A combined method for replacing damaged prefabricated hollow slab

Abstract

The application discloses a combined method for replacing damaged prefabricated hollow plates, which comprises the following steps: S1, erecting a temporary support system under the damaged prefabricated hollow plate to be replaced, and unloading the damaged prefabricated hollow plate; S2, removing the damaged prefabricated hollow plate along the wall edge by using a static cutting process, emptying the plug material in the plate end support hole of the prefabricated hollow plate, and placing a steel mesh at the end of the hole; S3, adding an anchor bolt at the wall edge and installing an angle steel to form a support; S4, welding a bolt at the new angle steel; S5, supporting a mold, binding a steel bar, pouring concrete to form a new pouring floor slab, and completing the replacement of the damaged prefabricated hollow plate. The static cutting removal process effectively avoids the stress mutation of the structure in the removal process, the temporary support system ensures the construction safety, and the efficient and safe replacement of the hollow floor slab is realized.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, specifically to a combined construction method for replacing damaged precast hollow slabs. Background Technology

[0002] In early residential buildings, office buildings, and factories, precast hollow core slabs (hereinafter referred to as "hollow core slabs") were widely used as floor components. Hollow core slabs have advantages such as light weight, fast construction speed, and low cost, but their bending and shear resistance is poor, and the slabs are only connected by mortar at the joints, resulting in weak overall integrity. Precast hollow core slabs were commonly used in the early days, but were gradually replaced by prestressed precast hollow core slabs later on. With the increase in the service life of buildings and the growing demand for functional upgrades, many hollow core slabs have developed problems such as continuous cracks on the bottom, concrete carbonization, weathering, external damage, steel corrosion, and insufficient load-bearing capacity, seriously affecting building safety and functionality.

[0003] Currently, there are three main approaches to renovating hollow core slabs: First, adding a composite layer to the original slab for reinforcement. This method causes less disturbance to the original structure but increases the dead load significantly, and it doesn't fundamentally solve the problems of bottom cracks and rebar corrosion. Second, using steel bonding or carbon fiber cloth bonding for reinforcement. This method is complex, time-consuming, and its reinforcement effect is greatly reduced when the anchorage length at the slab ends is insufficient. All of these approaches require testing the concrete strength of the original precast hollow core slabs. However, the central holes in the precast hollow core slabs interfere with rebound tests, and it's difficult to extract standard-sized test blocks for compressive strength tests using core drilling, making reinforcement calculations impossible. Third, completely removing the hollow core slabs and replacing them with new precast slabs. However, this involves a long construction period, a large amount of formwork support system erection, significant dust and noise pollution affecting lower-floor residents, and the small quantity of new hollow core slabs available from factories, making on-site pouring quality unreliable.

[0004] Therefore, there is an urgent need for a hollow floor slab replacement method that can both ensure structural safety during the demolition process and is practically feasible. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a combined construction method for replacing damaged precast hollow slabs, thereby solving the problems of long construction period, large disturbance, and dust and noise pollution in the existing technology.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A combined construction method for replacing damaged precast hollow slabs includes the following steps: S1. Erect a temporary support system under the damaged precast hollow slab to be replaced and unload it.

[0007] S2. Use static cutting technology to remove the damaged precast hollow slabs along the wall edge, and remove the plugging material from the support holes at the ends of the precast hollow slabs. Place wire mesh at the end of the holes.

[0008] S3. Add anchor bolts to the wall and install angle steel to form a support.

[0009] S4. Weld studs at the newly added angle steel.

[0010] S5. Set up formwork and tie steel bars according to design requirements, pour concrete to form a new floor slab, and replace the damaged precast hollow slab.

[0011] Furthermore, the static cutting process used in step S2 is diamond wire saw cutting or hydraulic wall saw cutting. During cutting, the cutting is performed from the free end of the precast hollow slab towards the support, and each precast hollow slab is confirmed to be firmly supported by adjacent slabs before cutting.

[0012] Furthermore, the process for removing a single precast hollow slab in step S2 is as follows: S21. Unload the damaged precast hollow slab; S22. Use static cutting technology to cut the precast hollow slab on one side along the edge of the wall, and then gradually break it from one side to the other side. Stop breaking it 240~260mm away from the other side of the wall, and then use static cutting to remove the remaining part. S23. Cut off the ends of the precast hollow slabs embedded in the wall along the wall edge.

[0013] Furthermore, in step S3, the length of the newly added angle steel at the wall edge support shall not be less than 100mm.

[0014] Furthermore, in step S4, the spacing between the studs is no greater than 300mm.

