Existing subway structure side wall holing construction method

Abstract

The invention relates to an existing subway structure side wall holing construction method, and relates to the technical field of tunnel civil construction. The side wall holing construction method of the existing subway structure comprises the following steps that S1, foundation pits are excavated, specifically, the foundation pits are excavated on the two sides of the existing subway structure, and the whole side wall to be holed is exposed through earth excavation; during foundation pit supporting and earth excavation, graded gravel is reserved at the top of the subway structure to be piled and loaded so as to prevent the floating phenomenon of the existing subway structure; s2, holing preparation is carried out; the top of the existing subway structure is sequentially subjected to earthwork unloading in a regional mode according to the holing sequence, drilling cutting and block removing are conducted on the side wall of each holing region through a water drill, and then hole edge chiseling is conducted; s4, wall beam construction; and S5, waterproof construction. According to the existing subway structure side wall holing construction method, the influence on operation of an existing subway can be greatly reduced, and floating and cracking of the existing subway structure can be effectively prevented.

Description

Technical Field

[0001] The present application relates to the technical field of tunnel civil construction, and in particular to a method for constructing a hole in a side wall of an existing subway structure. Background Art

[0002] Subway construction is a complex infrastructure project. With the rapid development of cities, the original subway lines often cannot meet the growing passenger flow demand. Therefore, it is necessary to expand or renovate the existing subway stations. In order to achieve the interconnection between the expansion project or the new project and the existing subway project, it is necessary to open holes on the side walls of the existing subway structure. By setting up multiple doorways, the interconnection of multiple areas can be achieved while ensuring the support strength of the existing structure. Such projects usually face complex underground environments and high safety risks. The main treatment methods include completely stopping the line operation for closed construction, or taking the approach of closing the station for part of the time and opening it for part of the time to reduce the impact on the operation of the existing subway line. Although the former can invest more resources to speed up the progress, it will lead to greater social impact and service interruption; although the latter can alleviate the suspension problem to a certain extent, due to the limited construction time and space, it is inefficient and increases safety hazards.

[0003] When constructing a subway line that is in operation, opening a hole in the side wall of an existing subway line has the risk of excessive structural floating and cracking, which is a construction difficulty and key point; and because the line is "closed but not stopped", smoke and fire during the side wall opening process will have a great impact on trains and track sections. How to effectively isolate the construction site from the driving area, ensure the safety of passengers while not affecting the normal operation of the existing subway line, and complete the renovation of the subway line in normal operation is more challenging, and there is currently no mature technology. Summary of the invention

[0004] In order to complete the side wall hole construction without interrupting subway operations and effectively prevent problems such as subway structure cracking caused by construction, the present application provides a side wall hole construction method for an existing subway structure.

[0005] The present application provides a method for constructing a hole in the side wall of an existing subway structure using the following technical solution: A method for constructing a hole in a side wall of an existing subway structure comprises the following steps: S1: Excavation of foundation pit: excavation of foundation pit on both sides of the existing subway structure, excavation of earthwork to expose the entire side wall to be opened; during the foundation pit support and earthwork excavation, graded sand and gravel are reserved on the top of the subway structure for loading to prevent the existing subway structure from floating up; S2: Preparation for opening holes: The opening areas of the existing subway structure side walls are numbered in sequence, and the corresponding areas of the opening areas of the existing subway structure above the corresponding side walls are numbered accordingly; the existing subway structure platform is temporarily blocked; S3: Opening cutting: The top of the existing subway structure is unloaded in sections according to the opening sequence. The side walls of each opening area are drilled and cut in sections using a water drill, and then the opening is chiseled; S4: Wall beam construction: Drill holes and plant reinforcement on the side wall of the opening, then set up wall beam reinforcement and wall beam formwork, weld the wall beam reinforcement and the connecting reinforcement planted on the side wall of the opening to fix them; then pour concrete, remove the formwork after the concrete solidifies, and cut off the excess wall beam reinforcement; S5: Waterproof construction: Scrape off the damaged original waterproof layer, manually scrape and chisel to expose the joint of the original side wall waterproof protective layer, and use waterproof paint to seal the waterproof layer at the opening.

[0006] In this application, the upper loading measure is adopted to slow down the upward floating trend of the interval and reduce the interval floating value. Through sequential construction, gradual unloading, real-time observation, timely detection and other means, major safety hazards can be effectively prevented, the normal construction of the side wall opening can be ensured, and the cracking of the existing subway structure can be avoided. At the same time, after temporarily blocking the existing subway platform in this application, during construction, the noise, dust, water and fire entering the existing subway platform can be effectively reduced. By adopting the above technical solution, the impact on the operation of the existing subway can be minimized.

[0007] Optionally, in the above step S3, the side wall opening construction adopts a layered demolition construction process, that is, a water drill is used to cut the outer wall layer of at least three quarters of the thickness of the side wall on the side of the side wall away from the existing subway line, and the remaining wall layer is cut by manual chiseling without water.

[0008] By adopting the above technical solution, the holes in the side walls are cut in layers, the outer layer is cut with a water drill, and the inner layer is chiseled manually. The inner layer is operated without water to prevent water from entering the station, reducing the impact on subway operations.

[0009] Optionally, in the above step S3, the concrete in each opening area is divided into a left area and a right area, the left area and the right area are spaced apart and the concrete between the two forms a temporary support column; the concrete in the left area and the right area is cut and removed in blocks, and then columns are installed in the left area and the right area, and then the concrete of the temporary support column between the left area and the right area is cut and removed.

[0010] By adopting the above technical solution, each opening area is constructed in blocks and steps, and the existing concrete is used to form temporary support columns to ensure the supporting strength of the side walls. The width of each door opening can be made relatively large, which reduces construction safety risks while forming large-span door openings.

