Construction of Foundations for Concrete Prefabricated Houses

The construction of foundations for concrete prefabricated houses requires a combination of foundation treatment, foundation construction plans, and construction steps, strictly adhering to regulatory requirements. The specific methods are as follows:

I. Selection of Foundation Treatment Methods

Foundation treatment should be selected based on soil conditions to ensure that the bearing capacity meets design requirements.

• Compaction Method: Suitable for sites with relatively dense soil that requires further reinforcement. Compaction operations are performed on the original foundation soil layer using pneumatic hammers or heavy-duty road rollers to increase soil density and achieve the bearing capacity standard for self-built houses.
• Soil Replacement Method: For loose soil types (such as soft clay or backfill), the original soil layer is excavated and replaced with high-density materials like sand and gravel, significantly improving foundation bearing capacity. However, costs are higher, and economic feasibility must be assessed.
• Piling Method: Reinforced concrete piles are embedded into soft soil layers to increase stability through friction or end-bearing capacity between the piles and soil. This method is suitable for small buildings or temporary structures but has limited bearing capacity. Pile length and spacing must be determined based on geological reports.

II. Key Points for Construction of Reinforced Concrete Independent Foundations

Taking a certain project as an example, strict adherence to design requirements and construction specifications is necessary:

• Design Parameters: The characteristic value of foundation bearing capacity should be ≥150kPa, with a uniform top elevation of ±0.000m (0.3m below the outdoor ground level) to ensure waterproofing and stability. The dimensions of a single room in the concrete house are 6m×3.6m×3m, weighing approximately 12 tons, requiring foundation dimensions to be calculated based on the load.
• Materials and Components:
  • Ordinary Portland cement P·O 42.5 is selected, with sand and gravel containing ≤3% (medium-coarse sand) and ≤1% (crushed stone) mud content, respectively. Reinforcing steel bars of grade HRB400 are used.
  • Pre-embedded steel plates with dimensions of 300mm×300mm×10mm are provided, with four plates set for each foundation to connect with the steel beams at the bottom of the concrete house.
• Construction Process:
  1. Excavate soil to the design elevation and pour a C25 concrete cushion.
  2. Lay pre-embedded steel plates, ensuring accurate positioning and firm fixation.
  3. When installing the concrete house, form an integral structure by welding or bolting the steel beams to the pre-embedded steel plates.

III. Construction Steps for Simple Concrete Foundations (Suitable for Small Structures)

Taking a mini concrete house as an example, construction should be completed in stages:

• Foundation Pit Treatment: After excavating the foundation pit, mix cement and sand in a 1:3 ratio and pour it into the pit, leveling it to a thickness determined by load requirements (generally ≥200mm).
• Column Pouring: Place molds at the four corners or key positions of the foundation pit, pour concrete, and insert Φ12-Φ16 reinforcing steel bars for reinforcement. Remove the molds after solidification, with the column height matching the roof support requirements.
• Roof and Floor Construction:
  • Place prefabricated roof panels on the columns and secure them with angle steel or bolts.
  • When pouring the concrete floor, lay a steel bar mesh (Φ6@200mm), level the surface with a scraper, and cover it for curing.

IV. Key Considerations

• Adherence to Specifications: Reinforced concrete foundation construction must comply with the "Standard for Acceptance of Construction Quality of Building Foundation Engineering" (GB 50202-2018), controlling concrete strength (such as C25) and the thickness of the steel bar protective layer.
• Professional Involvement: Simple methods are only suitable for small structures (such as tool sheds or temporary buildings). Large concrete prefabricated houses require design and construction by professional teams to avoid structural safety hazards.
• Quality Inspection: After construction, bearing capacity tests (such as static load tests) and appearance inspections should be conducted to ensure no cracks, hollow spaces, or other defects are present.