An rescaled range analysis on the characteristics of coal seam development in the Eastern depression of the Liaohe Basin

The characteristics of coal seam development,and the prospects of a favorable coal-forming area,were evaluated for the Liaohe Basin located in China.The Number 3 and Number 9 coal seam thickness series from 60 nearly equally spaced bores in the Eastern depression of the Liaohe Basin were examined by a rescaled range analysis.The results indicate that the Hurst exponents of the Number 3 and Number 9 coal seam thickness series are 0.69 and 0.68,respectively.This suggests the presence of persistence.As the bore spacing increases the Hurst exponent of the Number 3 series gradually decreases（H changes from 0.69 to 0.52） and shifts from persistence to randomness.The Hurst exponent of the Number 9 thickness data gradually increases（H changes from 0.68 to 0.91） and always shows the characteristic of persistence.A combination of geological characteristics and the series data allow the conclusion that it is more suitable for the Number 9 coal seam to form in the Northeastern part of the Eastern depression than the Number 3 coal seam.

Investigation on the stress field characteristic of top coal at FMTC faces under the influence of caving thickness

In the background of the technology condition and the geological condition of the 1151（3） fully mechanized top-coal caving face （FMTC face）, and by means of taking nonlinear 3D numerical simulation, the stress redistribution rules of top coal with different thick coal seam were obtained by investigation on the numerical simulation of the redistributions of the stress with different coal seam＇s thickness. The research showes that there exists a certain difference on the stress distributions of the top coal at face, the maximum principal stress is located near to the tailentry＇s corner. The vertical stress＇s peak of the top coal decreases and the distance ahead of face position increases as the once mining thickness of the coal seam increases. At the same coal seam, the vertical stresses＇ peak of top coal gradually decreases from the top to the bottom, the peak＇s position is basically the same and its changes are gradually obvious with the thickness of coal seam increas- ing. The vertical stress of top coal places in a low stress state at a certain range ahead of face and over the face, which reveals the essence that the support loads are generally low under the condition of FMTC. The study supplies the theoretical foundation for the support design and selection, the theory of top coal＇s fragmentation, the movement rules of top coal and improving the recovery of top coal.

Influence of mining thickness to the mechanical characteristics of gateways at FMTC faces

To make a better understanding of the mechanical characteristics of the surrounding rocks in the tailentry and headentry with different coal seam thickness at fully mechanized top-coal caving face （FMTC face）, the stress transition and displacement around the periphery of the gateways with different coal thicknesses were investigated in details by means of in situ measurement and 3-D numerical simulation. The research shows that the stresses decrease in the two spallings of the headentry and floor at goal with the increase in mining thickness. The roof pressure in the gates does not change obviously with the coal thickness, but the thicker the coal seam is, the farther the maximum stress will apply to the coal rib at the working face. The vertical stress is higher than the horizontal stress at two spallings of the gate, while its horizontal stress is higher than the vertical stress at the roof. The relative displacement between the roof and floor and the two spallings in the gateways increases gradually with the increase in coal seam thickness in a definite range in front of the face. Near the mining face, the stress decreases in the surrounding rock of the gates, while the deformation appears the most intensive. It is proposed that the support concept to the tailentry and headentry should be changed from loading control to deformation control.

Research on Mineral Resource Prediction by GA-ANN

Fault recognition and coal seam thickness forecast are important problems in mineral resource prediction. Knowledge of multiple disciplines, which include mining engineering, mine geology, seismic prospecting etc, was used synthetically. Artificial neural network was combined with genetic algorithm to found integrated AI method of genetic algorithm artificial neural network(GA ANN). Fault recognition and coal seam thickness forecast were carried to completion by case studies. And the research results are satisfactory.