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In order to solve the problem, that the hard rock fault with a large throw hinders the advance of a fully mechanized mining face, this paper analyzes the disadvantages of the traditional method for passing through the fault and the existing technologie. Also, the paper carries out a systematic study on the deep hole pre-splitting blasting tech-nology for passing through the fault with a large throw. Aiming at the problems of unclear occurrence of fault with a large throw and inaccurate designed path for passing through fault, it puts forward fault occurrence detection technology and the optimized layout for fault detection roadway. Based on the revealed information, the fault strike calculation model is established. Aiming at the problem that deep hole blasting technology is not suitable for working face and groove, it studies the key technology of pre-excavation blasting roadway, and puts forward the layout principle and calculation method of layout parameters of blasting roadway. It determines the scheme of deep hole pre-splitting blasting in blasting roadway, designs the construction method of ear chamber, and solves the problem of concentrated blasting with large amount of explosive. Based on the theory of rock blasting, combined with the characteristics of fault engineering with large throw difference, the blasting parameter selection and calculation method are completed by designing the hole diameter, hole depth, charge mass, plugging length, hole layout and blasting vibration safety control. The underground roadway of 2302 N working face at Xinjulong Coal Mine reveals a hard rock fault with a comprehensive drop 12. 5 m. Through the exposure points of lower roadway and six detection holes arranged in sequence, the initial strike of the fault extending to the working face is verified, and the vertical strike of the fault, the driving scheme along the floor of the coal seam and the driving scheme along the floor of the coal seam under the fault are designed. Based on the measured information, it plans the path through the fault. According to the change of fault occurrence in the path, it divides eight blasting regions, designs the blasting layout parameters in each region, and predicts and analyzes the blasting effect by means of numerical simulation. The application results show that the blasting fissure penetration effect is good, the consumption of shearer picks through the fault is reduced by 40%-50%, and the time is reduced to half compared with the time using traditional method through the fault. The technology for passing large throw fault have been successfully applied in many working faces in Xinjulong coal mine. It has achieved good results in ensuring high efficiency continuous mining, reducing the cost of passing through fault and ensuring blasting safety. The practice has proved that this technique is widely applicable in dealing with large throw fault at a fully mechanized mining face. [ABSTRACT FROM AUTHOR]

Mine transient electromagnetic method has a low resistivity problem for using minor transmitter and receiver loops, which leads to data interpretation difficulties and decreases detection depth. Firstly, this paper studied the variation of secondary field with transmitter-receiver distance through numerical simulation and field test, and found that the simulant secondary field was almost unchanged with transmitter-receiver distance within 20 m while measured data decreases linearly in logarithm coordinate system. Theoretical analysis shows that the mutual induced electromotive force is the main component of measured data, which leads to low resistivity problem. Furthermore, the paper proposed a resistivity correction method based on the different properties of secondary field and mutual induced electromotive force. The method eliminates the mutual induced electromotive force by using two measured data with different transmitter-receiver distances. Finally, the proposed method was successfully used in a half-space field case and a whole-space field case to demonstrate its practical usefulness. [ABSTRACT FROM AUTHOR]

The rib spalling is a technical problem to be solved urgently in steeply dipping thick seam mining. Based on the geological conditions and characteristics of strata behaviors at No. 25221 working face in 2130 Coal Mine, the load and instability characteristics of coal wall is investigated by theoretical analysis, numerical simulation, physical analogue material simulation, and field monitoring. Results show that the asymmetry characteristics of mining pressure and strata behavior of large mining height face is higher than that of general mining height face in steeply dipping seam, which is due to mining height increase. Because the inhomogeneous characteristics of the overburden filling are further enhanced, the asymmetric characteristics of the supporting pressure of the coal wall are also obviously increased. During the process of mining, the mechanical properties of coal wall will gradually deteriorate, coal wall crazes and slip body appears. Then the slip body slides along the slip surface, rib spalling emerges, when the surrounding constraints of slip body are relieved or support pressure increases. In inclination direction, the central area is the high incidence area of rib spalling, upper secondary and lower minimum, which is consistent with the asymmetric loading characteristics of coal wall. Besides, in vertical direction, the displacement at the upper part of coal wall is larger than that at the lower part, and rib spalling is easy to occur near the roof area. And under the influence of the gravity tendency component of coal wall, the rib spalling is easy to spread to the upside. On the basis of safety production demands at No. 25221 working face in 2130 Coal Mine, some control measures have been proposed in the paper. [ABSTRACT FROM AUTHOR]