[0011] Optionally, in the above step S4, the wall beam construction is carried out in sections, and the edges are chiseled after removing the concrete in the left area and the right area. The left semi-ring wall beam and the right semi-ring wall beam are respectively constructed on the side walls of the door openings in the left area and the right area. The left semi-ring wall beam and the right semi-ring wall beam both include a bottom ring beam, a wall column and an upper ring beam. After the strength of the left semi-ring wall beam and the right semi-ring wall beam is greater than 50%, the top of the column is tightened with a steel wedge, and then the temporary support column concrete between the left area and the right area is cut and removed. Finally, an intermediate connecting beam is constructed on the upper and lower sides of the opening to connect the left semi-ring wall beam with the right semi-ring wall beam.

[0012] By adopting the above technical solution, the wall and beam construction is carried out in steps, and the safety of the construction is ensured by using temporary support columns and installed columns.

[0013] Optionally, in the above step S4, when pouring concrete of the left semi-ring wall beam and the right semi-ring wall beam, the "self-weight grouting" method is adopted, and the slurry is completely relied on for self-leveling by its own weight and filling the entire pouring space; the formwork support has a number of grouting holes and exhaust holes, the diameter of the grouting holes is not less than 50mm, the spacing is not more than 1000mm, and the grouting holes and the exhaust holes are 50mm higher than the highest point of the holes; the pouring is carried out in 4 times in sequence, and the pouring order is: bottom ring beam grouting, lower wall column grouting, upper wall column grouting and upper ring beam grouting.

[0014] By adopting the above technical solution, the slurry is completely leveled by its own weight and fills the entire pouring space, avoiding the noise and vibration generated by the traditional vibration method, which is conducive to reducing the impact on subway operations. In this technical solution, multiple grouting holes and exhaust holes are left to ensure smooth discharge of air, avoid residual bubbles, improve the density and strength of concrete, and thus ensure the construction quality of wall beams.

[0015] Optionally, in the above step S4, no vibration is performed during the grouting process, and the main board strips are used for pulling and drainage; the formwork is appropriately knocked during the process of pouring the grouting material into the formwork; if the construction time is in winter, after the grouting is completed, immediately cover with plastic film and cover with wet straw bags, or spray concrete curing agent to prevent frost damage, and no watering is allowed during curing under negative temperature conditions.

[0016] By adopting the above technical solutions, noise generation can be effectively reduced, a quiet construction environment can be ensured, and interference with subway operations can be avoided. Appropriate tapping of the formwork during the process of pouring grouting material into the formwork can help to remove air, make the grout more compact, and improve the stability and durability of the structure. If the construction time is in winter, immediately cover the plastic film and wet straw bags after grouting, or spray concrete curing agent to prevent frost damage, ensure that the concrete can harden smoothly under low temperature conditions, and ensure the quality of the project.

[0017] Optionally, in the above step S3, a certain opening area in the middle is first selected as a test hole for opening, and the earthwork in the numbered area corresponding to the test hole area is unloaded before the hole is opened; after the test hole is completed, if the opening construction is feasible after demonstration by all parties, the construction of the remaining openings is carried out; during the construction of the remaining openings, the earthwork in the two end areas is unloaded and the opening construction is carried out first, and then the earthwork in the remaining areas is unloaded and the opening construction is carried out.

[0018] By adopting the above technical solutions, it is possible to ensure that the effectiveness and safety of the construction plan are gradually verified during the actual construction process, reduce potential risks, and improve the success rate and reliability of the construction.

[0019] Optionally, during the drilling and rebar planting process, perform the following steps in sequence: placing the initial positioning line, determining the position of the original structural steel bars and marking them, placing the cross lines of the drilling position, checking the lines, drilling with an impact drill, cleaning the holes and temporarily protecting the holes, grinding before rebar planting, cleaning the steel bars, cleaning with acetone, performing hidden inspection, inserting the connecting bars after injecting adhesive, maintenance, and acceptance.

[0020] By adopting the above technical solution, the process of drilling and reinforcing bars is more standardized and normalized, ensuring quality control at every link; the quality of drilling and reinforcing bars is effectively improved, ensuring the safety and reliability of the existing subway structure side wall opening construction.

[0021] Optionally, during the hole opening process, a water retaining platform needs to be added on the side of the existing subway platform; before pouring the wall beam, the inner side of the hole under the platform slab is used as a template with the platform brick wall, and waterproof paint is applied on the surface of the brick wall, and thick iron sheets are tightly attached to the outside, and sealant is applied to the gaps to prevent water from seeping into the pipe trench during the grouting construction.

[0022] By adopting the above technical solution, it is possible to effectively prevent moisture from seeping into existing subway platforms during the construction process, ensuring that construction safety and subway operations are not affected.

[0023] Optionally, after the side wall beams are reinforced, a temporary blocking wall needs to be set up for temporary blocking according to the construction schedule. The temporary blocking wall is built with aerated concrete blocks, and the outer side is smoothed with waterproof mortar to prevent rainwater from entering the existing subway platform; When the hole is broken, if the original waterproof layer of the structure is intact, use non-curing rubber asphalt waterproof coating for sealing treatment; if the original waterproof layer of the structure is broken or not bonded to the base surface, the waterproof protective layer is partially chiseled, and non-curing rubber asphalt coating is scraped in the gap between the original waterproof layer and the base surface, and waterproof mortar is applied for temporary protection; After the main structures on both sides are constructed to the position below the existing subway platform, the temporary blocking walls will be gradually removed; MS sealant will be embedded in a ring on the inside of the opening.

