Construction method of large-span high-clearance metro station atrium main body structure

Abstract

The invention discloses a construction method of a large-span high-clearance metro station atrium main body structure. The construction method comprises the following steps that S1, construction sections are divided; s2, side wall construction; s3, large-span high-clearance steel support replacement installation construction is carried out; s4, dismantling an upper concrete support; s5, the last section of side wall is constructed; and S6, large-span high-clearance steel support replacement dismantling construction is carried out. Wherein the step S2 is repeatedly carried out to complete construction of different side walls, and the side wall construction in the step S2 comprises the steps that a mixed formwork supporting frame is constructed; constructing a side wall waterproof layer; mounting side wall steel bars; mounting a side wall composite material template; performing side wall concrete pouring construction; and dismantling the lower concrete support. According to the construction method, the side wall is subjected to construction section division, repeated dismounting and mounting are avoided, the construction efficiency is improved, and the construction conflict between mounting and dismounting of the atrium steel replacement support and the column structure is effectively handled. And the composite material template is adopted, so that the appearance quality of the high-thickness side wall finished product is greatly improved.

Description

Technical Field

[0001] The present application relates to the field of building construction technology, and in particular to a construction method for a main structure of a large-span and high-clearance atrium of a subway station. Background Art

[0002] In recent years, with the acceleration of urbanization, people have higher and higher requirements for the development and use of underground space. The atrium space structure of subway stations has been widely used in the construction of subway stations due to its comfortable spatial experience, transparent visual effects and beautiful shape. Subway stations are mostly constructed by open-cut method, and the main structure and enclosure structure adopt composite structure. When designing the atrium structure, the two-story structure of the station is generally combined into one layer as a whole or in part, so the net height of the atrium structure is generally very high, and its side wall structure needs to be constructed in sections in the vertical direction. In order to ensure the safety of the subway station foundation pit, steel replacement braces are generally set in the middle of the atrium side wall. In order to ensure a good spatial effect, the atrium structure is mostly designed as a column-free structure, and the side wall, top plate thickness and top plate armpit angle size need to be increased to meet the structural force effect.

[0003] The steel replacement support technology in foundation pit engineering is to set up a force transmission structure between the underground structure and the retaining structure. When the net height of the structure is too high, the steel support is installed layer by layer as the side wall of the structure is constructed. After the installation of the steel support is completed, the upper temporary internal support is removed to prevent the stress condition of the retaining part of the retaining structure from changing significantly, thereby ensuring that after the temporary internal support is removed, the retaining structure and the main structure are still in a relatively stable state.

[0004] Under the condition that the main structure and enclosure structure of underground buildings adopt a composite structure, and the main structure top plate and side walls form a closed box-type frame structure, there are two main methods for pouring concrete for the main structure top plate and side walls. One is that the main structure top plate and side walls are constructed separately. This method first constructs the side wall, and the side wall adopts a single-sided formwork construction method. The formwork support frame mostly uses steel pipe diagonal braces or steel triangle trusses. After the side wall is poured, the side wall formwork support system is removed, and then the main structure top plate formwork support system is erected. The structure top plate formwork support frame is mostly a unified fastener type, disc buckle type or bowl buckle type formwork support frame; the second is the main structure plate and side wall construction adopts a one-time casting and forming construction method. The main structure formwork support system construction of this method usually adopts a fastener type full-floor support frame. The frame vertical rods mainly bear the vertical load of the structure top plate, and the frame horizontal rods support the side walls on both sides and bear the horizontal load from the side walls; the above methods have significant application effects and the construction methods are relatively mature.

[0005] When the top plate and side wall formwork support system of the atrium structure of the subway station are being constructed, the disadvantages of using steel pipe diagonal braces or steel triangular trusses for the side wall formwork support frames become apparent. Either the steel pipe diagonal braces are not sufficiently stressed, or the steel triangular trusses are too large, occupying too much space, and difficult to install and remove. If a fastener-type full-floor support frame is used, the horizontal bars of the frame support the side walls on both sides, and the wall is cast in layers vertically for multiple times. On the premise of solving the floating problem of the frame, the side wall casting requirements can be met. However, when dealing with the situation where the top plate is very thick, the load is large, and the distance between the formwork support frames cannot be too close due to the position of the steel replacement support, the fastener-type full-floor support frame will not be applicable due to the small vertical bearing capacity of the steel pipe. In addition, when dealing with the layered construction of the high-height side walls, the setting of anti-floating measures for the support system of the side wall full-floor support frame, and the measures to ensure the verticality and flatness of the wall need to be explored more deeply. Summary of the invention

[0006] In order to solve at least one of the above technical problems, the present application provides a construction method for the main structure of a large-span and high-clearance subway station atrium, and the technical solution adopted is as follows.

