Construction method for building supporting structure above existing subway tunnel

Abstract

The invention belongs to the technical field of building construction methods, and particularly relates to a construction method for building a supporting structure above an existing subway tunnel. According to the construction method, three-dimensional software is used for deducing the assembling steps of the steel truss and the entering sequence of the prefabricated parts, building of the supporting structure can be accelerated, the supporting structure can replace a traditional reinforced concrete beam, the steel truss in the supporting structure and the floor bearing plate are combined to form an overall stress system, and after the supporting structure is built, the supporting structure can be conveniently constructed. Concrete can be directly poured on the floor bearing plate to achieve building of a high-load building, the load is transmitted to the main body supporting columns on the two sides of the existing subway tunnel through the steel truss, and building of the high-load building above the existing subway tunnel is completed under the condition that secondary reinforcement is not conducted on the existing subway tunnel. The technical problem of building the high-load building above the existing subway tunnel is solved, so that the construction period of building the high-load building above the existing subway tunnel is shortened, and the construction cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of building construction methods, and in particular relates to a construction method for building a supporting structure above an existing subway tunnel. Background Art

[0002] In the construction field, constructing high-load buildings above existing subway tunnels has always been a technical challenge.

[0003] Traditional high-load buildings are mostly reinforced concrete structures. To meet their bearing capacity requirements, the cross-sectional dimensions of the structural beams, walls, and columns of high-load buildings are large, and the requirements for foundation size and bearing capacity are also relatively high. However, the bearing capacity of the roadbed above the existing subway tunnel is limited and cannot meet the bearing capacity requirements of high-load buildings. Only after the existing subway tunnel is reinforced for the second time can buildings be constructed above the existing subway tunnel. The secondary reinforcement of the existing subway tunnel will lead to a significant increase in the construction period and cost of the high-load buildings above it. Summary of the Invention

[0004] The present invention provides a construction method for building a support structure above an existing subway tunnel, so as to solve the technical problem in the prior art that high-load buildings can only be built above an existing subway tunnel after secondary reinforcement of the existing subway tunnel, which leads to a significant increase in the construction period and cost of building high-load buildings above the existing subway tunnel.

[0005] To solve the above problems, the present invention is implemented through the following technical solutions: A construction method for constructing a support structure above an existing subway tunnel, wherein the support structure includes main support columns, steel trusses, and floor decking. The construction method comprises the following steps: Create a 3D model in 3D software based on the design drawings of the supporting structure, split the steel trusses in the 3D model into multiple parts, and make prefabricated components based on the parts; Cast main support columns on both sides of the existing subway tunnel and install lead core seismic rubber bearings on the upper ends of the main support columns; Using 3D software, multiple parts are assembled into a virtual steel truss from both ends to the middle to deduce the assembly steps of the steel truss. The assembly order of the prefabricated components is determined based on the assembly steps, and the prefabricated components are numbered according to the assembly order. The prefabricated components are brought to the site in the order of their numbers and assembled into steel trusses on the main support columns; The floor decking is laid on the steel truss, and the contact position between the vertical reinforcement of the floor decking and the steel truss is fixed by welding.

[0006] In order to better implement the present invention, the above method is further optimized, whereby the number of the floor decking plates is multiple, the multiple floor decking plates are laid in sequence along the same direction, and two adjacent floor decking plates are connected by buckling.

[0007] In order to better implement the present invention, the above method is further optimized. Before assembling the steel trusses, multiple support frames are first set between the main support columns on both sides of the existing subway tunnel. When assembling the steel trusses, the support frames are used to support the prefabricated components.

[0008] In order to better implement the present invention, the above method is further optimized, and the support frame is dismantled after the steel trusses are completed.

[0009] In order to better realize the present invention, the above method is further optimized. The unloading of the support frame is carried out by a synchronous micro-descent method. The descent amount in each stage is ≤20mm. During the unloading process of the support frame, the deformation of the steel truss is ≤10mm.

[0010] In order to better realize the present invention, further optimization is made in the above method, the horizontal installation error of the lead core seismic rubber bearing is ≤5mm, the lead core seismic rubber bearing is fixed to the connecting steel plate in the main support column by a double nut and welded to the connecting steel plate.

