Reversed construction method for reinforcing structure of multi-storey building concrete panel wall

Abstract

The construction steps of the existing multi-storey building concrete panel wall reinforcing structure reverse construction method include construction preparation, reverse construction first stage panel wall construction, step three, remaining structure reconstruction construction, foundation construction, junction panel wall integrated construction, remaining structure reconstruction construction, foundation pit backfilling step. The application effectively solves the influence of foundation first construction on upper structure reconstruction, reduces the influence period of foundation construction on residents, effectively solves the safety risk caused by traditional construction sequence, reduces the influence of foundation construction on upper structure reconstruction, effectively solves the problem of long construction period caused by foundation first excavation construction in traditional construction sequence, avoids the influence of foundation construction on the total construction period of old community reconstruction. The outer protection frame is once set and formed in the early construction period, the panel wall reinforcement reconstruction is synchronized with the reconstruction of roof, outer wall, thermal insulation and the like, and finally the foundation is excavated and constructed in sections, avoiding the delay of construction period.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of reinforcement construction of existing building outer wall, in particular to a top-down construction method of reinforcement structure of existing multi-storey building concrete slab wall. BACKGROUND

[0002] Cast-in-place reinforced concrete slab wall reinforcement is commonly used in seismic reinforcement construction of existing old community building outer wall. On the basis of the original masonry brick wall, cast-in-place concrete composite layer is added to form a "masonry-concrete" composite wall, thereby achieving a reinforcement method that greatly improves the bearing capacity and deformation performance of the wall. During construction, the slab wall foundation is generally constructed first, and then the wall reinforcement construction of each layer is completed from bottom to top in sections. However, due to the particularity of the construction environment and the limited construction site in old communities, there are many unpredictable cross factors during the slab wall foundation construction process:

[0003] 1. During the foundation construction process, large-area slope excavation causes difficulty in resident travel and social complaints;

[0004] 2. Large-area excavation in the rainy season leads to pollution of the community road surface and a high risk of foundation pit collapse;

[0005] 3. The long construction period of the foundation leads to the inability to set up the outer wall scaffold, affecting the smooth progress of a series of work such as house renovation and outer window renovation, and seriously affecting the construction progress.

[0006] In summary, certain measures need to be taken to solve the impact of foundation excavation on the surrounding environment during the bottom wall reinforcement process in the renovation of existing building outer walls. SUMMARY

[0007] The purpose of the present application is to provide a top-down construction method of reinforcement structure of existing multi-storey building concrete slab wall, which solves the technical problems of existing construction sequence, adverse effects on residents, high risk of foundation pit pollution and collapse, and long construction period affecting progress.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] A top-down construction method for reinforcing structure of existing multi-storey building concrete panel wall, the reinforcing structure of existing multi-storey building concrete panel wall comprises a wall to be reinforced, a panel wall foundation, a panel wall, a thermal insulation layer, an outdoor terrace and foundation backfill soil, the panel wall foundation is close to the outer surface of the original wall, i.e. the original wall surface, the panel wall foundation supports the bottom of the panel wall, the bottom of the panel wall is fixedly connected with the upper surface of the panel wall foundation, the panel wall is integrally connected with the original wall through tie bars, the thermal insulation layer is fixedly laid on the outer surface of the panel wall, the panel wall is divided into a first-stage panel wall constructed in the first stage and a second-stage panel wall constructed in the second stage according to the range of the construction stage, the elevation of the junction of the construction stages is higher than the outdoor terrace of the original wall, and a reserved height is arranged between the outdoor terrace and the junction;

[0010] The first-stage panel wall comprises a first panel wall steel mesh and first panel wall concrete, the second-stage panel wall comprises a second panel wall steel mesh and second panel wall concrete, the vertical steel bars in the first panel wall steel mesh are extended downward beyond the junction of the construction stages and correspondingly arranged with the vertical steel bars in the second panel wall steel mesh, the two parts of the vertical steel bars are lapped in the second-stage construction range below the junction, the upper half of the second-stage panel wall is located on the ground, the lower half is located in the foundation pit excavated in the second-stage construction range, the vertical steel bars of the second panel wall steel mesh are anchored into the panel wall foundation, and the outside of the panel wall foundation is covered with the lower half of the second-stage panel wall and the foundation backfill soil;

[0011] The construction steps of the reinforcing structure of existing multi-storey building concrete panel wall are as follows:

[0012] Step one, construction preparation;

[0013] Step a, processing the original wall;

[0014] Step b, determining the junction of the first-stage and second-stage construction ranges:

[0015] The parameters of the junction of the construction stages include the step distance of the scaffold to be erected, the steel bar lapping length between the two construction ranges and the interface treatment method of the junction, and the junction is determined through the parameters; the first-stage construction range above the junction includes the work of the first-stage panel wall above the junction and the remaining structure reconstruction construction, and the second-stage construction range below the junction includes the foundation construction, panel wall integrated construction and second-stage panel wall construction below the junction;

[0016] Step c, measuring and positioning the parameters of the tie bars:

[0017] The tie bars are connected with the original wall in the form of anchoring, and the parameters including the stress calculation design determine the spacing, drilling position, aperture and drilling depth of the tie bars, so as to ensure the bonding force between the tie bars and the subsequent construction of the panel wall steel mesh and the panel wall concrete, and then the tie bars are laid out, positioned and marked on the original wall surface treated in step a;

[0018] Step d, erecting double-row scaffolds: erecting double-row scaffolds on the outdoor ground outside the original wall;

[0019] Construction of the first reverse construction stage: including the construction of the first reverse construction stage panel wall and the remaining structure reconstruction construction, specifically as follows:

[0020] Step two, construction of the first reverse construction stage panel wall:

[0021] Step e, construction of tie bars:

[0022] According to the tie bar parameters designed in step c, the original wall above the outdoor ground is drilled, and then the tie bars are constructed by anchoring in the holes;

[0023] Step f, construction of the first panel wall steel mesh:

[0024] In the construction range of the first reverse construction stage, for the original wall with insufficient bearing capacity or not meeting the seismic requirements, the steel bars or steel meshes are supplemented according to the design requirements;

[0025] First panel wall steel mesh binding requirements: the first panel wall steel mesh is parallel to the original wall surface, the first vertical steel bar is on the inner side, and the first horizontal steel bar is on the outer side;

[0026] Connection of the first panel wall steel mesh and the tie bars: the outer end of the tie bar extends out of the first panel wall steel mesh to form a hook, and the hook is hung and anchored with the first horizontal steel bar;

[0027] Formation of the first stage lap steel bars: the first vertical steel bar is extended downward at the junction of the construction stage range to form the first stage lap steel bar, and the reserved length of the first stage lap steel bar needs to be guaranteed to meet the lap joint and percentage requirements of the steel bars;

