Ability of clay fill to support construction plant

Good ground conditions are required for the operation of modern earthmoving plants due to the higher contact pressures imposed by them on the supporting surface. The maximum allowable contact pressure has been arrived at by a simplified theory based on the bearing capacity of clay soils. From these considerations it appears that standards earthmoving tyres with inflation pressures of greater than 50 lb/in² should be used only on stiff or strong clays, but for firm clays it is necessary to reduce the inflation pressures to between 25 and 50 lb/in², depending on the shear strength of the soil. It would also seem desirable to replace the standard wheels on a particular plant with larger wheels capable of carrying the load under lower inflation pressures.