Mining Height Effect and Application of Upper Protected Layer Mining Pressure Relief

Abstract

In order to obtain the minimum mining height that can play an effective protective role in the mining of the non-full coal protective layer in the Hongyang No. 3 coal mine and improve its economic benefits, the relationship between the mining height and the pressure relief of the protected layer is studied. Theoretical analysis is used to establish a calculation model of the goaf stress distribution law, with the mining height as a variable. The calculation model research results show that the mining height adjusts the goaf stress distribution by adjusting the range of the “three zones”. The force of the falling zone and the frustration zone on the goaf is approximately trapezoidal geostatic stress, and the roof stress in the vertical projection area of the trapezoidal waistline is not transmitted to the goaf. The development heights of the “two zones” are different at different mining heights, and the corresponding pressure-relief ranges are different from the waistline vertical projection. The curved subsidence zone transmits stress to the goaf through the fissure zone and the caving zone below, which can be calculated by the elastic foundation beam model. The falling zone is the elastic foundation, and different mining heights have different foundation coefficients. With the increase in mining heights, the foundation coefficients first decrease and then tend to be stable. The pressure-relief range of the stress transmitted from the curved subsidence zone to the goaf first increases and then tends to be stable. According to the calculation model, the minimum mining height for effective pressure relief of the upper protective layer of thin coal in the Hongyang No. 3 coal mine is 2.5 m, which can effectively relieve the pressure of the protected layer with the floor layer spacing of 48 m.

Experimental study on rock strata movement and stope stress distribution law under mining height regulation

“…[6][7][8][9][10] At present, there have been a lot of studies on the stress distribution law under different mining height mining conditions. [11][12][13][14][15][16] However, the studies focus on the summary of the stress distribution law after mining at a given mining height, lacking a comparative analysis under different mining heights. There are relatively few studies on how mining height affects rock strata movement and stress distribution in stope.…”

“…For non‐full coal protective layer mining, it is of practical significance to obtain the role of mining height in regulating the stress distribution in the mining field and to determine the optimal mining height to reduce the amount of rock mining 6–10 . At present, there have been a lot of studies on the stress distribution law under different mining height mining conditions 11–16 . However, the studies focus on the summary of the stress distribution law after mining at a given mining height, lacking a comparative analysis under different mining heights.…”