[0028] Step g, construction of the first panel wall concrete:

[0029] Construction protection measures for the original wall surface in the construction range of the second reverse construction stage; then the formwork is supported and the concrete is poured or sprayed; when the sprayed concrete is used, an isolation structure is arranged at the junction of the construction stage range, and the first panel wall concrete is constructed upward from the isolation structure;

[0030] Step three, remaining structure reconstruction construction:

[0031] After the first board wall concrete construction and maintenance are completed, without secondary erection, directly using the double row scaffoldings which have been erected, the remaining reconstruction construction is completed synchronously: including the first board wall insulation layer construction of the first stage board wall outside in reverse, also including the replacement of doors and windows and the flat-to-slope conversion of the roof;

[0032] The construction of the second stage in reverse, including foundation construction and integrated construction of the board wall at the junction, is as follows:

[0033] Step four, foundation construction:

[0034] Step i, preparation before foundation pit excavation: along the surface of the original wall, excavate downward, and remove the double row scaffoldings of the part which needs to be excavated below the outdoor terrace;

[0035] Step j, segmented excavation of foundation pit: according to the resident walking route and daily life area, excavate in segments and layers, the cross section of the foundation pit excavation is inverted right angle trapezoidal, after the foundation pit excavation to the design elevation, the foundation cushion construction is carried out;

[0036] Step k, board wall foundation construction: after the foundation cushion construction is completed, the board wall foundation construction is carried out in the foundation pit, the embedded depth of the board wall foundation is the same as the existing foundation below the original wall, the second stage overlapping reinforcement of the board wall foundation is embedded into the foundation at the bottom and vertically protrudes from the surface of the foundation at the top, the second stage overlapping reinforcement is set one by one corresponding to the first stage overlapping steel bars above and below, the length of the second stage overlapping reinforcement is determined to ensure that the overlapping with the first stage overlapping steel bars meets the design requirements, then the foundation concrete is poured and maintained;

[0037] Step five, integrated construction of the board wall at the junction:

[0038] Step m: remove the isolation structure and the original wall surface construction protection measures, clean and construct the joint surface of the second stage board wall and other components;

[0039] Step n, steel bar binding: including overlapping steel bar binding and second board wall steel mesh binding:

[0040] Overlapping steel bar binding: the top end of the second stage overlapping reinforcement is directly connected with the bottom end of the first stage overlapping steel bar as a whole, or the two are connected as a whole by another lengthening steel bar;

[0041] Second board wall steel mesh binding: within the construction range of the second stage in reverse, for the original wall with insufficient bearing capacity or not meeting the seismic requirements, according to the design requirements, supplement the steel bars or steel mesh;

[0042] Tie bar binding: according to the tie bar parameters designed in step c, drill holes in the original wall below the outdoor terrace, then plant steel bars in the holes to construct tie bars;

[0043] Second panel wall steel mesh binding: the second panel wall steel mesh is parallel to the original wall surface, the second vertical steel is inside, and the second horizontal steel is outside; wherein the second vertical steel includes the first stage lap steel and the second stage lap steel or the first stage lap steel, the second stage lap steel and the lengthening steel in the construction range,

[0044] Second panel wall steel mesh and tieback steel connection: the outer end of the tieback steel extends out of the second panel wall steel mesh to form a hook, which is hung and anchored with the second horizontal steel;

[0045] Step p, construction of the second stage panel wall in reverse:

[0046] Second panel wall concrete construction method: formwork pouring concrete or shotcrete, so that the first panel wall concrete in step g and the second panel wall concrete in step p and the foundation concrete form an integral whole;

[0047] Step six, remaining structure reconstruction construction:

[0048] After the completion of the second panel wall concrete construction and maintenance, the second panel wall insulation layer construction outside the panel wall in the construction range is completed;

[0049] Step seven, foundation pit backfilling: after the completion of the panel wall reinforcement and reconstruction, the foundation backfilling construction of the foundation pit is carried out, and after the construction is completed, it is flush with the original outdoor ground.

[0050] In step k, the panel wall foundation is a reinforced concrete foundation beam arranged outside the original wall, and the foundation beam includes foundation beam steel and foundation beam concrete, and the foundation beam steel includes foundation longitudinal main reinforcement, foundation transverse hoop reinforcement, foundation horizontal anchor reinforcement and vertical second stage lap reinforcement,

[0051] The foundation longitudinal main reinforcement is arranged along the length direction of the foundation,

[0052] The foundation transverse hoop reinforcement is arranged along the length direction of the foundation, and is connected with the foundation longitudinal main reinforcement to form a load-bearing steel of the foundation beam,

[0053] The foundation horizontal anchor reinforcement is arranged along the length direction of the foundation, the inner half of the foundation horizontal anchor reinforcement is embedded in the original wall, and the outer half of the foundation horizontal anchor reinforcement extends out of the original wall surface and is bound and fixed with the load-bearing steel,

[0054] The bottom of the second stage lap reinforcement is embedded in the foundation beam and connected with the load-bearing steel, and the anchor depth is up to the bottom of the foundation beam.

[0055] In step m, the joint surface cleaning construction includes cleaning the joint surface of the concrete member in the reverse first stage construction range and cleaning the joint surface of the member in the reverse second stage construction range,

[0056] The concrete components in the first reverse construction stage include the first reverse stage wall and the wall foundation, and the cleaning steps are as follows:

[0057] Chiseling and cleaning: the joint surface is trimmed to expose the aggregate surface and chiseled or chiseled into a groove, and the surface is cleaned;

[0058] Coating interface agent: the joint surface is rechecked for processing quality before coating the structural interface agent, and then the structural interface agent is coated on the joint surface;

[0059] The components in the second reverse construction stage include the second stage lapping rib and the original wall surface, and the cleaning steps are as follows:

[0060] The original wall surface in this range is contaminated and the wall surface is cleaned and treated, and the second stage lapping rib is cleaned and treated.

[0061] In step g, the isolation structure is a wooden formwork fixed on the tie bar or steel mesh, the length and width of the wooden formwork are not less than the size of the to-be-sprayed wall concrete, and the gap between the wooden formwork and the original wall surface is filled with leak-proof slurry steel mesh.

[0062] The treatment of the original wall body in step a includes structural treatment and surface treatment:

[0063] Structural treatment: including replacing the damaged masonry brick wall of the original wall body, filling the holes, and repairing the structural cracks;

[0064] Surface treatment: removing the decorative layer of the original wall body, removing dust and contaminants, and watering one day in advance.

[0065] The protective measures for the original wall surface in the second reverse construction stage in step g are that the outer surface of the original wall body is covered with a plastic protective film to prevent the original wall surface above the outdoor terrace in the second reverse construction stage from being contaminated by the first reverse stage wall construction, and the plastic protective film is fixed to the original wall body with steel nails.

