Bond Yield Characteristics of Undisturbed Completely Decomposed Granite

Abstract

To investigate the bond yield characteristics of undisturbed completely decomposed granite (CDG) which is widely distributed in Southern China, a series of conventional drained tests were conducted. From the test data, some insights are obtained as follows: for undisturbed CDG soils, the bond yield point during shearing could be identified on the curve of the normalized tangential stiffnessEtan/p′versus axial strain on log-log scale. The consolidation pressureP0′has a significant influence on the bond yield characteristics of undisturbed CDG during shearing, the bonds inside undisturbed CDG tend to be damaged relatively more seriously asP0′is higher, accordingly the initial normalized stiffnessEitan/p′will be smaller at the beginning of the shearing process, and the axial strain at the bond yield point will also be smaller. Once consolidation pressureP0′excesses a critical value such as 475 kPa for this studied CDG, the bonds inside soil will be damaged totally at the consolidation compression stage. In this case, there will be no bond yield occurring during shearing and theEtan/p′-εacurves will coincide with the ones of reconstituted CDG soil. For reconstituted soils, no bond yielding was observed during shearing; theEtan/p′-εacurves are tightly consistent with no dependence of the value ofP0′.