Effect of inter-particle strength on K₀ correlation for granular materials

The coefficient of lateral earth pressure at rest K₀ is an important state soil variable that is necessary to characterize the in-situ stress state of natural soil deposits. In this study, the values of K₀ measured for various granular materials were analyzed and the effect of inter-particle strength on the K₀-φ′ correlation was presented. The inter-particle strength was referred to as the surficial frictional resistance mobilized on the contact areas of adjacent soil particles. The measured K₀ values indicated that denser and more angular materials tend to produce lower K₀ values, likely due to the interlocking effect as postulated by the Jaky's K₀ equation. It was also seen that neither the critical-state friction angle nor the peak friction angle for the Jaky's K₀ equation produced close match to the measured K₀ values. The use of peak friction angle in fact underestimated the values of K₀. A new K₀ correlation model based on the inter-particle strength analysis was presented. The effect of interlocking on the lateral effective stress was taken into account for the inter-particle strength K₀ correlation model. It was shown that the inter-particle strength model well described the dependency of K₀, a state variable, on the internal friction angle of soil, a strength parameter.