[0011] Compared with the prior art, the present invention has the following beneficial effects: In the construction method for building a support structure above an existing subway tunnel provided by the present invention, the method of using three-dimensional software to deduce the assembly steps of steel trusses and the order of prefabricated components entering the site can speed up the construction of the support structure, and the support structure can replace traditional reinforced concrete beams. The steel trusses in the support structure are combined with the floor deck to form an overall force-bearing system. After the support structure is completed, concrete can be poured directly on the floor deck to achieve the construction of a high-load building. The load is transferred to the main support columns on both sides of the existing subway tunnel through the steel trusses. The construction of the high-load building above the existing subway tunnel is completed without secondary reinforcement of the existing subway tunnel, thereby solving the technical difficulties of building a high-load building above the existing subway tunnel, thereby shortening the construction period of building a high-load building above the existing subway tunnel and reducing construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0013] Figure 1It is a schematic diagram of a support structure in a construction method for building a support structure above an existing subway tunnel according to the present invention.

[0014] In the picture: 1. Main support column; 2. Steel truss. DETAILED DESCRIPTION

[0015] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0016] In the description of the present invention, it should be noted that, unless otherwise specified, the term "plurality" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front," "rear," "head," "tail," etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0017] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention depending on the specific circumstances.

[0018] In an embodiment of the present invention, the construction method for constructing a support structure above an existing subway tunnel comprises the following steps: According to the design drawings of the supporting structure, a 3D model is created in the 3D software. Figure 1 As shown, the three-dimensional model can be established using commonly used three-dimensional software on the computer, and the three-dimensional software can be solid work, AutoCAD or caxa solid design, etc.; After the three-dimensional model is constructed, the three-dimensional model can be split using three-dimensional software to split the virtual steel truss 2 in the three-dimensional model into multiple parts, and then prefabricated components can be made based on the split parts. After the prefabricated components are prepared, they need to be inspected. The dimensional error of the inspected prefabricated components should be less than 2mm. At the same time, the weld quality of the prefabricated components needs to be inspected, that is, the prefabricated components need to be inspected for flaws. The weld quality inspection of the prefabricated components is carried out using ultrasonic flaw detection equipment. The ultrasonic flaw detection pass rate of the prefabricated components should be 100% to ensure the stability and safety of the constructed steel truss 2. The ultrasonic flaw detection equipment mentioned above may be a steel structure ultrasonic flaw detector of model MOUT-260, or other types of flaw detection equipment having the same function, effect and detection accuracy.

[0019] After the acceptance of the prefabricated components, the main support columns 1 can be cast on both sides of the existing subway tunnel. When the main reinforced concrete structure of the main support columns 1 is constructed to the support bracket, the axis of the main support columns 1 is rechecked. The axis is marked (positioning line) on the steel bars and formwork (the steel bars and formwork located inside the main support columns 1) with a marker pen according to the axis. This facilitates the positioning of the connecting steel plates when they are installed. Embed the connecting steel plates into the main support column 1 according to the positioning line, ensuring that all connecting steel plates are within the designed horizontal elevation, and the elevation error shall not exceed 1 cm, and the flatness error shall not exceed 1 cm. Use Φ12 threaded steel bars to weld and fix multiple connecting steel plates. The welding rods used are EX-50 series welding rods. The fixed connecting steel plates must be connected and tightened to the steel bars in the main support column 1 around the connecting steel plates, and the ends of the steel bars should be pressed tightly against the concrete formwork to prevent the connecting steel plates from shifting during concrete pouring; When pouring concrete, it is necessary to clean up the concrete spilled on the connecting steel plate in time to avoid affecting the subsequent welding of the lead core seismic rubber bearing and the connecting steel plate; When the strength of the main support column 1 meets the standard, a lead core seismic rubber bearing can be installed on the upper end of the main support column 1. The horizontal installation error of the lead core seismic rubber bearing should be ≤5mm. The lead core seismic rubber bearing is fixed to the connecting steel plate in the main support column 1 through a double nut and welded to the connecting steel plate to ensure the stability of the connection between the lead core seismic rubber bearing and the main support column 1.

[0020] A plurality of support frames are set between the two groups of main support columns 1, and the support frames can be used to support the prefabricated components that need to span the two sides of the existing subway tunnel in the future, ensuring that the multiple prefabricated components can be firmly connected and the steel truss 2 can be smoothly constructed.

