Assessment of Shear Strength Properties of Dredged Sand

Land reclamation using marine dredged sand has been a more popular method to provide land to meet the requirement of increment of population and expanding economic development over several decades. Therefore, there have been several geotechnical issues in line with the reclaimed land areas. The loose sand can lead to a high risk of liquefaction due to seismic actions and other vibrations. Unsuitable filling methods can also lead to unexpected short-term and long-term settlements with the construction of different structures having various load applications. To eliminate such failures, the sand has to be densified up to an acceptable level of compaction over the specified depths. The relative compaction can be assessed through the examination of the geotechnical properties of marine dredged sand. Due to the difficulty of extraction of undisturbed samples in cohesionless soils, CPT-based empirical correlations are used to evaluate the relative density and effective angle of friction. In general, cohesion and friction angle represent the shear strength parameters of soils, and the linear Mohr–Coulomb envelope has been widely used to explain the theoretical concept. However, due to the effect of factors such as confining pressure, relative density, mineralogy, particle crushing, and particle size distribution, the Mohr–Coulomb envelope deviates from the linear behavior. In this study, the variation of shear strength parameters of dredged sand with relative density was evaluated and nonlinear stress variation with the increase of normal stress was assessed using a series of direct shear tests. Tests were carried out for relative densities of 90, 95, and 97% with normal stresses varying from 20 to 800 kPa. Based on the results and using previous studies on dredged sand, a virtual direct shear test model was developed using the Discrete Element Method (DEM) reducing the experimental time and increasing the efficiency.