Cutting and Demolition of Old Houses with Prefabricated Slabs

The cutting and demolition of old houses with prefabricated slabs must follow a systematic process to ensure structural safety and construction compliance. The specific steps are as follows:

1. Structural Safety Assessment

Before demolition, a comprehensive inspection of the house must be conducted, focusing on key indicators such as the width of cracks in the prefabricated slabs (requiring reinforcement if exceeding 0.3 millimeters) and the connection status between the slabs and the ring beams (requiring replacement if the bolt corrosion rate exceeds 30%). If structural damage is found, priority should be given to repair or reinforcement to avoid the risk of collapse during demolition.

2. Temporary Support System Construction

Set up steel pipe supports every 1.2 meters along the length of the prefabricated slabs, and use H-shaped steel beams with a cross-section of no less than 200*200 millimeters for key nodes to ensure the stability of the support system. The supports must cover the entire demolition area and extend to adjacent structures to prevent deformation caused by uneven local stress.

3. Key Points of Demolition Construction

• Segmented Demolition Principle: Adopt a symmetrical demolition method of 'middle first, then sides', with a daily demolition volume not exceeding 30% of the total floor area to avoid structural instability caused by sudden load changes.
• Real-time Monitoring: Continuously monitor the stress changes in the support system during construction, using sensors or manual inspections to ensure that the stress values remain within safe limits.
• Prohibition of Heavy Hammer Impact: The use of violent demolition methods such as heavy hammers is strictly prohibited to prevent the impact force from being transmitted to the foundation and causing irreversible damage.

4. Requirements for Professional Teams

• Equipment Adaptability: The team must be equipped with equipment such as mini excavators that can enter conventional elevators or stairwells to adapt to the space limitations of old houses.
• Standardized Management: From preliminary surveys and load assessments to post-demolition cleanup and site restoration, clear acceptance standards must be established for each link to ensure that the construction process is traceable.

5. Subsequent Treatment Measures

• Slab Joint Repair: Remove the original filling material, implant No. 6 deformed steel bars, and pour C30 fine aggregate concrete to enhance the connection strength of the slab joints.
• Addition of Structural Columns: Add structural columns with a cross-section of 240*240 millimeters at the four corners of the house, using No. 6 and No. 8 steel bars for reinforcement and reliably connecting them to the floor slab to improve overall seismic performance.

6. Precautions

• Professional Operation: Demolition projects must be carried out by qualified teams to avoid safety hazards caused by improper construction.
• Owner Cooperation: Owners need to participate in the acceptance work to confirm that the construction meets design requirements and ensure scientificity and safety.

Strictly following the above process can minimize demolition risks and provide a stable foundation for subsequent renovations.