Quantification of Time-dependent Microstructural Change of a Silty Sand under Load

摘要

Imaging technology may be used in geotechnical engineering to enhance our understanding of microscopic characteristics and micro-mechanical behaviour of sands. In this study, silty sand samples loaded uniaxially under K_0 condition for ageing times of one hour and one week were preserved using low viscosity epoxy resin. High quality images were captured by scanning electron microscope utilizing a backscattered electron detector to give excellent contrast between the grains and the voids. Change in microstructure due to ageing is investigated statistically using particle orientation and distribution of spatial distance between particles in horizontal and vertical directions. It was found that although mean distance between particles only slightly reduces, overall ageing causes larger sand particles to rotate. It is suggested that only few fine particles (silt) rotate during ageing because the majority of them are not in the strongly loaded force chains, so that they just float within the voids.