A numerical design framework for unloading excavations in deep potash mining

Area of Science:

• Geotechnical Engineering
• Mining Engineering
• Rock Mechanics

Background:

• Deep underground structures in potash mines face stability challenges due to high rock pressure and heterogeneous rock masses.
• Conventional support methods are often insufficient, necessitating innovative strategies for ensuring structural integrity.

Purpose of the Study:

• To investigate the effectiveness of using unloading excavations as a safety measure for underground structures in potash salt rock masses.
• To evaluate the reduction in limit state zones achieved by this technique across various depths (300-1200 m).

Main Methods:

• Utilized finite element method (FEM) simulations with a complex limit state criterion to model rock mass behavior.
• Validated the FEM model against long-term field deformation data from a potash mining excavation.
• Analyzed the impact of unloading excavation placement and dimensions on stability.

Main Results:

• Strategic placement of unloading excavations significantly reduced limit state zones by 7% to over 90%.
• Optimal design parameters for the Starobin deposit include a 3m diameter unloading excavation placed 1.5-7m from the main excavation.
• A placement distance of 5-6m proved most effective in minimizing limit state zones.

Conclusions:

• Unloading excavations represent a viable technique for enhancing the stability of deep geotechnical structures in potash mining.
• The study provides preliminary design guidelines and suggests potential applicability to other geotechnical projects.
• This innovative approach offers a promising solution to the challenges posed by deep underground excavations.