Detection of Elastic Region Varied by Inherent Anisotropy of Reconstituted Toyoura Sand

Abstract

Inherent anisotropy affects deformation and strength characteristics of sand deposits. Accurate deformation modulus and shear strength are important parameters to design and construct soil structures such as retaining wall, foundation and tunneling. In this study, specimens having various angles of depositional plane (sedimentation angle) were artificially made using an inclined container to estimate soil inherent anisotropy. The container was designed to prepare easily a specimen with different inclined depositional plane by changing positions of its side walls. Specimens are made using Toyoura sand by air pluviation method to attain the same relative densities regardless of the depositional angle. The strength and deformation characteristic were evaluated using both bender elements (BE) method and local small strain (LSS) measurements. To compare the accuracy of acquired results, the both tests were conducted in the same specimens under drained condition of triaxial tests. Results from the experiments indicate that initial shear modulus has tendency to slightly increase with an increase of the depositional angle. However, shear strength has the obvious inverse relationship with changing of the depositional angles. Concerning elastic region, the elastic region tends to shrink with an increase of the depositional angle in spite of increasing of the initial shear modulus with the depositional angle. In comparison between BE and LSS tests, the initial shear moduli obtained from LSS tests are slightly greater than those obtained from BE tests.