Experimental investigation on the coefficient of lateral earth pressure at rest of silty sands: Effect of fines

The coefficient of lateral earth pressure at rest (K₀) is an important state variable of soils and is often estimated using Jaky's K₀ equation, which is based on the internal friction angle (Pdbl′ ). When fines are contained in sand, the effect of the fines content needs to be properly taken into account for the Pdbl′-based estimation of K₀, as the strength characteristics change because of changes in particle interlocking and contact conditions. In this study, an experimental testing program was established to measure and analyze K₀ and its correlation to shear strength characteristics of sand-silt mixtures focusing on the effect of silt content. Thin-wall oedometer tests, triaxial tests, and other property tests were conducted to obtain K₀ values and characterize the test materials. The values of K₀ became higher as the relative density and silt content decreased, which was found because of decreasing particle interlocking and friction angle. Jaky's K₀ equation using the peak strength tended to underestimate K₀ at lower relative densities, whereas the K₀ matched closely to measured values for higher relative densities. The K₀ correlation based on the mobilized inter-particle strength was proposed and was applicable to various sand conditions. The calculated results using the proposed K₀ correlation matched the measured results well, confirming the effectiveness of the proposed method.