MECHANICAL INSTABILITY OF SILTY SAND POROUS MEDIA UNDER MONOTONIC LOADINGS

In recent years, understanding the mechanisms of mechanical instability of sandy soils as porous media has been continuously revised to include new parameters that may control the mechanical behavior under static or dynamic loadings. Such instability may be manifested by severe damage of structures, leading to catastrophic failure in many cases. The accurate determination of critical or residual shear strength for soil susceptible to liquefaction phenomena has been a major challenge in geotechnical engineering. Consequently, it is essential to determine the main parameters that may control substantially the shear resistance and to provide a broad understanding on contractive and dilative phases of soil behavior in undrained conditions. In this work, an experimental program on reconstituted loose and medium dense specimens of terrigenous silica sands with different specified fine contents was conducted with the main goal to analyze its mechanical behavior under undrained conditions. The present article is an attempt to describe experimentally the mechanical behavior of low plastic silty sand soils and to represent the variation of the critical shear strength via the fine content, the density state, and the equivalent void ratio. The last characteristic seems to represent rightly the vulnerability of the material to instability.