The spherical element computer code DMC (Distinct Motion Code) used to model rock motion resulting from blasting has been enhanced to allow routine computer simulations of bench blasting. The enhancements required for bench blast simulation include: 1) modifying the gas flow portion of DMC, 2) adding a new explosive gas equation of state capability, 3) modifying the porosity calculation, and 4) accounting for blastwell spacing parallel to the face. A parametric study performed with DMC shows logical variation of the face velocity as burden, spacing, blastwell diameter and explosive type are varied. These additions represent a significant advance in the capability of DMC which will not only aid in understanding the physics involved in blasting but will also become a blast design tool.
Detonation of the explosive in a blastwell results in a transient stress wave that fragments the rock, and a high pressure, high tempera- ture gas pocket that expands pushing the rock in front of it. Events that occur during a blast have been difficult to understand because the short time scale, and the severe environment makes measurements diffi- cult. Numerical modeling can contribute greatly to an understanding of the physics involved in the blasting process and can also contribute to the blast design. This paper will describe the latest enhancements to the blast modeling code DMC (Distinct Motion Code) [Taylor and Preece, 1989] and will demonstrate the ability of DMC to model gas flow and rock motion in a bench blasting environment.
DMC has been used previously to model rock motion associated with blasting in a cratering environment [Preece and Taylor, 1990] and in confined volume blasting associated with in-situ oil shale retorting [Preece, 1990 a&b]. These applications of DMC treated the explosive loading as force versus time functions on specific spheres which were adjusted to obtain observed face velocities. It was recognized that a great need in explosives modeling was the coupling of an ability to simulate gas flow with the rock motion simulation capability of DMC. This was accomplished by executing a finite difference code that com- putes gas flow through a porous media [Baer and Gross, 1989] in con- junction with DMC. The marriage of these two capabilities has been documented by Preece and Knudsen, 1991.
