厚硬岩层结构调控低损开采方法及机理研究

Research on low-damage mining method and mechanism of overlying thick and hard rock strata structure regulation

为探究厚硬岩层采动结构对上覆岩层下沉破坏影响及新的低损开采方法,采用相似模拟、离散元数值模拟方法分析了厚硬基本顶采动破坏结构演化和堆积特征对覆岩下沉破坏的影响。相似模拟及数值模拟结果均表明,随采随垮的直接顶岩层和周期性破断的厚硬基本顶分别呈现小块度破坏杂乱堆积和大块度破断整齐堆积;受采动结构特征影响,直接顶岩层采动破坏产生的体积膨胀显著大于厚硬基本顶。根据模拟得到的采动岩层破坏堆积特征构建了厚硬基本顶条件下采动覆岩下沉计算模型。根据采动作用下随采随垮直接顶岩层采动破坏膨胀量显著大于周期性破断厚硬基本顶的规律,提出对厚硬基本顶进行采前大规模水力压裂并借助采动超前支承压力进一步破坏厚硬基本顶,降低厚硬基本顶采动破坏块度,使其随采随垮、杂乱堆积并充分充填采空区以控制上覆岩层下沉破坏,实现低损开采。采用数值模拟验证了压裂弱化厚硬岩层调控其采动结构,增大采动破坏岩层体积膨胀量,降低上覆岩层下沉的有效性。提出的厚硬岩层结构调控低损开采方法可为煤矿绿色高效开采提供一定的参考。

To explore the impact of thick and hard main roof of longwall coal mining on the settlement of overly-ing strata and a new low-damage mining methods,numerical simulations and physical simulations were conduct-ed.Both physical simulation and numerical simulation results show that the mining-induced bulking coefficient of immediate roof is significantly greater than that of main roof.Based on simulation of the characteristics of min-ing-induced strata movement,a calculation model for descrbling the settlement of the overburden induced by coal mining was developed.Based on the characteristic that the bulking coefficient of immediate roof significantly greater than that of hard basic roof,a new low-damage mining method for controlling the failure of the overburden is proposed by pre-fracturing the thick and hard basic roof using hydraulic fracturing before coal mining.The method uses hydraulic fracturing to weaken and fracture the thick and hard basic roof,which is further damaged by abutment pressure,causing it to collapse and scatter randomly in the goaf.The proposed method increases the mining-induced expansion of the hard roof and utilizes its self-expansion to fill the goaf,reducing the space for overburden to sink.Numerical simulations confirmed the effectiveness of this method in regulating the mining-induced deformation of the hard roof and reducing the sinking of overburden.This method provides guidance for green and efficient mining in coal mines.