[0007] The present application provides a construction method for a main structure of a large-span and high-clearance subway station atrium, and the process of the construction method includes the following steps:

[0008] S1, construction section division;

[0009] S2, side wall construction;

[0010] S3, large span and high clearance steel support replacement and installation construction;

[0011] S4, upper concrete support removal;

[0012] S5, the last section of side wall construction;

[0013] S6, large span and high clearance steel support replacement and removal construction;

[0014] Among them, step S2 is repeated to complete the construction of different side walls. The side wall construction in step S2 includes: construction of hybrid formwork support frame; construction of side wall waterproofing layer; installation of side wall steel bars; installation of side wall composite material formwork; side wall concrete pouring construction; and removal of lower concrete support.

[0015] In certain embodiments of the present application, the construction section division in step S1 includes longitudinal unit division and vertical stratification. Longitudinal unit division: The longitudinal unit construction joint is set at 1 / 3 to 1 / 4 of the longitudinal beam span, and the block length is 16 to 20m. Vertical stratification: The first horizontal construction joint of the vertical joints in the station atrium is set at 1000mm below the lower supporting waist beam, and the second construction joint is set at 1000mm below the upper supporting waist beam. The remaining upper side walls and top plates are cast together.

[0016] In certain embodiments of the present application, the construction of the hybrid formwork support frame in step S2 includes: installing starting vertical poles; installing horizontal poles; connecting vertical poles; installing longitudinal and transverse horizontal poles; installing scissors braces; installing adjustable top supports for side walls; and setting up a side wall construction platform.

[0017] In certain embodiments of the present application, the installation of the starting pole includes: laying out and positioning the pole according to the construction plan, setting a base and a pad, inserting the starting rod sleeve into the base with the starting rod facing upward, placing the lower end of the starting rod into the groove of the force plane of the adjustable nut, and the center line of the lowest horizontal rod of the sweeping rod is no more than 550 mm from the bottom plate of the base.

[0018] In certain embodiments of the present application, the installation of the cross bar includes: inserting the cross bar head into the small hole of the disc so that the front end of the cross bar head is against the main frame round tube, and then fixing it with an inclined wedge passing through the small hole, so that the center line of the bottom horizontal bar of the sweeping rod is no more than 550mm above the ground.

[0019] In certain embodiments of the present application, the docking of the vertical poles includes: inserting the long end of the vertical pole into the sleeve of the starting pole, staggering the positions of the connecting sleeve joints of adjacent vertical poles at the same horizontal height, and the staggered height is not less than 75mm, and when the height of the formwork support is greater than 8m, the staggered height is not less than 500mm.

[0020] In certain embodiments of the present application, the installation of the scissors brace includes: repeating the steps of connecting the vertical poles and installing the longitudinal and transverse horizontal poles, raising the frame to a height of 0 to 500 mm above the side wall construction joint, and setting scissors braces around the outer side of the full-floor support frame; setting scissors braces from bottom to top every 6 m in the longitudinal or transverse direction in the middle, the width of the scissors brace is 4 to 6 m, the bottom end of the rod of the scissors brace is pressed against the ground, and the angle between the rod and the ground is 45° to 60°.

[0021] In certain embodiments of the present application, the construction of the side wall waterproof layer includes: arranging the geotextile in a vertical direction on the base layer as a buffer layer, and when constructing the side wall waterproof board, first laying the non-woven fabric in a circumferential direction, fixing the PVC gasket and the geotextile on the base layer, arranging two rows of gaskets on each waterproof board, and setting a temporary baffle on the inner side of the side wall waterproof board.

[0022] In certain embodiments of the present application, the side wall concrete pouring construction includes: anti-floating measures for the side wall formwork support frame and side wall concrete pouring. The anti-floating measures for the side wall formwork support frame include: pre-embedding a row of hooks at a distance of 2m and 3m from the side wall, respectively, setting steel wire ropes between the ground hooks and the outermost horizontal bars of the side wall support frame at 1 / 3 and 1 / 2 of the side wall height for pulling, the steel wire ropes are hooked with bolts to the pre-embedded hooks, and the removed concrete support or steel support of the enclosure structure is hoisted to the top of the frame.

[0023] In certain embodiments of the present application, the last section of side wall construction in step S5 includes: construction of a two-way force-bearing mixed formwork support frame for the side wall and the top plate; laying of the bottom formwork for the top plate; waterproofing construction of the side wall; installation of steel bars and side formwork for the side wall and the top plate; pouring of concrete for the side wall and the top plate; and removal of the mixed full-floor support frame.

[0024] The present application has at least the following beneficial effects: The construction method of the present application divides the side wall into construction sections, avoids repeated disassembly and assembly, speeds up construction efficiency, and effectively copes with the installation and removal of the atrium steel support and the construction conflict between the column structure. The composite material formwork is used to greatly improve the appearance quality of the high and thick side wall finished product.

