Research And Application On The Technology Of Precasting Large Concrete Block Gob-side Entry Retaining Under Hard Roof Conditions

The rational determination of artificial side parameters is the key of successful gob-sideentry retaining under hard roof conditions. Taking Jixian Coal Mine’s left NO.1working faceof West NO.2panel as the research object, the technology of precasting large concrete blockgob-side entry retaining under hard roof conditions was systematically analyzed by theoreticalanalysis, numerical simulation and industrial experiment methods etc. The reasonableartificial side parameters were determined and the industrial experiment was conducted.At first, the structure of surrounding rock in gob-side entrying retaining was analysesedin detail. The static load of artificial side was determined by theoretical calculation analysis.Secondly, the width and stress of artificial side was determined by the numerical simulationmethod. The results also showed that the stress of artificial side was closely related to thefracture position of main roof. The stress of artificial side was maximum when the fractureposition of main roof located above roadway. So the pre-splitting blasting technology wasadopted to blast the main roof in advance. At last, using drilling peep technology, thereasonable hole-space was determined by the experiment of pre-splitting blasting.The above research results were successfully applied in West NO.2panel which showedthat the artificial side parameters were reasonable. The satisfactory economic and socialbenefits were obtained, and can promote the use of the technology under the similarconditions.