[0024] By adopting the above technical solution, the stability and waterproof performance of the temporary blockage can be effectively guaranteed, ensuring that the normal use of the subway platform will not be affected by rainwater infiltration during construction. In addition, when the hole is broken, the appropriate waterproof treatment method is selected according to different situations, which further enhances the waterproof effect and ensures the long-term stability and safety of the structure.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: 1. The method for opening a hole in the side wall of an existing subway structure in this application can effectively prevent the floating and cracking of the existing subway structure by reserving graded sand and gravel on the top of the side wall for loading and gradually unloading, thereby improving the safety and reliability of the construction.

[0026] 2. In this application, the side wall holes are cut in layers, the outer layer is cut with a water drill, and the inner layer is chiseled manually. The inner layer is operated without water to prevent water from entering the station, effectively isolating noise, dust, water and fire from entering the existing subway platform space, greatly reducing the impact on the operation of the existing subway.

[0027] 3. In this application, by effectively setting up a waterproof structure, the waterproof effect of the subway is improved, its service life is increased, and the operation and maintenance costs are reduced.

[0028] 4. In this application, each opening is constructed in blocks and columns are set up, which reduces the construction safety risk while forming a large-span opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a plan view of the location of the side wall openings in this application.

[0030] Figure 2 It is a cross-sectional view of the opening position of the side wall in this application.

[0031] Figure 3 It is a schematic diagram of the structure of the scaffold in this application.

[0032] Figure 4 It is a schematic diagram of dividing each hole into left and right areas for cutting in this application.

[0033] Figure 5 It is a schematic diagram of casting the left semi-ring wall beam and the right semi-ring wall beam respectively in this application.

[0034] Figure 6 It is a schematic diagram of setting the columns in this application.

[0035] Figure 7 It is a schematic diagram of cutting temporary support columns in this application.

[0036] Figure 8 It is a schematic diagram of casting the middle connecting beam in this application.

[0037] Fig. 9 It is a schematic diagram after the columns are removed in this application.

[0038] Fig.10 It is a schematic diagram of setting the wall beam formwork in this application.

[0039] Fig.11 It is a schematic diagram of setting up a temporary blocking wall in this application.

[0040] Fig.12 It is a schematic diagram of setting a waterproof structure in this application.

[0041] Fig.13 It is a caulking structure diagram of the bottom of the hole in this application.

[0042] Fig.14 It is a schematic diagram of setting up a water retaining platform at the platform in this application.

[0043] In the figure: 10. Foundation pit; 20. Opening; 30. Scaffolding; 40. Left area; 50. Right area; 60. Temporary support column; 70. Column; 80. Upper ring beam; 90. Bottom ring beam; 100. Wall column; 110. Shock-absorbing pad; 120. Temporary blocking wall; 130. Water retaining platform; 140. Thick iron sheet; 150. Side wall. DETAILED DESCRIPTION

[0044] The following will be combined with the attached Figure 1 -Attached Fig.14 , the technical solutions in the embodiments of the present invention are clearly and completely described. The described embodiments are only possible technical implementations of the present invention, not all possible implementations. Those skilled in the art can completely combine the embodiments of the present invention to obtain other embodiments without creative work, and these embodiments are also within the scope of protection of the present invention.

[0045] The side wall opening construction method in this embodiment is mainly used for the expansion or renovation of existing subway stations. For example, after adding an intersecting subway line to an existing subway line, the interconnection of the platforms of the two subway lines is realized, or in order to realize the renovation and expansion of existing subway platforms or station projects.

[0046] Reference Figure 1 and Figure 2As shown, in this embodiment, the reconstruction and expansion of the original platform of the existing subway M1 is taken as an example, and a new station is expanded on the basis of the original side platform of the existing subway M1. The original side platform has a total length of 166.48m, a width of 17-29.5m, an effective platform length of 118m, and a platform width of 4.25m on each side. The newly expanded station is located on both sides of the existing subway M1, and it is necessary to open a hole in the side wall 150 of the existing subway M1 so as to connect with the original side platform. In this embodiment, 14 door openings are opened on the side walls 150 on both sides of the existing subway M1 as an example. The 14 door openings are divided into 7 pairs, that is, 7 door openings are opened on each side wall 150. The 7 door openings on each side wall 150 are arranged side by side in sequence. The opening size is 5.7m*2.7m or 5.2m*2.7m, the net size is 4.5m*2.1m or 4m*2.1m, and the net spacing between the door openings 20 is about 6m.

[0047] Reference Figure 1 and Figure 2 As shown, during the construction process, the first step is to excavate the foundation pit 10: excavate the foundation pit 10 on both sides of the existing subway structure, and the earthwork is excavated to expose the entire side wall 150 to be opened; during the support of the foundation pit 10 and the earthwork excavation, graded sand and gravel are reserved on the top of the subway structure for loading to prevent the existing subway structure from floating up; Then proceed to the second step: S2 hole preparation: temporarily block the existing subway structure platform; according to the principle of symmetry and equal division, the hole areas required for the existing subway structure side wall 150 are numbered in sequence, and the corresponding area above the existing subway structure corresponding to the hole area required for the side wall 150 is numbered accordingly; for example, refer to Figure 1 and Figure 2 As shown, the areas to be opened on the left side wall 150 are numbered MD-1X, MD-2X, MD-3X, MD-4X, MD-5X, MD-6X, and MD-7X in sequence; the areas to be opened on the right side wall 150 are numbered MD-1D, MD-2D, MD-3D, MD-4D, MD-5D, MD-6D, and MD-7D in sequence; MD-1X and MD-1D are relatively arranged on both sides of the existing subway line, and the area above the existing subway line between the two is area No. 1, MD-2X and MD-2D are relatively arranged on both sides of the existing subway line, and the area above the existing subway line between the two is area No. 2, and so on. Among them, area No. 5 is the entrance and exit of the existing subway platform, which needs to be permanently blocked, and the side wall 150 opening construction in this area can only be carried out after the concrete strength of the blocking wall reaches 100%.

