Experimental studies of deformation anisotropy of gravel soils

Abstract

Abstract When gravel-pebble soil is laying and compacting into the dam body, particles are reoriented to form a layered body (transversely isotropic soil), in which not only the filtration but also the deformation properties are different in directions along and across the layering. To analyze the differences in the gravel-pebble soil deformations in correspondence with the particles’ orientation we have performed experimental researches on the river pebble gravel using odometer, vacuum triaxial compression machine, and a large scale triaxial apparatus. To obtain the deformation characteristics of the soil in different directions we’ve carried out experiments according to two schemes with gravel particles (fr. 10-60 mm) laid horizontally and vertically. More deformations occur in the cross-layerage axis of the soil rather than in the parallel direction (εy > εx), so for the soil in the dam body Ex > Ey. The experiments showed that for gravel-pebble soil the strain-induced anisotropy coefficient η is dependent on its loading conditions and changes in the range from 1 to 1.8. The change of anisotropy degree is bound with the main tension value σ1 with the increase in which the anisotropy decreases.