采用二维颗粒流软件PFC2D构建矿山模型，引入符合矿山实际节理产状的DFN网络，基于室内岩石试验及矿山实际崩落情况，标定模拟所用细观参数。以某工程应用为实例，模拟分析崩落破坏机理与崩落区演化趋势。结果表明：裂纹发起于推进面与顶板交界处，在拱形区域内密集扩展、贯通，矿岩破裂以节理拉伸破坏为主，矿堆以岩石剪切破坏为主；崩落区前期呈拱形演化，崩透地表后引起邻近高陡边坡滑动；部分拉底仅造成新开挖顶板上方局部崩落。该研究结果可对矿山崩落采矿起到指导作用。

Surface subsidence and rock burst may occur during mining in mines using natural caving method，which affect the safety of mine production and the life safety of underground workers.Therefore，it is necessary to research the evolution law of caving area with the advance of undercutting.The research process of this paper is as follows.Firstly:using two-dimensional discrete element software PFC2D to construct a geometric model consistent with the actual topography of a mine.Secondly，according to the complete rock parameters obtained from laboratory mechanical experiments，by means of simulating physical experiments，the meso-parameters are continuously adjusted to approximate the actual physical parameters，the meso-mechanical parameters used in PFC2D are calibrated.In addition，according to the statistic law of joint sets distribution obtained on the spot，choose an appropriate joint generation method，make use of discrete fracture network DFN to reconstructe a joint model consistent with the statistical law.Then，based on the caving height of a certain period obtained by mine drilling television，the simulation results are approximated to the monitoring values by dichotomy method，and the corresponding joint strength parameters are back analyzed.Finally，the whole mine model is coupled with the joint model，and the particles and joints are assign property.After stress balance，the excavation is simulated.Statistic simulation results，the conclusions are as follows:Cracks first develop at the intersection of the undercutting advance working face and the roof，then extend，develop and penetrate in the arch region，resulting in crushing and collapse of the original rock.The main failure types of ore and rock are joint tensile failure，while shear failure often occurs in caved ore and rock.In the early stage，the caving area develops arch upward，which causes the adjacent steep slope to slide to the valley after penetrating the surface.In some undercutting steps，the caving area only occurs in the local area above the newly excavated undercutting region，which is consistent with the change trend of caving quality and roof height.