Experimental investigation on strength behavior of reconstituted Zhenjiang clay under different consolidation stress paths

Abstract

Soils subjected to the loading or unloading in geotechnical engineering applications like foundation excavation, embankment, and tunnel construction will reconsolidate under different stress paths. This paper presents an experimental investigation on the effect of stress path on shear strength characteristic of reconstituted Zhenjiang clay. Specimens were isotropically or anisotropically consolidated and sheared without drainage in triaxial shear tests. Test results showed that undrained shear strength (Su) under various stress paths is markedly influenced by the stress ratio (η), which is defined as the ratio of the deviator stress to the mean effective stress (p′). Su almost linearly increases with p′ or η at a given η or p′. The value of Su for specimens consolidated under different stress paths can be predicted as a function of p′ and η, i.e., Su = (0.13η + 0.37)p′. It is concluded that Su of specimen under anisotropic consolidation is higher than that under isotropic consolidation at a certain p′. Moreover, specimen anisotropically consolidated to the same p′ at higher η results in an increase in Su compared with that at lower η. Duncan-Chang model can be employed to characterize the strength behavior of reconstituted clays under various consolidation stress paths. The variation of c or c′ is insignificant under different η, indicating that the effect of η on cohesion is negligible. φ increases linearly with η while φ′ shows an insignificant change.