Title: Mechanism study on the sandstone roof caving characteristics for improving the preconditioning measures to mitigate the windblast risk in coal mines

Authors: Jinhe Jia; Zhichao Wang; Zhen Zhang

Addresses: CCTEG Coal Mining Research Institute, Beijing, 100013, China ' CCTEG Coal Mining Research Institute, Beijing, 100013, China ' Coal Mining and Designing Department, Tiandi Science and Technology Co., Ltd., Beijing, 100013, China

Abstract: The geological feature of sandstone strata directly overlying coal seams is common in the Shendong shallow buried coal field, and causes delayed roof caving and the risk of windblasts in the initial longwall mining stage. To mitigate windblasts, preconditioning measures, such as hydraulic fracturing operations and temporary blasting operations, are employed to improve the roof caving performance. Site observations show that the thicker the overburden, the more difficult the roof caving becomes, and the conditioning measures do not produce very good roof caving performance as expected when the overburden thickness approaches 200 m. Numerical simulations are employed to investigate the roof-caving mechanism associated with the geological conditions of the Shendong coal field. The numerical results show that structurally controlled instability is the main mechanism of the roof caving; the gravitationally-loaded horizontal stress can lead to worse roof caving performance in the case of greater overburden thickness.

Keywords: first roof caving; sandstone-dominated strata; hydraulic fracturing; horizontal stress; numerical simulation; windblast.

DOI: 10.1504/IJMME.2024.138729

International Journal of Mining and Mineral Engineering, 2024 Vol.15 No.1, pp.49 - 70

Received: 18 Aug 2023
Accepted: 28 Feb 2024
Published online: 29 May 2024 *

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