相对湿度作用下的石膏矿护顶层突变破坏机制分析

Analysis of catastrophic failure mechanism of roof bed in gypsum mines induced by relative humidity

依据室内试验所得的石膏岩的基本力学性质随着大气中相对湿度变化的规律,并结合石膏矿采空区的破坏特征,将护顶层简化为铅直方向受均布荷载q作用的三铰拱分析模型,建立了相对湿度作用下的石膏矿采空区护顶层的尖点突变模型,研究了相对湿度作用下护顶层突发破坏的失稳机制。试验结果表明:石膏岩的力学性质在采空区中环境湿度的作用下,其强度和变形参数会大大降低。分析和工程计算结果表明:随着采空区中环境湿度的增加,支撑体系越不稳定,越容易跨越分叉集而发生突发失稳破坏;相空间的控制参数a随着采空区中环境湿度的增加,其代数值是逐渐增大的(绝对值减小,由负值向0变化),而控制参数b逐渐增大,系统突发失稳控制参数(a,b)的变化路径为向东北方向变化,该路径是系统较为容易发生突发失稳的路径。

Mechanical parameters of gypsum rock are influenced by the relative humidity in the mine atmosphere. Based on failure characteristics of the roof bed in gypsum mines, we proposed a simplified three-hinged arch analysis model under the uniform load q. Then a cusp catastrophe model was established to investigate instability mechanisms of the roof bed system influenced by the relative humidity. Experimental results show that mechanical parameters of gypsum rock are greatly reduced due to the influence of relative humidity. Analysis and calculation results show that the increase of the relative humidity around the roof bed leads to the instability of support system and the appearance bifurcation set. Therefore, it is more likely that the roof bed undergoes a catastrophic event. The algebraic value of control parameter （a） of the three-dimensional space gradually increases with the increase of relative humidity in the mine atmosphere （i.e., absolute value decreases and changes from negative to zero）, and the control parameter （b） gradually increases as well. The path of the control parameter （a, b） of system instability shows the northeast direction, which is the probable path for the system to lose stability.