9 A schematic diagram of the node between the middle longitudinal beam and the column in the UHPC-RC composite prefabricated subway station provided by an embodiment of the present invention; wherein the left figure is an axial cross-sectional view of the node between the middle longitudinal beam and the column; the right figure is a transverse cross-sectional view of the node between the middle longitudinal beam and the column, A is an ultra-high performance concrete post-cast layer; B is cast-in-place concrete (shaded part); C is a cast-in-place ultra-high performance concrete node; Fig.10 Schematic diagram of the top longitudinal beam and column node of the UHPC-RC composite prefabricated subway station provided in an embodiment of the present invention; wherein A is the ultra-high performance concrete post-cast layer; B is the cast-in-place concrete (shaded part); and C is the cast-in-place ultra-high performance concrete node.

[0018] In the figure: 1. Cast-in-place bottom plate; 2. Cast-in-place bottom longitudinal beam; 3. Composite side wall; 4. Prefabricated assembled column; 5. Prefabricated assembled middle longitudinal beam; 6. Composite middle plate; 7. Prefabricated assembled top longitudinal beam; 8. Composite top plate; 9. Truss reinforcement; 31. Prefabricated side wall formwork; 32. Cast-in-place ordinary concrete side wall; 311. Ultra-high performance concrete thin plate; 312. Tension reinforcement; 61. Prefabricated middle plate formwork; 62. Cast-in-place ordinary concrete middle plate; 63. Connection node between the side wall and the middle plate of the second underground floor; 81. Prefabricated top plate formwork; 82. Cast-in-place ordinary concrete top plate; 83. Connection node between the side wall and the top plate of the first underground floor; 91. Upper chord reinforcement; 92. Lower chord reinforcement; 93. Web reinforcement. 10. Corbel; 11. Temporary support. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] Ultra-High Performance Concrete (UHPC) distributes particle sizes based on the principle of maximum density. It mixes silica fume, water reducing agent and steel fiber into cement-based materials, avoiding the use of coarse aggregate in traditional concrete, and achieving excellent properties such as ultra-high strength, high toughness, low permeability and high volume stability. Ultra-high performance concrete is very suitable for the demand for building materials in subway stations, because underground projects are in a water environment in the long run, but UHPC is very expensive at the same time. If ultra-high performance concrete is used for the overall structure casting, the cost is too expensive and does not conform to the concept of green construction.

[0021] Therefore, the idea of ​​using ultra-high performance reinforced concrete structure (UHPC-RC) as a permanent formwork is constructively proposed, and then the construction method of assembled ultra-high performance reinforced concrete structure formwork subway station is proposed. This method has the following advantages: First, due to the universality and assembly characteristics of ultra-high performance reinforced concrete structure formwork components, factory prefabrication of components can be realized; second, the ultra-high performance reinforced concrete structure formwork has high strength and good volume stability, and a light and thin design can achieve better formwork function; third, the ultra-high performance reinforced concrete structure formwork as a permanent formwork can be used together with the cast-in-place ordinary concrete structure to bear and resist seepage, so the amount of ordinary concrete can be reduced, the structural size can be reduced, and the structural durability can be improved while achieving a larger available building space; fourth, the ultra-high performance reinforced concrete structure formwork as a permanent formwork reduces the demolding process, and the factory prefabrication of components can shorten the construction period. That is, compared with the traditional ordinary concrete cast-in-place subway station, the solution provided by the present invention has reduced structural size, increased available building space, reduced structural deadweight, reduced formwork and demolding processes, and improved structural durability, which is conducive to achieving the advantages of the subway station structure being solid inside and beautiful outside, and impermeable.

[0022] Please also read Figures 1 to 10 , the construction method of the UHPC-RC composite prefabricated subway station provided by the present invention is now described. The UHPC-RC composite prefabricated subway station construction method is carried out from bottom to top after the construction of the station foundation pit is completed, and the ultra-high performance reinforced concrete structure formwork is used as a permanent formwork together with cast-in-place ordinary concrete to form a load-bearing structure, wherein ultra-high performance concrete is used to prefabricate the formwork of the middle longitudinal beam, top longitudinal beam and column, as well as the side wall, middle plate and top plate, and the formwork and the cast-in-place ordinary concrete structure form the load-bearing structure of the station; the truss steel bar part of the structure is pre-buried in the formwork, and the other part of the structure is in the cast-in-place ordinary concrete after the ordinary concrete is poured. Specifically, it includes the following steps: S1. Please refer to FIG8 (a). After the construction of the station foundation pit is completed, the cast-in-place bottom longitudinal beam 2 and the cast-in-place bottom plate 1 of the station are constructed. Before the pouring work is carried out, the steel bars of the prefabricated assembled columns 4 are pre-buried.

