A construction method for opening holes in the side wall of an existing subway structure

Abstract

The present application relates to a construction method for opening holes in the side wall of an existing subway structure, belonging to the technical field of tunnel civil engineering construction. The construction method for opening holes in the side wall of the existing subway structure in the present application includes the following steps: S1: Excavating the foundation pit: Excavating the foundation pit on both sides of the existing subway structure, and the overall side wall to be opened is exposed during the earthwork excavation; during the foundation pit support and earthwork excavation, graded sand and gravel are reserved on the top of the subway structure for surcharge to prevent the existing subway structure from floating; S2: Preparation for hole opening; S3: Hole cutting: On the top of the existing subway structure, the earthwork is unloaded in areas according to the hole opening sequence. For the side wall of each hole opening area, a water drill is used for drilling and cutting to remove the blocks in parts, and then the edge of the hole is chiseled; S4: Wall beam construction; S5: Waterproof construction. The construction method for opening holes in the side wall of the existing subway structure in the present application can greatly reduce the impact on the operation of the existing subway, and can effectively prevent the floating and cracking of the existing subway structure.

Description

Technical Field

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

[0002] Subway construction is a complex infrastructure project. With the rapid development of cities, it often happens that the existing subway lines are difficult to meet the growing passenger flow demand. Therefore, it is necessary to expand or transform the existing subway stations. In order to connect the expansion project or new project with the existing subway project, it is necessary to carry out hole-opening construction on the side wall of the existing subway structure. By setting multiple door openings, multi-region interconnection can be achieved while ensuring the support strength of the existing structure. Such projects usually face complex underground environments and high safety risks. The treatment methods mainly include completely stopping the line operation for closed construction, or adopting the method 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 concentrate resources more to speed up the progress, it will cause greater social impacts and service interruptions. Although the latter can alleviate the operation suspension problem to a certain extent, due to the limited construction time and space, the efficiency is low, and safety hazards are increased.

[0003] When constructing on an operating subway line, there is a risk of excessive upward floating and cracking of the structure when opening a hole in the side wall of the existing subway, which is a construction difficulty and key point. Moreover, due to the "station closure without stopping operation" of the line, smoke and dust, and fire prevention during the side wall hole-opening process will have a greater impact on the train and the track section. 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 transformation construction of the subway line during normal operation is a higher challenge, and there is no mature technology at present. Summary of the Invention

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

[0005] A construction method for opening a hole in the side wall of an existing subway structure provided by this application adopts the following technical solutions:

[0006] A construction method for opening a hole in the side wall of an existing subway structure includes the following steps:

[0007] S1: Excavate the foundation pit: Excavate the foundation pit on both sides of the existing subway structure, and the overall side wall to be opened is exposed during the earthwork excavation. During the foundation pit support and earthwork excavation, graded sand and gravel are reserved for surcharge at the top of the subway structure to prevent the existing subway structure from floating upward;

[0008] S2: Preparation for opening holes: Number the areas on the side walls of the existing subway structure where holes need to be opened in sequence, and correspondingly number the areas above the side walls where holes need to be opened on the corresponding side above the existing subway structure; temporarily block the platform of the existing subway structure.

[0009] S3: Hole cutting: Unload the soil in areas on the top of the existing subway structure in sequence according to the hole opening order. For the side walls of each hole opening area, use a water drill to drill and cut the side walls into pieces and remove them, and then chisel the edges of the holes.

[0010] S4: Wall beam construction: Drill and implant steel bars on the side walls of the holes, then set up the steel bars and formwork of the wall beam, and weld and fix the steel bars of the wall beam to the connecting steel bars implanted on the side walls of the holes; then pour concrete, remove the formwork after the concrete solidifies, and cut off the redundant steel bars of the wall beam.

[0011] S5: Waterproof construction: Remove the damaged original waterproof layer, manually chisel to expose the joints of the original side wall waterproof protection layer, and use waterproof paint to seal the waterproof layer of the holes.

