考虑煤体状态的采动岩体移动规律

在传统采动岩体理论分析中将煤体作为采动岩体的刚性边界,这与现场实际有较大的出入。针对该问题,将煤体视为与其上覆岩层一起协调变形的弹性承载体,对覆岩的初次破断和周期性破断进行了理论分析和数值模拟,结果表明:覆岩的移动规律不仅与其自身性质有关,而且与其下伏支撑体的地基系数密切相关。当下伏支撑体的地基系数小时,覆岩初次垮落步距更小,覆岩初次断裂位置位于岩梁中间,覆岩周期断裂的位置更趋于支撑边界深处,同时支撑体本身的破坏范围更大;反之,覆岩初次垮落步距更大,覆岩周期断裂的位置更靠近支撑边界,同时支撑体本身的破坏范围变小。因此,在煤层开采过程中,覆岩的移动规律不仅需要考虑自身的力学性质,还需考虑其下伏支撑体的状态。在考虑软弱煤层时,不仅应考虑软弱煤层的力学性质,还需综合考虑煤层的开采厚度。

The Mined Rock Mass Movement Law Considering the Properties of Coal Seam

In the traditional theory of mining rock mass,the coal seam is always taken as the rigid boundary of the mining rock mass,which is distinct with the actual situation.According to this,this paper is going to consider the coal seam as elastic bearing of which deformation is coordinate together with its overlying strata rather than the rigid boundary.The first breaking and periodic breaking of overlying strata were analyzed.The analysis results show that:there are some differences with the traditional theory of mining rock mass.When the coal foundation coefficient is relatively large,the fracture position of the first breaking is near the coal wall;and when the coal foundation coefficient is relatively small,the overlying strata first broken in the middle of the rock beam.Thus,the rock movement law is not only relating to its mechanics properties but the foundation coefficient of the rock strata supporting it.When mining the soft coal seam,not only the properties of coal seam but the coal mining thickness should be taken into account.