As technology of digging and stiffening members develops and the importance on environment increases, underground space starts to be recognized as a spatial resource at a new level, and it develops as a concept of permanent mines. Such a characteristic of the permanent mine has various application ranges from public engineering works such as development of long tunnel to energy and environmental storage activity such as underground storage bases and garbage dumps. Also, in an aspect of resource development business, it creates expansion to spatial resources for developing environment-friendly mining industry by converting a breaking ground or concentrators into the underground mine using a shift draft design of the permanent mine. On the other hand, as the design and management of the permanent mine from an aspect of resource development business has higher characteristics in an aspect of business rather than the government-initiated business unlike general social overhead capital businesses, it usually uses a rock bolt as a main stiffening member which has quite a good ability of reinforcement as well as is economical under a disadvantaged condition. Also, as a shaft for mining is irregular unlike a tunnel business and explosive environment may cause crowding in near shafts, it has a limitation in measuring cycle. In addition, by creating direct destroy such as wedge destruction due to a joint according to the effect of free face in borehole parts having a large influence on explosion or explosive vibration or large-sized underground mines, or by declining stiffness of existing rock bolts, it may cause directly or indirectly safety accidents. So, studies to figure out the safety of large-sized mines according to explosive vibration or the characteristics of stiffening members have been conducted actively in the country and internationally. But, most studies focus on evaluating the effect on the single explosion, 2-dimensional discontinuum, or continuum which cannot consider the effect of a joint, so they have a limitation in figuring out the effect on digging space minutely.
Therefore, this study aimed to figure out change of stiffness of existing rock bolts installed initially in large-sized mines caused by explosive vibration generated repeatedly. For doing this, it conducted a numerical approach in a 3-dimensional individually-interpretative way which can consider the effect of a joint by setting breaking ground in mines, the large-sized mines which are promoting to change into environment-friendly sites in currently resource developing sites within the concept of large mines. Also, it performed a consecutive repetitive dynamic interpretation considering the displacement of fatigue failure of rocks due to explosive vibration after working on stabilization of the initial model through a static interpretation and figured out the result. In addition, as for setting of detailed modelling of numerical interpretation and a property of rocks, it aimed to attain the study result with a sense of realism by selecting a study mine which are preparing underground breaking ground and by attaining the property of matter and dynamic characteristics through a laboratory experiment and on-site tests.