Abstract: The traditional way of predicting subsidence range by stagger angle doesn’t adapt to production. This paper is to have a study of the relation between the height of critical bulk solid column in subsidence pit and subsidence range. After an analysis of lateral anchorage force of mobile bulk in pit, the paper proposed that the active pressure and passive pressure of dispersion both prevented the scaling of side wall rock while the thickness of bulk solid in pit is not less than the height of critical bulk solid column and the related factors affecting the height of critical bulk solid column is researched. The results show that filling subsidence pit with waste can lower the critical depth and control surface subsidence range.

Key words: critical depth, subsidence range, critical bulk solid column, passive pressure