[0048] Then proceed to the third step: S3 opening 20 cutting: select MD-3X in the middle as the test hole. Unload the soil in sections according to the hole breaking requirements, and unload the section that is broken in advance. Therefore, the soil in area 3 is unloaded first, and then the MD-3X opening is broken. After the test hole is completed, it is confirmed by all parties that the hole opening construction is feasible, and the remaining openings 20 can be constructed according to the same process; during the construction of the remaining openings 20, the soil in areas 1 and 7 can be unloaded first, and the MD-1X, MD-5X, and MD-7X openings 20 can be broken, and the MD-1D, MD-3D, MD-5D, and MD-7D openings 20 can be broken at the same time; then the remaining soil is unloaded and the remaining openings 20 are broken.

[0049] Reference Figure 3 As shown, after the top cover of each opening is unloaded and before the water drilling is carried out, a scaffold 30 is arranged at the opening position outside the subway as a personnel operation platform for construction. The scaffold 30 uses φ48mm*3.6m steel pipes, with a height of 4.0m and a length of 7.2m. The vertical distance of the vertical poles is 1.2m, the horizontal distance is 0.8m, the inner vertical poles are 30cm away from the side wall 150, and the horizontal pole step is 1.2m. The foundation of the scaffold 30 should be compacted, and the bearing capacity of the foundation meets the requirements for the erection of the scaffold 30. The vertical poles should be equipped with pads, and vertical and horizontal sweeping rods should be set, connected to the vertical poles, about 20cm away from the base. The large horizontal bar is placed under the small horizontal bar, with a vertical spacing of 1.2m, and a vertical net is set on the outside. The large horizontal bar is placed inside the vertical pole, and the extension length on each side is 150mm. A continuous scissors brace is set on the outer facade of the scaffold 30, and its overlap length is not less than 1m, and there are not less than 2 rotating fasteners. The vertical poles should be fully covered with scaffolding boards, without probe boards. The outside of the scaffolding 30 is closed with a safety net, and the safety net is fixed to the inside of the scaffolding 30; a 1.2m high guardrail and a 30mm high skirting board are set on the outside of the scaffolding 30. To ensure the stability of the scaffolding 30, two diagonal braces are set on the outside of the scaffolding 30, with a spacing of 2.4m.

[0050] Reference Figure 4 , Figure 5 and Figure 6 As shown, before cutting each opening 20, the opening position of the side wall 150 is measured and laid out according to the design drawings, and the position and size elevation of the opening 20 are strictly controlled. The concrete of each opening area is divided into a left area 40 and a right area 50, both of which have a size of 1850mm*2400mm (width*height). The left area 40 and the right area 50 are spaced apart and the concrete between the two forms a temporary support column 60; the concrete of the left area 40 and the right area 50 is cut and removed in blocks, and then the columns 70 are installed in the left area 40 and the right area 50, and then the temporary support column 60 between the left area 40 and the right area 50 is cut and removed.

[0051] The cutting construction adopts the method of static breaking with water drill and manual waterless chiseling to carry out layered cutting: the total thickness of the side wall 150 is 650mm, of which the thickness of the side wall 150 in the station hall area is 800mm. The side wall 150 is opened by first cutting the outer 550mm thickness (700mm in the station hall area) with a water drill, and then manually cutting the inner 100mm thickness to prevent the water from entering the platform; the diameter of the water drill is ф100mm, and the water drill holes are guaranteed to be at least 5mm apart. The process is as follows: ① Use a water drill to cut the upper and side edge areas, and pay attention to reserving manual chiseling parts when cutting; ② Cut vertically in blocks, a total of 4 blocks, with a horizontal spacing of 438mm and a vertical spacing of 400mm; after cutting, the net size of each block is 378*300*650mm, and the weight of each block is about 165kg; ③ After the water drill cutting is completed, use manual chiseling and angle grinder on the platform side to cut off the inner steel mesh of the subway side wall 150; use steel wire rope to pass through the 5mm lifting hole to fix the concrete block firmly, and use manual and lifting machinery construction methods to transport the divided concrete blocks. After the opening 20 is cut out, the opening 20 needs to be chiseled; specifically, the upper and lower 150mm of the opening 20 and the left and right sides of the two sides are manually chiseled to expose the original 150 steel bars of the side wall.