[0025] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present application is further illustrated below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments embodied in the following drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0027] Figure 1 The following is a process flow chart of the construction method.

[0028] Figure 2 This is a plan for erecting a bidirectional force-bearing hybrid formwork support frame in the atrium of a subway station.

[0029] Figure 3 This is a cross-sectional view of the atrium section of a subway station.

[0030] Figure 4 This is a schematic diagram of the vertical layered construction of the atrium structure of a subway station. DETAILED DESCRIPTION

[0031] The embodiments of the present application are described in detail below in conjunction with the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0032] In the description of the present application, it should be understood that the terms "center", "middle", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0033] In the description of this application, "several" means more than one, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0034] In the description of this application, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0035] In the description of the present application, if the reference terms "as an implementation", "an embodiment", "some instances", "some embodiments", "illustrative embodiment", "example", "specific example", "some examples", etc. appear, it means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0036] The present application relates to a construction method for a main structure of a large-span and high-clearance atrium of a subway station. Figure 1 To Attachment Figure 4 , the process flow of the construction method includes the following steps.

[0037] 1. Construction section division

[0038] Longitudinal unit division: The longitudinal unit construction joint is set at the part where the longitudinal beam is subjected to less force, that is, 1 / 3 to 1 / 4 of the longitudinal beam span (between longitudinal columns), while avoiding entrances and exits, stairways, and air ducts, and try to avoid reserved holes, hole edge beams, hidden columns, etc. The block length is 16 to 20m.

[0039] Vertical stratification: The first horizontal construction joint of the vertical division of the station atrium is left at 1000mm below the lower supporting waist beam; the second construction joint is left at 1000mm below the upper supporting waist beam, and the remaining upper side walls and top slabs are cast together.

[0040] 2. Construction of the first section of hybrid formwork support frame

[0041] The construction of the hybrid formwork support frame is a common force system for the atrium side wall top plate. The design scheme is comprehensively verified. In addition to meeting the construction load combination of the side wall top plate, the spacing must also avoid the rigid support position. The scope of the support erection should first be cleaned up and the foundation should be confirmed to be solid. Then, the vertical pole positioning line is determined according to the structural plane axis, beam line, and side wall edge line, the horizontal control elevation is set, and the site is marked.

[0042] (1) Install the starting pole

[0043] According to the special construction plan, layout and pole positioning are carried out, the base and pad are set, the sleeve part of the starting rod is inserted upwards onto the base, and the lower edge of the starting rod is placed in the groove of the nut force plane. The center line height of the lowest horizontal rod of the sweeping rod should not be greater than 550mm from the bottom plate height of the base.

[0044] (2) Install the first layer of crossbars (disc-type)

[0045] Insert the crossbar head into the small hole of the disc so that the front end of the crossbar head rests against the main frame round tube, and then use an inclined wedge to penetrate the small hole and tighten it. The pin connection ensures that it will not fall out after self-locking by hammering, and the pull-out force is not less than 3KN. The center line of the bottom horizontal rod of the sweeping rod is not more than 550mm above the ground.

[0046] (3) Docking pole

[0047] Insert the long end of the vertical pole into the sleeve of the starting pole to check the hole position and see if the flat main frame is inserted to the bottom of the sleeve. The positions of the connecting sleeve joints of adjacent vertical poles at the same level are staggered, and the staggered height is not less than 75mm. When the height of the formwork support is greater than 8m, the staggered height is not less than 500mm.

[0048] (4) Install longitudinal and transverse horizontal bars (fastener type)

[0049] Install the longitudinal and transverse horizontal rods. The longitudinal and transverse horizontal rods use fastener-type steel pipes made of carbon steel pipes or cast iron steel pipes. The transverse horizontal rods are extended by butt joints. The longitudinal horizontal rods are extended by butt fasteners or lap joints with rotating fasteners. The longitudinal and transverse horizontal rods are fastened to the vertical rods with rotating fasteners. The tightening torque of the fastener bolts shall not be less than 40N*m and not more than 65N*m.

[0050] (5) Install the scissor brace

[0051] Repeat steps (3) and (4) to raise the frame to a height of 0 to 500 mm above the construction joint of the first-story side wall, and install vertical continuous scissors braces from bottom to top around the outer perimeter of the full-floor support frame. Install vertical continuous scissors braces from bottom to top every 6 m in the longitudinal and transverse directions in the middle, with a width of 4 to 6 m. The bottom end of the scissors brace rod is pressed against the ground with an angle of 45° to 60°, and horizontal scissors braces are installed at the top of the scissors brace and the sweeping rod. When the building height is 8 to 20 m, in addition to meeting the above requirements, zigzag diagonal braces should be added between two adjacent vertical continuous scissors braces in the longitudinal and transverse directions, and a horizontal scissors brace should be added in the middle of each scissors brace where there is a horizontal scissors brace.