[0023] S2, please refer to FIG8 (b), install the prefabricated side wall formwork 31 of the second underground floor on the cast-in-place base 1, and then cast the ordinary concrete side wall 32 in the formwork. The prefabricated side wall formwork 31 is an ultra-high performance concrete structure.

[0024] S3, please refer to Figure 8 (b), install the prefabricated assembled columns 4 of the second underground floor, and use the connection nodes of the cast-in-place assembled columns 4, the cast-in-place bottom longitudinal beams 2, and the cast-in-place bottom plate 1; then install the brackets 10 of the prefabricated assembled columns 4 of the second underground floor, and hoist the prefabricated assembled middle longitudinal beams 5 onto the prefabricated assembled columns 4 of the second underground floor. Among them, the prefabricated assembled columns 4 are ultra-high performance concrete structures. The prefabricated assembled middle longitudinal beams 5 are ultra-high performance concrete structures. The concrete is preferably ultra-high performance concrete.

[0025] S4. Please refer to Figure 8 (c). Temporary supports 11 are set up inside the prefabricated side wall formwork 31 on both sides of the second underground floor. In order to ensure the stability of the support, the haunch position is avoided. Then the prefabricated middle plate formwork 61 is hoisted, and the two ends of the prefabricated middle plate formwork 61 are supported by the prefabricated assembled middle longitudinal beam 5 and the temporary supports 11. The shape of the prefabricated middle plate formwork 61 is an inverted "π" shape. The prefabricated middle plate formwork 61 is an ultra-high performance concrete structure.

[0026] In this step, attention should be paid to symmetrical lifting during construction, and appropriate temporary fixation should be performed to avoid overturning.

[0027] S5. Please refer to Figure 8 (c). Cast the cast-in-place ordinary concrete middle plate 62 in the composite middle plate 6 on the installed prefabricated middle plate formwork 61. Among them, the pre-embedded steel bars of the prefabricated assembled columns 4 used in the first underground floor should be done before pouring. The connection node 63 between the side wall of the second underground floor and the composite middle plate 6 should be cast together with the cast-in-place ordinary concrete middle plate 62. A 100mm high space is reserved at the top of the cast-in-place ordinary concrete middle plate 62 above the prefabricated assembled middle longitudinal beam 5 as an ultra-high performance concrete post-casting layer.

[0028] In this step, see Fig. 9 For the node positions where columns are set, ordinary concrete is used to cast the middle longitudinal beam and top plate to 100mm below the top elevation of the composite middle plate. Steel bars are laid in the recess of the prefabricated assembled middle longitudinal beam within 1000mm outside the column node along the axial direction, and concrete is poured to 100mm below the top elevation of the composite middle plate. At non-column node positions, ordinary concrete is poured above the prefabricated assembled middle longitudinal beam 5 to 100mm below the top elevation of the composite middle plate. In particular, concrete does not need to be poured in the recess. However, regardless of whether it is a column node position or not, a 100mm high space should be reserved above the top of the prefabricated assembled middle longitudinal beam 5 as a post-cast layer of ultra-high performance concrete.

[0029] In this step, after the initial setting of the middle plate concrete meets the construction requirements, the ultra-high performance concrete is poured into the ultra-high performance concrete post-casting layer. The pouring thickness is 100mm. After the strength of the cast-in-place ordinary concrete middle plate 62 meets the requirements, the bracket 10 and the temporary support 11 are removed.

[0030] S6. Please refer to Figure 8 (d). Install the prefabricated side wall formwork 31 of the underground first floor, and then cast the ordinary concrete side wall 32 in the formwork. Then install the prefabricated assembled columns 4 of the underground first floor, and cast them with ultra-high performance concrete. Then, install the brackets 10 of the prefabricated assembled columns 4 of the underground first floor, and hoist the prefabricated assembled top longitudinal beams 7 onto the prefabricated assembled columns 4 of the underground first floor.

[0031] S7. Temporary supports 11 are set up inside the prefabricated side wall formwork 31 on both sides of the underground first floor. To ensure the stability of the support, avoid the position of the armpit. The prefabricated top plate formwork 81 is hoisted, and the two ends of the prefabricated top plate formwork 81 are supported by the prefabricated assembled top longitudinal beam 7 and the temporary supports 11. Among them, the shape of the prefabricated top plate formwork 81 is an inverted "π" shape. The prefabricated top plate formwork 81 is an ultra-high performance concrete structure. The prefabricated assembled top longitudinal beam 7 is an ultra-high performance concrete structure.