[0015] Furthermore, in step S5, when placing the longitudinal reinforcement bars of the newly poured floor slab, the lower longitudinal reinforcement bars are placed inside the holes of the original precast hollow slab, and the upper longitudinal reinforcement bars are bent downwards at the edge of the wall.

[0016] Furthermore, in step S5, the width of the gap between the newly poured floor slab and the adjacent precast hollow slab is controlled to be 20~30mm.

[0017] Furthermore, in step S5, a flexible sealing material is placed inside the plate joint.

[0018] Furthermore, in step S1, the temporary support system adopts a disc-lock scaffolding with adjustable supports, the spacing between uprights is no greater than 800mm×800mm, the distance between the sweeping rod and the ground is no greater than 200mm, and the gap between the adjustable support and the bottom of the board is filled with wooden beams and tightened.

[0019] Furthermore, the cutting depth of the static cutting in step S22 is controlled to be two-thirds of the plate thickness.

[0020] The present invention has the following beneficial effects: (1) The static cutting combined with the temporary support system ensures that the structural load always has an alternative transmission path, avoiding the risk of collapse caused by sudden changes in the stress of the floor slab during the demolition process; the ends of the original precast hollow slab embedded in the wall are cut off along the wall edge, and the wall can still bear the load safely during the partial removal, effectively ensuring the structural safety of the construction process.

[0021] (2) The static cutting process is vibration-free and low-noise. Combined with the closed protective frame and the dust suppression measures of the fog cannon, it greatly reduces the impact on the residents on the lower floor. The thickness of the newly poured floor slab is 100~120mm, which is smaller than the original precast hollow slab thickness of 130~160mm. The net height of the room remains basically unchanged, and there is no need to simultaneously reinforce the walls and foundation, which reduces the project cost. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the replacement structure for the damaged precast hollow slab in this invention; Figure 2 This is a cross-sectional view of the replacement of the damaged precast hollow slab in this invention; In the diagram, 1-precast hollow slab, 2-wall, 3-support, 4-stiffening plate, 5-stud, 6-wire mesh, 7-newly poured floor slab, 8-upper longitudinal reinforcement, 9-lower longitudinal reinforcement. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] A combined construction method for replacing damaged precast hollow slabs, as shown in the attached diagram. Figure 1-2 As shown, it includes: Step S1: Erect a temporary support system under the damaged precast hollow slab 1 to be replaced, and use disc-lock scaffolding with adjustable supports to unload the original floor slab.

[0025] Specifically, the spacing between uprights should not exceed 800mm x 800mm, the distance between the ground-level support and the bottom of the scaffold should not exceed 200mm, and the gap between the adjustable support and the bottom of the scaffold should be filled with timber and tightened. After the scaffolding is erected, a pre-load test should be conducted by placing sandbags with 1.1 times the weight of the components and leaving them for 24 hours. After confirming that there is no settlement or deformation, the scaffolding can be put into use to ensure that there is always an alternative path for the structural load during dismantling.

[0026] Step S2: Use static cutting technology to remove the damaged precast hollow slab 1 along the two sides of the wall, and clear the plugging material of the support hole at the end of the precast hollow slab 1. Place wire mesh 6 at the end of the hole.

[0027] Specifically, the static cutting process uses either diamond wire saw cutting or hydraulic wall saw cutting. Taking diamond wire saw cutting as an example, the precast hollow slab 1 is cut on one side along position 2 of the wall, with the cutting depth controlled to two-thirds of the slab thickness. The process for removing a single precast hollow slab 1 is as follows: S21. Unload the damaged precast hollow slab 1; S22. Use static cutting technology to cut the precast hollow slab 1 on one side along the two sides of the wall. Then gradually break it from one side to the other side, stop breaking it 240~260mm away from the other side of the wall, and then use static cutting to remove the remaining part. S23. Cut off the end of the precast hollow slab 1 embedded in the wall 2 along the side of the wall 2.

[0028] During cutting, the precast hollow slab 1 is advanced from its free end toward the support, and each precast hollow slab 1 is confirmed to be firmly supported before cutting. After the plugging material at the support gap at the end of the wall 2 is removed, to prevent concrete from flowing into the holes of adjacent hollow slabs during concrete pouring, wire mesh 6 is used to seal the end of the holes.

[0029] The static cutting process is vibration-free and low-noise (controlled below 65dB during the day). Combined with a closed protective frame and dust suppression measures such as mist cannons, the dust concentration is controlled at 0.5mg / m³. 3 The following measures significantly reduced the impact on lower-level residents.

