Interference of two closely spaced footings embedded in unreinforced and reinforced soil medium: a finite element approach using ABAQUS

Abstract

The stress or the failure zone of footings placed at close proximity interfere altering the performance of the footings. The present study pertains finite element analysis of two closely spaced rough, rigid strip footings embedded in cohesion-less foundation soil medium using the commercially available software ABAQUS. The interfering footings are considered to be supported on homogeneous reinforced and unreinforced soil medium. The failure criterion of the soil is directed to follow Mohr–Coulomb criterion with the non-associated flow rule. The influence of interference phenomenon on the ultimate bearing capacity, settlement and load-settlement characteristics have been explored by considering and varying the various parameters such as depth of embedment, soil friction angle, depth of reinforcement (first layer and subsequent layer), number of reinforcement layers and length of reinforcement. The soil friction angle is one of the important factors to have an effect on bearing capacity, and the friction angle is varied between 20° to 40°. The ultimate bearing capacity of closely spaced footings over unreinforced and reinforced soils are represented by non-dimensionless efficiency factors (ξUR and ξR). The analyses results conclude that interference has a significant influence on bearing capacity and settlement of footings supported over unreinforced and reinforced soil medium. Although, soil friction angle affects the interference significantly (higher friction angle has the highest peak of efficiency factor), depth of footing embedment also has remarkable influence over the same. The peak of efficiency factor decreases with an increase in the depth of footing embedment for a specified soil friction angle; however, the same increases with increase in soil friction angle for a specified depth of footing embedment. The interference effect is found to be decreasing with increase in the embedment depth. The bearing capacity of interfering footings on reinforced soil is enhanced noticeably compared to that on unreinforced footings; however, the settlement is not predominant.