Apparent particle size grading is an important characteristic of superhigh bench dumping site; and the critical factors with the impact of its stability and disaster prevention are the fragmentation distribution and shear strength parameters of accumulate granulae. With the copper mine dumping site which has the feature of apparent particle size grading in Jiangxi province

the study of on-site particle size investigation and indoor laboratory tests are carried out. The particle-size distribution law with the changing of dumping-site height is analyzed; and quantitative relationship between the fragmentation distribution and the shear strength parameters of granulae is discussed. The research results indicate that the mean grain size

the coarse-grain contents P>5mm and the maximum grain size are increased significantly according to the decreasing of dumping-site height

which show that the dumping-site has the feature of apparent particle size grading. The distribution value B

by using the Gandin-Schuhmann model

fits the decrease with the increment of dumping-site height. The coarse particle content in the grain size composition and the internal friction angle φ of shear strength parameters increase with the obvious increment of the distribution value B. The relationship between distribution value B and the internal friction angle φ can be expressed by exponential function curve.