Piling for Prefabricated Houses

Piling for prefabricated houses requires the scientific selection of piling sequences and construction methods based on site conditions, pile foundation density, and soil type, while strictly adhering to quality control requirements.

1. Selection of Piling Sequence

1. Expanding from the Center Outwards: Suitable for projects with dense pile foundations, open sites, and favorable construction conditions in the center. This method reduces the risk of pile displacement and floating, especially effective for ultra-dense pile groups, balancing soil stress through symmetrical construction.
2. Advancing from One Side to the Other: Applicable to narrow and long sites (such as roads) or projects with obstacles on one side. Construction organization is simple, but attention should be paid to the disturbance of soil in the later piling area caused by early compression, which may affect the verticality of the pile foundation.
3. Zone-by-Zone Skip Piling: Divide the site into several blocks and construct in an “every other one” sequence, suitable for soft soil foundations or ultra-dense pile groups. By dispersing construction pressure, it reduces cumulative soil deformation and avoids uneven local settlement.

2. Adaptation of Construction Methods

1. Hammering Method: Drive piles into the soil by the impact of a heavy hammer's free fall on the pile top, suitable for cohesive soil layers. During construction, control the hammer weight and drop distance to avoid damage to the pile body.
2. Static Press Piling Method: Use hydraulic devices to apply static pressure to press piles into the soil, with low noise and no vibration, suitable for soft soil areas (such as coastal muddy soil). Ensure that the tonnage of the pile press matches the geological conditions.
3. Vibration Method: Reduce soil resistance to piles through high-frequency vibration, mostly used in sandy or silty soil layers. Construction efficiency is high, but it may cause liquefaction of surrounding soil, requiring monitoring of the vibration impact range.

3. Key Points of Quality Control

1. Pile Body Requirements: The strength of concrete solid piles should be no less than C30, and that of tubular piles no less than C40; steel piles require anti-corrosion treatment. The pile length is limited to ≤30 meters for on-site fabricated piles and ≤12 meters for factory-fabricated piles.
2. Construction Accuracy: After the pile driver is in place, the verticality should be calibrated with a deviation ≤0.5%; the pile spacing should be ≥3 times the pile diameter to avoid group pile effects.
3. Industry Standards: China implements a “one pile, one code” system, enabling full-process quality traceability through QR codes. In 2024, the production of prefabricated piles reached 423 million meters, with enterprises concentrated in South China, the Yangtze River Delta, and the Bohai Rim regions, with technology transitioning towards automation and green development.

Reasonable selection of piling sequences and construction methods, combined with strict quality control, can effectively ensure the bearing capacity of pile foundations and guarantee the safety and durability of the project.