[0012] In this application, measures such as upper surcharge are taken to slow down the upward floating trend of the section and reduce the upward floating value of the section. Through means such as sequential construction, gradual unloading, real-time observation, and timely detection, major safety hazards can be effectively prevented, the normal progress of the side wall hole opening construction can be ensured, and phenomena such as cracking of the existing subway structure can be avoided. At the same time, after temporarily blocking the existing subway platform in this application, during the construction, noise, dust, fire, and water entering the existing subway platform can be effectively reduced. By adopting the above technical solutions, the impact on the operation of the existing subway can be minimized.

[0013] Optionally, in the above step S3, the construction process of layered breaking is adopted for the side wall hole opening construction, that is, first use a water drill to cut at least three-quarters of the thickness of the outer wall layer on the side of the side wall far from the existing subway line, and the remaining wall layer is cut without water by manual chiseling.

[0014] By adopting the above technical solutions, the side wall hole opening adopts layered cutting, the outer layer is cut by a water drill, and the inner layer is cut by manual chiseling. The inner layer does not perform wet operation to prevent water from entering the station, reducing the impact on subway operation.

[0015] Optionally, in the above step S3, the concrete in each hole opening area is divided into a left area and a right area. The left area and the right area are arranged at intervals, and the concrete between them forms a temporary support column; the concrete in the left area and the right area is cut and removed in blocks, 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.

[0016] By adopting the above technical solution, each perforated area is constructed in blocks and in steps. The existing concrete is used to form temporary support columns to ensure the support strength of the side wall. The width of each door opening can be made relatively large, which reduces the construction safety risk while forming a large-span door opening.

[0017] Optionally, in the above step S4, the wall beam construction is carried out in sections. After removing the concrete in the left area and the right area, edge chiseling is performed. The left half-ring wall beam and the right half-ring wall beam are respectively constructed on the side walls of the door openings in the left area and the right area. Both the left half-ring wall beam and the right half-ring wall beam include a bottom ring beam, wall columns and an upper ring beam. After the strength of the left half-ring wall beam and the right half-ring wall beam is greater than 50%, a steel wedge is used to tightly wedge at the top of the column, and then the concrete of the temporary support column 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 half-ring wall beam and the right half-ring wall beam.

[0018] By adopting the above technical solution, the wall beam construction is carried out in steps, and the use of temporary support columns and installed columns ensures the safety of the construction.

[0019] Optionally, in the above step S4, when pouring the concrete of the left half-ring wall beam and the right half-ring wall beam, the "self-weight grouting" method is adopted, which completely relies on the self-weight of the slurry to level itself and fill the entire grouting space. The formwork support is provided with several grouting holes and exhaust holes. The aperture of the grouting holes is not less than 50 mm, the spacing is not more than 1000 mm, and the grouting holes and exhaust holes are 50 mm higher than the highest point of the hole. The pouring is carried out in 4 times in sequence, and the pouring sequence is: bottom ring beam grouting, lower part of wall column grouting, upper part of wall column grouting, and upper ring beam grouting.

[0020] By adopting the above technical solution, the slurry completely relies on its own weight to level itself and fill the entire grouting space, avoiding the noise and vibration generated by the traditional vibration method, which is beneficial to reducing the impact on subway operation. In this technical solution, by providing multiple grouting holes and exhaust holes, the smooth discharge of air is ensured, the residual bubbles are avoided, and the density and strength of the concrete are improved, thus ensuring the construction quality of the wall beam.

[0021] Optionally, in the above step S4, no vibration is carried out during the grouting process, and a main lath is 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, a plastic film is immediately covered and a wet straw bag is covered, or a concrete curing agent is sprayed to prevent frost damage, and watering is not allowed during the curing under negative temperature conditions.

[0022] By adopting the above technical solutions, the generation of noise can be effectively reduced, ensuring a quiet construction environment and avoiding interference with subway operation. During the process of pouring grouting material into the formwork, gently tapping the formwork helps to expel air, making the slurry more dense and improving the stability and durability of the structure. If the construction time is in winter, immediately cover with plastic film and add wet straw bags after grouting, or spray concrete curing agent to prevent frost damage, ensuring that the concrete can also harden smoothly under low-temperature conditions and guaranteeing the project quality.

[0023] Optionally, in the above step S3, first select a certain opening area in the middle as the test hole for opening, unload the soil in the corresponding numbered area of the test hole area and then open the hole; after the test hole is completed and it is determined through demonstration by all parties that the opening construction is feasible, then carry out the construction of the remaining holes; during the construction of the remaining holes, first carry out the soil unloading and opening construction in the areas at both ends, and then carry out the soil unloading and opening construction in the remaining areas.

