综放开采顶煤放出规律三维数值模拟

综放开采中支架上方顶煤在矿山压力作用下破碎成散体，其力学特性与均质岩体相比有较大差异。基于离散元的三维颗粒流程序（PFC3D）能真实地反映顶煤放出过程，建立了综放开采顶煤放出的三维数值模拟模型，进行了不同采放比、放煤步距和放出体形态等的模拟。初始放煤过程中，顶煤颗粒会形成稳定的速度场及二次松散区域；顶煤放出体呈现出支架限定的类偏转椭球体，放出体轴偏角随放煤时间增大呈指数关系减小，放出体高度随放煤时间增大呈幂函数关系增大；顶煤放出体切割煤矸分界面所形成的漏斗面是一个中心轴朝采空区偏移的三维漏斗曲面；不同采放比与放煤步距下，顶煤采出率随工作面的推进呈现出典型的渐进稳定效应。

3-D numerical simulation on the top-coal movement law under caving mining technique

In fully mechanized top-coal caving mining，the top-coal is broken into loose state under stratum pressure，whose mechanical characteristics are different from the complete rock.Based on the three-dimensional Particle Flow Code(PFC3D)，established the top-coal caving 3-D numerical simulation model，which can truly reflected the top-coal caving process，and carried out with different caving ratios and drawing interval simulations.During the initial caving process，top-coal particles will form a stable velocity field and the second loose region；the draw body is a deflect quasi-ellipsoid constrained by support shield，the deflect angle of axis decreases exponentially with the increasing of drawing time，the height of draw body decreases with increase in drawing time which presents the power function relationship；draw body cuts coal and gangue interface and forms a three-dimensional hopper surface，of which the central axis deflects towards the gob；under different cutting-caving ratios and drawing intervals，the top-coal extraction ratio shows a typical progressive stabilization effect with the face forward distance.