[0052] Then proceed to the fourth step, S4 wall beam construction: refer to Figure 7 , Figure 8 and Fig. 9As shown, the entire wall beam of each opening 20 is divided into a left semi-ring wall beam, a right semi-ring wall beam, and an intermediate connecting beam connecting the two and located on the upper and lower sides. The left semi-ring wall beam and the right semi-ring wall beam both include a bottom ring beam 90, a wall column 100, and an upper ring beam 80. During construction, firstly, holes are drilled and rebars are planted on the side wall of the opening 20. Specifically, the diameter of the steel bars used for rebar planting is Φ12mm, Φ22mm, and Φ25mm, and electric hammer drilling is used. The rebar planting adopts Class A glue, and the minimum anchoring depth is 18d, where d is the diameter of the rebar. The process flow of rebar planting is: placing the initial positioning line → determining the position of the original structural steel bars and marking them → placing the cross-cross line of the drilling position → checking the line → drilling with an impact drill → cleaning the hole and temporary protection of the hole → grinding and cleaning the steel bars before planting → cleaning with acetone → hidden inspection → inserting the connecting bars after injecting the adhesive → maintenance → acceptance. The key points of the rebar planting process are as follows: clean up the working surface, require the base of the hole to be hard and strong, lay out the initial drilling position line based on the professional structural layout, and then fill in the drilling hole position pre-inspection form and submit it for acceptance. When drilling, hold the impact drill firmly, align the drill bit with the crosshairs to drill, and start drilling according to the hole depth determined by the design and field test, mark the corresponding position on the drill rod. After drilling, use a blower and cotton thread to remove the residue in the hole, wipe it clean, and block the hole with cotton thread to prevent dust and other debris from entering the hole. Before planting the rebar, it is necessary to clean the steel bars, use a wire brush to clean the rust, oil stains, etc. within the anchoring length of the steel bars, and wipe them clean with acetone. Fill in the hidden inspection form before filling the glue, and submit it for acceptance, check the glue certificate and batch number, and only after approval and acceptance can the glue filling operation be carried out. During the glue filling operation, place the agent tube into the sleeve, screw on the mixer, then place the sleeve into the glue gun and pull the trigger. Do not use the agents squeezed out for the first and second time (because the agents may not be mixed evenly at this time). Insert the mixing nozzle on the glue gun into the bottom of the hole and pull the trigger. After feeling obvious pressure each time you pull the trigger, slowly withdraw it step by step. When the agent fills 2 / 3 of the hole depth, stop pulling the trigger. Prepare glue according to 2 / 3 of the hole depth in advance. For vertical blind holes, just put the glue into the hole and then insert the connecting reinforcement. While inserting the reinforcement, keep rotating the reinforcement to facilitate the discharge of bubbles in the colloid and increase the grip between the connecting reinforcement and the adhesive. At the same time, ensure that the steel bar is in the center of the hole. After inserting the connecting reinforcement, determine the curing time after injecting the adhesive in combination with the instructions for use of the adhesive, and prevent disturbance of the implanted materials to ensure the quality of anchoring. Generally, the curing period of chemical adhesives at standard temperature should be more than 2 hours, and the curing period of cement-based adhesives should be more than 72 hours. Finally, fill out the acceptance form for the single project and submit it for acceptance.

[0053] Then, build the reinforcement and formwork. Fig.10As shown in the figure, the wall beam steel bars are connected to the implanted connecting bars and the existing structural steel bars by lap welding. The welding method is arc welding, and the electrode type is E50. The welding requirements are as follows: 1. Before steel bar welding, rust, oil, dirt and other impurities on the steel bar welding part and the contact surface between the steel bar and the electrode should be removed; when the end of the steel bar is bent or distorted, it should be straightened; 2. According to the design requirements: the welded steel is HRB400 grade steel bar, so the electrode type is E50; 3. The axes of the two connecting steel bars should be consistent, and the length of the double-sided weld should not be less than 5d; 4. When welding rib steel bars, it is advisable to place and weld the longitudinal ribs opposite to the longitudinal ribs; 5. The weld height should be equal to or greater than 0.3d and not less than 4mm, and the width should be equal to or greater than 0.8d and not less than 8mm; 6. The welding process parameters should be selected according to the lower grade steel bar; 7. Arc welding should increase the welding current and reduce the welding speed; when the temperature is lower than -20°C, welding is not advisable; 8. For the joints of lap welding and fillet welding, the appearance inspection should be carried out one by one. The weld surface should be smooth, without defects such as cracks, slag inclusions and large weld beads; 9. It is not advisable to carry out welding on site in rainy or snowy days; when welding must be carried out, effective shielding measures should be taken. The uncooled welded joints should not touch ice or snow. When welding on site, when the wind force exceeds level 4, wind shielding measures should be taken. The wall beam formwork uses 15mm thick multi-ply board. The secondary keels of the wall columns with a size of 100 are 50mm×100mm wooden squares, and the main keels (transverse) use double steel pipes with a diameter of Φ48.3mm×3.6mm, with a spacing of 500mm. The first one at the bottom is close to the upper part of the platform slab, and the first one at the top is close to the top wall. There is no scaffolding with a size of 30 on both the inside and outside of the side wall with a size of 150, and it is only erected at the opening position. In the formwork support structure of the upper ring beam with a size of 80, the middle keel uses a steel pipe with a diameter of ø48mm, and is welded into a "soil" shape with ø25mm steel bars and embedded in the bottom ring beam with a size of 90. The lower end of the steel pipe is sleeved on the upper part of the "soil" shaped steel bar frame. The steel bars of the bottom ring beam with a size of 90 are welded to the original steel bars exposed by chiseling, and are directly poured as the wall beam steel bars in the later stage. When the inner and outer formworks are erected, they are directly tightened and reinforced with steel pipes and tie bolts. The upper part of the outer ring beam with a size of 80 is made into a funnel shape for facilitating the pouring of grout, and is removed in the later stage. The exposed "soil" shaped steel bars are directly poured in the wall beam and cut outside the wall beam. Wooden squares are set on the upper part of the steel pipe to support the formwork. After checking and calculating, this support system can meet the construction requirements. The whole system does not cause any load or pressure on the platform slab.

