Numerical study on tunnel damage subject to blast loads in jointed rock masses

• Published in: Environmental earth sciences Vol. 81; no. 24; p. 548
• Main Authors: Chen, Shujie, Zhu, Zhengguo
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2022; Springer Nature B.V
• Subjects: Biogeosciences; Blast loads; Blasting; Codes; Crack propagation; Damage assessment; Deformation; Depth; Dimensions; Discrete element method; Dredging; drilling; drills; Earth and Environmental Science; Earth science; Earth Sciences; Efficiency; Environmental Science and Engineering; Excavation; Failure; Geochemistry; Geology; Hydrology/Water Resources; Inclination angle; Jointed rock; Laboratories; Loads (forces); mass; Mathematical models; Mechanical properties; Methods; Numerical analysis; Original Article; Rock; Rock masses; Rocks; Sensitivity analysis; standard deviation; Terrestrial Pollution; Tunnels; Blast-induced damage zones (BIDZ); Three dimension Distinct Element Code (3DEC); Joint properties; Drill and blast method; Advanced length
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-022-10676-3

Drill and blast method is an accepted technique of tunnel excavation but it often causes over-break or even threatens the stability of the surrounding rock. Moreover, the rock mass mostly contains different forms of discontinuities and so more severe damage may develop under the blasting loads. In this paper, numerical modeling on the damage of jointed tunnel excavation subject to blast shock was carried out with three-dimension Distinct Element Code (3DEC). The blast-induced damage zones (BIDZ) including failure zones and open zones are as evaluation indicators. The effects of joint geometrical and mechanical properties, tunnel depth and advance length on damage depth were evaluated. The influence extent of these factors was also compared by arithmetic mean of maximum damage depth and its standard deviation. Lastly, the results are contrasted with an existing empirical formula. It is found that increasing advance length has a more obvious effect on tunnel damage comparing with other factors, and failure zones begin to develop when the advance length exceeds 2 m in the model. If the joint inclination angle increases above 60°, the tunnel is prone to instability and the failure rocks is mainly found at the tunnel roof. For all joint strike angles, there is a clear damage zones in the surrounding rock, and failure zones are mainly located at the sidewall. The damage depth is highly dispersive within 1 m of the joint spacing. This research provides an insightful understanding of damage magnitude of jointed rock mass during tunnel excavation with blasting.