Abstract
The deformation and instability of roadway surrounding rock reflect the processes of energy accumulation and release. To reveal the instability of roadway surrounding rock, based on the engineering geological conditions of a certain mine, this paper established a nonuniform superimposed stress model of a coal pillar, starting from the energy accumulation and release of the surrounding rock of the floor roadway after coal pillar failure. The essence of the deformation of the lower roadway was revealed, and the following conclusions were drawn: (1) The elastic strain energy accumulated in the lower roadway roof and upper coal pillar is related to not only the physical properties of the coal seam but also the distance between the coal pillar and surrounding rock, the caving height and shape, the burial depth, and the retained pillar width. (2) The elastic strain energy accumulated in the lower roadway roof and the upper coal pillar induced large displacements of the roadway due to the energy release during excavation. (3) It is proposed that the “stress relief degree” and failure morphology are used to identify zones in the rock and coal, and the two zoning modes have a high consistency. (4) The stress distribution in a narrow coal pillar should be calculated in segments. (5) Based on the zoning and energy release characteristics, the following control factors are suggested regarding the coal pillar width and roadway layout: (a) for the coal pillar, avoid the overlap or intersection of the peak values in the limit equilibrium zone and ensure a sufficient elastic zone; (b) arrange the roadway in shear slip Zone B-2 or the moderate pressure relief Zone B-2 to reduce the accumulation of elastic strain energy in the surrounding rock.
Highlights
Spaced coal seams are quite common in China [1], and a large proportion are mined [2], such as at Datong and Lianghuai and Liupanshui [3,4,5,6]
The above research results have greatly enriched the theory of deformation failure and surrounding rock control of floor roadways, the mechanism of surrounding rock deformation caused by a nonuniform superimposed stress in the retained coal pillars in close coal seam roadways is still unclear. erefore, to provide scientific decision-making and theoretical guidance to maintain the stability of lower mining roadways, in this paper, the authors simplify the superimposed stress model of a coal pillar, considering the mechanism of energy accumulation and release after the pillar failure, and discuss rational suggestions for the size of the retained coal pillars in the upper coal seam and the arrangement of the mining roadway
(1) e elastic strain energy accumulated in the roadway roof and upper coal pillar is related to the physical properties of the coal seam and to the distance between the coal pillar and surrounding rock, the caving height and shape, the burial depth, and retained pillar width
Summary
Spaced coal seams (close coal seams) are quite common in China [1], and a large proportion are mined [2], such as at Datong and Lianghuai and Liupanshui [3,4,5,6]. Many scholars have performed a considerable amount of research on the deformation and instability of lower mining roadways: Xu et al [7] used numerical simulation and theoretical analysis to study the evolution characteristics of the stress deviation in the floor under a pillar after mining in an upper coal seam, revealed the mechanical control of roadway surrounding rock deformation, proposed roadway control measures, and achieved a good engineering. The above research results have greatly enriched the theory of deformation failure and surrounding rock control of floor roadways, the mechanism of surrounding rock deformation caused by a nonuniform superimposed stress in the retained coal pillars in close coal seam roadways is still unclear. The above research results have greatly enriched the theory of deformation failure and surrounding rock control of floor roadways, the mechanism of surrounding rock deformation caused by a nonuniform superimposed stress in the retained coal pillars in close coal seam roadways is still unclear. erefore, to provide scientific decision-making and theoretical guidance to maintain the stability of lower mining roadways, in this paper, the authors simplify the superimposed stress model of a coal pillar, considering the mechanism of energy accumulation and release after the pillar failure, and discuss rational suggestions for the size of the retained coal pillars in the upper coal seam and the arrangement of the mining roadway
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
