The Study On Mechanism Of Increasing Lump Ratio In Blasting Mining

The fragment distribution of blasting is the important index of estimating blasting. The fragment of blasting is different with the different demand of engineering. Because the different fragmentation of blasting directly affects the production, transport of the coal, also influences the economic increase of the mine. The studies on the increase of fragmentation of blasting have been done much, but most focused on the one process of production of coal. The thesis completely considers the factors that affect the increase of fragmentation of coal from the perspective of system, and analyses the mechanics and measures of increasing fragmentation of coal from the process of coal transport and blasting craft. In the process of transport of coal, the thesis finds the reasons of loss of coal fragmentation and loss rate in the different processes of coal production by combining the theoretic analysis and the experiment, and gives the measures of avoiding the loss of coal fragmentation.In the blasting craft, the thesis first uses the apparent of point load to measure the strength of coal sample. And then by the attenuation regulation and distribution character of stress wave under the linear charge blasting, the paper bring forward the idea that the calumniation stress wave can be regarded as cylinder stress wave, the end stress wave as spherical wave. The perfect stress attenuation formula in radical direction is established in complete elastic medium. On thefoundation, the thesis also analyses the damage mechanics of blasting in the medium of coal mass, and the theory of the action zone of the liner charge blasting wave is established, and acquires the calculation of radii of smashed ring and cracked ring, at the same time, the conditions next the free face that form a normal throwing blasting are discussed. And a method of numerical simulation of underground explosion of the linear charge blasting is used, the result of numerical simulation agree with the blasting theory. The optimised parameter of blasting is acquired to increase the fragment of blasting; the relationship between the fragment of coal blasting and the explosive specific charge is studied by fractal geometry for prediction of he fragment distribution of blasting.