Accidents in Prefabricated Houses
In recent years, accidents in prefabricated houses have mainly been caused by factors such as structural aging, overload, improper construction, and extreme weather conditions.
Structural Aging and Inadequate Maintenance
In the collapse incident at Tongling Longyuan Community, the involved house was a brick-concrete prefabricated panel structure built in 2001. Although the exterior walls were renovated in 2020, no systematic reinforcement was carried out on the internal structure. Victims had previously reported safety hazards in the house, indicating that long-term use had led to aging at the connection points between the prefabricated panels and the walls. After heavy rainfall soaked the foundation, the soil's bearing capacity decreased, further weakening the structural stability. The design life of prefabricated houses is typically 30-50 years. If regular inspections and maintenance are not conducted, issues such as rusting of connectors and carbonation of concrete can significantly reduce structural safety.
Overload and Unauthorized Use
The direct cause of the prefabricated panel fracture incident in Zhong County was the temporary stacking of goods on the second-floor slab, exceeding the design load capacity of the prefabricated panel. Prefabricated panels are brittle materials with limited bending and shear resistance, making them prone to fracture under overload. Additionally, the mixed use of a mahjong parlor on the ground floor and a warehouse on the second floor may have altered the original design load distribution, exacerbating structural risks. Similar cases include unauthorized additions of floors or modifications to house functions, which can trigger accidents due to load imbalance.
Improper Construction Practices
The collapse incident at Banana East Hot Spring exposed technical flaws in the demolition work. Construction workers did not follow the sequence of "demolishing walls first and then clearing slabs." They prematurely chiseled the prefabricated panel bedding before removing the outer railings of the cantilever beams, resulting in a reduction in the load of construction debris and an imbalance in the anti-overturning moment of the cantilever beams. The renovation of prefabricated houses must strictly adhere to the principles of structural mechanics. Arbitrary changes to the construction sequence can disrupt the original force system and trigger a chain reaction of collapses.
Impact of Extreme Weather
In the Tongling incident, continuous heavy rainfall led to foundation softening, serving as one of the triggers for the collapse. Prefabricated houses are sensitive to foundation settlement. If the drainage system is inadequate, rainwater infiltration can accelerate soil liquefaction and reduce foundation stability. Such accidents highlight the need to strengthen inspections of old prefabricated houses during extreme weather conditions and take timely emergency measures such as drainage and reinforcement.
Prevention Recommendations
- Regular Inspections: Conduct structural safety assessments on prefabricated houses that have been in use for more than 20 years, focusing on inspecting connectors, cracks in prefabricated panels, and foundation settlement.
- Standardized Use: Avoid unauthorized changes to house functions or overloading with stacked items. Before renovation, entrust a professional institution to conduct load verification.
- Scientific Construction: Develop a specialized plan for renovation work, adhering to the principles of "supporting first and demolishing later, layer by layer and section by section." Unauthorized operations are strictly prohibited.
- Emergency Management: Before extreme weather events, inspect the drainage system and take temporary support measures or evacuate personnel from houses with potential hazards.
