Normalized Behavior of very Loose Non-Plastic Soils: Effects of Fabric

Abstract

In order to clarify the behavior of loose sandy and non-plastic silty soils, which are the most susceptible to liquefaction, a multiple series of tests were undertaken, concentrating on the effects of fabric. For this purpose, three distinctively different specimen preparation methods were chosen, and two or three were used for each of the materials, to prepare specimens with a very loose structure. The loosest state of packing was found to exist, for each of the preparation methods with different void ratios. In the loosest state, the normalization of the undrained stress ~ strain curves and stress paths to the initial confining pressure, can provide a meaningful interpretation of the soil behavior. This procedure is similar to the one adopted for normally consolidated clays. Regarding the effects of fabric on the undrained behavior, it was found that they are negligible up to the peak strength. However, once the shear straining reaches the state beyond the peak, the fabric becomes a very important factor governing the undrained response of non-plastic soil, which includes the minimal or residual shear strength. When the soil is largely sheared to reach the steady state, gradual remoulding erases the initial fabric and ultimate stress state is, governed by the void ratio only, once again not affected by the initial fabric.