STIFFNESS OF FINE-GRAINED SOIL AT VERY SMALL STRAINS

The stiffness of soil at very small strain G(o) is a useful parameter for characterizing the non-linear stress-strain behaviour of soil for monotonic loading and it is required for analyses of the dynamic and s mall strain cyclic loading of soils, Tests were carried out on fine-gr ained soils in a hydraulic triaxial cell fitted with bender elements a nd with local axial gauges. From the results of these tests simple exp ressions were obtained which describe the variation of G(o) with curre nt state in terms of the current stress and overconsolidation ratio, T he parameters in these expressions were found to depend on plasticity index, The simple expressions for G(o) were found to apply generally a t larger strains, with the values for the parameters also depending on the current strain, Values of G(o) measured in laboratory tests on re constituted London clay agree well with values measured in tests on un disturbed samples and in field tests which make allowance for the diff erent states in the various tests.