[0054] Finally, pour the grouting material: before construction, the filling space should be cleaned, the contact surface with the original subway structure should be roughened, the loose concrete should be removed and the steel bars should be exposed, the vertical shape should be removed along the reinforcement depth direction, and it should be fully cleaned without debris, dust, oil stains and other debris. 24 hours before grouting, the concrete surface should be fully moistened. 1 hour before grouting, the accumulated water should be sucked dry and the interface agent should be brushed. The wall beams and wall columns 100 use Class IV non-shrinkage cement-based grouting material with a water resistance grade of P10. The cement-based grouting material should be mixed with water according to the water consumption specified in the product, and the grouting material should be mechanically stirred; the mixing location should be close to the grouting location; the stirring time is generally 1 to 2 minutes, and the amount of each stirring should be determined according to the amount used to ensure that the material is used up within 30 minutes. The grouting adopts the "self-weight grouting" method, which completely relies on the self-weight of the slurry to level itself and fill the entire grouting space. The formwork support should leave enough grouting holes and vent holes. The diameter of the grouting holes should not be less than 50mm, and the spacing should not exceed 1000mm. The grouting holes and vent holes should be 50mm higher than the highest point of the holes. The construction site should be poured in 4 times. The pouring sequence is: 90 grouting of the bottom ring beam → 100 grouting of the lower part of the wall column → 100 grouting of the upper part of the wall column → 80 grouting of the upper ring beam, combined with Fig. 9 As shown, the middle connecting beams on the upper and lower sides are grouted to connect the left semi-ring wall beam and the right semi-ring wall beam to form a closed ring beam. When grouting, grouting should be carried out from one side or multiple points on the adjacent two sides until it overflows from the other side, so as to facilitate the exhaust during the grouting process; after the grouting starts, it must be carried out continuously without interruption, and the grouting time should be shortened as much as possible. In order to reduce the impact of grouting on the lower brick wall of the platform slab, the grouting material is poured in layers when the bottom ring beam 90 is poured. First pour the 150mm high wall beam, and pour the remaining 150mm before the initial setting. By pouring in layers, the lateral pressure on the brick wall is reduced. It is not advisable to vibrate during the grouting process. If necessary, bamboo strips can be used for pulling and drainage; the template should be properly knocked during the process of pouring the grouting material into the template; if there is slurry leakage during the grouting, it should be handled in time.

[0055] If the construction period is in winter, after the grouting is completed, the surface should be immediately covered with plastic film and wet straw bags, or sprayed with concrete curing agent to prevent frost damage. Watering is not allowed during curing under negative temperature conditions. When covering with plastic film, the exposed surface of the cement-based grouting material should be covered tightly to ensure that there is condensation water in the plastic film. The curing period is 7-14 days, and the curing period needs to be extended during winter construction. If the daily average temperature is lower than 5℃, winter construction should be carried out and the following regulations should be met: (1) Before grouting, the foundation surface should be preheated to keep its temperature above 10℃, and the accumulated water should be removed. (2) Warm water not exceeding 65℃ should be used to mix the cement-based grouting material, and the slurry should be placed in the mold at a temperature above 10℃. (3) Before freezing, the compressive strength of the cement-based grouting material shall not be less than 5MPa.

[0056] Reference Figure 6 and Figure 7As shown, the columns 70 installed in the left area 40 and the right area 50 in this application are Φ300*12 (Q235b) steel columns. The columns 70 also serve as the wall beam construction support system and are set up during the erection of the scaffolding 30 and the formwork. The top and bottom of the columns 70 do not extend into the wall beam. When the columns 70 are erected, the bottom ring beam 90 is welded to the columns 70 using embedded steel plates. The embedded steel plates are set on the original concrete structure through the bottom frame. The thickness of the embedded steel plates is 5mm and the size is 400×400mm. The top elevation of the embedded steel plates is flush with the top of the bottom ring beam 90. The bottom frame legs are welded with φ22mm steel bars. After the wall beam strength reaches 50%, the top of the column 70 is tightened with a steel wedge, and then the middle part of the side wall 150 is broken with a water drill; after the overall wall beam strength reaches 100%, the columns 70 and the scaffolding 30 here are removed.

[0057] Finally, the fifth step is to temporarily seal and waterproof the S5 side wall 150: refer to Fig.11 , Fig.12 and Fig.13 As shown, after the reinforcement of the side wall 150 wall beam is completed, temporary blocking is required according to the construction schedule. The blocking is built with aerated concrete blocks and the outside is smoothed with 2.0mm thick waterproof mortar to prevent rainwater from entering the subway platform. When the main structures on both sides are constructed to the second underground floor, the temporary brick wall blocking will be gradually removed.

[0058] After the opening 20 of the side wall 150 is broken and the structure of the opening 20 is chiseled out, if the original structural waterproof layer is intact, a 2.5mm thick non-curing rubber asphalt waterproof coating is used for sealing; if the original structural waterproof layer is fragmented or not bonded to the base surface, the waterproof protective layer is partially chiseled, and the non-curing rubber asphalt coating is scraped in the gap between the original waterproof layer and the base surface, and waterproof mortar is applied for temporary protection. Furthermore, before the new structural side wall 150 is built, a shock-absorbing pad 110 is attached to the outside of the original side wall 150, so that there is a buffering and shock-absorbing effect between the new structural side wall 150 and the original side wall 150. After the temporary blocking wall 120 is removed, MS sealant is embedded in a ring on the inside of the door opening.

[0059] In this embodiment, the non-curing rubberized asphalt waterproof coating is applied by mechanical spraying or manual brushing, and the film thickness is required to be not less than 2.0mm, and the amount used per square is about 2.0-2.5kg. The details such as the corners of the plane and the vertical surface are first brushed, and the scraping method is used for construction. The thickness is 1.0mm, and the reinforced fiber cloth (14-16 mesh) is cut into corresponding shapes and attached. After the additional layer is completed, the overall construction is carried out to ensure that the overall coating maintains a consistent thickness; when constructing on a large surface, a special sprayer is used to evenly spray the non-curing rubberized asphalt waterproof coating. When spraying, different spray gun nozzles can be adjusted according to the designed thickness, and the waterproof layer is formed in one time.