[0032] During construction, attention should be paid to symmetrical lifting and appropriate temporary fixing to avoid overturning.

[0033] S8. Cast the cast-in-place ordinary concrete top plate 82 in the composite top plate 8 on the installed prefabricated top plate formwork 81, and cast the connection node 83 between the side wall and the top plate of the underground floor together with the cast-in-place ordinary concrete top plate 82. A 100mm high ultra-high performance concrete post-casting layer is reserved on the top of the cast-in-place ordinary concrete top plate 82 above the prefabricated assembled top longitudinal beam 7. After the initial setting of the top plate concrete meets the construction requirements, cast a 100mm thick ultra-high performance concrete post-casting layer.

[0034] In step S8, for the node positions where columns are set, steel bars should be laid and concrete should be poured in the hollow cavity of the prefabricated top longitudinal beam 7. Specifically, ordinary concrete is used to cast the top longitudinal beam and top plate to 100mm below the top elevation of the composite top plate, and steel bars should be laid and concrete should be poured in the hollow cavity of the prefabricated top longitudinal beam within 1000mm outside the column node along the axial direction; for non-column node positions, ordinary concrete is poured above the prefabricated top longitudinal beam 7 to 100mm below the top elevation of the composite top plate 8.

[0035] The present invention also provides a UHPC-RC composite assembled subway station prepared according to the steps in the UHPC-RC composite assembled subway station construction method described in any one of the above. Please refer to Figures 1 to 10The UHPC-RC composite assembled subway station is an open-cut rectangular double-layer two-span station in terms of structure, including: an underground second-floor structure and an underground first-floor structure, wherein the underground second-floor structure includes: a cast-in-place bottom longitudinal beam 2; a cast-in-place bottom plate 1, located on the top of the cast-in-place bottom longitudinal beam 2; the cast-in-place bottom plate 1 is connected and fixed to the cast-in-place bottom longitudinal beam 2; a prefabricated assembled column 4 located on the underground second floor, connected to the cast-in-place bottom plate 1; a plurality of composite side walls 3 located on the underground second floor, each of which is respectively connected and fixed to the side of the cast-in-place bottom plate 1; a prefabricated assembled middle longitudinal beam 5, connected to the prefabricated assembled column 4 located on the underground second floor; a composite middle plate 6; connected to one end of the composite side wall 3 located on the underground second floor away from the cast-in-place bottom plate 1, and connected to the prefabricated assembled column 4 and the prefabricated assembled middle longitudinal beam 5 located on the underground second floor; The underground layer structure includes: a plurality of composite side walls 3 located on the underground layer, each composite side wall 3 is respectively connected and fixed to the side of a composite middle plate 6; a prefabricated assembled column 5 located on the underground layer, connected to the composite middle plate 6; a prefabricated assembled top longitudinal beam 7, connected to the prefabricated assembled column 4 located on the underground layer; a composite top plate 8, connected to one end of the composite side wall 3 located on the underground layer away from the composite middle plate 6, and connected to the prefabricated assembled column 4 and the prefabricated assembled top longitudinal beam 5 located on the underground layer.

[0036] Preferably, see Figure 2 The structural measure is to select truss steel bars 9. The truss steel bars 9 are composed of upper chord steel bars 91, lower chord steel bars 92 and web bar steel bars 93. The performance of the composite member can be effectively guaranteed.

[0037] Preferably, see Figure 3 The composite side wall 3 is composed of a prefabricated side wall formwork 31, a cast-in-place ordinary concrete side wall 32 and a truss steel bar 9. The prefabricated side wall formwork 31 is a non-disassembly formwork, in order to ensure the integrity and reliable force-bearing performance of the composite side wall. The prefabricated side wall formwork 31 is composed of two high-performance concrete thin plates 311 and tension steel bars 312. The tension steel bars 312 connect the two high-performance concrete thin plates 311 to form a reliable high-performance concrete side wall formwork 31. The upper chord steel bars 91 and the lower chord steel bars 92 of the truss steel bar 9 are respectively embedded in the two high-performance concrete thin plates 311, and the web steel bars 93 connect the upper chord steel bars 91 and the lower chord steel bars 92 in the two high-performance concrete thin plates 311. After the cast-in-place ordinary concrete side wall 32 is cast, the web steel bars 93 are located in the cast-in-place ordinary concrete side wall 32. Therefore, the truss steel bar 9 can ensure that the prefabricated high-performance concrete side wall formwork and the cast-in-place ordinary concrete side wall are tightly connected.

