CAJ | 학술논문

在分析支架后上方顶煤及直接顶破碎、冒落特性和运动准则的基础上，建立了放顶煤的离散元数值模拟模型。从煤岩块体运动特性和接触力场演化规律2个方面论述了顶煤架后成拱机理：1)顶煤成拱的运动学机理为：在放煤口上方存在一个顶煤运动高速区，其两侧块体的运动速度较小，局部顶煤块体在放煤口两侧产生“淤积”，从而在放煤口上方形成不稳定接触力拱，造成放煤口附近顶煤运移速度减小，当更高层位的大块顶煤涌向放煤口时，容易产生挤压成拱；2)顶煤成拱的力学机理为：散体顶煤的放出过程，可以看做是接触力拱不断形成和破坏的过程，当上位接触压力大于成拱块体间由挤压而产生的摩擦阻力时，接触力拱破坏，否则，形成稳定的接触力拱，堵塞放煤口。现场观测验证了上述理论分析。
재분석지가후상방정매급직접정파쇄、모락특성화운동준칙적기출상，건립료방정매적리산원수치모의모형。종매암괴체운동특성화접촉력장연화규률2개방면논술료정매가후성공궤리：1)정매성공적운동학궤리위：재방매구상방존재일개정매운동고속구，기량측괴체적운동속도교소，국부정매괴체재방매구량측산생“어적”，종이재방매구상방형성불은정접촉력공，조성방매구부근정매운이속도감소，당경고층위적대괴정매용향방매구시，용역산생제압성공；2)정매성공적역학궤리위：산체정매적방출과정，가이간주시접촉력공불단형성화파배적과정，당상위접촉압력대우성공괴체간유제압이산생적마찰조력시，접촉력공파배，부칙，형성은정적접촉력공，도새방매구。현장관측험증료상술이론분석。
By analyzing the broken, caving characteristics and motion criterion of top coal and imme-diate roof behind the shield, the discrete element numerical simulation model for top coal was estab-lished in this paper. Meanwhile, from the moving characteristics of coal-rock blocks and evolvement rules of contact force, the top-coal arching mechanism behind shield was discussed. The kinematic mechanism of top coal arching is that there exits a high-speed area of top coal above the coal draw-point, and the moving speeds of coal-rock blocks on the two sides of high-speed area are smaller. The top coal silts at both sides of the coal draw-point, and develops unstable contact force arching above the coal draw-point, which can result in moving speed of top coal near the coal draw-point decreasing. When large-scale top coal blocks in the higher level surge up to the coal draw-point, they can be easily squeezed and form an arch in mining process. The mechanics mechanism of top coal arching is that the drawing process of granular top coal can be seen as a formation and destruction process of the contact force arch. When the upper contact pressure is greater than the frictional resistance formed by the arch-ing extrusion blocks, the contact force arch may damage, otherwise the stable contact force arch appears, and the coal draw-point may be jammed. Field measurements have verified the theoretical analysis.