Experimental Study On Dynamic Characteristics Of Liquefied Sand Mixed With Fine Particles

Research on the liquefaction of saturated sand is one of the research focus of attention of the international academic and engineering circles. A large number of experimental studies show that the liquefaction, liquefaction and fine content, dry density, consolidation pressure, dynamic stress, dynamic stress cycle times closely related factors. Among them, the fine content is an important factor influencing liquefaction, and even affect the mechanism of liquefaction induced. Happened to this point is derived from the soil particle size composition. So, fine existence can make the relative stability between coarse particles changes, and improve soil viscosity. In this paper, by using the software of the following several problems:three axis instrument and ABAQUS simulation:(1) In the case of Kc=1, when the fine content is 21%,23%,25%,27%,29%, how to dynamic strength of fine sand mixed with the change of.(2) In the Kc=1 and Kc=1.5 case, carries on the comparison to the fine content for the dynamic strength of sand sample 21%,23%,25%,27%,29%, to analyze its change trend.(3) In the case of Kc=1, the change trend of dynamic shear strength of fine sand, two doped monolayer layer with fine sand, fine sand mixed with three layers, and in the case of Kc=1, comparison of dynamic strength of five kinds of mixing of fine sand, and get the result which method of mixed fine good.(4) The use of dynamic test data of three axis three axis and the static calculation of sand (fine content is 21%,25%,29%) strain rate coefficient.This paper got the following conclusions:(1) In the consolidation under conditions than Kc=1.0, the dynamic strength of blended fine sand is highest in the fine content is 21% and 29% when the fine content, dynamic strength exhibits a monotonic decline in 21%～25%, fine content dynamic strength exhibits a monotonically increasing in 25%～29%, in the fine particle content of 25% dynamic strength at the lowest value, presents inverted "parabola" trend. Based on the same fine content, confining pressure of each increase of 50kPa, the dynamic strength increase about 10～15kPa.(2) In the consolidation under conditions than Kc=1.5, trend and consolidation ratio when the Kc=1 keep consistent. When the fine content in 21%～25%, sand particles plays a leading role, the fine the main "storage" within the pores between the sand particles, under cyclic load, the fine play "lubricating" effect, reducing the friction between sand particles, so cause sand dynamic strength is more and more low. This is because the fine plays a lubricating effect, have occurred to the liquefaction phenomenon. When the fine content in 25%-29%, the dynamic strength of sand is more and more high. This is because the fine of the role is hampered by the occurrence of liquefaction phenomenon.(3) For the three layered mixed fine specimens of dynamic strength curve, from single doped fine-grained to two layer doped fine-grained, dynamic strength did not change significantly, almost no change. In contrast to the three layer doped with a layer with fine fine, can be seen at the same confining pressure, dynamic strength increase of around 3%. We can draw a conclusion, comparing mixing fine, using a hierarchical approach, the effect is not obvious. This is because although the sand specimen mixed with a certain amount of fine, but because of fine grained and fine sand particles are arranged hierarchically, and did not let the fine completely "into" to fine sand particles, very difficult to play the role of fine-grained bond.(4) Fine content as the difference between the three kinds of fine sand 21%,25%,29% of the dynamic strength and static strength is relatively large, much larger than the difference between the static strength and dynamic strength of cohesive soil. Can be seen from the data, the static strength is far greater than the dynamic strength, the average ratio of about 0.102. Description of sand soil under dynamic load strength decreased sharply under the. Among them, when the fine content is 25%, the minimum strain rate coefficient, it shows that the difference between static and dynamic strength of the biggest, under dynamic load, the largest decline of soil strength. When the fine content is 25%, the biggest drop of saturated sand strength, strain rate coefficient is lowest, the most prone to liquefaction.