In-situ flipping construction method for brick-concrete building by using existing brick soil retaining outer wall

Abstract

The invention discloses a brick-concrete building in-situ flip construction method using an existing brick soil retaining outer wall. The method comprises the steps that firstly, systematic diagnosis and digital modeling are conducted on an original structure; secondly, other internal structures except the bearing columns are dismantled layer by layer from top to bottom and transported out of the building, and deep interface treatment is conducted on the inner sides of the brick walls; thirdly, when part of the internal structure is dismantled, a temporary support is constructed in time at the dismantling position; fourthly, an original foundation is reinforced; 5, reconstructing a structural system layer by layer from bottom to top, performing embedded composite bar planting on the brick masonry subjected to interface treatment, connecting the brick masonry with a new structural frame, and then performing integrated pouring; and 6, dismantling the temporary support of the upper layer along with the construction progress layer by layer, and monitoring the health state of the brick wall. According to the construction method, the original soil retaining outer wall which has important functions and is extremely high in dismantling risk is completely reserved, and thousands of tons of construction waste and corresponding new material consumption are avoided.

Description

Technical Field

[0001] This invention relates to the field of building repair and renovation technology, specifically to a method for in-situ reconstruction of brick-concrete buildings using existing brick retaining walls. Background Technology

[0002] Many mountain roads and old town streets have brick-concrete houses built in the last century that are close to the embankment and are in urgent need of renovation.

[0003] This type of architecture has two main characteristics: Firstly, its outer wall on the side facing the road directly bears the lateral earth pressure of the embankment fill, and is essentially a structure that integrates load-bearing and earth-retaining functions. Secondly, the space around the building is narrow, and the working space is extremely limited.

[0004] Traditional renovation methods are essentially of two types: one is "demolition and reconstruction," which involves first setting up a temporary retaining structure, then completely demolishing the old building and rebuilding. This method is costly, time-consuming, and has a significant impact on the passage of adjacent roads. The other is "partial reinforcement and renovation," which involves repairing and reinforcing the interior. However, due to the inherent weaknesses of the original brick-concrete structure, it is impossible to achieve a fundamental improvement in spatial layout, functionality, and safety. Summary of the Invention

[0005] To address the technical problems mentioned above, this invention provides a method for in-situ reconstruction of brick-concrete buildings using existing brick retaining walls.

[0006] The technical solution of this invention is as follows: A method for in-situ reconstruction of a brick-concrete building utilizing an existing brick retaining wall includes the following steps: Step 1: Conduct a systematic diagnosis and digital modeling of the original structure; Step two: Remove the remaining internal structure, except for the load-bearing columns, layer by layer from top to bottom, transport it outside the building, and perform deep interface treatment on the inside of the brick wall; Step 3: After each section of the internal structure is demolished, temporary supports should be constructed at the demolition location in a timely manner. Step four: Reinforce the original foundation; Step 5: Reconstruct the structural system layer by layer from bottom to top, embed composite rebars on the brick masonry with the interface treated, connect them with the new structural frame, and then cast the concrete in one piece. Step 6: As construction progresses, remove the temporary supports of the previous layer one by one and monitor the health of the brick wall.

[0007] In step two, when demolishing the internal structure of the current floor of the building, static demolition equipment is used to demolish the secondary components first, and then the main components.

[0008] Furthermore, in step two, the deep interface treatment involves using a high-pressure water gun to flush the wall surface, exposing the solid brick base, repairing the cracks in the brick masonry with pressure grouting, and applying an interface treatment agent to the brick wall surface.

[0009] In one implementation method, in step three, the temporary support includes frame columns and frame beams, with the frame beams connecting the wall and the load-bearing columns, and the frame columns vertically connected to the frame beams.

[0010] Preferably, a hydraulic support is also provided between the wall and the temporary support, or between the wall and the load-bearing column.

[0011] In one implementation method, in step four, the foundation is excavated downwards on both sides to below the original brick and stone foundation, anchor rods are inserted and concrete is poured to reinforce the foundation.

[0012] In one implementation method, step five involves embedding composite rebar, which means drilling holes in the treated brick wall surface, cleaning the holes, injecting repair mortar, and then inserting connecting rebars with ribbed surfaces coated with a nano-silicon-based active coating. Self-compacting micro-expansion concrete is then poured. This concrete has excellent fluidity, fully filling all the voids on the rough surface of the brick wall. Furthermore, its micro-expansion properties generate slight self-stress during hardening, actively compressing the interface between the old and new sections, significantly improving shear resistance.

