Abstract
This paper studies and introduces the successful case of gob‐side entry retaining technology and the typical mining pressure law in Luan mining area, which is the main mining coal seam in Qinshui coalfield. Qinshui coalfield has an estimated coal reserve of 300 billion tons, accounting for 9.58% of the total national coal reserve in China, especially anthracite, chemical coal, and coking coal. The methods of field investigation, theoretical analysis, physical experiment, and industrial test are adopted. Through the field investigation, theoretical analysis, physical experiments, and industrial test, the following conclusions have been drawn in this study: (1) A thorough engineering geological investigation was conducted on the entry retaining along the gob side on noncoal pillar mining working face, which covers multiple periods of mining process including the roadway excavation period, primary mining period, primary mining stability period, and secondary mining influence period. A series of analysis and tests were conducted such as core sampling, rock mechanics property testing, borehole detection, and flexible formwork support evaluation, which laid a foundation for identifying the mining pressure law of gob‐side entry retaining by using noncoal pillar mining. (2) The mining pressure law was studied through the collection of the field measurements taken from the entry retaining along the gob side on noncoal pillar mining working face. The keys to achieve the roadway surrounding rock stability through noncoal pillar mining are obtained. According to the study, the stability control of retained roadway surrounding rock mainly depends on the stability of top coal, coal side, and shoulder angle coal. (3) In this study, a roadway reinforcement scheme is proposed to improve the surrounding rock control technology for gob‐side entry retaining by noncoal pillar mining, whose effectiveness has been verified by a series of industrial test. Therefore, the wide adoption of the noncoal pillar mining method in Number #3 coal mine can significantly relieve the predicament of coal pressing under a large number of buildings in Luan mining area, which provides insightful guidance to the coal‐free pillar mining in the whole Luan mining area.
Highlights
(3) In this study, a roadway reinforcement scheme is proposed to improve the surrounding rock control technology for gob-side entry retaining by noncoal pillar mining, whose effectiveness has been verified by a series of industrial test. erefore, the wide adoption of the noncoal pillar mining method in Number #3 coal mine can significantly relieve the predicament of coal pressing under a large number of buildings in Luan mining area, which provides insightful guidance to the coal-free pillar mining in the whole Luan mining area
Entry retaining along the gob side refers to that in order to recover the protective coal pillars reserved in the traditional mining method, the roadway in the upper section is resupported by certain technical means and left to the section for use. is is of practical significance to the technical transformation of production mine, relaxation of mining relationship, and extension of mine life
Comprehensive Assessment of E1316 Gob-Side Entry Retaining. e measurement of rock mechanics properties, detection of the surrounding rock structure, and statistical study and theoretical calculation of premining failure of the surrounding rock and the flexible formwork filling body of E1316 gob-side entry retaining have suggested that the surrounding rock of E1316 intake entry had undergone great deformation and destruction. e serious damage of support structure had made the supporting system more vulnerable and fragile
Summary
Entry retaining along the gob side refers to that in order to recover the protective coal pillars reserved in the traditional mining method, the roadway in the upper section is resupported by certain technical means and left to the section for use. is is of practical significance to the technical transformation of production mine, relaxation of mining relationship, and extension of mine life. No 3# coal seam is the main mining area. Ordovician limestone is the basement of the coal measures in the mining area, and the coal-bearing strata are mainly Carboniferous and Permian strata, with Shanxi Formation of the Lower. Permian and Taiyuan Formation of the Upper Carboniferous as the main bodies. No 3# coal seam locates in the middle and lower parts of Shanxi Formation as the main mineable coal seam in this area. Under the event that no pillar is utilized in the mining process of No. coal, a higher coal recovery rate can be achieved by eliminating the pillar and additional constructions [1,2,3]. Erefore, the study of the mining pressure law of 3# coal seam mining can provide insightful guidance to the coal-free pillar mining in the whole Luan mining area. A typical mine called Gaohe was selected as the main study subject [4,5,6]
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