Experimental study on optimizing parameters of flexible reinforcement technology of coal wall

In recent years,the proposal of flexible reinforcement technology of coal wall in working face has enriched the theory of prevention and control of face failure. In order to further reveal the mechanism of flexible coir rope in flexible reinforcement technology of coal wall,clarify the coupling relationship between grout and flexible coir rope,and reduce the technical cost and application difficulty,this paper optimized the flexible reinforcement technology of coal wall by the means of physical experiment,theoretical analysis,equipment development and engineering application.The failure characteristics of coal wall with no support,grouting support and flexible support were studied through three-dimensional simulation experiments,which reveals the mechanism of flexible reinforcement technology of coal wall and flexible coir rope. The ratio of borehole diameter to flexible coir rope diameter is defined as borehole-rope di- ameter ratio. Through the pull-out test of “flexible coir rope,grout and coal”,the influence of borehole-rope diameter ratio and grouting type on the effect of flexible support was studied,and the quantitative coupling relationship between grout and flexible coir rope was determined,and a low-cost flexible support grouting material and a semi-annular grou- ting pipe were developed. The research showed: The flexible reinforcement technology of coal wall can effectively im- prove the integrity of coal body and reduce the wall damage depth;When the borehole-rope diameter ratio was between 1. 6 and 1. 9,the effect of the flexible support was the best,and the closer to 1. 9,the better the flexible support effect; Using “superfine cement,slag and sodium silicate” mixture as flexible support grouting material,the amount of slag added was not more than 30% ,and the amount of sodium silicate added was not more than 10% ,which can reduce the application cost of flexible support technology;The semi-annular grouting pipe developed can effectively reduce the re- quired borehole diameter and reduce the difficulty of technical application;Finally,through the engineering application of flexible reinforcement technology of coal wall in Ruilong Coal Mine,the occurrence of coal wall failure was effective- ly alleviated and the face stability was improved. Through a series of experimental studies,this paper systematically op- timized the flexible reinforcement technology of coal wall,which provides a reference for the scientific appli-cation of the technology.