[0052] (6) Install the first layer of adjustable side wall supports

[0053] Insert the thread head of the U-shaped adjustable top support into the horizontal rod tube (fastener-type steel tube) extending to the side wall, and then adjust it to the set length with a wrench.

[0054] (7) Set up the first layer of side wall construction platform

[0055] Adjustable top supports, primary and secondary square timber ribs and fixed formwork are installed on the top of the 5-span vertical poles close to the side walls on both sides, serving as a construction platform for the first layer of side wall reinforcement and formwork. A 1.2m-high guardrail is installed on the side of the platform away from the side wall, and a dense protective net is installed.

[0056] 3. Construction of the first section of side wall waterproofing layer

[0057] First, prepare the base surface of the side wall waterproofing board. The base surface should be flat, clean, without looseness or cracks, and the flatness should meet the requirement of D / L≤1 / 6. The concave and convex corners and edges of the base surface should be chamfered with 50*50mm cement mortar.

[0058] Arrange the geotextile vertically on the base layer as a buffer layer. The overlapping width of the waterproof board is 100mm. The overlapping parts are spot welded with a hot air welding gun to ensure that they are flat and straight without distortion.

[0059] When constructing the side wall waterproof board, first lay the non-woven fabric in the circumferential direction, use a nail gun to nail the PVC gasket and geotextile to the base layer, nail the geotextile on the overlapping edge with a nail gun, and use PVC gaskets to fix the geotextile to the base layer. Two rows of gaskets are arranged on each waterproof board, and each row of gaskets is 400mm away from the edge of the waterproof board in a rectangular arrangement. The gasket spacing is 800mm, and a temporary baffle is set on the inside of the side wall waterproof board to prevent mechanical damage and electric sparks from burning the waterproof board. If there is any damage, it should be repaired in time.

[0060] 4. Installation of the first section of side wall reinforcement

[0061] The side wall reinforcement is mainly vertical reinforcement, which is set on the outside, and the horizontal distribution reinforcement is set on the inside. The side wall reinforcement connection adopts straight thread sleeve connection. The joint quality must be guaranteed, and the joint percentage and joint interval setting must meet the design and specification requirements.

[0062] 5. Installation of composite material formwork for the first section of side wall

[0063] The side wall formwork adopts composite material formwork, and the formwork installation is carried out in a construction order from top to bottom. When assembling the formwork, the composite material formwork is passed through the keyhole on the formwork, and the formwork is assembled using connectors. When assembling, align the two pieces of formwork, pass the connecting handle through the keyhole, and then rotate the handle to connect the formwork. After the formwork is assembled layer by layer, the secondary and main ribs on the outside of the formwork are installed. The secondary ribs are made of wood, and the main ribs are made of carbon steel pipes or channel steel. After the formwork is re-measured, adjust the adjustable top support to tighten the side wall formwork.

[0064] 6. Concrete pouring of the first section of side wall

[0065] The anti-floating measures for the first layer of side wall formwork support frame are: a row of hooks are embedded in the foundation position 2m and 3m away from the side wall, and steel wire ropes are set between the ground hooks and the outermost horizontal bars of the side wall support frame at 1 / 3 and 1 / 2 of the side wall height for tensioning. The steel wire ropes are hooked on the embedded hooks through the rope. The removed concrete support or steel support of the enclosure structure is hoisted to the top of the frame to increase the deadweight of the frame and prevent the frame from floating during the side wall pouring process.

[0066] When pouring side wall concrete, first lay a layer of mortar of the same strength on the bottom. The side walls on both sides need to be poured symmetrically, and the pouring speed (v < 1.5m / h) and the pouring thickness of each layer (h ≤ 30cm) must be strictly controlled. During the pouring of side wall concrete, the height of the pipe outlet from the surface of the newly poured concrete shall not exceed 2m, and the support frame shall be monitored and inspected throughout the pouring process.

[0067] 7. Removal of lower concrete support

[0068] When the concrete strength of the first section reaches more than 75% of the design strength, the lower concrete support is removed. The cutting method is rope saw cutting combined with gantry hanger block lifting.

[0069] 8. Carry out the second section of side wall construction

[0070] Repeat steps 2 to 6 to construct the second section of the side wall. Note that after the lower side wall is poured and meets the conditions for demolding, the formwork of the lower side wall must be removed because the concrete must be cured as required. Before pouring the upper side wall, push the adjustable top support and square timber of the lower hybrid full-floor support frame back to the side wall structure surface to increase the friction between the frame and the side wall to prevent the frame from floating up when pouring the upper side wall.

