ABSTRACT
Fully considering the breaking action of the explosion stress wave and the moving fragmented blocks extrusion and collision under the action of the detonation gas expansion and infiltration flow pressure, Zhang & Chen (2002) proposed a theoretical calculation model of the fragmentation size distribution containing damage variable. The average fragment size (k50) and the percentage of undersize are derived from the dynamic average fragmentation size formula for fragile materials given by Grady on the basis of fragmentation energy rules. Some numerical simulations and verification tests are carried out. The results of numerical simulations coincide well with testing data. Simulations and tests show that the action of the extrusion and collision between moving fragment blocks is a significant factor affecting the average fragmentation size regardless the type of rock mass, especially for the rock mass with very bad quality.
