Abstract: In order to deepen the understanding on the mechanism of ore-rock particle flow at the side ore-drawing， a three-dimensional numerical model without pillar was designed by using discrete element method and describing the composition of ore-rock block by uniformly distributed spherical particles， and the micro-analysis on the flow characteristics of ore-rock bulk was carried out. The contact force and force network distribution between particles in the process of ore-rock flow were calculated by the contact mechanics method. The results showed that: ① the ratio of contact force between particles and average contact force in the process of ore drawing is not affected by the ore drawing， and its peak value is about 1， which obeys power function when f > 1 and negative exponential function when f < 1； and ② the probability of force chain in which the inner length L is longer than 3 particles obeys the exponential relationship e. The exponential relationship shows that the probability of longer force chain in primary drawing decreases slightly， but it decreases rapidly with the increase of the length of force chain at any time. ③ in the whole process of ore drawing， the contact force decreases linearly with the increase of the times of ore drawing when f∈［1,2］， but the contact force is not affected by ore drawing when f> 2.

Key words: Caving method, Granular flow, Contact mechanics, Force chain