[0071] 9. Large span and high clearance steel support installation and construction

[0072] In order to avoid the conventional double-drawer steel support movable end occupying the full support frame space of the top plate, a single-drawer steel support movable end is selected. The steel support is placed on the structural concrete lining wall, and the support is placed on the pre-embedded steel plate pre-embedded on the lining wall. After the support tray and steel connecting beam are erected, the steel pipe support is hoisted into place. The steel pipe support is hoisted in two sections using a gantry crane.

[0073] 10. Removal of upper concrete support

[0074] When the second section concrete strength reaches more than 75% of the design strength, the upper concrete support is removed by rope saw cutting combined with gantry hanger block lifting.

[0075] 11. Construction of the last section of the side wall and top plate two-way force mixed formwork support frame

[0076] According to the formwork support frame erection height marked by the structural top plate elevation, the hybrid formwork support frame is raised to the designed height, the U-shaped top support is installed, the U-shaped top support tooth tube is inserted into the main frame tube, and the arch is performed according to the requirements of the drawing. The arch height is slightly 1 / 1000 to 3 / 1000 of the span, and the U-shaped top support nut is adjusted to the set height. The cantilever length of the adjustable bracket of the formwork support extending out of the top horizontal bar shall not exceed 500mm, and the exposed length of the screw rod shall not exceed 300mm. The length of the adjustable bracket inserted into the vertical bar shall not be less than 150mm.

[0077] 12. Top plate bottom formwork laying

[0078] Before installing the top plate formwork, the support frame must be pre-pressed. The direction of the main keel should be clarified, the channel steel main keel should be placed on the U-shaped support, the secondary keel of the bottom wood beam should be laid according to the designed spacing, and the plywood panel should be laid on the secondary keel.

[0079] 13. The last section of side wall waterproofing construction

[0080] First, prepare the base surface of the side wall waterproofing board. The base surface should be flat, clean, without looseness or cracks, and the flatness should meet the requirement of D / L≤1 / 6. The concave and convex corners and edges of the base surface should be chamfered with 50*50mm cement mortar.

[0081] Arrange the geotextile vertically on the base layer as a buffer layer. The overlapping width of the waterproof board is 100mm. The overlapping parts are spot welded with a hot air welding gun to ensure that they are flat and straight without distortion.

[0082] When constructing the side wall waterproof board, first lay the non-woven fabric in the circumferential direction, use a nail gun to nail the PVC gasket and geotextile to the base layer, nail the geotextile on the overlapping edge with a nail gun, and use PVC gaskets to fix the geotextile to the base layer. Two rows of gaskets are arranged on each waterproof board, and each row of gaskets is 400mm away from the edge of the waterproof board in a rectangular arrangement. The gasket spacing is 800mm, and a temporary baffle is set on the inside of the side wall waterproof board to prevent mechanical damage and electric sparks from burning the waterproof board. If there is any damage, it should be repaired in time.

[0083] 14. The last section of the side wall and top plate reinforcement installation and side formwork installation,

[0084] The side wall reinforcement is mainly vertical reinforcement, which is set on the outside, and the horizontal distribution reinforcement is set on the inside. The side wall reinforcement connection adopts straight thread sleeve connection. The joint quality must be guaranteed, and the joint percentage and joint interval setting must meet the design and specification requirements.

[0085] The side wall formwork adopts composite material formwork, and the formwork installation is carried out in a construction order from top to bottom. When assembling the formwork, the composite material formwork is passed through the keyhole on the formwork, and the formwork is assembled using connectors. When assembling, align the two pieces of formwork, pass the connecting handle through the keyhole, and then rotate the handle to connect the formwork. After the formwork is assembled layer by layer, the secondary and main ribs on the outside of the formwork are installed. The secondary ribs are made of wood, and the main ribs are made of carbon steel pipes or channel steel. After the formwork is re-measured, adjust the adjustable top support to tighten the side wall formwork.

[0086] 15. Concrete pouring of the last section of side wall and top slab

[0087] According to the side wall pouring method, after the side walls on both sides are symmetrically poured to a height of 2m, in order to prevent the support frame from floating up, the side wall pouring is suspended, and a layer of top slab concrete is poured. After pouring two meters of side walls, a layer of top slab concrete is poured until the side wall and top slab concrete pouring is completed. The top slab pouring direction is symmetrically poured along the long side direction toward the middle, and the thickness of each layer is 30cm.

[0088] 16. Removal of hybrid full-floor support frame

[0089] The support frame shall be dismantled in the reverse order of erection, i.e., "erect first and dismantle later, and later erected and dismantled first", from top to bottom layer by layer. Within the same step, the horizontal crossbars shall be dismantled first, followed by the horizontal straight bars, and finally the vertical bars.

