Mining-induced strata stress changes, fractures and gas flow dynamics in multi-seam longwall mining

摘要

This paper presents key findings from a recent comprehensive study of longwall mining-induced strata movement, stress changes, fractures, and gas flow dynamics in a deep underground coal mine in Anhui, China. The study includes field monitoring of overburden displacement, stress and water pressure changes at the longwall panel 1115 (1) of the Guqiao Mine. In addition, 3D modelling of strata behaviour at the longwall panel using a 3D finite element code and goaf gas flow simulations with a CFD code are carried out. This research has resulted in many new insights into the complex dynamic interaction between mining induced strata stress changes, fractures, and gas flow patterns. Based on the findings from the field monitoring and numerical modelling, a three-dimensional annular-shaped overlying zone along the perimeter of the longwall panel is identified for optimal methane drainage during mining. A practical method that helps define the geometry and boundary of this zone is proposed. This study provides a new methodology and a set of engineering principles for the design of optimal co-extraction of coal and methane.