Liquefaction Resistance of Sand-Kaolin Mixtures: Effect of Sand Sizes

Abstract

Grading characteristics, particle sizes, particle shapes and fines content are the factors contributing to liquefaction incidents besides major factors such as earthquake magnitude. Recent publications and reports from incidents of liquefied or potential liquefied soils show some evidence that the size of sand particles, particle shapes and grading characteristics will increase or decrease the liquefaction resistance. However, to date the results are still disputed and need to be expanded. Hence, the aim of this paper is to investigate the effects of different sizes of sand in sand-kaolin mixtures on liquefaction resistance. The liquefaction resistance of sand mixtures with the application of different sizes of sand-coarse sand, medium sand and fine sand mixed with fines (kaolin) content (0%,10%, 20%, 30%, and 40%) are investigated through a cyclic triaxial test under undrained conditions. Each reconstituted sample was prepared with a target relative density of 15% (loose state) and 5% of initial moisture content for the triaxial test. Effective consolidation pressures of 100 kPa were applied on the cyclic triaxial tests. Microstructure analysis on the soil samples were carried out to explain the behaviour of the samples tested. The centrifuge test was carried out on selected samples so that the behaviour of the soils in actual conditions could be visualised. The results clearly show that the liquefaction resistance was reduced at reduced sand sizes. At a constant fines content for each parent sand, the liquefaction resistance decreased with an increase of fines content up to certain percentage, then increased thereafter. The fth decreased from 30% to 20% of fines content with a decrease in parent sand sizes. The outcomes of this study are useful to advance the understanding of the behaviour of sand mixtures with different sizes of sand for design purposes.