The coefficients of friction are the ratio of the actual force transmitted to the pile along its length to the calculated forces acting on the outer face of the pile (usually as predicted from soil investigations, of down drag, heave or negative skin friction). Our spiral tubes can be provided with a twin skin outer casing to reduce friction coefficients. The friction coefficient for twin plastic skins will be 0.2. For cases where very low coefficients are required, an inert, long life lubricant can be provided to form a greased sleeve wherein the friction coefficient reduces to approximately 0.1. It should be noted that the friction casings have very high chemical resistance and are inert to most reactants. The casings can therfore be used to prohibit corrosion and damp penetration to the pile.
This “twin-wall” system uses an external HDPE sleeve casing to reduce the friction co-efficient to as low as 0.2 and 0.1. The result is a unique answer to resist short term hydrostatic pressures from fresh concrete in weak surrounding soil, and long term subsoil movement, especially clay heave and negative skin friction. Uplift forces can be reduced by between 50% and 75%.
Diameters up to 2.2m readily available.
Ultra low friction coefficients down to 0.1
Uplift forces reduced between 50% and 70%
Negative skin friction reduced by 80% to 90%
Significant savings on pile size and reinforcements
Very high chemical resistance to sleeve
Mild steel, galvanised steel and other coated variants available