Ground subsidence may be occurred by a collapse of mine gangway, a loss of support capacity of rock mass caused by discharge of groundwater, and a consolidation of soft ground. Ground subsidence has been causing serious problems on national transport, and threatening the public safety in residential areas. So there have been many attempts to understand subsidence phenomena and to predict their effects. Subsidence prediction methods can be classified into empirical methods, physical models and numerical methods. A numerical method, which is considered as the most rigorous and sophisticated subsidence prediction technique, could be used to find out the mechanism of ground subsidence. In this study, 2-dimensional particle flow code (PFC2D) was used to figure out how various components of a ground subsidence process influence each other. Such components include the depth of an opening, its dimension, the strength and deformability of rock mass and the characteristics of joint structure (e.g., orientation, spacing). The variation of these parameters was evaluated in terms of model results and the evolution of the falling and fragmentation of rock blocks. The subsidence type was classified into a sinkhole type or a trough type according to the relation between the depth of an opening and its dimension. In addition, the characteristics of joint structure play an important role in making the fall and fragmentation of rock blocks and giving rise to the ground subsidence. From these results, the PFC2D was found to be very efficient tools for studying the subsidence mechanism.
Ground subsidence may be occurred by a collapse of mine gangway, a loss of support capacity of rock mass caused by discharge of groundwater, and a consolidation of soft ground. Ground subsidence has been causing serious problems on national transport, and threatening the public safety in residential areas.
Most of advanced nations are coping with the situation in an active manner via a systematic analysis of subsidence, a draw up of the natural hazard map on subsidence, and an evaluation of subsidence possibility. However, it is not easy to carry out these works in Korea because of the complicated geological conditions and case-by-case ground reinforcement without analyses on subsidence mechanism.
Consequently, it is very important that the cases of subsidence in Korea should be classified by its cause, its state, and its region. With this classification, the database work should be accomplished on the area that has an experience of ground subsidence or has a possibility of ground subsidence [1].
So there have been many attempts to understand subsidence phenomena and to predict their effects. Subsidence prediction methods could be classified into empirical methods, physical models and numerical methods. A numerical method, which is considered as the most rigorous and sophisticated subsidence prediction technique, could be used to find out the mechanism of ground subsidence.
In this study, a 2-dimensinal particle flow code (PFC2D) [2] was used to understand how various components of a ground subsidence process influence each other. Such components include the depth of an opening and its dimension, and the characteristics of joint structures (e.g., orientation and spacing).
