Abstract: This paper presents the comparative study between the synthetic transparent sand samples and the natural standard quartz sand samples throughout a series of direct shear tests. The characters mainly include the internal friction angle, the cohesion value and the stress-strain curve. Throughout the comparative study, it is concluded that there are some differences between the two sands, for instance, the internal friction angle of the synthetic transparent sand sample is larger than that of the standard quartz sand sample by 5.3°. The shear strength value is larger than the standard sand by 9.8kPa. To prepare a synthetic transparent sand sample that has similar direct shear parameters with that of natural standard quartz sand, studies on the test results from single grain size samples of both sand samples concluded that the internal friction angle increases with the increase of sample grain size; while the grain size of the sand sample is between 0.1 and 0.25 mm, the internal friction angle of the synthetic transparent sand is greater than that of standard quartz sand; However, when the sand sample has a grain size between 1.0 and 2.0 mm, the internal friction angle of synthetic transparent sand is smaller than that of the quartz sand. Based on the test results, the synthetic transparent sand with different gradation can have the same direct shear parameters with the natural standard quartz sand.

Key words: Direct Shear Test, Standard Quartz Sand, Internal Friction Angle, Grain Size, Gradation