Energy Equilibrium During Crushing of Sandy Soils Under Isotropic Compression

The crushing of sand particles under high stress leads to decrease the shear resistance of the soil. Previously, some theoretical procedures were presented for the quantitative investigation of crushing in sand during shear loading, based on the work equilibrium. However, these equations cannot be applied to crushing in sand under pure isotropic compression due to the absence of a frictional term in the work equation. This paper proposes a theoretical procedure for volumetric strain and consequent work equilibrium in an element subjected to isotropic compression. In this procedure, participant of the rearrangement and crushing in sample volumetric strain is separated, and then, the corresponding work of each contribution is determined. Moreover, isotropic compression tests are conducted on two sands from Hormuz Island and Bushehr Port in the Persian Gulf. The test results showed that the compressibility of both sands increased as density decreased. In addition, the study found that Bushehr sand was more susceptible to compressibility and crushing than Hormuz sand. Moreover, the validity of the new theoretical equation of energy equilibrium was verified by applying it to the experimental data. According to the verification results, the theoretical equation is properly conformed to the experimental data and the analogous parameters were close, with an error of up to 30%. In addition, surface energy parameter in isotropic compression was obtained at a higher magnitude relative to shear loading, which implied that the loading type affected the crushing of sand grains.