A Modeled Demonstration of Hydromechanical Coupling in an Active Open Pit Mine

Abstract

Understanding the interaction of rock and water under stress is often a key factor in assessing slope stability in open-pit mining. Mining activity can increase or decrease the total stress acting on a rock mass, affecting the properties and behavior of the rock and water in the subsurface. In this research project, numerical modeling is used to demonstrate the concept of hydromechanical coupling based on an open-pit mining case study where coupled behavior due to slope excavation is observed in a piezometer monitoring sensor. The theory behind hydromechanical coupling and the physical parameters contributing to this behavior are discussed. Site monitoring data are analyzed, and their behavior are reproduced using the 2D numerical modeling software FLAC and a simplified coupled modeling process to produce mechanical- and flow-induced changes to a starting model developed based on the mine site conditions and mining activity. The work then assesses the sensitivity of contributing material parameters to modeled pore pressure responses and examines the range of important parameter values. This research aims to promote the understanding of hydrologic monitoring data behavior in pit slopes by producing a modeled hydromechanical explanation to provide improved knowledge for mine practitioners to use when planning mining activity, monitoring programs, and slope design. This work helps hydrogeologists interpret piezometer data and therefore make better decisions and models.