[0066] In step c, the tie bar is arranged in a plum blossom shape with a horizontal and vertical spacing of 600 mm, a diameter of 8 mm, and a vertical implantation depth of 120-180 mm.

[0067] In steps f and n, the first vertical steel bar and the second vertical steel bar have the same size and spacing, with a diameter of 8-12 mm and a spacing of 150-200 mm, and the first horizontal steel bar and the second horizontal steel bar also have the same size and spacing, with a diameter of 6-8 mm and a spacing of 150-200 mm.

[0068] The first wall concrete and the second wall concrete are the same, and the strength grade is C20 or above;

[0069] The maximum particle size of the coarse aggregate is:

[0070] Not more than 20mm for mixed concrete;

[0071] Not more than 12mm for shotcrete;

[0072] Not more than 10mm for short fiber mixed concrete;

[0073] The fine aggregate is medium and coarse sand, and the fineness modulus is not less than 2.5.

[0074] Compared with the prior art, the present application has the following characteristics and beneficial effects:

[0075] The present application is suitable for the field of reinforcement construction of existing building outer plate wall of multi-storey building in old community and the building height is not more than 24 meters. The overall idea is to first determine the reinforcement starting position of the ground structure plate wall, carry out the upper wall modification construction, and finally carry out the foundation excavation and backfill construction in sections after the upper structure modification is completed. The present application has significant advantages in many aspects after application:

[0076] I. Effectively solve the influence of traditional construction sequence on the upper structure modification, reduce the influence period of foundation construction on residents, and avoid the influence on daily life of residents caused by large-area excavation of foundation.

[0077] II. Effectively solve the safety risk caused by traditional construction sequence and reduce the influence of foundation construction on upper structure modification.

[0078] By optimizing the concrete mix ratio, calculating the configuration of tie bars and steel mesh, ensuring the bonding strength of concrete and steel, effectively transferring tensile stress and shear stress on the bonding surface, and ensuring the stability of the first constructed part of the wall.

[0079] In order to ensure the integrity and structural safety of the plate wall reverse construction, the bonding surface treatment is well done at the junction position, the steel bar lap joint length is reserved enough, and finally the foundation and upper structure connecting wall construction is carried out, forming a complete stress system, ensuring the stability and safety of the plate wall reinforcement structure.

[0080] While ensuring the construction progress of the project, the environmental problems caused by large-area excavation of the foundation can be reduced, the construction progress of the old community renovation can be effectively improved, which is beneficial to green construction, civilized construction and site management, and the social benefits are significant. Ensure the green and safe construction on site.

[0081] III. Effectively solve the problem of long construction period caused by foundation excavation construction in traditional construction sequence, avoid the influence of foundation construction on the total construction period of old community reconstruction. The outer protection frame is once set and shaped in the early construction stage, the board wall reinforcement reconstruction is synchronous with the reconstruction of roof, outer wall, insulation and other reconstruction, and finally the foundation is excavated and constructed in sections, which greatly promotes the smooth development of the engineering project, significantly speeds up the construction period and avoids the delay of construction period. BRIEF DESCRIPTION OF DRAWINGS

[0082] The application will be further described in detail below with reference to the drawings.

[0083] Figure 1 is the structural schematic diagram of step one of the construction method of the application.

[0084] Figure 2 is the structural schematic diagram of step e completed in step two of the construction method of the application.

[0085] Figure 3 is the structural schematic diagram of step f completed in step two of the construction method of the application.

[0086] Figure 4 is the plan layout of Figure 3 .

[0087] Figure 5 is the perspective schematic diagram of Figure 3 .

[0088] Figure 6 is the structural schematic diagram of step g completed in step two of the construction method of the application.

[0089] Figure 7 is the structural schematic diagram of step h completed in step two of the construction method of the application. Figure 6 is the structural schematic diagram of step i completed in step two of the construction method of the application. Figure 1 .

[0090] Figure 8 is the structural schematic diagram of step j completed in step four of the construction method of the application. Figure 6 is the structural schematic diagram of step k completed in step four of the construction method of the application. Figure 2 .

[0091] Figure 9 is the structural schematic diagram of the completion of the insulation layer in step three of the construction method of the application.

[0092] Figure 10 is the structural schematic diagram of step j completed in step four of the construction method of the application.

[0093] Figure 11 is the structural schematic diagram of step k completed in step four of the construction method of the application.

[0094] Figure 12 is the local enlarged schematic diagram of Figure 11 .

[0095] Figure 13 is the structural schematic diagram of the step n of the step five of the construction method of the present application.

[0096] Figure 14 is the structural schematic diagram of the step n of the step five of the construction method of the present application.

[0097] Figure 15 is the structural schematic diagram of the step n of the step five of the construction method of the present application. Figure 14 is the structural schematic diagram of the step n of the step five of the construction method of the present application.

[0098] Figure 16 is the structural schematic diagram of the step n of the step five of the construction method of the present application.

[0099] Figure 17 is the structural schematic diagram of the step n of the step five of the construction method of the present application. Figure 16 is the structural schematic diagram of the step n of the step five of the construction method of the present application.

[0100] Figure 18 is the structural schematic diagram of the step n of the step five of the construction method of the present application.

[0101] Figure 19 is the structural schematic diagram of the step n of the step five of the construction method of the present application.

[0102] Figure 20 is the structural schematic diagram of the step n of the step five of the construction method of the present application.

[0103] Figure 21 is the structural schematic diagram of the step n of the step five of the construction method of the present application. Figure 20 is the structural schematic diagram of the step n of the step five of the construction method of the present application.

[0104] BRIEF DESCRIPTION OF DRAWINGS DETAILED DESCRIPTION

[0105] The embodiment is described in the following. Figure 20As shown, a kind of reverse construction method of multi-storey building concrete panel wall reinforcing structure, the multi-storey building concrete panel wall reinforcing structure, including the original wall body 1 to be reinforced, panel wall foundation 2, panel wall 3, insulation layer 4, outdoor terrace 5 and foundation backfill 6, the panel wall foundation 2 is close to the outer surface of the original wall body 1, i.e.the original wall surface, the panel wall foundation 2 supports the bottom of the panel wall 3, the bottom of the panel wall 3 is fixedly connected with the upper surface of the panel wall foundation 2, the panel wall 3 is integrally connected with the original wall body 1 by the tieback 7, the insulation layer 4 is fixedly laid on the outer surface of the panel wall 3, the panel wall 3 is divided into the first-stage reverse construction panel wall 31 of first construction and the second-stage reverse construction panel wall 32 of later construction according to the range of reverse construction stage; the elevation of the junction 8 of construction stage range is above the outdoor terrace 5 of the original wall body 1, and the reserved height is arranged between the outdoor terrace 5; the first-stage reverse construction panel wall 31 and the second-stage reverse construction panel wall 32 are connected as a whole.