[0090] 17. Large span and high clearance steel support replacement and dismantling construction

[0091] When the structural top plate concrete reaches the design strength, remove the steel support. Before removing the steel support, fix the electric hoist on the embedded lifting ring, and use the electric hoist to hang the steel wire rope to fix the steel support, tighten the electric hoist to prevent falling.

[0092] Place two dismantling trucks on top of the steel support, with the fulcrum at the 1 / 4 position of the steel support, and then set the jack on the jack seat at the pipe end, and operate the jack to gradually unload the pipe support. After complete unloading, remove the steel wedge between the pipe end and the side wall of the structure, and then remove the support plate and triangular bracket, and use the forklift to pull the electric hoist to slowly lower the steel support to the middle plate of the structure.

[0093] It should be noted that in step 2, the horizontal bars and diagonal bars in the disc buckle support frame system are replaced with fastener-type steel pipe horizontal bars and scissors braces. The horizontal bars and scissors braces are connected to the disc buckle vertical bars by fasteners. The horizontal bars that support the side walls are overlapped by butt fasteners, which mainly bear the horizontal load from the side walls. The horizontal bars parallel to the side walls are connected or overlapped by butt fasteners. The joints of two adjacent horizontal bars should not be set in synchronization or the same span. The horizontal offset distance of two adjacent joints that are not synchronized or in different spans should not be less than 500mm. The distance from the center of each joint to the nearest main node should not be greater than 1 / 3 of the longitudinal distance. The overlap length should not be less than 1m, and 3 rotating fasteners should be set at equal intervals for fixing. The distance from the edge of the end fastener cover plate to the end of the overlapping longitudinal horizontal bar should not be less than 100mm.

[0094] In step 5, since the side wall is too high, the side wall pouring process exerts great pressure on the side of the formwork. The side wall is constructed in multiple times, which places high requirements on the verticality and deformation of each section of the wall. Therefore, the side wall formwork is selected to be a composite material composite formwork. The formwork adopts long fiber reinforced thermoplastic composite material. The formwork structure design adopts a double-layer side rib design. The two layers of side ribs are connected by short reinforcing ribs. Reinforcing ribs are arranged in the middle part of the formwork. It has good heat resistance and dimensional stability. The material stiffness, strength and integrity are more guaranteed, which greatly reduces the deviation of the side wall concrete pouring section and verticality, and improves the side wall concrete molding quality and appearance.

[0095] In step 6, the layer height of the super-high side wall shall not exceed 6m, and the side walls on both sides shall be poured symmetrically, and the pouring speed (v < 1.5m / h) and the pouring thickness of each layer (h ≤ 30cm) shall be strictly controlled. When using a full-frame as the single-sided formwork support system for the side wall, during the pouring of the side wall structure concrete, considering that the horizontal rods of the full-frame support are prone to bulge, a vertical load is applied to the top of the full-frame or a downward tension is applied to the middle and lower parts during construction to form a bidirectional force-bearing full-frame support frame to increase the stability of the full-frame support frame rods. The two specific measures are as follows.

[0096] 1. The anti-floating measures for the side wall formwork support frame are as follows: a row of hooks are embedded in the foundation at 2m and 3m away from the side wall, and steel wire ropes are set between the ground hooks and the outermost horizontal bars of the side wall support frame at 1 / 3 and 1 / 2 of the side wall height for tensioning. The steel wire ropes are hooked on the embedded hooks through basket bolts.

[0097] 2. Apply vertical load to the top of the frame in advance, use the dismantled internal supports of the enclosure structure (concrete supports or steel supports) to evenly place them on the top of the frame, and check whether the measures such as the frame scissors braces, fasteners, etc. to ensure the integrity of the frame are complete and reliable.

[0098] In step 8, the side wall formwork is removed and maintained in time. Before pouring the upper side wall, the adjustable top supports and square timbers of the lower side wall are pushed back onto the side wall structure surface to increase the friction between the frame and the side wall to prevent the frame from floating up when pouring the upper side wall.

[0099] In step 11, the hybrid formwork support system with bidirectional forces in both horizontal and vertical directions is a clip-type full-span support frame formwork support system. Due to the influence of steel replacement support, the spacing between the uprights of the full-span support frame is too large, and the conventional clip-type steel pipes cannot meet the vertical bearing capacity requirements. It is necessary to replace the clip-type steel pipes used as uprights with disc-type steel pipes. In addition to setting the scissors braces and the free end length of the uprights according to the clip-type full-span support frame, the cantilever length of the adjustable bracket of the formwork support extending out of the top horizontal bar shall not exceed 500mm, and the exposed length of the screw rod shall not exceed 300mm, and the length of the adjustable bracket inserted into the upright shall not be less than 150mm.

