Abstract
In order to further analyze the stability and control mechanism of surrounding rock in the gob-side entry retaining, the slip instability coefficient k1 and compression failure coefficient k2 are proposed by the mechanical analysis of the established filling body mechanics model, and when both k1 and k2 are less than 1, the roadside filling body can keep stable. The mechanical model of main roof is analyzed by the static equilibrium method, and the formula for calculating the maximum roof subsidence is deduced. Based on the data of haulage gateway of No. 21201 coal face of Juncheng Coal Mine, using the formula to calculate the amount of roof subsidence at the junction point of filling body and the roof, and proposes two methods to reduce roadway floor heave by increasing the roadside filling width and transferring the surrounding rock stress to the gob. Finally, the corresponding surrounding rock control technology is proposed according to the surrounding rock deformation characteristics during roadway excavation, roadway retention and roadway reuse, and then carries out field monitoring and evaluation. The results show that after adopting the corresponding supporting technology, the surrounding rock of the gob-side entry retaining has been effectively controlled from the excavation to the reuse period with the coal face advancing, the roof-to-floor convergence of roadway solid coal side is less than 220 mm, the roof-to-floor convergence of filling body side is less than 280 mm, and the convergence on the both sides of the roadway is about 190 mm. At the same time, the calculated roof subsidence with the junction point of filling body and the roof is similar to the field monitoring results, which achieves the expected control effect, and the research contents provides a certain reference for the support technology of the gob-side entry retaining.
Highlights
The gob-side entry retaining is a special mining roadway, which needs to go through three stages, namely: roadway excavation, mining of first coal face and mining of second coal face
In view of this, based on the previous research results, this paper studies the overall stability of the gob-side entry retaining, and establishes the surrounding rock structure model of the gob-side entry retaining to study the interaction mechanism between the filling body and the surrounding rock, and the stability conditions of the filling body are determined; By establishing the basic mechanical model of the roof of the gob-side entry retaining, we can get the formula for calculating the maximum subsidence value of the roof of the gob-side entry retaining
Aimed to the deformation characteristics of surrounding rock in the three periods of roadway excavation, roadway retention and roadway reuse, we propose the corresponding surrounding rock control technology, and it verified by industrial experiments
Summary
The gob-side entry retaining is a special mining roadway, which needs to go through three stages, namely: roadway excavation, mining of first coal face and mining of second coal face. The deformation of surrounding rock caused by roadway excavation is small, and the deformation of surrounding rock of the gob-side entry retaining is mainly concentrated in the two stages of mining in the first coal face and mining in the second coal face. The roof of the gob-side entry retaining is shared by the solid roadside and the roadside filling body, and the cutting form of the roof can be divided into three situations [1,2,3,4].
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