[0060] Reference Fig.14As shown, in this embodiment, the inner side of the lower opening 20 of the existing subway structure platform plate is made of the platform brick wall as a template, and the surface of the brick wall is painted with waterproof paint, and the outer side is closely attached to the 0.5mm thick iron sheet 140, and the gap is painted with sealant to prevent water from seeping into the pipe trench during the grouting material construction. A 300mm high and 24mm thick water retaining platform 130 is built at each opening position on the platform plate, and the two sides along the length of the opening are expanded by 200mm to prevent external water from flowing into the platform.

[0061] In this application, during the unloading of earthwork, attention should be paid to observe whether there is any floating of the subway section. If any problem is found, feedback should be given in time, the operation should be stopped for investigation, and measures such as spare steel pipes should be used for encrypted support. Only after the treatment plan is clarified can the next step be carried out. Strengthen communication and contact with the monitoring unit during the hole opening process. When the data alarm is triggered, inspection should be strengthened. If cracks and deformations are found in the surrounding structure during the cutting process, the cutting should be stopped immediately, and the relevant units such as Party A, subway operating company, design and supervision should be reported as soon as possible. Measures such as spare steel pipes for encrypted support should be used. Only after the treatment plan is clarified can the next step be carried out. When the station hole is opened during the rainy season or when there is water operation, a special person should be assigned to inspect the leakage. When there is a small amount of local seepage, it should be cleaned manually at any time; when construction water enters the station, stop construction immediately, turn off the water source, and use a water pump or manual pumping to the outside in time. At the same time, cooperate with the station staff to check the lines in the station to ensure the safety of the subway line and operation. Construction shall not continue if the leaking part is not cleaned up.

[0062] The construction method in this application must achieve certain quality goals, that is, meet the requirements of the current national engineering construction acceptance specifications and standards (qualified), and at the same time achieve safety and civilization goals and green construction management goals; achieve zero accidents and zero fires in production safety, and achieve zero mechanical injury accidents in mechanical management; achieve zero fire accidents in fire management and avoid fire accidents. According to the green construction specifications of construction projects, improve energy utilization, reduce energy consumption, improve water efficiency, make full use of non-traditional water sources, ensure water safety, improve the effective utilization rate of temporary facilities, protect the surrounding natural ecological environment, reduce the impact of construction activities on the surrounding, improve material utilization, make full use of waste, classify, collect, recycle and recycle construction waste, and use green materials. In terms of environmental protection, dust, dust and gas emissions must be controlled and not exceed the specified values ​​of laws and regulations; noise emissions must meet the "Construction Site Noise Limit" regulations; reduce the generation of solid waste, and reasonably recycle usable construction waste; production and domestic sewage discharge meets the "Comprehensive Sewage Discharge Standard" regulations; control the consumption of resources such as water, electricity, paper, and materials, classify and treat construction waste, and recycle it as much as possible.

[0063] The implementation principle is as follows: This technical solution provides a method for opening holes in the side wall of an existing subway structure, which realizes the completion of the side wall 150 hole construction without interrupting the operation of the subway, and effectively prevents the subway structure cracking caused by the construction. After the temporary blocking of the platform is completed, the existing subway side wall 150 hole construction is carried out. In order to prevent the existing subway structure from floating up too much during the foundation pit 10 support and earthwork excavation process, graded sand and gravel are reserved on the top for loading. In order to avoid excessive floating of the subway structure and cracks, the "top part of the area earthwork is unloaded, and then the hole is opened, and then carried out in sequence" is adopted within the width range of the hole opening 20 before the hole is opened. The overall construction sequence adopts the "interval jump" method, and the top plate unloading sequence is consistent with the side wall 150 hole opening sequence. The construction method in this application successfully realizes the completion of the necessary side wall 150 hole construction on the basis of ensuring the normal operation of the existing subway through scientific and reasonable construction process planning, which significantly reduces the inconvenience caused by construction activities to public travel.

[0064] This construction method utilizes advanced temporary blocking technology and precise construction management strategies to effectively avoid the risk of structural damage that is prone to occur under traditional construction modes and improve the overall safety and reliability of the project.

[0065] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are represented by the same figure marks. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for opening a hole in the side wall of an existing subway structure, characterized in that: The construction method comprises the following steps: S1: excavating a foundation pit (10): excavating a foundation pit (10) on both sides of the existing subway structure, and excavating the earthwork to expose the entire side wall (150) to be opened; during the foundation pit support and earthwork excavation, graded sand and gravel are reserved on the top of the subway structure for loading to prevent the existing subway structure from floating up; S2: preparation for opening holes: the areas required for opening holes on the side wall (150) of the existing subway structure are numbered in sequence, and the areas required for opening holes on the corresponding side wall (150) above the existing subway structure are divided and numbered accordingly; the existing subway structure platform is temporarily blocked; S3: Cutting of the opening (20): The top of the existing subway structure is unloaded in sections according to the order of opening, and the side wall (150) of each opening area is drilled and cut by a water drill to remove the blocks, and then the opening (20) is chiseled; S4: wall beam construction: drilling holes on the side wall of the opening (20) to plant reinforcement, then setting up wall beam reinforcement and wall beam formwork, welding the wall beam reinforcement to the connecting reinforcement planted on the side wall of the opening (20); then pouring concrete, removing the formwork after the concrete solidifies, cutting off the excess wall beam reinforcement, and forming a wall beam reinforcement structure surrounding the side wall of the opening (20); S5: Waterproof construction: remove the damaged original waterproof layer, manually scrape and chisel to expose the joint of the original side wall (150) waterproof protective layer, and use waterproof paint to seal the waterproof layer of the opening (20).

