Reliability analysis framework for shallow foundations resting on reinforced cohesionless soils

Abstract

Improving soil mechanical properties using reinforcement inclusions has become of major interest to many researchers. Accordingly, several numerical, analytical, and experimental studies have been conducted to explore the improvement of soil’s mechanical properties under shallow foundations. However, a comprehensive Reinforced Soil Foundations (RSF) design framework has not been established. This paper introduces a novel design framework for RSF based on the Load and Resistance Factor Design (LRFD) approach. Resistance factors for improved bearing capacity are computed using the First Order Reliability Method (FORM) for strip and square footings resting on loose sandy soil. A spreadsheet-based model is developed to compute the resistance factors at a targeted reliability index ( ) equal to 3 for ASCE-7 2000, AASHTO 1998, and EC7 (DA2) load factors. The resistance factors developed using ASCE-7 load factors ranged from 0.2 to 0.55 and 0.27 to 0.7 for a geogrid tensile strength of 45 kN/m and 160 kN/m, respectively. Load factors of different established design codes had a significant effect on the developed resistance factors. Soils with high frictional angles and embedment ratios resulted in conservative resistance factors. Moreover, the computed resistance factors for square footings were slightly higher in reinforced cases and lower for unreinforced cases than in strip footings.