[0024] By adopting the above technical solutions, it can be ensured that the effectiveness and safety of the construction plan are gradually verified during the actual construction process, reducing potential risks and improving the success rate and reliability of the construction.

[0025] Optionally, in drilling and implanting steel bars, the following steps are carried out in sequence: laying the initial positioning line, determining the position of the original structural steel bars and making marks, laying the cross lines of the drilling positions, checking the lines, drilling with an impact drill, cleaning the hole and temporarily protecting the hole, grinding before implanting steel bars, cleaning the steel bars, cleaning with acetone, hidden inspection, inserting the connecting steel bars after injecting the adhesive, curing, and acceptance.

[0026] By adopting the above technical solutions, the process of drilling and implanting steel bars is more standardized and normalized, ensuring the quality control of each link; effectively improving the quality of drilling and implanting steel bars and ensuring the safety and reliability of the opening construction on the side wall of the existing subway structure.

[0027] Optionally, during the 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 uses the platform brick wall as the formwork, and waterproof coating is applied on the surface of the brick wall, and thick iron sheets are closely attached to the outside, and sealant is applied at the gaps to prevent water from seeping into the pipe trench during the grouting material construction.

[0028] By adopting the above technical solutions, it is possible to effectively prevent water from seeping into the existing subway platform during the construction process, ensuring construction safety and not affecting subway operation.

[0029] Optionally, after the reinforcement of the side wall beam is completed, a temporary blocking wall needs to be set for temporary blocking according to the construction schedule. The temporary blocking wall is made of aerated concrete blocks, and the outside is plastered with waterproof mortar to prevent rainwater from entering the existing subway platform;

[0030] 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;

[0031] 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.

[0032] 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.

[0033] In summary, the present application includes at least one of the following beneficial technical effects:

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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

[0038] Figure 1 It is a plan view of the location of the side wall openings in this application.

[0039] Figure 2 It is a cross-sectional view of the opening position of the side wall in this application.

[0040] Figure 3 It is a schematic diagram of the structure of the scaffold in this application.

[0041] Figure 4 It is a schematic diagram of dividing each hole into left and right areas for cutting in this application.

[0042] Figure 5It is a schematic diagram of separately pouring the left semi-circular wall beam and the right semi-circular wall beam in this application.

[0043] Figure 6 It is a schematic diagram of setting up columns in this application.

[0044] Figure 7 It is a schematic diagram of cutting the temporary support columns in this application.

[0045] Figure 8 It is a schematic diagram of pouring the middle connecting beam in this application.

[0046] Figure 9 It is a schematic diagram after removing the columns in this application.

[0047] Figure 10 It is a schematic diagram of setting up the wall beam formwork in this application.

[0048] Figure 11 It is a schematic diagram of setting up the temporary sealing wall in this application.

[0049] Figure 12 It is a schematic diagram of setting up the waterproof structure in this application.

[0050] Figure 13 It is a caulking structure diagram at the bottom of the hole in this application.

[0051] Figure 14 It is a schematic diagram of setting up a water retaining platform on the platform in this application.

[0052] In the figure:

[0053] 10. Foundation pit; 20. Hole; 30. Scaffold; 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 pad; 120. Temporary sealing wall; 130. Water retaining platform; 140. Thick iron sheet; 150. Side wall. Specific implementation manners

[0054] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the attached Figure 1 - attached Figure 14 , and 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 labor, and these embodiments are also within the protection scope of the present invention.

[0055] In this embodiment, the construction method for opening holes in the side wall is mainly applied to the expansion or renovation project of existing subway stations. For example, after adding intersecting subway lines to the existing subway line, the interconnection of the platforms of the two subway lines can be realized, or the renovation and expansion of the existing subway platform or station project can be achieved.

