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

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 (G(max)) were obtained from tests performed on kaolinite soil specimens. The methodology and procedures that were utilized to obtain values of M, G(max), large-strain shear modulus (G), drained Poisson's ratio (nu), horizontal effective stress (sigma'(h)), vertical effective stress (sigma'(v)), specific volume (v), coefficient of lateral earth pressure during unloading (K-o,K-UL), and drained friction angle (phi') are discussed herein. The following five observations were made. (1) The G(max) values increased with increasing values of sigma'(v) and decreased with increasing values of the overconsolidation ratio (OCR). (2) The G(max) values that were obtained by utilizing correlations and the large-strain BP-CRS-BE testing data (identified as G(max, CRS, p')), which were back-calculated by considering the modulus reduction, matched the G(max) values that were obtained from the bender element measurements within the BP-CRS-BE device (G(max,BE)). (3) The nu values increased with increasing sigma'(v) values but decreased with the increasing void ratio (e) values. (4) The K-o,K- UL values increased with increasing OCR values. (5) The phi' values that were calculated for the soil that was tested within the BP-CRS-BE device by using the K-o,K- UL-OCR data that were obtained from the BP-CRS-BE device (21.2 degrees, 16.0 degrees, and 24.7 degrees) were similar to the phi' values that were obtained from modified Mohr-Coulomb diagram from triaxial tests on the same soil (20.7 degrees).