Modeling Coal Seam Damage in Cast Blasting
A discrete element computer program named DMC_BLAST (Distinct Motion Code) has been under development since 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employs explicit time integration and uses spherical or cylindrical elements that are represented as circles in two dimensions. DMC_BLAST calculations compare favorably with data from actual bench blasts (Preece et al, 1993). Coal seam chilling refers to the shattering of a significant portion of the coal leaving unusable fines. It is also refereed to as coal damage. Chilling is caused during a blast by a combination of explosive shock energy and movement of the adjacent rock. Chilling can be minimized by leaving a buffer zone between the bottom of the blastholes and the coal seam or by changing the blast design to decrease the powder factor or by a combination of both. Blast design in coal mine cast blasting is usually a compromise between coal damage and rock fragmentation and movement (heave). In this paper the damage to coal seams from rock movement is examined using the discrete element computer code DMC_BLAST. A rock material strength option has been incorporated into DMC_BLAST by placing bonds/links between the spherical particles used to model the rock. These bonds tie the particles together but can be broken when the tensile, compressive or shear stress in the bond exceeds the defined strength. This capability has been applied to predict coal seam damage, particularly at the toe of a cast blast where drag forces exerted by movement of the overlying rock can adversely effect the top of the coal at the bench face. A simulation of coal mine cast blasting has been performed with special attention being paid to the strength of the coal and its behavior at t he bench face during movement of the overlying material.
- Research Organization:
- Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1905
- Report Number(s):
- SAND98-2618C; ON: DE00001905
- Resource Relation:
- Conference: 25th Annual Conference on Explosives and Blasting Technique; Nashville, TN; 02/07-10/1998
- Country of Publication:
- United States
- Language:
- English
Similar Records
Expanded rock blast modeling capabilities of DMC{_}BLAST, including buffer blasting
Computer cast blast modelling