[0106] The first-stage reverse construction panel wall 31 includes the first panel wall steel bar net 311 and the first panel wall concrete 312, and the second-stage reverse construction panel wall 32 includes the second panel wall steel bar net 321 and the second panel wall concrete 322, the vertical steel bars in the first panel wall steel bar net 311 are correspondingly arranged with the vertical steel bars of the second panel wall steel bar net 321 by extending downward beyond the junction of construction stage range, the two parts of vertical steel bars are overlapped in the reverse construction range below the junction, the upper half of the second-stage reverse construction panel wall 32 is located on the ground, and the lower half is located in the foundation pit 9 excavated in the reverse construction range, the vertical steel bars of the second panel wall steel bar net 321 are anchored into the panel wall foundation 2, and the outside of the panel wall foundation 2 is covered with the lower half of the second-stage reverse construction panel wall 32 by the foundation backfill 6.

[0107] The construction steps of the multi-storey building concrete panel wall reinforcing structure are as follows:

[0108] Step one, construction preparation;

[0109] Step a, processing the original wall body 1;

[0110] The processing of the original wall body includes structural processing and surface processing: the processing step is the key procedure of structural component reinforcement, which is the base treatment of the original wall body to be reinforced.

[0111] Structural processing: including replacing the damaged masonry brick wall of the original wall body, filling the holes and repairing the structural cracks; when replacing and filling, the loose bricks are removed, the holes are filled with new bricks, and the cracks are repaired by epoxy cement grouting.

[0112] Surface processing: removing the decorative layer of the original wall body, removing dust and pollutants, and watering one day in advance to make the wall fully wet.

[0113] Step b, determining the junction of the first-stage reverse construction and the second-stage reverse construction:

[0114] The parameters of the construction phase range intersection 8 include the step distance of the scaffold to be erected, the steel bar lap length between the two construction ranges, and the interface treatment method of the intersection. The intersection is determined by the parameters. The range above the intersection is the first reverse construction phase range, and the construction content of the range includes the work of the first reverse construction phase wall 31 above the intersection and the remaining structure reconstruction construction. The range below the intersection is the second reverse construction phase range, and the construction content of the range includes the foundation construction, the wall integration construction, and the second reverse construction phase wall 32 construction below the intersection.

[0115] Step c, measuring and positioning the parameters of the tie bar:

[0116] The tie bar 7 is connected to the original wall 1 in the form of a planted bar. The parameters include the spacing, drilling position, hole diameter, and drilling depth of the tie bar determined by force calculation and design, which ensure the bonding force of the tie bar with the subsequent construction of the wall steel mesh and wall concrete. Then, the tie bar is positioned and marked on the original wall surface treated in step a, and the position is required to be accurate.

[0117] The tie bar 7 is arranged in a plum blossom shape with a horizontal and vertical spacing of 600 mm, a diameter of 8 mm, and a vertical planting depth of 120 mm-180 mm in the original wall.

[0118] Step d, erecting double-row scaffolding: according to the construction schedule, determine the reinforced wall position, and erect double-row scaffolding 10 on the outdoor terrace 5 outside the original wall; facilitate the later wall reinforcement and remaining part reconstruction construction, and the frame body should meet the relevant specifications of the scaffolding construction, and the frame body horizontal distance, vertical distance, step distance, etc. parameters meet the actual construction needs. After completion, refer to Figure 1 .

[0119] First reverse construction phase construction: including the construction of the first reverse construction phase wall 31 and the remaining structure reconstruction construction, as follows:

[0120] Step two, first reverse construction phase wall construction:

[0121] Step e, construction of tie bar:

[0122] According to the parameters of the tie bar 7 designed in step c, drill holes in the original wall above the outdoor terrace. After drilling, immediately clean, wipe the hole wall with a brush, and blow the hole with compressed air. Then temporarily seal the hole with a clean object to prevent dust, sand, and other debris from falling in. Then, plant the tie bar 7 in the hole, and after completion, refer to Figure 2 .

[0123] Step f, construction of the first wall steel mesh:

[0124] In the first stage of the reverse construction, for the original wall that is not enough in bearing capacity or does not meet the requirements of anti-seismic, according to the design requirements, the steel bars or steel mesh are supplemented;

[0125] The first plate wall steel mesh binding requirements: the first plate wall steel mesh 311 is parallel to the original wall surface, when laying the steel mesh, the first vertical steel bar 31a is on the inside and the first horizontal steel bar 31b is on the outside;

[0126] The connection of the first plate wall steel mesh and the tie bar: the outer end of the tie bar 7 extends out of the first plate wall steel mesh 311 to form a hook, which is anchored with the first horizontal steel bar 31b;

[0127] The formation of the first stage lap steel bar: to ensure the effective connection of the underground foundation part and the upper reinforced plate wall, the first vertical steel bar 31a extends downward at the junction of the construction stage range to form the first stage lap steel bar 11, the reserved length of the first stage lap steel bar 11 needs to ensure the lap length of the second stage plate wall 32 of the reverse construction, to meet the steel bar lap and percentage requirements, after completion, refer to Figures 3-5 .

[0128] Step g, the construction of the first plate wall concrete:

[0129] The construction protection measures for the original wall surface in the second stage of the reverse construction range; then formwork pouring concrete or shotcrete; when using shotcrete, set the isolation structure 12 at the junction of the construction stage range, and the first plate wall concrete 312 is constructed upward from the isolation structure;

[0130] The protection measures for the original wall surface in the second stage of the reverse construction range: to avoid the pollution of the upper wall concrete construction to the bottom wall, the outer surface of the original wall is covered with a plastic protective film in advance to prevent the pollution of the first stage of the reverse construction to the original wall surface above the outdoor terrace 5 in the second stage of the reverse construction range, the plastic protective film is fixed with the original wall by steel nails to ensure the coverage of the original wall;

[0131] The isolation structure 12 is a wooden square formwork fixed on the tie bar or steel mesh, the length and width of the wooden square are not less than the size of the to-be-sprayed plate wall concrete, the gap between the wooden square and the original wall is filled with a leakage-proof steel wire mesh 16 to prevent the leakage of the concrete of the previously constructed part;

[0132] When using formwork pouring for the upper wall reinforcement construction, it is segmented along the height, and high-flowing concrete or non-vibrating concrete is used as much as possible, after the concrete pouring is completed, regular watering is carried out according to the requirements;

[0133] When using shotcrete, rapid compaction and smoothing are required before initial setting, and watering is started after final setting. After completion, refer to Figures 6-8 , and refer to Figures 7-8 for the concrete layered construction.