[0100] In step 15, during the one-time pouring of the top slab side walls, in addition to the symmetrical pouring of the walls on both sides, the pouring of the top slab must also be taken into consideration simultaneously, taking into account both the anti-floating of the frame and the initial setting time of the concrete. After each symmetrical pouring height of 2m on both sides of the side walls, the pouring of the side walls is suspended and a layer of 300mm thick top slab concrete is poured.

[0101] In step 17, the steel support is removed mainly by lowering it using electric hoists installed on both sides, and two large forklifts are used to assist in the construction to prevent the steel support from suddenly falling or tilting during the lowering process, thus providing double protection.

[0102] The construction method of this application studies the construction control technology of the verticality and flatness of the high-thick side wall. The side wall adopts a layered and segmented construction method, and at the same time applies a composite material formwork with high rigidity and strength, combined with the wall concrete pouring construction measures and the formwork floating control measures, so that the appearance quality of the high-thick side wall finished product is greatly improved. The segmented construction of the side wall and the top plate of the atrium of the large-span and high-clearance subway station share a hybrid full-floor support system. The support frame is a horizontal and vertical bidirectional force system. In addition to meeting the force requirements of the side wall and top plate construction, the design of the erection spacing must also consider the influence of the position of the steel replacement support in the middle of the frame. During the segmented construction process of the height direction of the main structure of the atrium, the frame only needs to be gradually raised without repeated installation and disassembly, which speeds up the construction efficiency. The construction of the steel replacement support inverted support in the middle of the atrium is related to the safety of the foundation pit support structure and the surrounding buildings and structures. Measures need to be taken to ensure the installation quality of the steel replacement support and the safety of the installation and disassembly construction. The use of this atrium structure has significantly improved the sensory effects of the underground station in terms of space, ventilation, and lighting.

[0103] The special functions of the construction method of this application are mainly reflected in the following four aspects.

[0104] First, the atrium structure of the subway station has unique architectural features. The structural plate in the atrium area of ​​the station has large openings, and there are no columns in the public area. This invention discusses the construction difficulties of the atrium column-free structure, the structural measures to be taken, and the engineering problems encountered during the actual construction process, providing a design and construction reference for future subway stations.

[0105] Secondly, when the hybrid two-way force-bearing formwork support frame of the present invention is used for one-time pouring construction of the top plate and side walls of the underground open-cut structure, the hybrid full-floor support frame has better performance when simultaneously meeting the vertical and horizontal two-way force conditions.

[0106] Third, when constructing high and thick side walls, the side wall formwork support frame adopts anti-floating measures such as lower tensioning, upper pressure, and side support to increase friction, and the effect is obvious.

[0107] Fourth, for steel replacement supports with high erection height and large span, they are lowered by electric hoists installed on both sides, and two large forklifts are used to assist in the construction, which ensures better construction safety.

[0108] The construction method of this application is efficient. The hybrid full-floor support frame does not need to be repeatedly installed and dismantled during the layered construction of the side wall. The last layer of the side wall and the top plate concrete are cast in one go. The fastener-type horizontal rods and the disc-type vertical rods have good vertical and horizontal load bearing effects, which greatly reduces the number of vertical rods, saves materials, increases construction efficiency, and saves construction time.

[0109] The construction method of this application can ensure the quality of the project. The concrete of the side wall and the top plate is poured at one time, which not only shortens the construction period, but also is more conducive to structural waterproofing; strengthening the anti-floating measures and integrity measures of the support frame can effectively constrain the formwork, control the deformation of the structure and the verticality of the wall, and improve the quality of the project.

[0110] The construction method of the present application is economical. The entire construction process is simple, easy, safe, reliable, economical and practical, which greatly reduces the cost of the atrium side wall top plate formwork support system, especially for projects with tight construction period requirements, the effect of shortening the construction period is significant.

[0111] The construction method of the present application can effectively ensure the verticality and flatness of the finished high-thick side wall, realize the two-way force of the side wall top plate template of the subway atrium structure, solve the problem of too low bearing capacity per unit area of ​​the vertical poles of the traditional fastener-type full-floor support frame system, and effectively respond to the construction conflicts between the installation and removal of the atrium steel replacement support and the main structure, as well as the safety issues of interlaced operations.

[0112] The above is a detailed description of the implementation methods of the present application in conjunction with the accompanying drawings, but the present application is not limited to the above implementation methods. Various changes can be made within the knowledge of ordinary technicians in the technical field without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A construction method for a main structure of a large-span and high-clearance subway station atrium, characterized in that: include S1, construction section division; S2, side wall construction; S3, large span and high clearance steel support replacement and installation construction; S4, upper concrete support removal; S5, the last section of side wall construction; S6, large span and high clearance steel support replacement and removal construction; Among them, step S2 is repeated to complete the construction of different side walls. The side wall construction in step S2 includes: construction of hybrid formwork support frame; construction of side wall waterproofing layer; installation of side wall steel bars; installation of side wall composite material formwork; side wall concrete pouring construction; and removal of lower concrete support.

