There are two states for the coal-mass on the goaf-side which is in stress equilibrium: the state of limit equilibrium(the bearing stress in the coal-mass equals its ultimate bearing stress) and the state of nonultima...There are two states for the coal-mass on the goaf-side which is in stress equilibrium: the state of limit equilibrium(the bearing stress in the coal-mass equals its ultimate bearing stress) and the state of nonultimate equilibrium(the bearing stress in the coal-mass is less than its ultimate bearing stress). To analyze the bearing characteristics of a coal pillar in the state of limit equilibrium and guide the design of pillar width, we established a mechanical analytical model of the non-ultimate equilibrium zone in the coal-mass on the goaf-side combined with the limit equilibrium theory as well as adopting the methods of theory analysis and mechanical analysis based on the assumption of a state of non-ultimate equilibrium. The width correction coefficient of the limit equilibrium zone has been given. The influence of mining depth, stress concentration coefficient of the surrounding rock, the non-limit strength of the coal-mass and stability of the coal rock interface has been studied. On this basis, we have confirmed that when the width of a longwall mining face roadway protection coal pillar is between 11.6 m and 13.16 m in No. 4 coal seam of Xinrui coal mine in Lvliang in Shanxi province the elastic core region in the coal pillar can be assured and the roadway will be located in the area of lower stress which is outside the peak stress. So the revised width of the limit equilibrium zone is more practical.展开更多
基金supported by the National Programs for Fundamental Research and Development (No. 2013CB227900)the National Natural Science Foundation of China (Nos. 51204166, 51174195 and 51474209)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘There are two states for the coal-mass on the goaf-side which is in stress equilibrium: the state of limit equilibrium(the bearing stress in the coal-mass equals its ultimate bearing stress) and the state of nonultimate equilibrium(the bearing stress in the coal-mass is less than its ultimate bearing stress). To analyze the bearing characteristics of a coal pillar in the state of limit equilibrium and guide the design of pillar width, we established a mechanical analytical model of the non-ultimate equilibrium zone in the coal-mass on the goaf-side combined with the limit equilibrium theory as well as adopting the methods of theory analysis and mechanical analysis based on the assumption of a state of non-ultimate equilibrium. The width correction coefficient of the limit equilibrium zone has been given. The influence of mining depth, stress concentration coefficient of the surrounding rock, the non-limit strength of the coal-mass and stability of the coal rock interface has been studied. On this basis, we have confirmed that when the width of a longwall mining face roadway protection coal pillar is between 11.6 m and 13.16 m in No. 4 coal seam of Xinrui coal mine in Lvliang in Shanxi province the elastic core region in the coal pillar can be assured and the roadway will be located in the area of lower stress which is outside the peak stress. So the revised width of the limit equilibrium zone is more practical.
