Probabilistic Analysis of Bearing Capacity of Strip Footings

Abstract

Predicting bearing capacity of shallow foundations is a common practice in geotechnical engineering and an accurate estimation of its value is essential for a safe and reliable design. Traditional deterministic methods of estimating bearing capacity of shallow foundations do not explicitly considerthe uncertainty associated with the factors affecting bearing capacity and rather employ a factor of safety that implicitly accounts for such uncertainty. This factor of safety is in reality "factor of ignorance" as it relies only on past experience and does not reflect the inherent uncertainty in relation to bearing capacity parameters, leading to unreliable bearing capacity predictions. In this paper, a more rational approach for estimating bearing capacity of strip footings subjected to vertical loads is proposed. The approach is based on probabilistic analyses using the Monte Carlo simulation and accounts for the uncertainty associated with two shear strength parameters, i.e. soil cohesion and soil friction angle. The probabilistic solutions negate the need for assuming a factor of safety and provide a more reliable indication of what the actual bearing capacity might be.