承压破碎煤体碎胀系数演变特征与机制

利用自制的承压破碎煤体渗流及自燃测试装置，实验测试及分析了破碎煤体在应力、应力-温度、应力-水分不同条件下的碎胀系数的演变特征与机制。研究结果表明：① 煤样随着应力增加，碎胀系数变化具有明显的阶段性，且随应力变化服从负指数变化规律；② 在相同的轴压下，碎胀系数随温度升高而增加，热膨胀效应明显，说明采空区煤自燃的热效应将造成破碎煤体的碎胀系数增大，堆积更为松散；③ 当破碎煤体外在水分含量增加，在相同的轴压情况下，碎胀系数随外在水分增加而增加。说明随着采空区破碎煤体外在水分的增加，破碎煤体的碎胀系数将增大；④ 破碎煤体在应力、热膨胀及湿膨胀作用下，堆积体内部颗粒发生相对移动、二次破碎、颗粒自组织再堆积，致使应力-应变曲线发生变化，进而影响其碎胀系数。

Bulking coefficient evolution characteristics and mechanism of compacted broken coal

Using the self-made testing device of coal seepage and spontaneous combustion of compacted broken coal,the evolution characteristics and mechanism of bulking coefficient of broken coal under different conditions of stress,stress-temperature,and stress-water were tested and analyzed.The results show that：① the bulking co-efficient of broken coal has obvious stage with the increase of stress,and the change rule of bulking coefficient under the stress meets with the negative exponent.② under the same axial compression,the bulking coefficient increases with the increase of temperature,and the thermal expansion effect is obvious,which indicates that the thermal effect of spontaneous combustion will increase the bulking coefficient and loose the accumulation of broken coal in gob.③ when the water content increases in vitro of the broken coal,under the same axial com-pression,the bulking coefficient increases with the increase of external moisture,which shows that the broken coal bulking coefficient will increase with the increase of water.④ under the action of stress,thermal expansion and wet expansion,the internal particles occur relatively moving in the accumulation body,secondary crushed and granular self-accumulation,which cause the stress-strain curve change,and the bulking coefficient affected.