[0021] Before constructing the steel truss 2, a virtual steel truss can be assembled using 3D software by splicing multiple components from both ends to the middle to simulate the assembly steps of the steel truss 2. The assembly order of the prefabricated components can then be determined based on the assembly steps, and the prefabricated components can be numbered according to the assembly order. The prefabricated components are brought to the site in the order of their numbers and assembled into steel trusses 2 in sequence on the main support columns 1 on both sides of the existing subway tunnel to speed up the installation speed and improve the installation efficiency. At the same time, it can reduce the risk of high-altitude operations and improve the safety of construction above the existing subway tunnel.

[0022] It should be noted that in the above-mentioned process of using three-dimensional software to assemble multiple components from both ends to the middle into a virtual steel truss, it is necessary to determine the three-dimensional model to deduce and optimize the mechanical behavior and key control points of the prefabricated components during the installation process on the main support column 1. The three-dimensional model deduction and optimization of the mechanical behavior and key control points of the prefabricated components during the installation process on the main support column 1 refers to: deducing the physical response characteristics of the prefabricated components under external loads on the main support column 1 according to the three-dimensional model, including deformation, energy absorption and destruction process, etc., and determining multiple key control points in the process of building the steel truss 2. During the construction process, the key control points are monitored to improve the safety of the construction process.

[0023] After the steel truss 2 is built, the support frame can be dismantled; The disassembly of the support frame is carried out by the synchronous micro-drop method. Specifically, after the steel truss 2 is completed, the quality of the weld of the steel truss 2 needs to be inspected. The inspection here is the same as the inspection of the prefabricated components mentioned above, and both are carried out by ultrasonic inspection. After ensuring that the weld quality of the steel truss 2 is qualified, the elevation and size of the steel truss 2 can be reviewed. After the review meets the specifications and design requirements, the support frame can be removed; The dismantling of the support frame must follow the principle of "deformation coordination and unloading balance". For example, the unloading method of "step-by-step multiple-cycle micro-descent" is adopted to dismantle the support frame. This dismantling method can avoid excessive deformation and / or displacement of the steel truss 2 and ensure safe and stable force conversion. Specifically, the support frame adopts the method of first synchronously unloading the middle support frame (the middle part of the steel truss 2). After the steel truss 2 is stable or the deformation is stable, the support frames between the middle and the end are unloaded. After the measurement is correct, the support frames at both ends of the steel truss 2 are synchronously unloaded. The unloading process adopts the method of synchronous and slow cutting of the support points, so that the steel truss 2 naturally and smoothly descends to the first stage. The lowering of several support frames to be disassembled each time must be carried out synchronously, and the lowering amount must be controlled within 10mm-20mm. Repeated unloading is carried out until the support frame is completely separated from the lower chord truss of the steel truss 2. Check the safety and overall descent of the steel truss 2. If normal, use the same method to descend to the second stage. Unloading the middle support frame and the support frames between the middle and the end must be at least 1 day apart to ensure that the load of the steel truss 2 after the previous unloading can be fully supported by the remaining support frames and concrete support points; After the second stage is completed, observe whether the steel truss 2 is completely detached from the support point. If so, the unloading situation is normal. The steel truss 2 is left stationary for one day. Then, the welds of the steel truss 2 are carefully checked one by one. At the same time, the steel truss 2 is tested with a total station. The deformation of the steel truss 2 is ≤10mm. After the deformation meets the design requirements, the support frame fulcrum is removed.

[0024] After the support frame is dismantled, the floor decking can be laid on the steel truss 2, and the contact position between the vertical reinforcement of the floor decking and the steel truss 2 is fixed by welding; There are multiple floor decking plates, which are laid sequentially in the same direction. Adjacent floor decking plates are connected by buckling to ensure that there are no gaps between them, thereby preventing concrete leakage during pouring. In this embodiment, the multiple floor decking plates are laid sequentially along the length of the steel truss 2, that is, along the direction across the existing subway tunnel. The vertical reinforcement on the floor decking plates is welded to the contact points with the steel truss 2, and the tensile bearing capacity of the weld points is ≥ 2kN. After the floor decking is laid, the edge formwork is installed on the edge of the floor decking and concrete is poured on the floor decking. The concrete is poured using a truck pump. After the concrete pouring is completed, it is cured for 14 days to ensure that the concrete strength on the floor decking meets the standard.

[0025] During the final acceptance, the weld quality, structural elevation and seismic performance of the steel truss 2 were tested again.

[0026] Once acceptance is completed, other buildings can be constructed on top of the supporting structure.