[0038] Preferably, the composite middle plate 6 is composed of a prefabricated middle plate formwork 61, a cast-in-place ordinary concrete middle plate 62 and truss steel bars 9. The prefabricated middle plate formwork 61 is a non-disassembly formwork. In order to ensure the integrity and reliable force performance of the composite plate, the lower chord steel bars 92 of the two truss steel bars 9 are embedded in the prefabricated middle plate formwork 61, and an upper chord steel bar 91 is outside the prefabricated middle plate formwork 61. The web steel bars 9 connect the lower chord steel bars 92 and the upper chord steel bars 91. After the cast-in-place ordinary concrete middle plate 62 is cast, the upper chord steel bars 91 and the web steel bars 93 are located in the cast-in-place ordinary concrete middle plate 62, thereby playing the role of connecting the prefabricated middle plate formwork 61 and the cast-in-place ordinary concrete middle plate 62.

[0039] Preferably, the composite top plate 8 is composed of a prefabricated top plate formwork 81, a cast-in-place ordinary concrete top plate 82 and truss steel bars 9. The prefabricated top plate formwork 81 is a non-disassembly formwork, in order to ensure the integrity and reliable force-bearing performance of the composite plate. The lower chord steel bars 92 of the two truss steel bars 9 are embedded in the prefabricated top plate formwork 81. An upper chord steel bar 91 is outside the prefabricated top plate formwork 81, and the web steel bars 93 connect the lower chord steel bars 92 and the upper chord steel bars 91. After the cast-in-place ordinary concrete top plate 82 is cast, the upper chord steel bars 91 and the web steel bars 93 are located in the cast-in-place ordinary concrete top plate 82, thereby playing the role of connecting the prefabricated top plate formwork 81 and the cast-in-place ordinary concrete top plate 82.

[0040] Preferably, the prefabricated middle longitudinal beam 5 is a notch-shaped component, and the prefabricated top longitudinal beam 7 is a hollow component.

[0041] The prefabricated formwork subway station construction method in this scheme uses the formwork components as permanent formwork for on-site concrete pouring. And the specific structure of the formwork components is an ultra-high performance reinforced concrete structure. Compared with the traditional ordinary concrete cast-in-place subway station, this prefabricated formwork subway station construction method reduces the structural size, increases the available building space, reduces the structural deadweight, reduces the formwork and demolding procedures, improves the structural durability, and is conducive to achieving a subway station structure that is solid inside and beautiful outside, and leak-proof.

[0042] The formwork for the middle longitudinal beam 5, the top longitudinal beam 7 and the column 4 as well as the side wall 3, the middle plate 6 and the top plate 8 is prefabricated with ultra-high performance concrete, and the formwork together with the cast-in-place ordinary concrete structure serves as the bearing structure during the service life of the station.

[0043] The use of high-strength ultra-high performance concrete can reduce the volume of beams, slabs, columns, and wall structures, which is conducive to improving the lightweight level of buildings and increasing the usable space of buildings; the use of partial structural prefabrication can improve the level of building industrialization and speed up construction efficiency.

[0044] For large-volume structural components such as side walls and slabs, the design that combines prefabrication and cast-in-place, ultra-high performance concrete and ordinary concrete is conducive to reducing project costs and saving costs.

[0045] In this construction method, the truss steel bars 9 are used as structural measures. Part of the truss steel bars are pre-buried in the ultra-high performance concrete formwork, and the other part is in the cast-in-place ordinary concrete after pouring the ordinary concrete. This can ensure the coordinated deformation and force integrity between the prefabricated ultra-high performance concrete formwork and the cast-in-place ordinary concrete structure.

[0046] When pouring the cast-in-place ordinary concrete middle plate 62 and the cast-in-place ordinary concrete top plate 82 , a 100 mm high ultra-high performance concrete post-casting layer is poured on the top of the prefabricated assembled middle longitudinal beam 5 and the prefabricated assembled top longitudinal beam 7 .

[0047] Because when calculating the main structure of the underground station, the middle plate and the top plate are support positions at the middle longitudinal beam and the top longitudinal beam, and the mechanical performance is that the upper part is under tension.

