Search

Accurately predicting pore-water pressure is essential for comprehending soil behavior under seismic loads and for estimating effective stresses. In recent years, various models have been proposed to estimate pore pressure development for clean sands, silts, and clays. However, in nature, soils often consist of mixed formations. Considering the nature of soil formations, in this study the pore pressure development of clayey sand was investigated. The excess pore water pressure development of clayey sand under dynamic loads using three different models from the literature is analyzed. For this purpose, stress-controlled dynamic triaxial test were performed on specimens prepared poorly graded sands with three different kaolin clay contents (FC=5-15) to measure excess pore water pressure generation at four cyclic stress ratios. Specimens were prepared by using wet tamping method to be ensure homogeneity. The tests were conducted under an effective confining pressure of 100 kPa. The results were used to obtain excess pore water pressure development of clayey sands under undrained dynamic conditions. Then, the results were compared with three different pore water pressure generation models. The model coefficients of three models were updated for clayey sand. Although it was proposed for clean sands, the model presented by Seed et al. [23] has also proven to be quite suitable for clayey sands. [ABSTRACT FROM AUTHOR]

Geopolymers are obtained by use of alteration of chemical composition and crystal structures of different minerals. Use of geopolymer is an effective and environmental friendly solution in stabilization of clayey soil. The vinyl based copolymer is used as an agent as dust controller, highway soil stabilizer, asphalt admixture, concrete production, etc. In this study, strength of a clay is improved by use of a commercial geopolymer. In this regard, soil was amended with polymer ranging among 0 % to 4 %, by volume of dry soil. Unconfined compression and oedometer tests were carried out to evaluate the effects of temperature, initial water content, compaction energy on strength and compression properties of a clay soil - within an experimental framework. The results revealed that, temperature has a considerable effect on geopolymerization. Besides, under constant moisture content during curing, increasing geopolymer content and curing period causes a slight increase in strength of specimens.