2. The method for opening a hole in the side wall of an existing subway structure according to claim 1, characterized in that: In the above step S3, the side wall (150) is opened by using a layered demolition construction process, that is, firstly, a water drill is used to cut at least three quarters of the thickness of the outer wall layer of the side wall (150) on the side away from the existing subway line, and the remaining wall layer is cut by manual chiseling without water.

3. The method for opening a hole in the side wall of an existing subway structure according to claim 1 or 2, characterized in that: In the above step S3, the concrete of each opening area is divided into a left area (40) and a right area (50), the left area (40) and the right area (50) are arranged at an interval and the concrete between the two forms a temporary support column (60); the concrete of the left area (40) and the right area (50) are cut and removed in blocks, and then the left area (40) and the right area (50) are installed with columns (70), and then the temporary support column (60) between the left area (40) and the right area (50) is cut and removed.

4. The method for opening a hole in the side wall of an existing subway structure according to claim 3 is characterized in that: In the above step S4, the wall beam is constructed in sections. After the concrete of the left area (40) and the right area (50) is removed, the edges are chiseled. A left semi-ring wall beam and a right semi-ring wall beam are constructed on the side walls of the opening (20) of the left area (40) and the right area (50), respectively. The left semi-ring wall beam and the right semi-ring wall beam both include a bottom ring beam (90), a wall column (100) and an upper ring beam (80). After the strength of the left semi-ring wall beam and the right semi-ring wall beam is greater than 50%, a steel wedge is used to tighten the top of the column (70), and then the temporary support column (60) between the left area (40) and the right area (50) is cut and removed. Finally, an intermediate connecting beam is constructed on the upper and lower sides of the opening (20) to connect the left semi-ring wall beam with the right semi-ring wall beam.

5. The method for opening a hole in the side wall of an existing subway structure according to claim 4 is characterized in that: In the above step S4, when pouring concrete of the left semi-ring wall beam and the right semi-ring wall beam, the "self-weight grouting" method is adopted, and the grouting material is completely leveled by its own weight and fills the entire pouring space; the formwork support is provided with a plurality of grouting holes and exhaust holes, the hole diameter of the grouting holes is not less than 50 mm, the spacing is not more than 1000 mm, and the grouting holes and the exhaust holes are 50 mm higher than the highest point of the hole; the pouring is carried out in four times, and the pouring order is: grouting of the bottom ring beam (90), grouting of the lower part of the wall column (100), grouting of the upper part of the wall column (100), and grouting of the upper ring beam (80).

6. The method for opening a hole in the side wall of an existing subway structure according to claim 5, characterized in that: In the above step S4, no vibration is performed during the grouting process, and bamboo strips are used for pulling and drainage; the formwork is appropriately knocked during the process of pouring the grouting material into the formwork; if the construction time is in winter, after the grouting is completed, it is immediately covered with plastic film and covered with wet straw bags, or sprayed with concrete curing agent to prevent frost damage, and no watering is allowed during curing under negative temperature conditions.

7. The method for opening a hole in the side wall of an existing subway structure according to claim 1, characterized in that: In the above step S3, a certain opening area in the middle is first selected as a test hole for opening, and the earthwork in the numbered area corresponding to the test hole area is unloaded before the hole is opened; after the test hole is completed, after the feasibility of the opening construction is determined by all parties, the remaining openings (20) are constructed; during the construction of the remaining openings (20), the earthwork in the two end areas is unloaded and the opening is constructed first, and then the earthwork in the remaining areas is unloaded and the opening is constructed.

8. The method for opening a hole in the side wall of an existing subway structure according to claim 1, characterized in that: In the process of drilling and rebar planting, the following steps are carried out in sequence: placing the initial positioning line, determining the position of the original structural steel bars and marking them, placing the cross lines of the drilling position, checking the lines, drilling with an impact drill, cleaning the holes and temporarily protecting the holes, grinding before planting the steel bars, cleaning with acetone, performing hidden inspection, inserting the connecting bars after injecting adhesive, maintenance, and acceptance.

9. The method for opening a hole in the side wall of an existing subway structure according to claim 1, characterized in that: During the hole opening process, a water retaining platform (130) needs to be added on the side of the existing subway platform; before pouring the wall beam, the inner side of the hole (20) under the platform slab is formed with the platform brick wall as a template, and waterproof paint is applied on the surface of the brick wall, and thick iron sheets (140) are closely attached to the outer side, and sealant is applied to the gaps to prevent water from seeping into the pipe trench during the grouting material construction.

10. The method for opening a hole in the side wall of an existing subway structure according to claim 1, characterized in that: After the wall beams of the side wall (150) are reinforced, a temporary blocking wall (120) is set up for temporary blocking according to the construction schedule. The temporary blocking wall (120) is built with aerated concrete blocks. The outer side of the temporary blocking wall (120) is smoothed with waterproof mortar to prevent rainwater from entering the existing subway platform. When the hole (20) is broken, if the original waterproof layer of the structure is intact, a non-curing rubber asphalt waterproof coating is used for sealing treatment; if the original waterproof layer of the structure is broken or not bonded to the base surface, the waterproof protective layer is partially chiseled, and the non-curing rubber asphalt coating is scraped in the gap between the original waterproof layer and the base surface, and waterproof mortar is applied for temporary protection; After the main structures on both sides are constructed to the position below the existing subway platform, the temporary blocking wall (120) is gradually dismantled; and MS sealant is embedded in the inner side of the opening (20) to form a ring.

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