无煤柱切顶沿空留巷顶板“短砌体-铰接”结构及支撑阻力研究

Research on roof structure and support resistance of gob-side entry retaining with roof cutting and non-pillar mining

为探索无煤柱切顶沿空留巷顶板破断特征及结构形态,得到科学有效的巷内支撑阻力计算方法,以董东煤矿无煤柱切顶开采为背景,采用现场监测、物理模拟、数值计算及理论分析相结合的方法,明确了留巷顶板破断特征,揭示了顶板“短砌体-铰接”结构形成机理,建立了巷道顶板力学结构模型,确定了巷内支撑阻力的计算方法。研究表明,留巷顶板回转运动造成了巷道的非对称破断特征,切顶控制层与基本顶关键层的组合结构稳定性是影响巷道稳定的关键,2者沿巷帮同步的切落式破断严重威胁巷道稳定。切顶高度与采高比值(切采比)是影响顶板结构形态的主要因素。物理模拟试验结果表明,切采比一定时,切顶控制层破断出现“短砌体”结构,切顶高度范围外的基本顶“大结构”表现为砌体梁铰接结构,由此得到了无煤柱切顶沿空留巷典型的“短砌体-铰接”顶板结构。通过建立顶板结构力学模型,提出了巷内支撑阻力的计算方法,为无煤柱切顶绿色高效开采提供了新的理论依据。

Based on the mining operation of Dongdong Coal Mine,this paper uses a combination of on-site measurement,physical simulation,numerical calculation and theoretical analysis to explore the roof structure and movement law of the gob-side entry retaining with roof cutting and non-pillar mining.At the same time,the scientific and effective calculation method of the support resistance is further obtained.The research reveals the basic principle for the formation of the“combined short masonry rock beams-articulated rock beams”,understands the law of roof movement,establishes the mechanical structure model and determines the calculation method of the support resistance in the roadway.The field observation and simulation results show that the rotary movement of the roof in the remained roadway results in the asymmetric fracture characteristics of the roadway,the combined structural stability of the cutting control stratum and the basic key stratum is the key influencing factor,the split-breaking of the two along the roadway is a serious threat to the stability of the roadway.The ratio of cutting height to mining height affects the roof structure.Comparative test shows that when the cutting-mining ratio achieves the right range,the control stratum of the cutting roof is prone to“short masonry”structure,and the basic top is the hinge structure of the masonry beam.Therefore,a typical“combined short masonry-articulated”roof structure is obtained.By analyzing the stress state of the support structure inside the entry,the calculation method of support resistance is finally proposed,enriching the coal-face basic theory of rock stratum control along the cut-off roof,which provides a new theoretical basis for an environment friendly efficient mining with roof cutting and non-pillar method.