[0134] Step three, the remaining structure modification construction:

[0135] After the first board wall concrete 312 construction and maintenance are completed, without the need for secondary erection, directly using the double row scaffold 10 which has been erected, the remaining modification construction is completed synchronously: including the first board wall insulation layer 41 construction of the first board wall 31 outside of the reverse construction first stage, after completion, see Figure 9 , also including the replacement of doors and windows and the flat-to-slope conversion of the roof.

[0136] Reverse construction of the second stage, including foundation construction and integrated construction of the board wall at the junction, as follows:

[0137] Step four, foundation construction:

[0138] Step i, preparation before foundation pit excavation: along the surface of the original wall, excavate downward, and remove the double row scaffold 10 for the part of the outdoor terrace 5 below which needs to be excavated; before removing the scaffold, remove the materials, tools and sundries on the scaffold, and set up a warning zone and warning signs when removing the scaffold; before the foundation pit excavation, set up a warning zone in advance according to the excavation position, and assign a person to be responsible for the warning, and complete the preparation work before excavation.

[0139] Step j, foundation pit excavation by sections: excavate by sections and layers according to the resident walking route and daily life area, the cross section of the foundation pit 9 excavation is an inverted right angle trapezoid, after the foundation pit 9 excavation to the design elevation, the foundation cushion 13 construction is carried out; during the foundation pit excavation, the support structure should reach the design required strength, and the earthwork construction condition should meet the design requirements; after the foundation pit excavation to the design elevation, the cushion construction is carried out in time, after completion, see Figure 10 .

[0140] Step k, board wall foundation construction: after the foundation cushion 13 construction is completed, the board wall foundation 2 construction is carried out in the foundation pit 9, when the conditions permit, the board wall foundation 2 has the same depth as the existing foundation below the original wall, the board wall foundation 2 is provided with the second stage overlapping steel bars 14 which are embedded into the foundation at the bottom and vertically protrude out of the foundation surface at the top, the second stage overlapping steel bars 14 are arranged one by one corresponding to the first stage overlapping steel bars 11 up and down, the length of the second stage overlapping steel bars 14 is determined to ensure that the overlapping with the first stage overlapping steel bars 11 meets the design requirements, then the foundation concrete is poured and maintained;

[0141] The board wall foundation 2 is a reinforced concrete foundation beam arranged around the outside of the original wall, the foundation beam includes foundation beam steel bars and foundation beam concrete 24, the foundation beam steel bars include foundation longitudinal main steel bars 21, foundation transverse stirrup steel bars 22, foundation horizontal anchor steel bars 23 and vertical second stage overlapping steel bars 14,

[0142] The foundation longitudinal main steel bars 21 are arranged along the length direction of the foundation,

[0143] The foundation transverse stirrups 22 are arranged along the length direction of the foundation and are connected with the foundation longitudinal main stirrups 21 to jointly constitute the force bearing bars of the foundation beam,

[0144] The foundation horizontal anchor bars 23 are arranged along the length direction of the foundation, the inner half of the foundation horizontal anchor bars 23 is embedded in the original wall, and the outer half of the foundation horizontal anchor bars 23 extends out of the original wall surface and is fixed with the force bearing bars,

[0145] The bottom of the second stage lap bars 14 is pre-buried in the foundation beam and is connected with the force bearing bars, in order to ensure the effective connection between the underground foundation part and the upper wall, the anchor depth reaches the bottom of the foundation beam, and meanwhile, according to the diameter of the second stage lap bars 14, the lap percentage and other design requirements, sufficient length of the steel bars is reserved at the top of the foundation to facilitate the lap construction in the later period, and after completion, refer to Figures 11-12 .

[0146] Step five, integrated construction of the board wall at the junction:

[0147] Step m: remove the isolation structure 12 and the original wall surface construction protection measures, and clean and construct the joint surface of the reverse construction first stage board wall 32 and other components;

[0148] In the step m, the joint surface cleaning and construction includes cleaning of the joint surface of the concrete components in the reverse construction first stage construction range and cleaning of the joint surface of the components in the reverse construction second stage construction range,

[0149] The concrete components in the reverse construction first stage construction range include the reverse construction first stage board wall and the board wall foundation, and the cleaning steps are as follows:

[0150] Chiseling and cleaning: the joint surface is trimmed, the aggregate surface is exposed and chiseled or chiseled into a groove, and the surface is cleaned; after the joint surface is chiseled, loose aggregates, sand, dregs and dust on the surface of the original component concrete are removed by using a steel wire brush and the like, and are washed clean by clean pressure water; if shotcrete is used for reinforcement, it is washed clean by alternating compressed air and water;

[0151] Brushing of interface agent: before brushing of the interface agent, the treatment quality of the joint surface is reviewed, and then the interface agent is brushed on the joint surface; before brushing of the interface agent, the surface interface treatment quality of the original component is reviewed, and there should be no loose stones, floating sand, cracks and other dirt which are not removed or not repaired;

[0152] The components in the reverse construction second stage construction range include the second stage lap bars and the original wall surface, and the cleaning steps are as follows:

[0153] In order to ensure the force bearing effectiveness of the joint surface, the original wall surface in this range which is contaminated is cleaned and treated, is watered one day in advance to make the wall fully wet, and the contaminated part of the second stage lap bars is cleaned.

[0154] Step n, reinforcement binding: including lap reinforcement binding and second panel wall reinforcement net binding:

[0155] Lap reinforcement binding: the top end of the second stage lap reinforcement 14 is directly connected with the bottom end of the first stage lap reinforcement 11, or the two are connected as a whole through another lengthening reinforcement 15;

[0156] In the scope of the second stage construction in reverse, for the original wall that is insufficient in bearing capacity or does not meet the seismic requirements, according to the design requirements, the reinforcement or reinforcement net is supplemented;

[0157] Tie reinforcement binding: according to the parameters of the tie reinforcement 7 designed in step c, the original wall below the outdoor terrace is drilled, and then the tie reinforcement 7 is constructed by planting reinforcement in the hole; after completion, see Figure 13 .

[0158] Second panel wall reinforcement net binding: the second panel wall reinforcement net 321 is parallel to the original wall surface, the second vertical reinforcement 32a is on the inner side, and the second horizontal reinforcement 32b is on the outer side; wherein the second vertical reinforcement 32 includes the first stage lap reinforcement 11 and the second stage lap reinforcement 14 or the first stage lap reinforcement 11, the second stage lap reinforcement 14 and the lengthening reinforcement 15 in the scope of the construction; the embodiment structure constructed after step six through the lap method of the first stage lap reinforcement 11 and the second stage lap reinforcement 14 is shown in Figure 19 .

[0159] Connection between the second panel wall reinforcement net and the tie reinforcement: the outer end of the tie reinforcement 7 extends out of the second panel wall reinforcement net 321 to form a hook, which is hung and anchored with the second horizontal reinforcement 32b; after completion, see Figures 14-15 .

