Experimental Study on the Coefficient of Earth Pressure at Rest for Sand

The coefficient of earth pressure at rest K-0 is a state soil variable correlated with relative density D-r. As previously conducted K-0 tests could not guarantee zero lateral deformation in the sand specimens, significant errors occurred in the test results. In this paper, a centrifugal model test method is used to study the K-0 of sand with varying densities. The sand specimens with varying relative densities are prepared by sand pluviation, and a 50 g-ton centrifugal force is applied. Subsequently, the relationship of K-0 and D-r with different densities is analyzed. The test results show that for the same type of sand, the value of K-0 gradually increased with D-r. Based on the meso-evolution characteristics of sand particle recombination, various relationships between K-0, the displacement deflection angle, and the friction offset angle between particles are analyzed. Furthermore, the relationship between particle volume fraction and K-0 is derived, the assumption of increasing the coefficient K-0 with the increase in D-r is verified, and the effect of D-r of sand on the force transfer behavior of the internal particle fabric is briefly discussed. The research results could significantly improve the current earth pressure theories.