Safety thickness and dynamic characteristics of rock pillar of uncovering coal at rock cross-cut in Guigala tunnel

doi:10.16265/j.cnki.issn 1003-3033.2021.07.008

Abstract

Abstract: In order to address geological disasters such as gas leakage, explosion, coal seam outburst, extrusion and pulsion in construction of highway tunnel with coal-bearing strata, with Guigala tunnel of Laze highway as research object, theoretical analysis on structural mechanics was conducted, and blasting damage range size of rock pillar and its safety thickness under pressure of coal seam gas were considered to deduce calculation formula of safety thickness for uncovering coal at rock cross-cut in tunnels with different inclination of coal seams, by using which safety thickness in Guyala tunnel was obtained. Then, numerical simulation was applied to establish a dynamic model of uncovering coal at rock cross-cut in highway tunnels with coal-bearing strata, dynamic characteristics of coal seam and its roof and floor, which was under millisecond time of cutting blasting of the uncovering coal, were studied, and dynamic response characteristic of coal seam contacting roof and floor were acquired. The results show that safety thickness of rock pillar at 8m in Guyala tunnel is reasonable. Dynamic response strength decreases as millisecond interval time increases, and the best interval for uncovering coal at rock cross-cut is 50ms. However, the strength increases along with increase of coal seam dip angle, so it is necessary to properly reduce coal uncovering depth in steeply inclined and inclined coal seams and increase that of gently inclined coal seams.

Key words: uncovering coal at rock cross-cut, safety thickness of rock pillar, dynamic response, coal-bearing strata, highway tunnel

CLC Number:

X915.5

XIE Quanmin, YAN Lixiang, ZHOU Shengguo, WANG Zhide, YANG Wendong. Safety thickness and dynamic characteristics of rock pillar of uncovering coal at rock cross-cut in Guigala tunnel[J]. China Safety Science Journal, 2021, 31(7): 56-62.

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