[0160] Step p, construction of the second stage panel wall in reverse:

[0161] Construction method of the second panel wall concrete: formwork pouring concrete or spraying concrete, so that the first panel wall concrete 312 in step g and the second panel wall concrete 322 in step p and the foundation concrete form an integral whole; after completion, see Figures 16-17 .

[0162] Step six, remaining structure reconstruction construction:

[0163] After the construction and maintenance of the second panel wall concrete 322 are completed, the second panel wall insulation layer 42 construction on the outer side of the panel wall in the scope of the construction is completed; after completion, see Figure 18 .

[0164] Step seven, pit backfill: after the completion of the whole panel wall reinforcement reconstruction, the foundation backfill soil 6 of the foundation pit 9 is constructed, and after the construction is completed, it is flush with the original outdoor ground 5; the filling should be layered, the thickness of each layer is determined according to the soil quality, compaction degree requirement and machine performance, and after completion, see Figures 20-21

[0165] In steps f and n, the first vertical steel bars 31a and the second vertical steel bars 32a are the same in size and spacing, with a diameter of 8mm-12mm and a spacing of 150mm-200mm, and the first horizontal steel bars 31b and the second horizontal steel bars 32b are also the same in size and spacing, with a diameter of 6mm-8mm and a spacing of 150mm-200mm.

[0166] The requirements for main materials of the application are as follows:

[0167] I. Concrete:

[0168] Performance requirements: considering that the elastic modulus of concrete and brick masonry is quite different, the strength grade of concrete should not be too high, and the concrete is tested and matched according to the design requirements, the strength grade of concrete should be C20 and above; when the upper wall reinforcement construction is carried out by the formwork and pouring method, the height is segmented, and high-flowing concrete or vibration-free concrete is used as much as possible; the concrete mixing ratio is optimized to ensure the bonding strength of concrete and steel bars.

[0169] That is, the first panel wall concrete 312 and the second panel wall concrete 322 are the same, and the strength grade is C20 or above.

[0170] II. Coarse and fine aggregates: the types and quality of coarse and fine aggregates for preparing the concrete for structural reinforcement should meet the following requirements:

[0171] The maximum particle size of coarse aggregate:

[0172] Not more than 20mm for mixed concrete;

[0173] Not more than 12mm for sprayed concrete;

[0174] Not more than 10mm for concrete mixed with short fibers;

[0175] The fine aggregate is medium and coarse sand, and the fineness modulus is not less than 2.5.

[0176] III. Steel bars: the types, specifications and performance of steel bars for structural reinforcement should meet the design requirements.

[0177] Longitudinal load-bearing steel bars: the strength test value should meet the current national standard;

[0178] ​Strengthening stress steel: In any case, the recycled steel and steel unknown number of steel should not be used. The reinforcing steel should be straight, no damage, the surface should not have cracks, oil stains and granular or sheet rust, and the bending steel should not be used as a stress bar after being straightened.

[0179] Four, structural interface agent: concrete structural interface glue, also known as structural interface agent, uses modified epoxy interface agent, or other varieties of interface agent confirmed by independent testing institutions as having equivalent efficacy.

[0180] The construction quality control and safety measures of the present application are as follows:

[0181] I. During the drilling and steel bar planting construction process, the following provisions should be followed:

[0182] During the drilling construction of the wall reinforcement, the drilling should be straight and perpendicular to the structure surface as much as possible. The hole wall after drilling should be intact without cracks and honeycombs, and the drilling hole diameter should be 4-6mm larger than the embedded steel bar diameter. The drilling depth must meet the design requirements. During the base tie bar construction, the tie bar spacing should be controlled according to the positioning and drilling position. During the base tie bar construction, the steel bar should be first tested physically, and the mechanical method or steel wire brush should be used to remove the rust and oxidation layer on the surface of the steel bar. Then, the treated steel bar should be embedded in the hole as soon as possible to avoid recontamination. The surface of the embedded steel bar should be clean to increase the adhesion of the structural adhesive.

[0183] II. During the construction of the wall steel mesh, the following provisions should be followed:

[0184] During the ground wall reinforcement and foundation part steel bar binding, sufficient length should be reserved according to the design requirements. During the laying of the steel mesh, the steel mesh should be fixed flat and firmly on the wall surface, with vertical steel bars inside. The outer protective layer thickness of the steel mesh should be ≥25mm.

[0185] III. During the construction of the wall reinforcement concrete, the following provisions should be followed:

[0186] The wall can be formwork poured or use the shotcrete process to ensure that the wall top and floor intersection concrete is dense. After pouring, the maintenance should be strengthened. Within 6h after the completion of concrete construction at room temperature, reliable moisture conservation measures should be taken, and the maintenance time should be not less than 7d. During the reinforcement of the reinforced concrete wall, considering the large difference in elastic modulus between concrete and brick masonry, the strength grade of concrete should not be too high, generally ≥C20, and the thickness should not be too large, which is required to be 80mm-140mm.

[0187] The shotcrete should be rapidly compacted and smoothed before initial setting, and water curing should be started after final setting. The surface should be kept wet during the curing period, which should last for at least 7 days. The rebound and actual mix proportion of the shotcrete should be measured in time to guide the construction. The shotcrete should be applied in sections and layers from bottom to top. The width of each section should be 1.5-2.0 m, and the thickness of each layer should be less than 70 mm. The height of each layer should be less than 2.0 m. The upper isolation structure should be fixed firmly during the construction, and the gaps should be filled with steel mesh to prevent leakage.

[0188] The rebound of the shotcrete should be reduced, and the rebounded materials should be recycled.

[0189] The following measures should be taken to reduce the dust concentration during the construction of the shotcrete:

[0190] A water curtain should be set up in the area with high dust concentration. The local ventilation in the working area should be strengthened. Dust collectors or dust removers should be set up near the shotcrete equipment or the mix agitator.

[0191] The water content of the aggregate and the adhesion enhancer should be increased for the dry-mixed shotcrete, provided that the sprayability of the shotcrete is ensured.

[0192] The wet-mixed shotcrete should be used when the construction area is located in a residential area. The noise reduction measures should be taken for the on-site agitator and air compressor to reduce the noise of the machines.

[0193] Four, the following provisions should be followed during the excavation of the foundation pit:

[0194] Five, the following provisions should be followed during the connection of the ground slab wall and the foundation:

[0195] The interface treatment of the concrete should be carried out after the treatment of the interface of the concrete is completed. The interface of the concrete should be smoothed to expose the aggregate, and the interface should be roughened with a tool. If necessary, a groove can be made. The interface of the original concrete should be coated with a structural interface agent according to the design requirements. Before the coating of the structural interface agent, the quality of the interface treatment of the original component should be reviewed to ensure that there are no loose stones, floating sand, unsealed cracks, and other impurities.

