Abstract：Karstic collapse column is a kind of vertical structure typically formed at Carboniferous-Permian coalfields of north China，and widely distributed in 45 coal mine areas of 20 coalfields. Water inrush from the karstic collapse columns is harmful to mining safety. For simulating them and forecasting water volume with mathmatic models，their properties and controlling mechanisms of water-bearing are studied，and hydro- geological models are set up. The study shows that the water-bearing properties of karstic collapse columns are controlled and influenced by several conditions and factors，such as tectonic movements，groundwater flow conditions，substance，solid and cementation in the columns，as well as confining pressure. All factors promote and restrict each other，so that only in karstic runoff or discharged zones or under water table，there could be danger of water inrush. But if water inrush from them happens unexpectedly，water volume will be destructive，and it is difficult to forecast and prevent. According to viewpoint of systems，karstic collapse column is one kind of media in a mine groundwater system with generalized multiple porous media seepage，and are also special hydro–geological subsystems where karstic groundwater is recharge source，columns are flow pathways，and roadways or working faces are their discharge points. Three kinds of patterns can be classified by interior properties，complete strong water bearing pattern，brim water bearing pattern，and weakly penetrated and runoff pattern. Accordingly，karstic collapse columns are generalized as vertical pipelines，main fractures or vertical cross-stream media，and water barrier or media of aquifer uninfluenced. The mining water volume can be accurately forecast with mathmatic models of mine groundwater systems.
