Several strategies can be employed to reduce the effect of negative skin friction on piles:
Utilize Slender Pile Sections: Employing slender pile sections, such as H-piles or precast piles, maximizes deformation under load due to the smaller pile area. This increased deformation enhances the relative downward movement of the pile, counteracting the upward pull of negative skin friction.
Apply Protective Coatings: In regions of the H-pile subject to groundwater table fluctuations, applying a protective coating like paint can mitigate corrosion caused by the cyclic wetting and drying process. Additionally, applying bitumen to the pile surface within the zone experiencing negative skin friction can reduce the adhesion between the pile and soil, thus diminishing the upward drag. However, it’s crucial to avoid coating the entire pile section with bitumen, as this would prevent the development of necessary frictional resistance for load-bearing.
Design as End-Bearing Piles: Opting for end-bearing pile designs allows for a greater proportion of the load to be carried by the pile’s base rather than through shaft friction. This reduces the reliance on frictional resistance and minimizes the impact of negative skin friction on the pile’s overall capacity.
By implementing these strategies, engineers can effectively mitigate the adverse effects of negative skin friction, ensuring the stability and performance of pile foundations in challenging soil conditions. It’s important to note that the choice of mitigation measures should be tailored to the specific project requirements and geotechnical conditions to achieve the most optimal and cost-effective solution.