[0013] Furthermore, in step five, the new structural frame includes newly tied columns and beams, with the new beams connected to the steel bars embedded in the brick wall.

[0014] In one implementation method, in step six, when removing the temporary supports of the upper layer one by one, the supporting force of the hydraulic supports is gradually reduced first, and the health status of the brick wall is monitored. Then, the temporary supports are removed symmetrically, and the secondary supports are removed first, followed by the main supports.

[0015] As one preferred embodiment, the present invention also includes a brick wall health monitoring system, including strain sensors and tilt sensors pre-embedded in the outer wall, pressure sensors installed in the foundation, and pressure sensors installed between the hydraulic support and the wall surface. Each sensor transmits data to the central monitoring platform via a wireless transmission module.

[0016] Through the above design, the present invention provides a method for in-situ reconstruction of brick-concrete buildings utilizing existing brick retaining walls, which, compared with the prior art, has the following advantages: (1) Safety is mentioned. This invention actively controls construction risks through "intelligent temporary support + real-time monitoring" and achieves reliable connection between new and old materials through "composite rebar system + self-compacting micro-expansion concrete", solving the problem of weak connection in brick-concrete structure renovation.

[0017] (2) The renovation method is green and low-carbon, with significant social benefits. This invention completely preserves the original retaining wall, which has important functions and is at high risk of demolition, thus avoiding the generation of thousands of tons of construction waste and the corresponding consumption of new materials, which is in line with the concept of green construction and sustainable development.

[0018] Moreover, the construction is confined to the interior of the existing brick-concrete buildings, which greatly reduces the impact on external road traffic. The construction period can be shortened by about 40% compared with the traditional demolition and reconstruction method, and the overall cost is reduced by about 25%, providing an economical and feasible technical path for the renovation of a large number of similar old buildings. Attached Figure Description

[0019] In the attached diagram: Figure 1 This is a schematic diagram of the construction scenario of the present invention. Detailed Implementation

[0020] See Figure 1 This embodiment provides a method for in-situ reconstruction of a brick-concrete building using an existing brick retaining wall, specifically including the following steps: Step one involves a systematic diagnosis and digital modeling of the original structure to confirm its condition and determine whether in-situ overhaul is feasible. The diagnostic focus includes: 1) The compressive strength, weathering degree, existing crack distribution and development history of the brick retaining wall; 2) The original building foundation form, depth and current status are assessed using data to determine which parts can be reused and which parts must be renovated to achieve functional remodeling, thereby determining a comprehensive utilization plan; 3) Embankment fill properties, slope gradient, and vehicle dynamic load parameters. A precise point cloud model of the building is obtained using 3D laser scanning technology and imported into the BIM platform to create a digital twin foundation model that includes existing defects, providing a precise basis for subsequent design.

[0021] 4) Adjust the comprehensive utilization plan based on the impact of road operation parameters.

[0022] Step two: Remove the remaining internal structure, except for the load-bearing columns, layer by layer from top to bottom, transport it outside the building, and perform deep interface treatment on the inside of the brick wall; Specifically, the demolition height for each floor is controlled between 2.8 and 3.2 meters. When demolishing the internal structure of the current floor, static demolition equipment such as hydraulic shears, diamond wire saws, and disc saws are used. The demolition sequence is to demolish secondary components first, and then demolish the main components.

[0023] During demolition, care should be taken to protect the horizontal reinforcing bars connected to the walls, and direct cutting is prohibited. First, remove the non-structural components of the roof. Then, use a diamond wire saw or disc saw to perform non-destructive static cutting to separate the connection between the floor slab and the exterior wall, avoiding violent vibrations to the brick wall. During demolition, the structure should be divided into sections as much as possible; the entire structure must not be demolished without proper partitioning. Demolish the floor slabs, interior walls, stairs, etc., layer by layer. Construction waste generated during demolition should be transported out through pre-designated vertical channels to minimize the occupation of confined spaces.

[0024] Furthermore, the deep interface treatment involves using a high-pressure water gun to flush the wall surface. The pressure of the high-pressure water gun is between 10-15 MPa to remove the floating dust, efflorescence layer and old plaster layer on the wall surface, exposing the structural column steel bars or tie bars inside the original brick wall.

[0025] Then, pressure grouting was used to repair the cracks in the brick masonry. Epoxy grout was used for cracks less than 0.3 mm wide, and polymer cement grout was used for cracks wider than 0.3 mm wide.

