June 28, 2024, Denver, CO, USA – Dr. Rami Abousleiman, a geomechanical engineer at Knight Piésold USA, introduced a technical paper on the conceptual evaluation of the safety and efficacy of the proposed felling of a mineralized rock tower at the Golden 2024 Symposium of the American Rock Mechanics Association (ARMA), held on June 23–26, 2024, in Golden, USA. Additionally, as one of the co-authors of the paper, Jim Cremeens, the chief geotechnical engineer of Knight Piésold USA, attended the symposium together with Joy Foley, a project engineer at the company.

Now in its 58th year, the annual ARMA symposium, which was hosted by the Colorado School of Mines, focused on seven major technical tracks on the latest advances and applied research in rock mechanics, rock engineering, and geomechanics.

“Attending, presenting, and exhibiting on behalf of Knight Piésold at the ARMA symposium were a privilege and a pleasure,” said Dr. Abousleiman. “We hope to continue to elevate our profile among our peers, learn from our academic mentors, and network with existing and prospective clients through engagement in both the civil and mining tracks at future conferences of ARMA and the International Society for Rock Mechanics and Rock Engineering.”

Dr. Abousleiman presented the paper titled, “Concept Feasibility and Predicted Behavior of Mining a Rock Tower with Drill-and-Blast Undermining Using Dynamic Three-Dimensional Discontinuum Numerical Models,” during the numerical modeling session of the mining technical track. Other co-authors of the paper include Carlos Contreras of Stantec, Tristan Worsey of DynoConsult, and Nathan Rouse of Thoroughbred Drill and Blast Consultants.

The Dragon’s Tooth is a mineralized rock tower located near the base of an existing open pit mine along the bank of a perennial river. The rock tower and its underlying material were not mined with the completion of the open pit due to limited safe access for conventional open pit mining equipment. A novel mining method was developed to safely collapse the rock tower away from the adjacent river, using a wedge-shaped “key-cut” blast pattern and post-split hinge to topple the rock tower towards the open pit.

Integrated site-specific and -adjacent data were used to develop a proof-of-concept numerical model to approximate the possible post-blast spatial configuration of the fallen rock blocks of the blasted tower. A three-dimensional discrete element method model implemented in 3DEC was used.

“By working with the operations and blasting teams, we identified critical aspects for modeling the novel mining method using the simplest representations that we could justify given the level of design,” said Dr. Abousleiman. “Unsafe options were removed from consideration, and blasting was modified to account for critical geomechanical considerations.”

The model results indicated that the novel mining method would likely result in only three percent of the Dragon’s Tooth block volume being cast towards the adjacent river. More detailed assessment of block fragmentation and gas pressures using bonded block method (BBM) models or hybrid finite-discrete element method (FDEM) models may be needed in future design phases.

Cremeens added, “The safe mining of the rock tower was our primary objective. The use of a novel approach to modeling rock mass conditions in a state-of-the-art three-dimensional numerical model afforded a high level of confidence in our model results, which will translate to a high degree of confidence when executing the mine plan.”

“At Knight Piésold, from concept through to operations and closure, we use state-of-the-art technologies and methodologies, coupled with engineering judgment, to analyze the behavior of rocks and rock masses for safe and effective open pit and underground mining.”