Analysis on rational loading time of coal pillar in wedge pillar type goaf

Sun Chuang; Xu Naizhong; Fan Zhenli; Wang Mingli

doi:10.13199/j.cnki.cst.2017.03.008

Abstract：In order to solve the wedge pillar type goaf of the coal mining face with a hard roof affected to the mining in the upper seam,based on the description on the rheological features of the coal pillar with the general Kelvin Body,a dynamics model of the coal pillar-roof system was established.In combination with the min potential energy principle,an effective loading time calculation formula of the coal pillar in the goaf was obtained.An analysis was conducted on the formula affected to the factors of the coal pillar effective loading time and finally in combination with the engineering cases,verifications were conducted.The results showed that the coal pillar-roof system of the goaf would be steadily in failure and instability with the time passed.The effective loading time of the coal pillar and self viscosity coefficient would be in a positive linear relationship,would approximately be in a " parabola" relationship to the instantaneous elastic coefficient,would be in a positive proportion relationship to the cross section area and would approximately be in a negative index relationship to the long term elastic coefficient,roof rigidity and coal pillar height.The established mechanics model of the goaf coal pillar-roof system based on the rheological features of the coal pillar could derive the calculation formula of the coal pillar effective loading time with certain accuracy.