Determination of critical saturation degree in rocks based on maximum loss of uniaxial compression strength and deformation modulus

Abstract

Strength and deformation modulus are two basic parameters in rock engineering designs. So far, many studies have been done on the effect of the water content on the foregoing two parameters all of which emphasize on the reduction of them by increase of water. In spite of performing many studies carried out in this field, two important questions have been remained unanswered: (1) Is there any degree of saturation in which the greatest variations in compressive strength and deformation modulus occur? (2) Does the saturation have more effect on the strength or on the deformation modulus? This matter has been discussed in this paper by conducting uniaxial compressive strength tests on 78 rock samples from 4 different lithologies in two dry and saturated conditions. The results showed that the compressive strength and the modulus of deformation have the highest losses in the saturation water content ranging between 0.2 and 2%, and the modulus of deformability decreases more than the compressive strength. In addition, the loss of compressive strength and deformation modulus is independent of the rock strength class proportionate to the saturation.