Volume 34, Issue 4 (July 2011)
Assessment of the Coefficient of Lateral Earth Pressure at Rest (Ko) from In Situ Seismic Tests
The coefficient of the earth pressure at rest (Ko) is an important soil parameter that influences shear strength, stress-strain behavior, and compressibility characteristics of both cohesive and cohesionless soils. This paper presents a research study in which the Ko values of natural soil deposits are interpreted on the basis of seismic shear wave velocity measurements made at two research sites in Jiangsu province of China. Seismic piezocone penetration tests and cross-hole seismic logging tests were performed at both sites and these results have been used in two existing Ko-shear wave velocity models for prediction of Ko. The predicted Ko at both sites are compared with values determined utilizing Jaky’s formula via laboratory measured strength parameters. Certain variations between predictions and measurements are noted for soils at shallow depths, which are attributed to stress history and desiccation in these layers. Further analysis developed correction factors that accounted for both soil types and overconsolidation ratio effects. These factors can be used with original models for better interpretation of Ko for overconsolidated clays. This approach showed a reasonable match between interpreted Ko properties from both models and those that utilize laboratory test results.