[0056] Referring to Figure 1 and Figure 2 As shown, in this embodiment, taking the renovation and expansion of the original platform of the existing subway M1 as an example, a new expanded station is built on the basis of the original side platform of the existing subway M1. The total length of the original side platform is 166.48m, the width is 17 - 29.5m, the effective platform length is 118m, and the width of each side platform is 4.25m. The newly expanded stations are located on both sides of the existing subway M1, and it is necessary to open holes in the side wall 150 of the existing subway M1 to connect with the original side platform. In this embodiment, taking the example of opening 14 door openings on the side walls 150 on both sides of the existing subway M1, the 14 door openings are divided into 7 pairs, that is, 7 are opened on each side wall 150. The 7 door openings on each side wall 150 are arranged side by side at intervals in sequence. The opening size is 5.7m * 2.7m or 5.2m * 2.7m, and the net size is 4.5m * 2.1m or 4m * 2.1m. The net spacing of the door opening 20 is about 6m.

[0057] Referring to Figure 1 and Figure 2 As shown, during the construction process, the first step is carried out first: S1 Excavating the foundation pit 10: Excavate the foundation pit 10 on both sides of the existing subway structure, and the earthwork excavation exposes 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 surcharge to prevent the floating phenomenon of the existing subway structure;

[0058] Then the second step is carried out: S2 Preparation for opening holes: Temporarily block the platform of the existing subway structure; according to the principles of symmetry and equal division, number the areas to be opened on the side wall 150 of the existing subway structure in sequence, and correspondingly number the areas above the areas to be opened on the side wall 150 corresponding to the existing subway structure; for example, referring to Figure 1 and Figure 2As 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%.

[0059] 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.

[0060] 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.

[0061] ReferenceFigure 4 , Figure 5 and Figure 6 As shown in Figure 4 , Figure 5 and Figure 6 , before cutting each opening 20, according to the design drawings, measure and set out the opening positions on the side wall 150, and strictly control the position, size and elevation of the opening 20. The concrete in each opening area is divided into a left area 40 and a right area 50, with dimensions of 1850mm * 2400mm (width * height) for both. The left area 40 and the right area 50 are arranged at intervals, and the concrete between them forms a temporary support column 60; cut and remove the concrete in the left area 40 and the right area 50 in blocks, then install columns 70 in the left area 40 and the right area 50, and then cut and remove the temporary support column 60 between the left area 40 and the right area 50.

[0062] The cutting construction is carried out by means of hydrodrill static breaking and manual dry chiseling for layered cutting: the total thickness of the side wall 150 is 650mm, and the thickness of the side wall 150 in the concourse area is 800mm. When cutting the opening in the side wall 150, first use a hydrodrill to cut the outer 550mm thick (700mm in the concourse area), and then use manual cutting for the inner 100mm thick to prevent the water from the hydrodrill from entering the platform; the diameter of the hydrodrill is ф100mm, and the hydrodrill holes are guaranteed to be at least 5mm apart. The process is as follows: ① Use a hydrodrill to cut the upper and two side edge areas, and pay attention to leaving a part for manual chiseling during cutting; ② Vertically cut 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 hydrodrill cutting is completed, use manual chiseling and a angle grinder to cut off the inner steel mesh of the subway side wall 150 on the platform side; pass a steel wire rope through the 5mm lifting hole to fix the concrete block firmly, and use the construction method of manual and hoisting machinery to hoist and transport the divided concrete blocks. After the opening 20 is cut out, the edge of the opening 20 needs to be chiseled; specifically, the upper and lower 150mm of the opening 20 and the left and right 100mm on both sides of the two side areas are manually chiseled to expose the original side wall 150 steel bars.

