A series of true-triaxial compression tests were performed on red sandstone cubic specimens with a circular hole to investigate the influence of depth on induced spalling in tunnels. The failure process of the hole sidewalls was monitored and recorded in real-time by a micro-video monitoring equipment. The general failure evolution processes of the hole sidewall at different initial depths (500 m, 1000 m and 1500 m) during the adjustment of vertical stress were obtained. The results show that the hole sidewall all formed spalling before resulting in strain rockburst, and ultimately forming a V-shaped notch. The far-field principal stress for the initial failure of the tunnel shows a good positive linear correlation with the depth. As the depth increases, the stress required for the initial failure of the tunnels clearly increased, the spalling became more intense; the size and mass of the rock fragments and depth and width of the V-shaped notches increased, and the range of the failure zone extends along the hole sidewall from the local area to the entire area. Therefore, as the depth increases, the support area around the tunnel should be increased accordingly to prevent spalling.

在带圆孔的红砂岩立方试样上进行了一系列真三轴压缩试验，以研究深度对隧道诱发剥落的影响。孔侧壁的破坏过程通过微视频监控设备进行实时监控和记录。得到了在垂直应力调整过程中，不同初始深度（500 m，1000 m和1500 m）孔侧壁的一般破坏演化过程。结果表明，孔侧壁在产生应变岩爆之前都形成了剥落，并最终形成了V形缺口。隧道初始破坏的远场主应力与深度呈良好的线性正相关。随着深度的增加，隧道初始破坏所需的应力明显增加，剥落变得更加强烈；岩石碎块的大小和质量以及V形槽口的深度和宽度增加，破坏区域的范围沿孔侧壁从局部区域扩展到整个区域。因此，随着深度的增加，隧道周围的支撑面积应相应增加，以防止剥落。