Experimental Study On Liquefaction Resistance Of Silty Sand

Silty sand is a special sand soil formed by the mixing and deposition of sand and silt soil in the same soil layer,and the silt content is below 30%.The silty sand is mainly distributed in the southern coastal area,the Yangtze River area and the southwest of Sichuan Province.These areas are not only the most frequent earthquakes,but also the active areas of the economic construction in China.The liquefaction of sand caused by earthquakes seriously endangers the building on the foundation.However,there are few studies on the liquefaction resistance of silt sand at home and abroad,so it is necessary to conduct further research on it.In order to study the anti liquefaction property of the silty sand,the silty sand with different silt content and different particle size distribution is arranged in this paper.The configured silty sand consists of a single particle of sand,double particle size sand,and three grain of sand.These specimens are tested by the DDS-70 vibrating triaxial apparatus for indoor dynamic triaxial tests.The axial dynamic strain curves and pore pressure ratio curves of the specimens were plotted by analyzing the experimental data,and the dynamic deformation and pore pressure variation characteristics of the silty sand were summarized,and the destructive vibration times of the sample are determined when the sample is liquefied.By comparing the anti liquefaction strength curve of the sample,the law of the anti liquefaction property of the silt sand was analyzed and summarized.The results of the test are summarized as follows:(1)The liquefaction resistance of sandy silt with single grain size increases with the increase of sand particle size,namely: coarse granular silt sand has the strongest liquefaction resistance,the second is the medium granular silt sand,and the fine granular silt sand is the worst.(2)The anti-liquefaction ability of two particle size silty sand and three grain silty sand is related not only to the average particle size,but also to the type of particle size distribution.The greater the average particle size of sand grains in silty sand,the stronger the liquefaction resistance,the smaller the average particle size of sand grains,the worse the liquefaction resistance.The large span grain gradation is unfavorable to the liquefaction resistance of silt sand,and the continuous gradation has the liquefaction resistance of silt sand.(3)Under cyclic loading,the effect of silt content on the liquefaction resistance of single particle size and two particle size silty sand is consistent.The effect of silt content on the liquefaction resistance of silty sand is not monotonous,whether its sand particles is single particle size or double particle size.The relationship between the liquefaction resistance of silty sandy and the content of silt is the parabolic line with open upward.There is a critical value of silt content,which makes the sand has the worst liquefaction resistance.