Experimental study on the influence of saturation degree on unstable behavior within granular material

According to regulations and standards, risks of liquefaction are considered only if a soil is fully saturated. However, some authors have demonstrated that a soil can liquefy even with an initial degree of saturation under 100%. However, those studies remain descriptive and do not provide specific frameworks for evaluating the risk of liquefaction, taking the degree of saturation into account. This article presents an experimental study on the unstable behavior of sand as a function of its initial degree of saturation. Saturation states are defined and three saturation zones are investigated as a function of their pore fluid distribution patterns. Cyclic triaxial tests are performed on Fontainebleau sand to study the unstable behavior of each saturation zone. The results show that a soil can liquefy even if it is not initially fully saturated. They also provide new data on the role of suction and pore fluid compressibility in the unstable behavior of granular materials. The final aim of this article is to study the general unstable behavior of Fontainebleau sand under cyclic loading, and more specifically the influence of the degree of saturation on the triggering of these instabilities.