Bearing capacity and deformation behavior of shallow footing loads on geogrid reinforced marine coral sand

Abstract

Investigation of the bearing behavior of geogrid-reinforced coral sand (GRCS) is essential for engineering construction safety in the island and coastal regions. Coral sand, characterized by its weak and irregularly shaped particles, presents unique challenges compared to clay and silty sand, influencing bearing and deformation performance. In this study, laboratory model tests are conducted to assess the impacts of various factors on the bearing capacity and deformation performance of rigid shallow footings on the GRCS, including footing size, the number of geogrids, burial depth, and spacing of geogrids. A three-dimensional discrete-continuous coupled numerical method was developed to explore the microscopic bearing and deformation mechanisms, focusing on the particle-crushing effect. Test results show that the bearing capacity suffers from the burial depth of the single-layer geogrid and decays more slowly than the conventional soils after reaching the critical depth. For multi-layer reinforcements, optimizing burial depths and spacing allows doubling of the bearing capacity compared to the unreinforced condition. The microscopic numerical results show that particle crushing reduces the stress level and failure area of the foundation soil, degrading the macroscopic bearing performance. Although various factors influence the bearing behavior, the geogrid-particle interaction within the core bearing zone determines bearing, settlement, stress, and particle crushing. This study enhances the understanding of the macro-micro bearing behavior of shallow footings on GRCS and provides insight into the potential reinforcement design and engineering geological disaster prevention on marine coral sand sites.