[0063] After that, the fourth step is carried out, the construction of the S4 wall beam: Refer to Figure 7 , Figure 8 and Figure 9As shown in the figure, the entire wall beam of each opening 20 is divided into a left semi-circular wall beam, a right semi-circular wall beam, and intermediate connecting beams located on the upper and lower sides connecting the two. The left semi-circular wall beam and the right semi-circular wall beam both include a bottom ring beam 90, a wall column 100, and an upper ring beam 80. During construction, first, drilling and rebar planting are carried out on the side wall of the opening 20. Specifically, the diameters of the rebars selected for rebar planting are Φ12mm, Φ22mm, and Φ25mm, and a hammer drill is used for drilling. A-level glue is used for rebar planting, and the minimum anchorage depth is 18d, where d is the diameter of the rebar planted. The technological process of rebar planting is as follows: laying the initial positioning line → determining the positions of the original structural rebars and making marks → laying the crosshair for the drilling position → checking the line → drilling with a percussion drill → cleaning the hole and temporarily protecting the hole → grinding and cleaning the rebar before rebar planting → cleaning with acetone → hidden inspection → inserting the connecting rebar after injecting the adhesive → curing → acceptance. The key points of the rebar planting process operation are as follows: Clean up the working surface, requiring the base of the formed hole to be hard and of high strength. Based on the structural professional's line setting, lay the initial drilling position line, then fill out the pre-inspection form for the drilling hole position and submit it for acceptance. When drilling, firmly hold the percussion drill, align the drill bit with the crosshair for drilling, and mark the corresponding position on the drill rod according to the hole depth determined by the design and on-site tests to start drilling. After drilling, use a blower and cotton thread to remove the soil and debris in the hole, wipe it clean, and block the hole mouth with cotton thread to prevent dust and other sundries from entering the hole. Before rebar planting, the rebar needs to be cleaned. Use a wire brush to clean the rust, oil stains, etc. within the anchorage length range of the rebar, and wipe it clean with acetone. Before pouring the glue, fill out the hidden inspection form and submit it for acceptance. Check the certificate of conformity and batch number of the glue. Only after being approved and passing the acceptance can the glue pouring operation be carried out. During the glue pouring operation, place the reagent tube into the sleeve, screw on the mixer, then place the sleeve into the caulking gun, pull the trigger. Do not use the reagent extruded for the first and second times (because the reagent may not be evenly mixed at this time). Insert the mixing nozzle on the caulking gun into the bottom of the hole, pull the trigger, and after feeling obvious pressure each time the trigger is pulled, slowly withdraw step by step. When the reagent fills 2 / 3 of the hole depth, stop pulling the trigger; Prepare the glue in advance according to 2 / 3 of the hole depth volume. For vertical blind holes, just put the glue into the hole and then insert the connecting rebar. While inserting the rebar, keep rotating the rebar continuously to facilitate the discharge of air bubbles in the glue body, increase the bond strength between the connecting rebar and the adhesive, and at the same time ensure that the rebar is in the center position of the hole. After inserting the connecting rebar, determine the curing time after injecting the adhesive in combination with the usage instructions of the adhesive, prevent disturbing the planted materials, and ensure the anchorage quality. 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 individual project and submit it for acceptance.

[0064] Then, set up the rebars and formwork. Refer to Figure 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 twisted, it should be straightened; 2. According to the design requirements: the welded steel is HRB400 grade steel bars, so the electrode type is E50; 3. The axes of the two connected 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 against 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 bars; 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 side bar welding, the appearance should be inspected 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-layer boards. 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 to facilitate the pouring of grout, and is removed in the later stage. The exposed "soil" shaped steel bars are directly poured inside 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 calculation, the support system can meet the construction requirements. The entire system does not cause any load or pressure on the platform slab.

[0065] 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 to expose the steel bars, the vertical shape should be removed along the reinforcement depth direction, and it should be thoroughly cleaned without debris such as gravel, dust, and oil stains. 24 hours before grouting, the concrete surface should be fully wetted. 1 hour before grouting, the accumulated water should be sucked dry and the interface agent should be brushed. For the wall beams and wall columns 100, Class IV non-shrinking cement-based grouting material is used with an impermeability grade of P10. The cement-based grouting material should be mixed with water according to the water consumption specified in the product. The grouting material is mechanically stirred; the mixing location should be close to the grouting location; the stirring time is generally 1 - 2 minutes, and the amount of each mixing should depend on the usage amount to ensure that the material is used up within 30 minutes. The grouting adopts the "self-weight grouting" method, completely relying on the self-weight of the slurry to level itself and fill the entire pouring space. The formwork support should leave enough grouting holes and vent holes. The diameter of the grouting holes should not be less than 50 mm, the spacing should not exceed 1000 mm, and the grouting holes and vent holes should be 50 mm higher than the highest point of the hole. The construction site is poured in 4 times, and the pouring sequence 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 → grouting of the upper ring beam 80, combined with Figure 9 As shown, finally, the middle connecting beams on both the upper and lower sides are grouted to connect the left semi-circular wall beam and the right semi-circular wall beam to form a closed ring beam. During grouting, grouting should be carried out from one side or multiple points on adjacent sides until it overflows from the other side to facilitate exhaust during the grouting process; after grouting starts, it must be continuous without interruption, and the grouting time should be shortened as much as possible. To reduce the impact of grouting on the brick wall under the platform slab, when pouring the grouting material for the bottom ring beam 90, a layered pouring construction method is adopted. First, pour a 150 mm high wall beam, and pour the remaining 150 mm before the initial setting. By means of layered pouring, the lateral pressure on the brick wall is reduced. During the grouting process, vibration is not advisable. When necessary, a bamboo strip can be used for pulling and draining; the formwork should be tapped appropriately during the process of pouring the grouting material into the formwork; if there is any grout leakage during grouting, it should be dealt with in a timely manner.

