The Development of Shear Strength for Sedimentary Soft Clay with Respect to Aging Effect

Abstract

It is widely known that shear strength of clay continues to increase after the end of primary consolidation. Some reports show that the strength gain is remarkable especially for marine clays near surface of natural deposits. However, not much is understood on this subject. An attempt has been made to reveal the phenomenon of strength gain with time. The developing mechanism of shear strength is characterized by assuming that shear strength gain during the secondary process can be understood as two contributing components : secondary compression and effect of cementation. The increase rate of shear strength for a sedimentary from clay slurry is investigated. It is found that a remarkable increase in shear strength is obtained during the secondary process, though little change takes place in water content. Based on experimental data, the authors suggest that cementation effect on shear strength gain is in relation with overburdened pressure p0. The increasing rate can be expressed simply by Δcu/Δlog t=0.3√(p0). This relation is verified as nearly valid when overburdened pressure is extended to p0=0.01-1000 kPa.