Collapse of loose sands with additions of fines

Abstract

Loose sand, when sheared under undrained conditions, tends to collapse rapidly with a very low residual strength. The consequences of this flow type response can be disastrous in geotechnical applications. Natural sands encountered in situ usually contain some amount of fines and the effect of fines on the undrained behavior of sand is of great concern. Several experimental studies have shown that the addition of fines increases the resistance of sand to collapse, whereas several others show the contrary. The lack of convergence and consistency results in difficulty in quantifying the effect of fines. This paper reports new data and interpretations from an experimental program aimed at a fundamental understanding of the undrained behavior of sands with additions of fines. Results are discussed with particular attention on the role of fines in modifying the position of critical state line and the potential for collapse.