[0196] Six, the following provisions should be followed during the excavation and backfilling of the foundation: The excavation and backfilling should be carried out in sections to avoid dust and pollution of the road surface.

Claims

1. A reverse construction method for reinforcing existing multi-story concrete slab wall structures, characterized in that: The existing multi-story building concrete slab wall reinforcement structure includes the original wall to be reinforced (1), slab wall foundation (2), slab wall (3), insulation layer (4), outdoor ground (5), and foundation backfill soil (6). The slab wall foundation (2) is close to the outer surface of the original wall (1), i.e., the original wall surface. The slab wall foundation (2) supports the bottom of the slab wall (3). The bottom of the slab wall (3) is fixedly connected to the upper surface of the slab wall foundation (2). The slab wall (3) and the original wall (1) are connected as a whole by tie bars. (7) Connecting, the insulation layer (4) is laid flat and fixed on the outer surface of the panel wall (3). The panel wall (3) is divided into the first stage panel wall (31) and the second stage panel wall (32) according to the scope of the reverse construction stage. The elevation of the boundary (8) of the construction stage is above the outdoor ground level (5) of the original wall (1), and a reserved height is set between it and the outdoor ground level (5). The first stage panel wall (31) and the second stage panel wall (32) are connected as one unit. The first stage of the reverse construction slab wall (31) includes a first slab wall steel mesh (311) and a first slab wall concrete (312). The second stage of the reverse construction slab wall (32) includes a second slab wall steel mesh (321) and a second slab wall concrete (322). The vertical steel bars in the first slab wall steel mesh (311) extend downward beyond the boundary of the construction stage and are set one-to-one with the vertical steel bars of the second slab wall steel mesh (321). The two parts of vertical steel bars overlap in the second stage of the reverse construction below the boundary. The upper half of the second stage of the reverse construction slab wall (32) is located on the ground, and the lower half is located in the foundation pit (9) excavated in the second stage of the reverse construction. The vertical steel bars of the second slab wall steel mesh (321) are anchored downward into the slab wall foundation (2). The exterior of the slab wall foundation (2) and the lower half of the second stage of the reverse construction slab wall (32) are covered by foundation backfill soil (6). The construction steps for reinforcing existing multi-story building concrete slab walls are as follows: Step 1: Construction preparation; Step a, process the original wall (1); Step b, determine the boundary between the construction areas of the first and second stages of reverse construction: The parameters for determining the boundary (8) of the construction phase range include the step distance of the scaffold to be erected, the lap length of the steel reinforcement between the two construction ranges, and the interface treatment method at the boundary. The boundary is determined by the parameters. The area above the boundary is the first stage of reverse construction. The construction content of this area includes the construction of the first stage of reverse construction slab wall (31) above the boundary and the remaining structural modification construction. The area below the boundary is the second stage of reverse construction. The construction content of this area includes the foundation construction, slab wall integrated construction and the second stage of reverse construction slab wall (32) construction below the boundary. Step c, measure the parameters of the positioning tie bar: The tie bar (7) is connected to the original wall (1) by means of anchoring. The parameters include the spacing, drilling position, hole diameter and drilling depth of the tie bar determined by the stress calculation design. The parameters ensure the bonding force between the tie bar and the subsequent construction of the wall reinforcement mesh and the wall concrete. Then, the original wall surface treated in step a is laid out, positioned and marked. Step d, erect double-row scaffolding: erect double-row scaffolding (10) on the outdoor ground (5) outside the original wall. Construction of the first stage of reverse construction: including the construction of the first stage of reverse construction panel wall (31) and the remaining structural modification construction, as follows: Step 2, First stage of reverse construction of the panel wall: Step e, construct the tie bars: Drill holes in the original wall above the outdoor ground level according to the tie bar (7) parameters designed in step c, and then install tie bars (7) in the holes. Step f, Construction of the steel reinforcement mesh for the first slab wall: Within the first stage of reverse construction, for existing walls with insufficient bearing capacity or that do not meet seismic requirements, steel bars or steel mesh shall be added according to design requirements. Requirements for binding the first wall reinforcement mesh: The first wall reinforcement mesh (311) is parallel to the original wall surface, the first vertical reinforcement (31a) is on the inside, and the first horizontal reinforcement (31b) is on the outside; Connection between the first wall reinforcement mesh and the tie bar: The outer end of the tie bar (7) extends out of the first wall reinforcement mesh (311) to form a hook, which is hooked and anchored to the first horizontal reinforcement bar (31b); Formation of the first stage lapped reinforcement: The first vertical reinforcement (31a) extends downward at the boundary of the construction stage to form the first stage lapped reinforcement (11). The reserved length of the first stage lapped reinforcement (11) must ensure the lap length with the second stage slab wall (32) of the reverse construction, and meet the requirements of reinforcement lap and percentage. Step g, Construction of the first concrete slab: Protective measures for the original wall surface within the construction scope of the second stage of reverse construction; then formwork is erected and concrete or shotcrete is poured; when shotcrete is used, an isolation structure (12) is set at the boundary of the construction stage scope, and the first wall concrete (312) is constructed upward from the isolation structure; Step 3, construction of the remaining structural modifications: After the first concrete panel (312) is constructed and cured, there is no need for secondary erection. The existing double-row scaffolding (10) can be used directly to complete the remaining renovation construction at the same time: including the construction of the first insulation layer (41) on the outside of the first stage panel (31) of the reverse construction, as well as the replacement of doors and windows and the roof flat to pitch conversion. The second phase of reverse construction includes foundation construction and integrated construction of the junction wall panels, as detailed below: Step 4, Foundation Construction: Step i, preparation before excavation of the foundation pit: excavate downward along the surface of the original wall, and dismantle the double-row scaffolding (10) for the part to be excavated below the outdoor ground level (5); Step j, segmented excavation of the foundation pit: according to the residents' walking routes and daily living areas, the foundation pit (9) is excavated in segments and layers. The cross-section of the foundation pit (9) is an inverted right trapezoid. After the foundation pit (9) is excavated to the design elevation, the foundation cushion layer (13) is constructed. Step k, construction of the slab wall foundation: After the foundation pad (13) is completed, the slab wall foundation (2) is constructed in the foundation pit (9). The burial depth of the slab wall foundation (2) is the same as the existing foundation below the original wall. The slab wall foundation (2) is equipped with a second-stage lap bar (14) that is buried in the foundation at the bottom and extends vertically out of the foundation surface at the top. The second-stage lap bar (14) is set up one-to-one with the first-stage lap bar (11) in step f. The length of the second-stage lap bar (14) is based on ensuring that the lap with the first-stage lap bar (11) meets the design requirements. Then, the foundation concrete is poured and cured. Step 5, Integrated construction of the wall panels at the junction: Step m: Remove the isolation structure (12) and the original wall surface construction protection measures, and clean the joint surface between the second stage of the reverse construction panel wall (32) and other components; Step n, rebar tying: including tying lapped rebars and tying the second wall panel rebar mesh: Lap reinforcement binding: The top of the second stage lap reinforcement (14) is directly connected to the bottom of the first stage lap reinforcement (11) to form a whole, or the two are connected end to end by another extension reinforcement (15); Second wall reinforcement mesh binding: Within the construction scope of the second stage of reverse construction, for the original wall with insufficient bearing capacity or that does not meet the seismic requirements, reinforcement bars or reinforcement mesh shall be added according to the design requirements. Tie bar binding: Drill holes in the original wall below the outdoor ground level according to the tie bar (7) parameters designed in step c, and then install tie bars (7) in the holes; The second wall reinforcement mesh is tied: the second wall reinforcement mesh (321) is parallel to the original wall surface, the second vertical reinforcement (32a) is on the inside, and the second horizontal reinforcement (32b) is on the outside; wherein the second vertical reinforcement (32a) includes the first stage lap reinforcement (11) and the second stage lap reinforcement (14) within the construction area or the first stage lap reinforcement (11), the second stage lap reinforcement (14) and the extension reinforcement (15). Connection between the second wall reinforcement mesh and the tie bar: The outer end of the tie bar (7) extends out of the second wall reinforcement mesh (321) to form a hook, which is hooked and anchored to the second horizontal reinforcement bar (32b); Step p, construction of the second stage of the reverse construction of the panel wall: Construction method of the second wall concrete: formwork and pour concrete or spray concrete, so that the first wall concrete (312) in step g, the second wall concrete (322) in step p, and the foundation concrete form a whole. Step Six: Construction of the remaining structural modifications: After the construction and curing of the second concrete panel (322) is completed, the construction of the second insulation layer (42) on the outside of the panel wall within the construction area is completed; Step 7, backfilling the foundation pit: After the entire reinforcement and renovation of the wall is completed, the foundation pit (9) will be backfilled with soil (6). After the construction is completed, it will be flush with the original outdoor ground level (5).

