Bearing capacity of shallow foundation under cyclic load on cohesive soil

摘要

The bearing capacity of shallow foundations under static loads has been widely studied by various authors. In contrast, the bearing capacity under dynamic loads has been solved indirectly by adopting an equivalent pseudostatic approach or by means of reduction coefficients. The study of the problems related to cyclic loads has focused mainly on the behavior of granular soils. However, in the case of cohesive soils, these began to be studied in detail as a result of the Northridge, Kocaeli and Chi-Chi earthquakes that took place in the 90s.The object of the present work is to evaluate the influence of pore pressure in the calculation of bearing capacity of shallow foundation on cohesive soil and dynamically requested. This research is based on the results of cyclic simple shear tests carried out with samples from the Prat port (Barcelona). A pore-water pressure generation equation is proposed that depends on the effective vertical stress "in situ" (sigma(ov)'), static shear stress (tau(o)), cyclic shear stress (tau(c)), and void ratio (epsilon(0)). The formulation was implemented to the finite difference software FLAC2D, by which the bearing capacity of foundations can be determined. The proposed formulation can calculate the maximum cyclic load (CL) that a cohesive soil can resist before failure by cyclic softening, as a consequence of cyclic loads transferred by a shallow foundation. The practical application of this research is to provide a chart to calculate the bearing capacity of cohesive soils requested by cyclic loading (CL). This application takes into account the properties of the ground, the static load capacity (Phe) and the effective load outside the foundation (q). In addition, the formulation is validated in the application of a real case.