Quasi-static mechanical behaviour of soils used for natural turf sports surfaces and stud force prediction

The quasi-static testing of soils used in natural turf pitches yields key parameters in soil modelling, including elastic moduli, Poisson’s ratio and Mohr–Coulomb parameters for shearing resistance and cohesion in soil. The bulk strength of a Sand soil used in the construction of elite sports surfaces was found to increase initially and then decrease with increasing water content due to apparent cohesion effects. For a Clay Loam soil, more common in recreational facilities, shear strength decreased with water content. Reducing density resulted in a reduction of shear strength and elastic moduli in both soils due to reduced packing of particles reducing particle–particle contact surface area. The effect of roots on the shear strength of a Sand soil was not significant but reduced elastic moduli significantly. Horizontal forces measured during running and turning in a biomechanics laboratory were in good agreement with forces predicted using a simple quasi-static soil model for coarse-grained (Sand) soils although this was not the case with the Clay Loam soil.