望田煤矿垮落基本顶稳定前的动态响应分析

Dynamic response analysis of caved main roof at pre-stable state in Wangtian Coal Mine

以山西望田煤矿为工程背景,通过力学分析得到垮落基本顶稳定前的动态响应数学模型,并在此基础上分析基本顶垮落步距、煤层厚度、液压支架阻尼系数和冒落矸石弹性模量对顶板振动响应的影响规律。结果显示:望田煤矿顶板初次垮落振动时间比周期垮落振动时间长0.25s,两者的振动能量均在0.5s内消耗85%;顶板最大振动位移在垮落步距每增加10m时,就相应地增大10mm,在支架阻尼系数每增加一个单位时,就相应地减小7mm;顶板振动响应在煤层开采厚度小于4m、矸石弹性模量大于3.5GPa时会显著降低。

Taking Wangtian Coal Mine as the engineering background,mathematical expressions about dynamic response of cracked roof at pre-stable state is obtained through vibrating mechanics analysis. Several factors-basic top collapse step,thickness of coal seam,damping coefficient of hydraulic support and rocking elasticity of waste rock-are discussed in order to understand the influence of them on dynamic response of cracked roof. The results show that the vibration time of roof initial collapse is 0. 25 s longer than that of roof cycle collapse,and the vibration energy consumes 85% in 0. 5 s; maximum vibration displacement of roof will increase 10 mm with collapse step increasing 10 m,and reduce 7 mm with coefficient of hydraulic support increasing one unit; dynamic response of cracked roof will be significantly lower when coal seam thickness of mining is less than 4 m,and elastic modulus of waste rock is greater than 3. 5 GPa.