Failure Characteristics of the Water-Resisting Coal Pillar under Stress-Seepage Coupling and Determination of Reasonable Coal Pillar Width

Abstract

Groundwater inrush hazard has always been a great threat to the construction of vertical shafts in coal mines. Generally, the failure of the water-resisting coal pillar under coupled stress-seepage conditions around the vertical shaft is the main reason for the generation of the water inrush channel. In order to understand the mechanical behaviors of the water-resisting coal pillar, the strength of typical coal affected by the size and water content was investigated, and the stress sensitivity of permeability was investigated by a stress-seepage coupling test. The stress field and deformation of the water-resisting coal pillar were investigated by numerical simulation, the stability of the water-resisting coal pillars with different widths was evaluated, and the reasonable width of the coal pillars under coupled stress-seepage condition was determined. Results show that the water content and coal pillar width have a great influence on the mechanical characteristics of coal samples. Under the conditions of lower water content and larger coal sample width, the coal sample presents higher strength, smaller axial deformation, smaller permeability and porosity, and weak sensitivity to stress. The simulation results show that the boundary of the main roadway at the end of the coal pillar is dominated by tensile stress, and fractures can significantly contribute to the destruction of coal pillars. With the increase in the width of the water-resisting coal pillar, the internal damage variable, maximum tensile stress, porosity, and average water flow velocity of the coal pillar decrease, which reduces the risk of water inrush and improves the safety of the water-resisting coal pillar. An evaluation model of the reasonable width of the water-resisting coal pillar under the stress-seepage coupling was proposed, and the model was verified by the shear slip law and experimental results. This study provides theoretical and experimental guidance for the risk management of groundwater inrush disaster during the construction of vertical shafts in coal mines.

Study on the Stress Distribution and Stability Control of Surrounding Rock of Reserved Roadway with Hard Roof

“…According to the field geological parameters of the Gushuyuan Mine, the radius of the plastic softening zone, Rp = 3.4 m, and the radius of fracture zone, Rt = 2.74 m, can be calculated. Given the serious deformation and failure of the loose coal on the two sides of the roadway, some theoretical formulas from at home and abroad [34][35][36], such as the A. H. Wilson formula, large plate fracture theory formula, and limit equilibrium theory formula, can be used to calculate the failure depth of the two sides of the reserved roadway in combination with the parameters of the on-site geological conditions. It is known that the failure depth of the two sides is 4.54 m~5.96 m.…”

Correction: Liu et al. Failure Characteristics of the Water-Resisting Coal Pillar under Stress-Seepage Coupling and Determination of Reasonable Coal Pillar Width. Water 2023, 15, 1002

“…In the original publication [1], there was a mistake in Figure 4 as published. The geographical location label "Mongolia" should be changed to "Inner Mongolia" in Figure 4.…”

Characteristics of waterproof failure and optimal width of narrow coal pillars under the coupled effects of mining, excavation and seepage

“…The presence of water inrush accidents poses a tremendous threat to the safety of coal mining operations (Maiti et al 2009;Bukowski 2015;Ma et al 2019;Wang et al 2022b;Liu et al 2023a). During the excavation of roadways, various water inrush problems are frequently encountered (Gui and Lin 2016;Polak et al 2016).…”