[0048] Therefore, pouring a 100 mm high ultra-high performance concrete post-casting layer on the top of the prefabricated assembled middle longitudinal beam 5 and the prefabricated assembled top longitudinal beam 7 can effectively utilize the high tensile strength of ultra-high performance concrete to prevent the middle plate and the top plate from cracking above the middle longitudinal beam and the top longitudinal beam.

[0049] Through optimization, the longitudinal beam is designed as a notch and hollow structure, and steel bars are locally laid and concrete is poured at the node between the longitudinal beam and the column. In the present invention, the prefabricated and assembled middle longitudinal beam 5 is a notch structure, and the prefabricated and assembled middle longitudinal beam 7 is a hollow structure, which can reduce the amount of ultra-high performance concrete and reduce the project cost; Laying steel bars and pouring concrete locally at the beam-column joints can ensure stable force transmission and structural safety. In this way, both cost and safety can be taken into account.

[0050] Compared with the prior art, the UHPC-RC composite prefabricated subway station construction method provided by the present invention has the characteristics of versatility and assembly in the formwork components, which can realize the factory prefabrication of components, which is beneficial to improving the level of building industrialization and saving construction period. The ultra-high performance reinforced concrete structure formwork has high strength and good volume stability, and the light and thin design can achieve better formwork function; the ultra-high performance reinforced concrete structure formwork reduces the demolding process as a permanent formwork, and the factory prefabrication of components can shorten the construction period. The ultra-high performance reinforced concrete structure formwork is used as a permanent formwork and is load-bearing and impermeable together with the cast-in-place ordinary concrete structure, which can reduce the amount of ordinary concrete used, reduce the size of the structure, and improve the durability of the structure while achieving a larger usable building space. According to the stress characteristics of the structure, ultra-high performance reinforced concrete materials are only used locally to reduce the stress redundancy of high-strength materials, which can save engineering costs.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. UHPC-RC composite assembled subway station construction method, characterized in that: include: After the construction of the station foundation pit is completed, work is carried out from bottom to top, using truss steel bars as structural measures, and using ultra-high performance reinforced concrete structural formwork as permanent formwork to form a load-bearing structure together with cast-in-place ordinary concrete; among them, ultra-high performance concrete is used to prefabricate the middle longitudinal beams, top longitudinal beams and columns, as well as the formwork for the side walls, middle plates and top plates, and the formwork and cast-in-place ordinary concrete structure form the load-bearing structure of the station; part of the truss steel bar structure is pre-buried in the formwork, and after pouring ordinary concrete, the other part of the structure is in the cast-in-place ordinary concrete.

2. The UHPC-RC composite assembled subway station construction method according to claim 1, characterized in that: The following steps are involved: After the station foundation pit construction is completed, the station's cast-in-place bottom longitudinal beams and cast-in-place bottom slabs will be constructed; Install precast side wall formwork for the second underground floor and pour ordinary concrete side walls within the formwork; Install the prefabricated columns of the second underground floor, and use the connection nodes of the cast-in-place concrete prefabricated columns with the cast-in-place bottom longitudinal beams and cast-in-place bottom slabs; then install the corbels on the prefabricated columns, and hoist the prefabricated middle longitudinal beams onto the prefabricated columns; Temporary supports are set up on the inner side of the prefabricated side wall formwork on both sides of the second underground floor, and then the prefabricated middle plate formwork is hoisted, and the prefabricated middle plate formwork is supported by the prefabricated assembled middle longitudinal beam and temporary supports; Constructing cast-in-place ordinary concrete middle slab onto the precast precast middle slab formwork; Install the precast side wall formwork for the first basement level, and then cast the ordinary concrete side walls in the formwork; then install the precast assembled columns for the first basement level, and cast them with ultra-high performance concrete; Then, install the corbels and hoist the prefabricated top longitudinal beams onto the prefabricated columns on the first underground floor; Temporary supports are set up on the inner side of the prefabricated side wall formwork on both sides of the underground first floor, and the prefabricated top plate formwork is hoisted. The two ends of the prefabricated top plate formwork are supported by prefabricated assembled top longitudinal beams and temporary supports; Cast the cast-in-place ordinary concrete top slab in the composite top slab on the installed prefabricated top slab formwork, and cast the connection node between the side wall and the top slab of the underground first floor together with the cast-in-place ordinary concrete top slab; The cast-in-place ordinary concrete top slab reserves a space of a certain height at the top above the prefabricated assembled top longitudinal beam.

