Based on the prototype of caving coal under the metal nets and caving coal on total high in hard coal of Datong,the rules of charging decoupling coefficient and explosive charge along line influencing the size of top-coal lump were researched through the virtual blasting experiment in perpendicular to coal stratification and parallel to the coal stratification.

The article is beginning with the factors of the restricting light-explosion trial of the mixture gas and help us to find the best conditions which makes the experiment successful by using the method of orthogonal design and analysis of variance.

8 detonator with paper shell in air and in rigid polyurethane foam plastics (RPUF) were obtained by sympathetic tests, and the pressure distributions in the blast fields in the two mediums were also measured respectively by a piezoelectric crystal sensor and by PVDF sensors.