Finite element and empirical solutions for estimating bearing capacity and settlement of a jointed, multi-layered dam rock foundation

This study discusses the bearing capacity and settlement behaviour of highly jointed mica-schist rock mass that is divided into multilayers along depth beneath the foundation of Burgaz Dam in Izmir, Turkey. These layers have different geotechnical properties; hence they impose an inherent heterogeneity on the rock mass. The empirical solutions for bearing capacity based on Hoek-Brown and other rock mass parameters and pressuremeter test data were correlated with the finite element (FE) solutions. A new technique for determining the allowable and ultimate bearing capacities based on the stress-displacement curve derived from the FE shear strength reduction (SSR) method was proposed. This technique utilises the critical settlement and strength reduction factor (SRF) provided from FE-SSR. Variations in bearing capacity estimations by different solutions considering one-layered and multi-layered mediums were evaluated in detail. In addition, the amount of immediate settlement calculated from the pressuremeter test results, empirical solutions based on the one-layered and multi-layered medium, and FE model were correlated. It was determined that the settlement occurs mainly within the upper mica-schist layer. Pressuremeter tests were found to be underestimating the settlement. While the bearing capacity was not significantly changed in the multi-layered FE model as compared to the one-layered model, the amount of settlement was found to be significantly decreased to 53.7%.