[0026] Then, apply an interface treatment agent to the brick wall surface. The interface treatment agent can be an acrylic polymer emulsion. The coating thickness is 0.8-1.2mm. After application, let it stand for 12-24 hours to ensure that the interface treatment agent is fully penetrated and cured.

[0027] Step 3: After each section of the internal structure is demolished, temporary supports should be constructed at the demolition location in a timely manner. As one implementation method, temporary supports include frame columns and frame beams. The frame beams connect the wall surface to the load-bearing columns, and the frame columns are vertically connected to the frame beams. Through the design of the frame columns and frame beams, after the internal structure of the building is demolished, the beams and columns in their original positions are replaced by temporary supports to continue supporting the exterior walls.

[0028] Preferably, a hydraulic support is also provided between the wall and the temporary support, or between the wall and the load-bearing column.

[0029] Step four: Reinforce the original foundation; As one implementation method, the soil is excavated downwards on both sides of the original foundation to below the original masonry foundation, and then anchored to the original foundation and the deep stable strata by full-length bonded prestressed anchor rods implanted at the bottom of the foundation, forming a "joint load-bearing body of the old and new foundations".

[0030] Step 5: Reconstruct the structural system layer by layer from bottom to top, embed composite rebars on the brick masonry with the interface treated, connect them with the new structural frame, and then cast the concrete in one piece. In this embodiment, embedded composite rebar installation refers to drilling holes in the treated brick wall surface, cleaning the holes, injecting repair mortar, and then inserting connecting rebars with ribbed surfaces coated with a nano-silicon-based active coating. Self-compacting micro-expansion concrete is used for pouring. This concrete has excellent fluidity, fully filling all voids on the rough surface of the brick wall. Its micro-expansion properties generate slight self-stress during hardening, actively compressing the interface between the old and new sections, significantly improving shear resistance.

[0031] Specifically, the composite rebar uses basalt fiber reinforced polymer rebar with a diameter of 16-25mm.

[0032] The preferred drilling location is the middle of the brick. A diamond core drill should be used, with the hole diameter 4-6mm larger than the diameter of the rebar. The drilling depth should be 15-20 times the diameter of the rebar, and the verticality deviation of the drilling should not exceed 0.5%.

[0033] After drilling is completed, the hole is cleaned in three steps: high-pressure air blowing, acetone solution rinsing, and drying. The water content in the hole is controlled to be below 3%.

[0034] After cleaning the hole, a high-flow, non-shrink composite epoxy repair mortar is injected into the hole. This mortar has excellent permeability and can penetrate into the micro-cracks of the surrounding bricks to form a reinforced zone of "mortar-brick" composite material.

[0035] Before the repair mortar initially sets, connecting steel bars with special ribs and a nano-silica-based active coating are inserted. After insertion, the coating reacts chemically with the repair mortar, forming a chemical coupling layer far stronger than ordinary physical bonding. This connection system ensures that, under extreme conditions, the steel bar yields before the bond fails.

[0036] Preferably, the mortar injection volume is 80%-90% of the borehole volume. After the rebar is inserted, it is rotated and squeezed to ensure that the mortar layer is uniform and free of air bubbles.

[0037] Furthermore, the new structural frame of the present invention includes newly tied new columns and new beams. The new beams are connected to the steel bars planted on the brick wall surface using equal-strength straight threaded sleeves to ensure smooth force transmission.

[0038] When the new structural frame is poured as an integrated unit with the old wall, a flexible water-conducting layer is first laid between the brick wall and the new structural frame. Then, the formwork is erected, and C40-C50 self-compacting concrete is used for pouring. The concrete spread is not less than 700mm, the inverted cone flow time is not more than 20 seconds, the initial setting time is not less than 8 hours, and the final setting time is not more than 12 hours.

[0039] The pouring sequence is columns first, then beams, and then slabs. A layered pouring method is adopted, with each layer not exceeding 500mm in thickness. An immersion vibrator is used for compaction, with a compaction time of 20-30 seconds per point and a compaction spacing of no more than 400mm to avoid under-vibration and over-vibration.

[0040] Cover and moisturize the concrete within 12 hours after pouring, and cure for no less than 14 days. During the curing period, the temperature difference between the concrete surface and the ambient temperature shall not exceed 25℃.

[0041] Step 6: As construction progresses, remove the temporary supports of the previous layer one by one and monitor the health of the brick wall.

