Underground rock engineering, such as mines and tunnels, is gradually turning to deep excavation as there are increasing requirements for mineral resources and underground spaces in the deep crust. In deep excavation, some unconventional rock fracture and failure phenomena, such as rockburst, slabbing, large deformation, and zonal disintegration, present significant differences with those around shallow openings. These rock instabilities are a serious threat to underground operation safety. Coupled static-dynamic loads are the primary stress conditions in the deep rock mass, which consist of the high-stress concentration around openings due to excavation-induced stress redistribution and the strong dynamic disturbances induced by drilling and blasting, excavation unloading, roof caving, and fault-slip microseisms. The occurrence and development of deep rock instabilities are significantly influenced by the complex stress conditions, resulting in the vague understanding and the difficult characterization of deep rock fracture and failure. In addition, the high geostress has been confirmed to be a key factor to influence the fragmentation performance of rock excavation methods including drilling and blasting, and mechanized cutting.

However, there are few studies on rock fragmentation considering different confining stress conditions resulting in the unclear determination of breakage parameters for rock fragmentation in the deep underground. Rock fracture, rock failure, and rock fragmentation are the different stages of rock separated from the rock mass during excavation. Rock fragmentation is the necessary step to excavate an opening, which follows rock fracturing. Rock fracture and rock failure will occur in the surrounding rock opening. There are many unexplained problems in deep rock engineering where high stress is a key factor that cannot be ignored. For example, dynamic responses of rock under coupled static-dynamic loads, coupling effect between high geostress and breakage load, stress wave propagation in high-stressed rock, etc. The traditional rock mechanics only considering the static load, fatigue load, or impact load is unsuitable for explaining the unconventional fracture and failure phenomena of deep rock and for directing the rock fragmentation in deep excavation.

The aim of this Special Issue is to bring together original research and review articles discussing innovations in investigating the dynamic response of deep rock during fracture, failure and fragmentation processes. Submissions showcasing laboratory testing, field investigations, theoretical analysis, numerical modelling, and big data-driven computational intelligent simulations are welcome.

Potential topics include but are not limited to the following:

• Constitutive model and failure criterion of deep rock
• Measurement methods for in-situ geostress and excavation-induced stress in deep rock mass
• Dynamic responses of rock around deep openings, including stress, deformation, fracturing, failure, and the associated precursory signals that can be monitored
• Estimation of rock burst proneness, determination of rock burst risk and control for rockburst in deep excavation
• Safe and efficient methods of rock fragmentation in the deep underground
• Mechanized excavation methods and thermal-shock, water-jet and hydraulic fracturing assisted breakage methods in deep hard rock engineering
• Big data-driven characterization, estimation, prediction, determination, and control for evaluating the dynamics responses of deep rock during fracture failure and fragmentation processes
• Application of artificial intelligence technology for the monitoring and control of rock fracture, rock failure, and rock fragmentation