Study On The Height Of Water Flowing Fractured Zone Of Hidden Collapse Columns

The collapse column is a special geological phenomenon in North China coal mine.The water flowing collapse column is difficult to detect, large water inrush, difficult to manage and it is a serious threaten in North China type of coal mine safety mining.In this paper, through mathematical derivation, numerical simulation and similarity simulation experiment and combined with the practical engineering to study the collapse column of water flowing fractured zone in detail.We regarded the collapse columns plate as a sheet model, use mathematical derivation with the rock beam theory, we deduced the limiting radius of collapse column in the situations of roof caving and cut off. We analysised the relationship between the collapse column radius, thickness, elastic modulus and explained the relationship. When the collapse pillar caving rock attached the beneath rock, we deemed it to be the Winkler plate model, we obtained the expressions of bending curve and the stress through mathematical deduction,and obtained the relational expression between ground coefficient and the collapse column water flowing fractured zones.Through the analysis of collapse column of water inrush precursor, selected the water pressure, water temperature, water quality and coal metamorphism and used them as index to forecast collapse column water inrush whether or not, and theoretically demonstrates the feasibility of these indicators.Using FLAC3 D software to simulate the influence of mining to karst collapse pillar stress distribution and the plastic regional, it is concluded that mining working face’s plastic zone below the diagonal attached the plastic zones of collapse column,and the angle is about 45 degrees. This explained why hidden collapse column often happen delaying water bursting and reminds us if we want to explore the collapse column, we should drill below 45 degrees, is easier to detect the collapse column.Similar simulation experiment shows that, with the mining, the collapse column’s water moist curve will continue to expand and top and bottom is larger than the central, it can explain the lagging water inrush phenomenon in a certain extent.