[0042] As one implementation method, when removing the temporary supports of the upper layer layer by layer, the supporting force of the hydraulic supports is gradually reduced, with the unloading amount at each level being 10%-15% of the total supporting force, and the health status of the brick wall is monitored. Then, the temporary supports are removed symmetrically, with secondary supports removed first and then main supports removed. The stress and strain changes of the external wall are monitored immediately after each support component is removed to ensure the structural safety and stability.

[0043] As one preferred embodiment, the present invention also includes a brick wall health monitoring system, comprising several sensors, a data acquisition and transmission module, and a data analysis and early warning module.

[0044] The sensors include strain sensors and tilt sensors pre-embedded every 3-5m inside the exterior wall, 2-4 settlement observation points on each floor, pressure sensors installed in the foundation, and pressure sensors installed between the hydraulic supports and the wall. Each sensor transmits data to the central monitoring platform via a wireless transmission module.

[0045] Data is collected once per hour under normal operating conditions and once every 15 minutes under extreme weather conditions (heavy rain, strong winds). The data is uploaded to the central monitoring platform in real time via a wireless transmission module. The data analysis module uses machine learning algorithms to establish a structural health assessment model. When the monitoring data exceeds the warning threshold, such as strain ≥1500με, tilt angle ≥0.1°, or settlement ≥5mm, the system automatically issues an audible and visual alarm and generates emergency handling suggestions.

[0046] When dismantling the internal structure in step two, it is important to monitor that the horizontal displacement of the brick wall does not exceed 5mm and the vertical settlement of the foundation does not exceed 3mm.

Claims

1. A method for in-situ reconstruction of a brick-concrete building utilizing an existing brick retaining wall, characterized in that, Includes the following steps: Step 1: Conduct a systematic diagnosis and digital modeling of the original structure; Step two: Remove the remaining internal structure, except for the load-bearing columns, layer by layer from top to bottom, transport it outside the building, and perform deep interface treatment on the inside of the brick wall; Step 3: After each section of the internal structure is demolished, temporary supports should be constructed at the demolition location in a timely manner. Step four: Reinforce the original foundation; Step 5: Reconstruct the structural system layer by layer from bottom to top, embed composite rebars on the brick masonry with the interface treated, connect them with the new structural frame, and then cast the concrete in one piece. Step 6: As construction progresses, remove the temporary supports of the previous layer one by one and monitor the health of the brick wall.

2. The construction method according to claim 1, characterized in that, In step two, when demolishing the internal structure of the current floor of the building, static demolition equipment is used to demolish the secondary components first, and then the main components.

3. The construction method according to claim 2, characterized in that, In step two, the deep interface treatment involves using a high-pressure water gun to flush the wall surface, exposing the solid brick base, repairing the cracks in the brick masonry with pressure grouting, and applying an interface treatment agent to the brick wall surface.

4. The construction method according to claim 2 or 3, characterized in that, In step three, the temporary support includes frame columns and frame beams. The frame beams connect the wall and the load-bearing columns, and the frame columns are vertically connected to the frame beams.

5. The construction method according to claim 4, characterized in that, Hydraulic supports are also installed between the wall and the temporary supports, or between the wall and the load-bearing columns.

6. The construction method according to claim 5, characterized in that, In step four, the foundation is excavated downwards on both sides to below the original brick and stone foundation, anchor bolts are inserted, and concrete is poured to reinforce the foundation.

7. The construction method according to claim 6, characterized in that, In step five, the embedded composite rebar refers to drilling holes in the treated brick wall surface, cleaning the holes, injecting repair mortar, and then inserting connecting rebars with ribbed surfaces and coated with a nano-silicon-based active coating.

8. The construction method according to claim 7, characterized in that, In step five, the new structural frame includes newly tied columns and beams, with the new beams connected to the steel bars embedded in the brick wall.

9. The construction method according to claim 8, characterized in that, In step six, when removing the temporary supports of the upper layer layer by layer, first gradually reduce the supporting force of the hydraulic supports and monitor the health status of the brick wall, then remove the temporary supports symmetrically, and remove the secondary supports first and then the main supports.

10. The construction method according to any one of claims 5-9, characterized in that, It also includes a brick wall health monitoring system, including strain sensors and tilt sensors embedded in the exterior wall, pressure sensors installed in the foundation, and pressure sensors installed between the hydraulic support and the wall surface. Each sensor transmits data to the central monitoring platform via a wireless transmission module.

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