Influences Of The Clay Size Partical Content On The Mechanical Properties Of Sand

Soils from slope flow sliding, liquefaction of underground et al disasters field contain clay particle. Clay particle shows significant effect on liquefaction. Therefore,it is of great significance to study the engineering properties of sand blended with clay.The fine sand in the shallow coast in Qingdao was taken as frame sand bodies, effects of different clays and contents on the relative density, gravity and minimum/maximum void ration were studied, as well as the effect of clays on the permeability and shear strength. The research results are as follows:(1) Specific gravity test and relative density test were separately conducted to measure the gravity and maximum/minimum void ration. Following is basic physical.Results show that the gravity of sand increases as the clay content increases, while the maximum void ratio increases, the minimum void ratio decreases, and the value of(emax-emin) increases. The relative density of sand-clay mixtures climbs up with the clay content increasing when the clay content range from 5% to 30%. The effect of kaolin on sandy soil is greater than that of bentonite.(2) Permeability tests were conducted to measure the permeability coefficient of clay-sand mixture samples, and compared with pure sand, which have shown that the clay have appreciable impact on samples. The greater the content of clay particles,the smaller the permeability coefficient is. The effect of bentonite on the permeability coefficient of sand is more significant than that of kaolin. The permeability coefficient reduced by about 374 times when the content of kaolin of sand-kaolin mixtures ranges from 0% to 30%. The permeability coefficient reduced by about 374 times when the content of bentonite of sand- bentonite mixtures ranges from 0% to 30%.(3) Sand grain inter-granular void ratio increases as the clay content increases while clay grain inter-granular void ratio decreases. The clay category has no effect on sand grain inter-granular void ratio and clay grain inter-granular void ratio. Clay grain inter-granular void ratio of sand- bentonite mixtures under different dry density approximately equal when the content reachs 40%. The permeability coefficient decreases with sand grain inter-granular void ratio increasing while increasing as clay grain inter-granular void ratio increases.(4) Direct shear tests were carried out on sand blended with clay size particals to investigate both kaolin and bentonite reduced shear strength of sand. The results indicate that bentonite caused the apparent degree of shear strength to decrease is weaker than kaolin. Sand blended with lower content of clay size particals exhibit shear contraction-dilatation-contraction, while sand blended with higher content of clay size particals only exhibit shear dilatation. In addition, clay size particals caused the increase of cohesive strength and the decrease of internal friction angel.