3. The UHPC-RC composite assembled subway station construction method according to claim 1, characterized in that: The cast-in-place ordinary concrete middle plate is constructed on the prefabricated middle plate formwork, and the connection node between the underground second floor side wall and the middle plate is cast together with the cast-in-place ordinary concrete middle plate, including: a space of a certain height is reserved at the top of the prefabricated assembled middle longitudinal beam of the cast-in-place ordinary concrete middle plate; and the height of the space is 80-120mm; and / or The method comprises: casting a cast-in-place ordinary concrete top slab in the composite top slab on the installed prefabricated top slab formwork, and casting a connection node between the side wall of the underground floor and the top slab together with the cast-in-place ordinary concrete top slab, comprising: reserving a space of a certain height at the top of the prefabricated assembled top longitudinal beam of the cast-in-place ordinary concrete top slab, wherein the height of the space is 80-120 mm; and then after the initial setting of the top slab concrete meets the construction requirements, pouring ultra-high performance concrete into the space.

4. The UHPC-RC composite assembled subway station construction method according to claim 3, characterized in that: For the node positions where columns are set, ordinary concrete cast-in-place top longitudinal beams and top plates are used to 100mm below the top elevation of the composite top plate. Steel bars should be laid and concrete should be poured in the hollow cavity of the prefabricated top longitudinal beams within 1000mm outside the column node along the axial direction. For non-column node positions, ordinary concrete is poured above the prefabricated top longitudinal beams to 100mm below the top elevation of the composite top plate.

5. The UHPC-RC composite assembled subway station construction method according to claim 3, characterized in that: For the node positions where columns are set, ordinary concrete is used to cast the center longitudinal beam and top plate to 100mm below the top elevation of the composite center plate. Steel bars are laid in the recess of the prefabricated and assembled center longitudinal beam within 1000mm outside the axial direction of the column node, and concrete is poured to 100mm below the top elevation of the composite center plate. For non-column node positions, ordinary concrete is poured above the prefabricated and assembled center longitudinal beam to 100mm below the top elevation of the composite center plate.

6. The UHPC-RC composite assembled subway station construction method according to claim 1, characterized in that: After the construction of the station foundation pit is completed, the cast-in-place bottom longitudinal beams and cast-in-place bottom slabs of the station are constructed, including pre-embedded steel bars of prefabricated assembled columns before the pouring work.

7. UHPC-RC composite prefabricated subway station, characterized by: The method is prepared based on the steps in the UHPC-RC composite prefabricated subway station construction method according to any one of claims 1 to 6; the structure is an open-cut rectangular double-layer two-span station, including an underground two-layer structure and an underground one-layer structure, wherein the underground two-layer structure includes; Cast-in-place bottom longitudinal beams; A cast-in-place bottom plate is located on the top of the cast-in-place bottom longitudinal beam; the cast-in-place bottom plate is connected and fixed to the cast-in-place bottom longitudinal beam; Prefabricated assembled columns located on the second underground floor are connected to the cast-in-place base plate; There are multiple superimposed side walls located on the second underground floor, and each of the superimposed side walls is respectively connected and fixed to the side of the cast-in-place bottom plate; A prefabricated middle longitudinal beam connected to the prefabricated columns located on the second underground floor; The composite middle plate is connected to the end of the composite side wall located on the second underground floor away from the cast-in-place bottom plate, and is connected to the prefabricated assembled columns and the prefabricated assembled middle longitudinal beam located on the second underground floor; The underground structure includes: A plurality of laminated side walls are provided on the first underground floor, each of which is respectively connected and fixed to the side edge of the laminated middle plate; Prefabricated assembled columns located on the first underground floor are connected to the composite middle plate; A prefabricated top longitudinal beam connected to the prefabricated columns located on the underground floor; The composite top plate is connected to the end of the composite side wall located on the underground floor facing away from the composite middle plate, and is connected to the prefabricated assembled columns and the prefabricated assembled top longitudinal beams located on the underground floor.

8. The UHPC-RC composite assembled subway station according to claim 7, characterized in that: The laminated side wall comprises: Prefabricated side wall formwork is provided with accommodation space so as to avoid dismantling the formwork; Truss reinforcement is arranged in the accommodation space; The cast-in-place ordinary concrete side wall is filled in the accommodation space and is connected with the prefabricated side wall formwork and the truss steel bars.

9. The UHPC-RC composite assembled subway station according to claim 8, characterized in that: The prefabricated and assembled top longitudinal beam is a hollow component.

10. The UHPC-RC composite assembled subway station according to claim 9, characterized in that: The prefabricated and assembled middle longitudinal beam is a notched component.

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