Research Progress of Coal Damage under Unsteady Load in China

Abstract

Coalbed methane mining, suppression of coal dust, and elimination of dynamic disasters are closely related to the expansion of coal body cracks and internal damage. Understanding the expansion mechanism of pore-cracks is critical to investigate coal body damage. In this study, research from 2016 to 2021 conducted on the coal damage mechanism in China was sorted and the progress in this field was analysed to systematically investigate coal body damage. Critical topics of research in this field in recent years were identified, and load types were classified into static and dynamic loads. Dynamic loads with obvious characteristics and considerable damage-increasing effects were classified into impacting, cyclic, pulsating, and other dynamic load types. The current load-generating devices, various detection techniques and methods, research results, and the future research directions under various load types were discussed. The current coal damage research is primarily based on macrocharacteristic analysis and the stage characteristics of characterisation variables. The use of scanning electron microscopy, computerised tomography three-dimensional reconstruction technology, and acoustic emission technology can reveal the pore propagation mechanism at the micro level.

Numerical Simulation Research on the Pressure Relief and Permeability Enhancement Mechanism of Large-Diameter Borehole in Coal Seam

“…The mechanism of the drilling technology and method is to form a cavity at a specific location in the coal and rock mass, thereby changing the stress of the coal mass, redistributing the pores and gaps in the coal mass, and forming new gaps suitable for the desired state, thereby venting the coal mass [34][35][36]. To ensure the safe and efficient mining of high gas and low gas permeability coal seams, the key issue is how to continuously and quickly desorb and release a large amount of adsorbed gas in low gas permeability coal [37][38][39]. At present, the soft and low-permeability coal seams have the characteristics of small drainage volume, low drainage concentration, and rapid flow attenuation during predrainage, which seriously affects the predrainage effect [40][41][42].…”

Research on the Dust Diffusion and Pollution Behaviour of Dynamic Tunneling in Header Excavators Based on Dynamic Mesh Technology and Field Measurement

“…This in turn leads to an increase in the rate of pneumoconiosis among miners, which has been increasing year after year, and thus seriously threatens the lives and health of workers onsite [7]. As highlighted in Figure 1, according to data published by the National Health and Wellness Commission, new pneumoconiosis cases accounted for up to 84.19% of the total occupational cases in 2020 [8,9]. The study of the spatial and temporal evolution of ai tunnel, as well as the investigation of the theoretical basis of the ventilation and dust removal, are necessary in order of dust pollution in the working environment, and the heaving face.…”