Subsidence of House Prefabricated Slabs

There is no fixed numerical standard for determining whether the subsidence of house prefabricated slabs is normal. It requires comprehensive judgment based on multiple factors and professional assessment in accordance with relevant norms. Details are as follows:

Assessment Criteria:
In terms of settlement volume, the maximum allowable settlement varies for buildings of different types, uses, and heights. The reasonable range of settlement for rural self-built houses needs to be comprehensively evaluated based on specific geological conditions, building structural types, and design requirements. In addition to settlement volume, attention should also be paid to the settlement difference between different foundation points in the same building and the overall inclination. If the subsidence of prefabricated slabs causes significant settlement differences between adjacent parts or overall inclination, it may affect the structural safety of the building. For example, when the settlement difference between adjacent foundations exceeds the allowable value specified in the norms, it may lead to problems such as wall cracks and door/window deformation, threatening residential safety.

Influencing Factors:

• Foundation Conditions: Geological conditions have a significant impact on settlement. A solid and uniform foundation experiences less and more stable settlement, while poor geological conditions such as soft soil and backfill soil may result in larger and unstable settlement. If the foundation is not properly treated (e.g., compaction, replacement) or changes in the groundwater level cause foundation softening, it may trigger the subsidence of prefabricated slabs.
• Building Structural Type and Construction Quality: Buildings with good overall integrity and high stiffness, such as frame structures and shear wall structures, have strong adaptability to settlement, while masonry structures are more sensitive to settlement. If the foundation treatment is improper (e.g., insufficient foundation depth, lack of extended foundation), the foundation construction quality is poor (e.g., insufficient concrete strength, incorrect steel bar placement), or the installation of prefabricated slabs is not standardized (e.g., insufficient resting length, loose connections), abnormal subsidence may occur.
• Surrounding Environment: Surrounding engineering activities (e.g., excavation of foundation pits, stacking of loads) may change the stress state of the foundation, and changes in the groundwater level (e.g., long-term pumping leading to foundation consolidation settlement) may also affect the stability of prefabricated slabs.

Countermeasures:

• Regular Monitoring: Conduct settlement observations on rural self-built houses, record settlement data at key points (e.g., corners of walls, column bases), and analyze the change trends. If an accelerated settlement rate or differential settlement is detected, the causes should be promptly investigated.
• Professional Inspection: If significant subsidence or inclination of prefabricated slabs is observed (e.g., wall cracks, inability to open/close doors and windows normally), a professional engineer should be immediately commissioned to conduct an inspection and assessment to determine the causes of settlement (e.g., foundation failure, structural damage) and formulate solutions.
• Reinforcement Treatment: Take targeted reinforcement measures based on the foundation conditions and settlement situation. For example, for soft soil foundations, methods such as grouting reinforcement and root piles can be used to improve the bearing capacity; for structurally damaged parts, treatments such as carbon fiber reinforcement and additional supports can be carried out to restore the stability of the building.