软弱夹层对煤矿主斜井围岩稳定性的影响分析

Analysis of stability of surrounding rock of coal inclined shaft with weak intercalated layer

深部煤层的开采导致上部覆岩运动与破坏,覆岩中的软弱夹层是影响井筒、硐室及地下巷道等地下工程围岩稳定的关键因素之一。针对弱胶结砂岩中软弱夹层对主斜井围岩稳定性问题,基于分层位移场的软弱夹层静力计算模型,计算得到软弱夹层各点的精确位移。采用理论分析与数值模拟的方法分析了软硬互层弹性模量之比、软弱夹层的泊松比以及软硬互层厚度之比对穿越软弱夹层的斜井围岩变形规律。结果表明:软硬互层弹性模量之比对主斜井围岩稳定性有显著影响;当k值小于0.1时,即软弱夹层弹性模量与硬层弹性模量相差一个数量级以上时,软弱夹层围岩变形显著增加,二者呈幂函数关系;随着软硬互层弹模比值的减小,软弱夹层与上下硬层之间应力梯度变化值增高,斜井顶底板在软硬层接触面变形最大;软弱夹层泊松比由0.1增大至0.4过程中,斜井围岩变形量逐渐减小,顶板位移量减小0.42m;软硬互层的厚度比越大,围岩稳定性越差,竖直方向的移近量约为两帮移近量的3倍。

Movement and failure of overlying rock caused by mining of deep coal seams. The weak intercalated layer is one of the key factors influencing the stability of the surrounding rock stability of the shaft, the chamber and the underground tunnel. In order to study the stability of surrounding rock of inclined shaft with weak intercalated layer in weak cementation sandstone, the model of statics account at weak intercalated layer based on stratified displacement field. It calculates the exact displacement of each point of the soft and hard rock layers. Theoretical analysis and numerical simulation method are used to analyses surrounding rock deformation law,which is affected by the soft and hard rock layers elastic modulus ratio, weak interlayer poison＇ s ratio and the thickness. The results showed that there are significant effects on surrounding rock stability of the Inclined Shaft with soft and hard rock layers elastic modulus ratio. When the k value is less than 0.1 ,that is,when the elastic modulus of the soft layer and the hard layer differs by one order of magnitude and above, the deformation of the surrounding rock increases significantly, and the two becomes a power function relationship. The stress gradient between the weak and the upper and lower hard layers increases with the decrease of k. The maximum deformation occurs in the inclined roof and floor at the junction of soft and hard layer. The deformation of surrounding rock slope decreases with the Poisson ＇s ratio of weak intercalation layer is increased from 0.1 to 0.4, roof displacement decreases 0.42m. The greater the thickness ratio,the worse the stability of the surrounding rock. The roof to floor displacement is about 3 times of that of the two sides in inclined shaft.