Determination of Efficiency Factors for Closely Spaced Strip Footings on Cohesive–Frictional Soils

Abstract

The bearing capacity of closely spaced footings has become one of the important topics in geotechnical engineering research owing to the rapid development in urban areas around the world. In this paper, we propose three efficiency factors that can be used to describe the bearing capacity effects of closely spaced footings using Terzaghi’s traditional bearing capacity equation. With an advanced finite-element limit analysis of upper and lower bounds, both the closely spaced strip footings and the multiple closely spaced strip footings on cohesive–frictional soil with a surcharge effect were investigated. The numerical results showed that the efficiency factors were significantly influenced by the internal frictional angle and the spacing ratio. Several comparisons were made with those published in the literature. Furthermore, the failure mechanisms of closely spaced footings are presented, while design charts were produced with a wide range of practical parameters. This study should be of great interest to foundation engineering practitioners.