Laboratory and field determinations of small-strain shear modulus for a structured Champlain clay

Abstract

Values of small-strain shear modulus Gmax, for a Champlain Sea clay deposit were obtained both under an embankment built 18 years ago, and outside of the area influenced by this embankment. The small-strain shear moduli Gmax were measured in the laboratory by using resonant column tests and in the field by spectral analysis of surface waves. In addition to verifying the two methods, comparison of the in situ and laboratory values allowed evaluation of the influence of the sampling and the need to correct the laboratory values to account for the age of the deposit. The test program also made it possible to verify the influence of the deposit's consolidation and the existing models predicting small-strain shear moduli in clay deposits. Key words : shear modulus, shear-wave velocity, resonant column, in situ test, surface waves, soft clay.

A unified model for estimating the in-situ small strain shear modulus of clays, silts, sands, and gravels

“…(5) Table 2 lists the values of c3 and c4 and their standard errors. Figure 2 shows that equation (5) and the model derived for n by Menq [4] for cohesionless soils are similar.…”

“…[2][3][4]). Results from laboratory tests generally give lower values of Gmax than in-situ tests due in part to sample disturbance, loss or lack of cementation and soil structure, and the effect of confinement time [5][6]. It is common practice to adjust the results from empirical models developed from laboratory results with a constant factor (e.g.…”

Analysis of the behavior of embankment dams under seismic loading

“…The value of G max is related to soil rigidity, the same way the value of shear wave velocity Vs does. Relations between G max and Vs have been presented by Lefebvre et al (1994). But in the presence of severe earthquakes, the value of G max diminishes as a function of the induced cyclic shear strain.…”

Deformation Analysis in Soft Ground Improvement

“…The adopted profile of elastic shear modulus G was based on independent dynamic measurements reported by Lefebvre et al (1994), as shown in Fig. Values for the parameters N, λ * and κ * were derived from the results of oedometer tests, whereas values of the parameters R and ψ were estimated based on experience.…”