A new method to measure fragment-size composition of muckpiles and its experiments

摘要

Several typical methods measuring the fragment-size composition are systematically analysed and their different features are emphatically discussed in this paper. And then proceed from stereoscopy theorem, based on the distribution of chord lengths of which the random scanlines intersect the section circle, the size distribution of line segments obtained by the random scanlines intersecting the rock fragments in the same size grade is deduced. According to the quantitative relation between the quantity density of all chord lengths obtained by the intersection of random scanlines with a given-size sphere and the spatial quantity density of this kind of spheres, the formula of calculating the spatial quantity density of rock fragments in a muckpile is developed. Thus, a new method of measuring the 3-dimension fragment-size composition stereoscopic probability calculation method (SPCM) is proposed by the composition information of the section lengths obtained by random scanlines intersecting rock fragments on the surface of a muckpile. And the corresponding formula of calculating the fragment-size composition are also given. The gradation experiments prove that without any correction, the average value of measuring errors under the same size grade is 8.67 per cent and that the fragment-size compositions measured from 10 experiments under different size grades are quite close to their corresponding screening values and the average value of the absolute errors of each grade content does not exceed 5.26 per cent.