[0066] If the construction time is in winter, after grouting, plastic film should be immediately covered and wet straw bags should be added, or a concrete curing agent should be sprayed to prevent frost damage, and watering is not allowed during curing under negative temperature conditions. When using plastic film for covering, the exposed surface of the cement-based grouting material should be covered tightly to ensure that there is condensed water inside 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 °C, winter construction should be carried out and the following regulations should be met: (1) Before grouting, the surface of the foundation should be preheated to keep its temperature above 10 °C, and the accumulated water should be removed. (2) Warm water not exceeding 65 °C should be used to mix the cement-based grouting material, and the temperature of the grout entering the formwork should be above 10 °C. (3) Before being frozen, the compressive strength of the cement-based grouting material should not be lower than 5 MPa.

[0067] Refer to 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.

[0068] Finally, the fifth step is to temporarily seal and waterproof the S5 side wall 150: refer to Figure 11 , Figure 12 and Figure 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.

[0069] 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.

[0070] 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.

[0071] Reference Figure 14As shown in the figure, in this embodiment, for the opening 20 inside the platform slab of the subway structure, the platform brick wall is used as the formwork, and waterproof coating is applied on the surface of the brick wall. On the outside, a 0.5-mm-thick iron sheet 140 is closely attached, and sealant is applied at the joints to prevent water from seeping into the pipe trench during the construction of the grouting material. At each opening position on the platform slab, a water retaining platform 130 with a height of 300 mm and a thickness of 24 mm is built, and it is extended by 200 mm on both sides along the length of the opening to prevent external water from flowing into the platform.

[0072] During the earthwork unloading process in this application, it is necessary to pay attention to observing whether there is any floating of the subway section. In case of problems, feedback should be given in a timely manner, the operation should be stopped for investigation, and measures such as adding dense supports with spare steel pipes should be taken. Only after clarifying the treatment plan can the next step be carried out. Strengthen communication and contact with the monitoring unit during the opening process. When the data alarms, inspections should be strengthened. During the cutting process, if cracks and deformations are found in the surrounding structures, the cutting should be stopped immediately, and the relevant parties such as the Party A, the subway operation company, the design unit, and the supervision unit should be reported immediately. Measures such as adding dense supports with spare steel pipes should be taken, and only after clarifying the treatment plan can the next step be carried out. When opening holes in the station during rainy season construction or water operation, assign special personnel to patrol for water leakage. When there is local minor water seepage, clean it up manually at any time; when construction water enters the station, stop construction immediately, close the water source, and pump it out to the outside in time with a water pump or manually. At the same time, cooperate with the station area staff to check the in-station lines to ensure the safety of the subway lines and operations. Construction cannot continue until the water leakage area is cleaned up.

