水平应力对深部大采高开采煤壁稳定性影响研究

Study on the Influence of Horizontal Stress on Stability of Coal WallunderDeep Mining withLarge Mining Height

煤壁片帮破坏一直是影响大采高工作面安全生产的一大难题,这一问题在深部开采条件下更加突出,水平应力对煤壁稳定性程度愈加明显。针对这一问题,以某矿1303工作面为背景,采用现场实测、岩石力学试验、数值模拟等手段研究了水平应力对煤壁稳定性的影响。研究结果表明:深部开采条件下,大采高工作面煤壁片帮主要表现为压剪以及拉剪两种破坏形式,且以拉剪形式为主,其原因可能是深部开采地应力比较大,水平应力普遍大于垂直应力;围压越大,卸围压条件下,煤样破坏时的强度越小,对应到工程实际,深部开采条件下水平应力越大,开挖卸荷程度越大,煤壁越容易发生破坏;当水平应力很小时,煤壁片帮程度较轻,随着水平应力的增加,煤壁破坏的深度与破坏面积都明显增加,煤壁水平位移逐渐增大,且最大水平位移发生在煤壁的中上部,受水平应力影响,煤壁破坏前变形很大。

The failure of coal wall caving is always a major problem affecting the safety production of large mining height working face.This problem is more prominent under deep mining conditions,and the horizontal stress has more obvious affect on the stability of coal wall.In order to solve this problem,the influence of horizontal stress on the stability of coal wall was studied by means of field measurement,rock mechanics test and numerical simulation on No.1303 working face of a mine.The research results showed that under deep mining conditions,the main failure modes of coal wall on large mining height face included compression-shear and tension-shear,and the main failure mode was tension-shear.The reason may be that the insitu stress in deep mining was relatively large,and the horizontal stress was generally larger than the vertical stress.The greater the confining pressure,the smaller the strength of coal sample when the confining pressure was unloaded.Corresponding to the actual engineering,the greater the horizontal stress under the deep mining condition,the greater the excavation unloading degree,and the more easily the coal wall would be destroyed.When the horizontal stress was very small,the failure degree of the coal wall caving was light.With the increase of the horizontal stress,the destruction depth and area of the coal wall increased obviously,and the horizontal displacement of the coal wall increased gradually.Moreover,the maximum horizontal displacement occurred in the middle and upper part of the coal wall.Under the influence of horizontal stress,the deformation of coal wall before failure was very large.