[0027] The construction method of building a supporting structure above an existing subway tunnel reduces the construction difficulty of building a high-load building above an existing subway tunnel, ensures that the lower part of the high-load building is a space with a large span, a large space, and a wide field of view, and the upper part has functional rooms. There is no need to perform secondary reinforcement on the existing subway tunnel, thereby reducing the construction cost of the high-load building. In addition, the lead core seismic rubber bearings arranged on the main support column 1 can improve the seismic performance of the high-load building, which has great economic value and social benefits.

[0028] A long-span building refers to a building that spans a roof space of more than 30 meters. The supporting structure in this invention spans both sides of an existing subway tunnel, with a span greater than 30 meters. The supporting structure and the high-load buildings constructed above it can all be considered long-span buildings. In the construction method for constructing a support structure above an existing subway tunnel, the support structure adopts steel trusses 2 instead of traditional reinforced concrete beams, and the load can be directly transferred to two groups of main support columns 1. The existing subway tunnel does not need to bear the load of the high-load building above it. Therefore, during the process of constructing the support structure and when other buildings are constructed on the supporting structure, there is no need to perform secondary reinforcement on the existing subway tunnel, so as to shorten the construction period of the high-load building above the existing subway tunnel and save the cost of secondary reinforcement of the existing subway tunnel, thereby reducing construction costs.

[0029] In addition, the construction method of building a supporting structure above an existing subway tunnel breaks through the construction restrictions directly above an existing subway tunnel. It not only meets the functional requirements and structural load transfer requirements for building high-load buildings above an existing subway tunnel, but also ensures the normal operation of the existing subway tunnel during the construction of the high-load building.

[0030] At the same time, the construction method of building a support structure above the existing subway tunnel by arranging lead core seismic rubber bearings on the main support columns 1 can effectively solve the seismic buffering problem of the support structure, thereby improving the safety of the support structure.

[0031] It should be noted that the above-mentioned floor deck is a steel truss floor deck; wherein, The reinforced truss floor deck is a composite floor deck that is made by processing steel bars into reinforced trusses and connecting them with corrugated steel plates through resistance spot welding. It has good mechanical properties and can effectively resist the internal forces of the floor deck and reduce the deformation of the floor deck. The overall force system formed by combining it with the steel truss 2 can effectively improve the stability of the supporting structure.

[0032] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A construction method for constructing a support structure above an existing subway tunnel, characterized by: The support structure includes main support columns, steel trusses and floor decking, and the construction method includes the following steps: Create a 3D model in 3D software based on the design drawings of the supporting structure, split the virtual steel truss in the 3D model into multiple parts, and make prefabricated components based on the parts; Cast main support columns on both sides of the existing subway tunnel and install lead core seismic rubber bearings on the upper ends of the main support columns; Using 3D software, multiple parts are assembled into a virtual steel truss from both ends to the middle to deduce the assembly steps of the steel truss. The assembly order of the prefabricated components is determined based on the assembly steps, and the prefabricated components are numbered according to the assembly order. The prefabricated components are brought to the site in the order of their numbers and assembled into steel trusses on the main support columns; The floor decking is laid on the steel truss, and the contact position between the vertical reinforcement of the floor decking and the steel truss is fixed by welding.

2. The construction method for constructing a support structure above an existing subway tunnel according to claim 1, characterized in that: There are multiple floor decking plates, which are laid in sequence along the same direction, and two adjacent floor decking plates are connected by buckling.

3. The construction method for constructing a support structure above an existing subway tunnel according to claim 1, characterized in that: Before assembling the steel trusses, a plurality of support frames are first arranged between the main support columns on both sides of the existing subway tunnel. When assembling the steel trusses, the support frames are used to support the prefabricated components.

4. The construction method for constructing a support structure above an existing subway tunnel according to claim 3, characterized in that: The support frame will be removed after the steel trusses are connected.

5. The construction method for constructing a support structure above an existing subway tunnel according to claim 4, characterized in that: The unloading of the support frame is carried out by the synchronous micro-descent method, with the descent amount in each stage ≤20mm. During the unloading process of the support frame, the deformation of the steel truss is ≤10mm.

6. The construction method for constructing a support structure above an existing subway tunnel according to claim 1, characterized in that: The horizontal installation error of the lead core anti-seismic rubber bearing is ≤5mm, and the lead core anti-seismic rubber bearing is fixed to the connecting steel plate in the main support column through a double nut and welded to the connecting steel plate.

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