Small-Strain and Large-Strain Modulus Measurements with a Consolidation Device

Abstract

By using a back-pressure saturated, constant rate-of-strain consolidation device with bender elements (BP-CRS-BE), values of large-strain constrained modulus (M) and small-strain shear modulus (Gmax) were obtained from tests performed on kaolinite soil specimens. The methodology and procedures that were utilized to obtain values of M, Gmax, large-strain shear modulus (G), drained Poisson’s ratio (ν), horizontal effective stress (σh′), vertical effective stress (σv′), specific volume (v), coefficient of lateral earth pressure during unloading (K0,UL), and drained friction angle (ϕ′) are discussed herein. The following five observations were made. (1) The Gmax values increased with increasing values of σv′ and decreased with increasing values of the overconsolidation ratio (OCR). (2) The Gmax values that were obtained by utilizing correlations and the large-strain BP-CRS-BE testing data (identified as GmaxCRS,p′), which were back-calculated by considering the modulus reduction, matched the Gmax values that were obtained from the bender element measurements within the BP-CRS-BE device (Gmax,BE). (3) The ν values increased with increasing σv′ values but decreased with the increasing void ratio (e) values. (4) The K0,UL values increased with increasing OCR values. (5) The ϕ values that were calculated for the soil that was tested within the BP-CRS-BE device by using the K0,UL-OCR data that were obtained from the BP-CRS-BE device (21.2°, 16.0°, and 24.7°) were similar to the ϕ′ values that were obtained from modified Mohr-Coulomb diagram from triaxial tests on the same soil (20.7°).