Abstract:
To address the issues of local stress concentration, damage instability, and failure in surrounding rock of deep buried roadways caused by unreasonable cross-section shapes, the transportation roadway of the 1301 working face in Lilou Coal Mine is taken as the engineering background, and the mechanical characteristics of roadway models with different bottom angles
θ are analyzed through the theoretical analysis, similar material simulation tests and acoustic emission monitoring technology. Numerical simulation is employed to investigate the distribution laws of surrounding rock stress and fractures, aiming to reveal the influence mechanism of cross-sectional shape variation on the energy evolution and damage failure of surrounding rock. The results indicate that: The peak strength, elastic modulus, and pre-peak accumulated energy of the surrounding rock first increase and then decrease with increasing bottom angle, reaching their maximum values at
θ=90°; The pre-peak energy accumulation rate demonstrates low sensitivity to variations in the bottom angle, whereas the post-peak energy release rate first decreases and then increases with increasing bottom angle, attaining its minimum at
θ=90°; The damage evolution process of the surrounding rock exhibits an asymmetrical “V”-shaped distribution with increasing bottom angle, with damage change rates of 0.013/(°) and 0.017/(°) for bottom angle increases from 70° to 90° and from 90° to 110°, respectively; The number of tension cracks in the lower right area of the roadway surrounding rock shows a monotonic decreasing trend with the increase of the bottom angle, the failure mechanism gradually transitions from tension dominated to shear tension composite type with the increase of angle. The distribution of cracks in the upper right area of the roadway surrounding rock remains relatively stable, and the fluctuation amplitude of the proportion of tension and shear cracks is only 1.47%, the failure mode is less affected by the cross-sectional shape.