Many metal mines in China will gradually enter the depth range of 1000–2000 m during the 14th Five Year Plan Period, suggesting that deep mining will become widespread in the coming decades. The high initial static stress, high ground temperature, high permeability, and strong engineering disturbances confronted by deep underground engineering make it a challenging problem worldwide, for which there is neither a mature theory and method nor successful international experience . It has been acknowledged that one of the biggest differences between metal mines and coal mines is that the orebody and surrounding rock in metal mines are generally hard rocks . The hard and brittle rocks at great depths often exhibit significantly different mechanical properties from rocks at shallow depths. The frequent disasters induced by excavation activities in roadways and caverns restrict the safe and efficient operation of deep underground engineering and cause tremendous casualties and economic losses [3–5]. In these deep hard metal mines, special failure phenomena such as slabbing, rockburst, buckling, and roof caving are frequently encountered around caverns or chambers where stresses are always concentrated, which potentially affect the stability and increase the cost of rock supporting [6–9].
It has been demonstrated that the stress conditions of deep surrounding rocks are significantly affected by self-excavation unloading activities (typically called excavation disturbance), in which the tangential stress increases and the radial stress decreases under high static stresses (in situ stress). In practice, the surrounding rocks of deep roadways and caverns are inevitably affected by external dynamic disturbances, such as ore collapse, ore caving, mechanical drilling, and blasting of adjacent stopes during the exploitation of solid mineral resources [10, 11]. The two aforementioned types of disturbances are collectively denoted as “mining effects.” Therefore, the stress state of the deep engineering rock mass can be attributed to “high initial static stress + external dynamic disturbance,” and the analysis and interpretation of rock mechanical behaviors in deep hard rock mining—particularly for rockburst, slabbing, and zonal disintegration—should be focused on the coupled static and dynamic loads in the mining process . There are two types of dynamic loads in deep mining: low-frequency disturbances generated by regional stress adjustments [12, 13] and strong dynamic disturbances induced by blasting loads . Considerable effort has been directed toward investigating the failure properties of rocks subjected to these two types of dynamic loads. For example, Du et al.  performed true-triaxial unloading and local dynamic disturbance tests on three rock types. They found that under local dynamically disturbed loading, none of the specimens displayed obvious fracturing at low-amplitude local dynamic loading, while the degree of rock failure increased as the local dynamic loading amplitude increased. Li et al.  developed a modified split Hopkinson pressure bar (SHPB) for a coupling load experiment at medium-to-high strain rate, and investigated the mechanical properties and energy dissipation law of rock under different pre-stresses and impact disturbances.
In addition to the stress conditions in deep mining activities, the presence of geological discontinuities significantly affects the stability of the engineering structure, which has been confirmed by engineering practice [17–19]. The randomness and differentiation of the spatial distribution makes a fissured rock mass a complex engineering medium. A structural plane (mainly refers to a discontinuity joint, hard structural plane, discontinuity, or other structural plane in the rock mass) is a geological discontinuity that cuts the stratum and destroys its continuity and integrity in deep mining. Researchers have investigated the mechanical behaviors and failure properties of caverns with nearby structural planes at the laboratory and engineering scales under such conditions. For example, for the former one, Lin et al.  investigated the mechanical behavior of a jointed rock mass with a circular hole under compression-shear loading by means of DIC (Digital Image Correlation) and DEM (Discrete Element Method) modeling, and the crack evolution process was investigated and four types of crack coalescence among joints were summarized. Chen et al.  studied the fracture evolution characteristics of sandstone containing double fissures and a single circular hole under uniaxial compression. The results show that the peak strength, peak strain and elastic modulus of defected specimens decrease comparing with those for intact sample, and the rock bridge angle has a great influence on crack initiation, coalescence, final failure mode, crack initiation stress and transfixion stress. Yang et al.  conducted a series of laboratory testing to investigate the failure behavior and crack evolution mechanism of a non-persistent jointed rock mass containing a circular hole. Their results show that the peak strength and elastic modulus of the non-persistent jointed rock specimens display a “U” type variation with respect to the joint inclination. For the latter one, Feng et al.  used Elfen software to modeling the hard rock failure induced by structural planes around deep circular tunnels. They found that that the failure intensity of rock tunnel is a function of both dip angles and frictional coefficients of structural planes, and the lateral pressure coefficient may affect the damage range and location. Ma et al.  investigated the distance effects of the fault on the rock mass stability of the main powerhouse at the Huanggou pumped-storage power station, and concluded that when the distance is low, the damage of the surrounding rock masses subjected to excavation evolved from the spandrel toward the fault, eventually causing a V-shaped collapse if the strength reduction continues.
To better understand and prevent the aforementioned dynamic disasters, it is necessary to consider the combined effects of the external dynamic disturbances and the geological structure on the failure properties of deep underground structures. For example, Li et al.  studied the failure mechanism of rock with fissure-opening flaws under coupled static-dynamic loads. The crack process of rock under coupled loads was observed in real time by DIC system, and crack initiation positions and failure modes of granite specimens were summarized. However, the opening was pre-fabricated during the preparation of specimens, indicating that the excavation unloading effect prior to be impacted by dynamic loads was ignored in their research. Therefore, the entire failure process during the construction phase and service life was not reproduced. Manouchehrian and Cai [26, 27] analyzed the rockburst in tunnels subjected to static and dynamic loads, with particular attention paid to the effects of nearby faults. The modeling results confirm that the presence of geological structures in the vicinity of deep excavations could be one of the major influence factors for the occurrence of rockburst. Because the dip angles of fault were not fully considered in their research, the conclusions still needs further validation and evaluation. Moreover, the dynamic stress direction was not taken into account in the numerical simulation.
Numerical simulation is an effective method for analyzing the failure behaviors of rock materials subjected to complex stress conditions, stress paths, and geological structures at the engineering scale. In the present study, the combined finite–discrete element method (FDEM) was adopted to simulate the failure process of a deep underground cavern. This method can reveal the failure properties of deep hard rock, which are affected by key factors such as the dynamic stress-wave amplitudes, disturbance direction, and dip angles of the structural plane. Typical hard marble extracted from Hongling Lead-Zinc mine in Inner Mongolia, China was selected for the numerical simulation, and the stress-field distribution, displacement, velocity of failed rock, and failure zone around the circular cavern were analyzed. This study provides insight into failure mechanism of hard surrounding rock, which is affected by the external dynamic disturbances (mainly refers to blasting loads), excavation unloading effects, and geological conditions in deep mining engineering.