2. The reverse construction method for reinforcing existing multi-story concrete slab walls according to claim 1, characterized in that: In step k, the wall foundation (2) is a reinforced concrete foundation beam set around the outer side of the original wall. The foundation beam includes foundation beam reinforcement and foundation beam concrete. The foundation beam reinforcement includes foundation longitudinal main reinforcement (21), foundation horizontal stirrups (22), foundation horizontal anchor bars (23), and vertical second-stage lap reinforcement (14). The longitudinal main reinforcement (21) of the foundation is arranged along the length of the foundation. The horizontal stirrups (22) are arranged at intervals along the length of the foundation and connected with the longitudinal main reinforcement (21) to form the reinforcing bars of the foundation beam. The foundation horizontal anchor bars (23) are arranged at intervals along the length of the foundation. The inner half of the foundation horizontal anchor bars (23) is embedded in the original wall, and the outer half of the foundation horizontal anchor bars (23) extends out of the original wall and is tied and fixed to the reinforcing bars. The bottom of the second-stage lap bar (14) is pre-embedded in the foundation beam and connected with the reinforcing bar, with the anchorage depth extending to the bottom of the foundation beam.

3. The reverse construction method for reinforcing existing multi-story concrete slab walls according to claim 1, characterized in that: In step m, the joint surface cleaning construction includes cleaning the joint surfaces of concrete components within the first stage of reverse construction and cleaning the joint surfaces of components within the second stage of reverse construction. The concrete components within the scope of the first stage of reverse construction include the first stage of reverse construction slab walls and slab wall foundations. The cleaning steps are as follows: Chiseling and cleaning: The mating surfaces need to be trimmed to expose the aggregate surface and chiseled or grooved, and the surface needs to be cleaned. Applying interface agent: Before applying the structural interface agent, re-inspect the quality of the bonding surface treatment, and then apply the structural interface agent to the bonding surface. The components within the scope of the second stage of reverse construction include the second stage lapped reinforcement bars and the original wall surface. The cleaning steps are as follows: The contaminated original wall surface in this area was cleaned, and water was poured on it one day in advance. At the same time, the contaminated parts of the lap joints in the second stage were cleaned.

4. The reverse construction method for reinforcing existing multi-story building concrete slab walls according to claim 1, characterized in that: In step g, the isolation structure (12) is a wooden bottom formwork fixed to the tie bar or steel mesh. The length and width of the wooden formwork are not less than the size of the concrete to be sprayed on the wall panel. The gap between the wooden formwork and the original wall surface is filled with a leak-proof wire mesh (16).

5. The reverse construction method for reinforcing existing multi-story concrete slab walls according to claim 1, characterized in that: The treatment of the original wall in step a includes structural treatment and surface treatment: Structural treatment includes replacing damaged masonry brick walls, filling holes, and repairing structural cracks. Surface treatment: Remove the original decorative layer of the wall, remove dust and contaminants, and wet the surface with water one day in advance.

6. The reverse construction method for reinforcing existing multi-story building concrete slab walls according to claim 1, characterized in that: The protection measures for the original wall surface within the scope of the second stage of reverse construction in step g are as follows: the outer surface of the original wall surface is covered in advance with a plastic protective film to prevent the original wall surface above the outdoor ground level within the scope of the second stage of reverse construction from being contaminated by the first stage of reverse construction of the panel wall. The plastic protective film is fixed to the original wall with steel nails.

7. The reverse construction method for reinforcing existing multi-story building concrete slab walls according to claim 1, characterized in that: In step c, the tie bars (7) are arranged in a plum blossom pattern with a horizontal and vertical spacing of 600mm, with a diameter of 8mm, and are vertically embedded into the original wall to a depth of 120mm-180mm.

8. The reverse construction method for reinforcing existing multi-story concrete slab walls according to claim 1, characterized in that: In steps f and n, the first vertical steel bar (31a) and the second vertical steel bar (32a) have the same size and spacing, with a diameter of 8mm-12mm and a spacing of 150mm-200mm. The first horizontal steel bar (31b) and the second horizontal steel bar (32b) also have the same size and spacing, with a diameter of 6mm-8mm and a spacing of 150mm-200mm.

9. The reverse construction method for reinforcing existing multi-story concrete slab walls according to claim 1, characterized in that: The first wall panel concrete (312) and the second wall panel concrete (322) are the same, with a strength grade of C20 or higher; Maximum particle size of coarse aggregate: For mixed concrete, the thickness should not exceed 20mm; For shotcrete, the thickness should not exceed 12mm; For concrete with added short fibers, the fiber length should not exceed 10mm; The fine aggregate is medium to coarse sand with a fineness modulus of not less than 2.5.

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