AN EXPERIMENTAL STUDY ON DETERMINING THE SHEAR STRENGTH OF CORAL ROCK USING DIRECT SHEAR TESTS

Abstract

With the increasing number of engineering structures being constructed on coral foundations in island and coastal areas, determining the mechanical parameters of coral rock is of significant importance for stability analysis and foundation design. This study aims to determine the shear strength parameters of coral rock and evaluate the stress–strain behavior of the material under different levels of normal stress. The research methodology was carried out through direct shear tests on coral rock specimens prepared from rock samples collected at the construction site. A total of 36 specimens were divided into three groups subjected to normal loads of 10 kN, 20 kN, and 35 kN, corresponding to normal stresses of approximately 4.21 MPa, 8.42 MPa, and 14.74 MPa, respectively. The experimental results indicate that the shear stress increases almost linearly with shear strain until reaching the peak shear stress. The obtained internal friction angle of coral rock ranges from 27.09° to 35.82°, while the cohesion varies from 1.09 MPa to 3.30 MPa. In addition, the shear strain at peak stress increases from approximately 0.3% to 0.6% with increasing normal load. These findings contribute to a better understanding of the mechanical behavior of coral rock and provide a useful reference for the analysis, design, and numerical simulation of engineering structures founded on coral rock.