Study on optimization of permeability coefficient of structural fractal for mine water inflow

Accurate hydrogeological parameters have played a crucial role in the prediction of mine gushing water. Permeability coefficient is the most commonly used parameter in hydrogeology. It is not only an important indicator for evaluating the richness of aquifer water, but also an important indicator for quantitative calculations such as mine gushing water forecast, information fusion water inrush forecast, and rock mass stability evaluation. In order to improve the prediction accuracy of water inflow, the fractal theory was used, and the capacity dimension in the fractal dimension was taken as the basic feature quantity. The Zhaozhuang No. 2 Mine was used as the research area. The complexity of the mine structure of Zhaozhuang No. 2 Mine was quantitatively evaluated by grid cover method. The weight fractal dimension of faults and folds was given, and the fractal dimension of structure was optimized to obtain the correction formula. On this basis, it is found that the structural complexity is positively correlated with the permeability coefficient obtained from the pumping test, so the values of the permeability coefficient in the “Large Well Wethod” empirical formula were optimized using the correlation analysis method. The results show that the structural complexity of the Zhaozhuang No. 2 Mine is quantitatively evaluated, and the capacity value of the whole area of the study area was calculated to be 1.166 5, indicating that the structure in the study area is relatively complex. It can be seen from the superposition map of the structural network capacity of the whole area that the structure in the area complexity has obvious inhomogeneities; Applying the optimization results to the prediction process of the “Large Well Method” water inflow in the No.2309 working face of Zhaozhuang No. 2 Mine, the error decreased from 42.5% to 7.8%. The “Large Well Method” used the optimized permeability coefficient to greatly improve accuracy rate of the mine water inflow; the capacity dimension in the fractal theory is introduced into the evaluation of the complexity of coal mine structure, and the quantitative evaluation of the structural complexity and the optimization of the permeability coefficient are realized, which is of great significance for the mine prevention and control of water and gas prevention in the study area. © 2021 Meitan Kexun Jishu/Coal Science and Technology (Peking). All rights reserve.