Confirmation of the upside-down drop shape theory in gravity flow and development of a new empirical equation to calculate the shape

Understanding the flow rules of caved ore and rock is the foundation for efficiently applying the caving mining method, and studying the change trends in both extraction zone (EZ) and movement zone (MZ) is the basis for researching these rules and for optimizing structural parameters. Ellipsoid draw theory is one of the traditional theories for the shapes of the extraction zone and the movement zone, which has played an important role in investigating the draw problems in caving mining method for a very long time. The isolated draw tests conducted in this study confirmed the upside-down drop shape theory's prediction that the EZ's shape has obvious longitudinal asymmetry, and is not a standard ellipsoid. The MZ's shape was further studied according to model experiments conducted by Castro, resulting in the fact that the MZ's shape is also the upside down drop shape. On this basis, a new way was proposed to investigate the extraction zone and movement zone shapes and their change trends, and then new empirical equations were deduced for calculation of their shapes.