2. The construction method of the main structure of the large-span and high-clearance subway station atrium according to claim 1 is characterized by: The construction section division in step S1 includes longitudinal unit division and vertical stratification; Longitudinal unit division: The longitudinal unit construction joint is set at 1 / 3 to 1 / 4 of the longitudinal beam span, and the block length is 16 to 20m; Vertical stratification: The first horizontal construction joint of the vertical joints in the station atrium is set at 1000mm below the lower supporting waist beam, and the second construction joint is set at 1000mm below the upper supporting waist beam. The remaining upper side walls and top slabs are cast together.

3. The construction method of the main structure of the large-span and high-clearance subway station atrium according to claim 1 is characterized by: The construction of the hybrid formwork support frame in step S2 includes: installing the starting vertical pole; installing the horizontal pole; connecting the vertical pole; installing the longitudinal and transverse horizontal poles; installing the scissors brace; installing the adjustable top support of the side wall; and setting up the side wall construction platform.

4. The construction method of the main structure of the atrium of a large-span and high-clearance subway station according to claim 3 is characterized in that: The installation of the starting pole includes: laying out and positioning the pole according to the construction plan, setting up the base and the pad, inserting the starting pole sleeve into the base with the starting pole facing upward, placing the lower end of the starting pole into the groove of the force plane of the adjustable nut, and the center line of the lowest horizontal pole of the sweeping pole is no more than 550mm from the bottom plate of the base.

5. The construction method of the main structure of the atrium of a large-span and high-clearance subway station according to claim 3 is characterized by: The installation of the cross bar includes: inserting the cross bar head into the small hole of the disc so that the front end of the cross bar head is against the main frame round tube, and then fixing it with an inclined wedge passing through the small hole, so that the center line of the bottom horizontal bar of the sweeping rod is no more than 550mm above the ground.

6. The construction method of the main structure of the atrium of a large-span and high-clearance subway station according to claim 3 is characterized by: The connecting poles include: inserting the long end of the pole into the sleeve of the starting pole, staggering the positions of the connecting sleeve joints of adjacent poles at the same horizontal height, and the staggered height is not less than 75mm, and when the height of the formwork support is greater than 8m, the staggered height is not less than 500mm.

7. The construction method of the main structure of the large-span and high-clearance atrium of a subway station according to claim 3 is characterized by: The installation of the scissors brace includes: repeating the steps of connecting the vertical poles and installing the longitudinal and transverse horizontal poles, raising the frame to a height of 0 to 500 mm above the construction joint of the side wall, and setting scissors braces around the outer side of the full-floor support frame; setting scissors braces from bottom to top every 6 m in the longitudinal or transverse direction in the middle, the width of the scissors brace is 4 to 6 m, the bottom end of the rod of the scissors brace is pressed against the ground, and the angle between the rod and the ground is 45° to 60°.

8. The construction method of the main structure of the large-span and high-clearance atrium of a subway station according to claim 1 is characterized by: The construction of the side wall waterproof layer includes: arranging the geotextile on the base layer in a vertical direction as a buffer layer, first laying the non-woven fabric in a circumferential direction during the construction of the side wall waterproof board, fixing the PVC gasket and the geotextile on the base layer, arranging two rows of gaskets on each waterproof board, and setting a temporary baffle on the inner side of the side wall waterproof board.

9. The construction method of the main structure of the atrium of a large-span and high-clearance subway station according to claim 1 is characterized by: The side wall concrete pouring construction includes: anti-floating measures for the side wall formwork support frame and side wall concrete pouring; The anti-floating measures of the side wall formwork support frame include: pre-embedding a row of hooks at a distance of 2m and 3m from the side wall respectively, setting steel wire ropes between the ground hooks and the outermost horizontal bars of the side wall support frame at 1 / 3 and 1 / 2 of the side wall height for tensioning, the steel wire ropes are hooked on the pre-embedded hooks by bolts, and the removed concrete supports or steel supports of the retaining structure are hoisted to the top of the frame.

10. The construction method of the main structure of the atrium of a large-span and high-clearance subway station according to claim 1 is characterized by: The last section of side wall construction in step S5 includes: construction of bidirectional force-bearing mixed formwork support frames for side walls and top plates; laying of top plate bottom formwork; waterproofing construction of side walls; installation of side wall and top plate steel bars and side formwork; pouring of side wall and top plate concrete; and removal of mixed full-floor support frames.

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