YANG S K, SUN K, DENG Z D ,et al.Zonal disintegration mechanism of surrounding rock during excavation of deep-buried multiple tunnels[J].Journal of Henan Polytechnic University(Natural Science) ,2026,45(4):30-38.

doi:10.16186/j.cnki.1673-9787.2024040037

Received:2024/04/20

Revised:2024/06/24

Published:2026/06/17

Zonal disintegration mechanism of surrounding rock during excavation of deep-buried multiple tunnels

Yang Shikou, Sun Kuan, Deng Zhengding, Hu Xinwei

School of Civil Engineering and Surveying & Mapping Engineering， Jiangxi University of Science and Technology， Ganzhou 341000， Jiangxi，  China

Abstract: Objectives Existing studies on zonal fracture of surrounding rock mainly focus on single tunnels， whereas the zonal fracture mechanism of surrounding rock in deep-buried multiple tunnels remains unclear in practical engineering. Therefore， the zonal fracture mechanism of surrounding rock during excavation of deep-buried multiple tunnels was investigated. Methods Taking the diversion tunnels of the Jinping II Hydropower Station as the engineering background， a numerical model based on the strain-softening constitutive model was established. The variation laws of zonal fracture morphology， maximum radial distance of fracture zones， and number of fracture zones with strength parameters， deformation parameters， and dilation angle after excavation unloading were analyzed. In addition， the influences of these parameters on the zonal fracture characteristics of surrounding rock were compared.  Results The results show that the fracture patterns around the four tunnels exhibit a certain symmetrical distribution after excavation unloading. More severe zonal fracture phenomena occur in the surrounding rock of Tunnel No. 2， and the zonal fracture on the right side of Tunnel No. 1 is more significant than that on the left side. With decreasing internal friction angle， cohesion， and elastic modulus， or increasing dilation angle， the zonal fracture becomes more pronounced. Poisson's ratio mainly affects the locations of fractured zones. As Poisson's ratio decreases， the fractured zones on both sides of the tunnel gradually migrate deeper into the surrounding rock， whereas the fractured zones near the crown and invert move closer to the tunnel wall. Among all parameters， the strength parameters have the greatest influence on the zonal fracture morphology， followed by the deformation parameters， while the effect of dilation angle is relatively small.  Conclusions The study reveals the zonal fracture mechanism of surrounding rock after excavation unloading of deep-buried multiple tunnels and provides theoretical support for surrounding rock support design in deep underground multi-cavern excavation engineering.

Key words:deep-buried tunnel;surrounding rock;strain softening;zonal fracture;strength parameters;excavation unloading