Deformation failure mechanism and asymmetric coupling support technology of roadways in large dip angle fully mechanized top coal caving mining

Abstract

One side of 7403 fully mechanized top coal caving mining with a large dip angle in Zouzhuang Coal Mine is a gob; the return airway is excavated along the floor, while the haulage roadway is excavated along the roof, and the working face is mined along the coal seam floor. The deformation and failure of the surrounding rock of the roadway show obvious asymmetry. The stability of the surrounding rock of the roadway cannot be guaranteed by using a conventional full-section equal-strength symmetrical support form. Taking the 7403 working face as the engineering background, a research method combining theoretical analysis, numerical simulation, and field measurements was employed to identify the key deformation and failure zones. The asymmetric coupled support technology for roadways was proposed, and a comparative analysis of the support effectiveness of different support schemes was conducted. The results showed that: (a) the main reason for the asymmetric deformation and failure characteristics of the roadway is due to the different layout layers and rock types of the two sides of the roadway. The high side of the haulage roadway and the low side of the return airway are the key parts of the deformation and failure of the surrounding rock in the roadway. (b) On the basis of the original symmetrical support of “anchor belt net cable,” the key parts that cause differential deformation and failure are reinforced with through-layer anchor cables to achieve coupled support of the key parts of deformation and failure of surrounding rocks in a large dip angle coal seam roadway. (c) The control effect of roadway surrounding rocks under different support schemes (no support, symmetric support, asymmetric support) is compared and analyzed. After the roadway adopts asymmetric support technology, the horizontal stress of the two sides of the roadway increases, the shear force distribution is more uniform, the range of the plastic failure zone decreases obviously, the stability of the roadway surrounding rock increases, and the deformation decreases.