[0073] The construction method in this application should achieve certain quality objectives, that is, meet the requirements of the current national relevant engineering construction acceptance codes and standards (qualified). At the same time, it should also achieve the safety and civilization objectives and the green construction management objectives; achieve zero accidents and zero fire incidents in terms of work safety, zero mechanical injury accidents in terms of machinery management; achieve zero fire accidents in terms of fire protection management and avoid fire alarm incidents. In accordance with the green construction code for building engineering, improve the energy utilization rate, reduce energy consumption, improve the water use efficiency, make full use of non-traditional water sources, ensure water use safety, improve the effective utilization rate of the floor area of temporary facilities, protect the surrounding natural ecological environment, reduce the impact of construction activities on the surroundings, improve the material utilization rate, make full use of waste, collect, recycle, and resourcefully utilize construction waste, and use green materials. In terms of environmental protection, control the dust, particulate matter, and gas emissions, not exceeding the limited values of laws and regulations; meet the requirements of the "Noise Limit for Construction Sites" in terms of noise emission compliance; reduce the generation of solid waste and reasonably recycle recyclable construction waste; the discharge of production and domestic sewage should meet the requirements of the "Integrated Wastewater Discharge Standard"; control the consumption of resources such as water, electricity, paper, and materials, classify and treat construction waste, and try to recycle it.

[0074] The implementation principle is as follows: This technical solution provides a construction method for opening holes in the side wall of an existing subway structure, achieving the construction of opening a 150-hole in the side wall without interrupting subway operation, and effectively preventing problems such as cracking of the subway structure caused by construction. After the temporary plugging of the platform is completed, the construction of opening a 150-hole in the existing subway side wall is carried out. To prevent the existing subway structure from having a large upward float during the foundation pit 10 support and earth excavation, graded sand and gravel are reserved at the top for surcharge. To avoid cracks caused by excessive upward float of the subway structure, within the width range of 20 of the hole opening before opening the hole, "unload the soil in the top part of the area, then open the hole, and proceed in sequence" is adopted. The total construction sequence adopts the "interval skip construction" method, and the soil unloading sequence of the roof is the same as the hole opening sequence of the side wall 150. Through scientific and reasonable construction process planning, the construction method in this application has successfully achieved the necessary construction of opening a 150-hole in the side wall on the basis of ensuring the normal operation of the existing subway, significantly reducing the inconvenience brought to the public's travel by construction activities.

[0075] This construction method uses advanced temporary plugging technology and precise construction management strategies to effectively avoid the risk of structural damage prone to occur in the traditional construction mode, improving the overall safety and reliability of the project.

[0076] The embodiments of this specific implementation manner are all preferred embodiments of this application, and do not limit the protection scope of this application accordingly. The same components are represented by the same reference numerals. Therefore, all equivalent changes made according to the structure, shape, and principle of this application shall be covered within the protection scope of this 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: Waterproofing construction: remove the damaged original waterproof layer, manually scrape and chisel to expose the joint of the waterproof protective layer of the original side wall (150), and use waterproof paint to seal the waterproof layer of the opening (20); In the above steps S2 and S3, the plurality of openings (20) on the side walls (150) are arranged in pairs and the door openings on each side wall (150) are arranged in parallel and spaced apart in sequence; 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 arranged relatively on both sides of the existing subway line and the area above the existing subway line between the two is area No. 1, and MD-2X and MD-2D are arranged relatively on both sides of the existing subway line and the area above the existing subway line between the two is area No.

1. The area is Area 2, and so on until MD-7X and MD-7D are relatively arranged on both sides of the existing subway line, and the area above the existing subway line between the two is Area 7; MD-3X located in the middle is selected as the test hole, and the soil is unloaded in sections according to the hole breaking requirements. The section to be broken is unloaded in advance, and the soil in Area 3 is unloaded first, and then the MD-3X hole opening is broken; after the test hole is completed, it is determined by all parties that the hole opening construction is feasible, and the remaining holes (20) are constructed according to the same process; during the construction of the remaining holes (20), the soil in Areas 1 and 7 is unloaded first, and the MD-1X, MD-5X, and MD-7X hole openings (20) are broken, and at the same time, the MD-1D, MD-3D, MD-5D, and MD-7D hole openings (20) are broken; then the remaining soil is unloaded and the remaining holes (20) are broken; In the above step S3, the side wall (150) is opened by using a layered breaking 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 operation; 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 a waterproof coating is applied on the surface of the brick wall, and a thick iron sheet (140) is attached to the outer side, and a sealant is applied to the gap to prevent water from seeping into the pipe trench during the grouting construction; 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.

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 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.

3. The method for opening a hole in the side wall of an existing subway structure according to claim 2 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. The left semi-ring wall beam and the 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%, the top of the column (70) is tightened with a steel wedge, 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.

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, 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).

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, 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.

6. 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.

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