Abstract: Typical spatial grading is the most apparent characteristic of the particle size of the bulk material in the ultra-high-bench dumping-site,its strength characteristics and stability are mainly controlled by the spatial distribution characteristics of the bulky blocks.So,analyzing the distribution regularity of the bulky rock in the ultra-high-bench dumping-site, and its mechanical characteristics and buckling failure mode are the determining the dumping-site Stability.The height of Zijin north dumping-site is 520 m,it belongs to the typical dumping-site with high steps.Based on the field test of the bulky material distribution of the north Dumping-site,the particle size ingredient of bulky material has been drawn up for the mechanical characteristics test. The relationship between the dumping-site strength parameters and the bulky material ingredient is thoroughly analyzed and the mechanical characteristics of the Zijin north dumping-site is determined.The study results of the paper can provide the guidelines for the development of the reasonable project plans of the dumping-site.

Key words: Ultra-high-bench dumping-site, Bulky material, Blocks distribution, Strength characteristics