When installing mobile homes on soft soil foundations, systematic reinforcement measures are required to address the soil's low strength, high compressibility, and low permeability, ensuring structural stability. These measures are typically designed in conjunction with the engineering geological conditions, the building's load characteristics, and the construction schedule. Their core objectives are to improve the foundation's bearing capacity, control settlement and deformation, and enhance anti-slip properties.
Replacement backfill is a fundamental method for treating soft soil foundations. When the soft soil layer is shallow, the weak soil layer within a certain range below the foundation bottom can be excavated and backfilled with well-graded sand, gravel, lime soil, or slag. This is then compacted layer by layer to form a composite cushion. This cushion not only directly shares the upper load but also accelerates drainage and consolidation of the soft soil layer, reducing subsequent settlement. The backfill material must meet low compressibility and high permeability requirements, and the interface with the original soil must be compacted to avoid the formation of a weak interlayer.
Deep mixing pile technology is suitable for soft soil layers of medium thickness. A special drilling rig injects a hardener such as cement or lime deep into the foundation. Forced mixing is used to thoroughly mix the hardener with the soft soil, triggering a hydration reaction and forming a cohesive pile body. These piles form a composite foundation with the surrounding soft soil, significantly increasing bearing capacity and reducing compressibility. During construction, the hardener dosage, mixing depth, and lifting speed must be strictly controlled to ensure pile uniformity. For lightweight structures like mobile homes, short pile designs can be used to balance cost-effectiveness and reinforcement effectiveness.
The gravel pile method achieves foundation reinforcement through vibration-driven pore creation and filler compaction. After a vibrator creates cavities in the soft soil, gravel is gradually filled and vibrated to form a dense pile body with the surrounding soil. This technique not only increases foundation bearing capacity but also improves drainage and accelerates soft soil consolidation. In mobile home projects, gravel piles are often used in conjunction with a sand cushion layer to form a composite drainage system with "upper cushion and lower piles" to effectively control post-construction settlement. During construction, careful attention should be paid to controlling pile spacing to avoid construction difficulties or increased costs caused by overcrowding.
The preloading method accelerates foundation consolidation by pre-applying loads. Before installing mobile homes, a sand cushion is laid on the foundation surface and an equivalent load is applied. This allows the pore water pressure in the soft soil to gradually dissipate, resulting in compaction and settlement. This method is suitable for projects with flexible construction schedules and can significantly reduce settlement during the life of the home. To improve preloading efficiency, vacuum preloading is often combined with vacuum preloading technology, which accelerates drainage and consolidation by laying a sealing membrane and applying a vacuum. Settlement rates must be continuously monitored during preloading to ensure that the foundation meets design requirements before proceeding with home installation.
The reinforcement method uses geosynthetics to strengthen foundation integrity. High-strength materials such as geogrids and geotextiles are laid in the foundation, leveraging their tensile properties to constrain lateral soil deformation and improve foundation shear strength. For mobile homes, reinforcing materials can be layered within the backfill to form a reinforced soil cushion. This method is simple to construct and low-cost, making it particularly suitable for situations where the foundation bearing capacity is slightly below the required level but settlement is manageable. The anchorage length and overlap width of the reinforcement material must strictly comply with specifications to ensure effective stress transfer.
Pile foundation technology is the ultimate solution for deep soft soil layers. When the soft soil layer is thicker than 10 meters, precast concrete piles or steel pipe piles can be used to transfer the load to the deeper bearing stratum. Pile foundation design must consider pile length, diameter, and pile layout to ensure sufficient lateral friction and end bearing capacity. For mobile homes, small-diameter piles combined with pile caps can be used to meet bearing requirements while controlling costs. During construction, attention must be paid to controlling the verticality of the pile shaft to avoid misalignment that could cause uneven stress on the structure.
The drainage consolidation method accelerates consolidation by improving foundation drainage. Vertical drainage channels, such as sand wells and plastic drain boards, are installed in the foundation, combined with a horizontal drainage sand cushion layer to shorten the pore water drainage path. This method is often used in conjunction with preloading, forming a synergistic "drainage-preloading" system. In mobile home construction, drainage consolidation is an effective method for controlling post-construction differential settlement, particularly in soft, silty soils with high water content. During construction, pore water pressure changes should be regularly monitored to assess consolidation progress.