[0030] Steps S3-S4: Add anchor bolts and install angle steel to form support 3 at the support of the two side plates of the wall. The length of the newly added angle steel shall not be less than 100mm. Fix the angle steel support 3 with through bolts, and weld stiffening plate 4 to the inside of the angle steel using bevel welding.

[0031] Studs 5 are welded to the newly added angle steel. The studs 5 are 20mm high and the spacing between them is no more than 300mm. Studs 5 are welded to the top surface of the angle steel using fillet welds to enhance the connection strength between the newly poured floor slab 7 and the support 3.

[0032] Step S5: Erect formwork and tie reinforcing bars according to design requirements, then pour concrete to form a new floor slab 7, completing the replacement of the damaged precast hollow slab 1. When placing the longitudinal reinforcement of the new floor slab 7, the lower longitudinal reinforcement 9 is placed inside the holes of the original precast hollow slab 1, and the upper longitudinal reinforcement 8 is bent downwards on both sides of the wall. Tie the main reinforcing bars and distribution bars of the cast-in-place layer.

[0033] The width of the joint between the newly poured floor slab 7 and the adjacent precast hollow slab 1 is controlled at 20~30mm, and flexible sealing material is placed in the joint. The thickness of the newly poured floor slab 7 is 100~120mm, which is reduced compared with the original precast hollow slab 1 thickness of 130~160mm, and the net height of the room remains basically unchanged.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A combined construction method for replacing damaged precast hollow slabs, characterized in that, Includes the following steps: S1. Erect a temporary support system under the damaged precast hollow slab (1) to be replaced and unload it; S2. The damaged precast hollow slab (1) is removed along the wall (2) using static cutting process, and the plugging material of the support hole at the end of the precast hollow slab (1) is removed. A wire mesh (6) is placed at the end of the hole. S3. Add anchor bolts and install angle steel to form a support (3) on the side of the wall (2); S4. Weld studs (5) at the newly added angle steel. S5. In accordance with the design requirements, formwork is erected, steel bars are tied, and concrete is poured to form a new cast floor slab (7), thus completing the replacement of the damaged precast hollow slab (1).

2. The assembly method for replacing damaged precast hollow slabs according to claim 1, characterized in that, The static cutting process used in step S2 is diamond wire saw cutting or hydraulic wall saw cutting. During cutting, the cutting is carried out from the free end of the precast hollow slab (1) towards the support. Before cutting, each precast hollow slab (1) is confirmed to be supported and stable.

3. The assembly method for replacing damaged precast hollow slabs according to claim 1, characterized in that, The process for removing a single precast hollow slab (1) in step S2 is as follows: S21. Unload the damaged precast hollow slab (1); S22. Use static cutting technology to cut the precast hollow slab (1) on one side along the edge of the wall (2), and then gradually break it from one side to the other side. Stop breaking it 240~260mm away from the other side of the wall, and then use static cutting to remove the remaining part. S23. Cut off the end of the precast hollow slab (1) embedded in the wall (2) along the edge of the wall (2).

4. The assembly method for replacing damaged precast hollow slabs according to claim 1, characterized in that, At the support (3) in step S3, the length of the newly added angle steel shall not be less than 100mm.

5. The assembly method for replacing damaged precast hollow slabs according to claim 1, characterized in that, In step S4, the spacing between the studs (5) is no more than 300mm.

6. The assembly method for replacing damaged precast hollow slabs according to claim 1, characterized in that, In step S5, when placing the longitudinal reinforcement of the newly poured floor slab (7), the lower longitudinal reinforcement (9) is placed in the hole of the original precast hollow slab (1), and the upper longitudinal reinforcement (8) is bent downward on the side of the wall (2).

7. The assembly method for replacing damaged precast hollow slabs according to claim 1, characterized in that, In step S5, the width of the gap between the newly poured floor slab (7) and the adjacent precast hollow slab (1) is controlled at 20~30mm.

8. The assembly method for replacing damaged precast hollow slabs according to claim 7, characterized in that, In step S5, flexible sealing material is placed inside the plate joint.

9. The assembly method for replacing damaged precast hollow slabs according to claim 1, characterized in that, The temporary support system in step S1 uses a disc-lock scaffold with adjustable supports. The spacing between the uprights is no more than 800mm×800mm, the distance between the sweeping rod and the ground is no more than 200mm, and the gap between the adjustable support and the bottom of the board is filled with wooden beams and tightened.

10. The assembly method for replacing damaged precast hollow slabs according to claim 3, characterized in that, In step S22, the cutting depth of the static cutting is controlled to be two-thirds of the plate thickness.

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