Punching shear coefficients for the design of working platforms

Working platforms provide a safeworking environment for the operation of tracked plant on sites with soft clay subgrades. The ultimate bearing capacity of such platforms is determined considering a layered soil model and assumes that collapse is governed by a punching shear mode of failure. The contribution of the platform to the bearing capacity is computed using a coefficient of punching shear which reflects the mobilised shearing resistance within the granular fill from which the platform is constructed. This paper investigates the punching shear coefficients using in computing the bearing capacity of layered soils. Finite Element Limit Analysis is used to obtain upper and lower bounds on the ultimate bearing capacity of layered soil system. Punching shear coefficients are obtained by back-calculating the ultimate bearing capacity of layered soils following the punching shear model by Meyerhof. The presented coefficients predict the actual ultimate bearing capacity of working platforms for a wide range of design conditions with 5 percent error or less.