温度冲击下煤样渗透率的围压敏感性试验研究

Experimental Study on the Sensitivity of Permeability of Coal Sample under Temperature Shock and the Confining Pressure

通过试验研究了温度冲击前后煤样在围压加、卸载条件下的渗透率变化。对试验结果进行非线性拟合,得出煤样的渗透率与围压之间存在负指数关系。温度冲击影响着煤样渗透率对围压的敏感性。煤样经过冷冲击和热冷冲击处理后,煤样的最大渗透率损害率增幅分别为2.88%和10.64%,渗透率损害率增幅分别为18.35%和21.60%;即热冷冲击对煤样应力敏感性影响更大,热冷冲击对煤样渗透率的伤害大于冷冲击对煤样渗透率的伤害。在卸载过程中,渗透率的恢复存在明显的应力滞后效应,产生了塑性变形,由加载过程造成的渗透率伤害不能完全消除。冷冲击和热冷冲击都一定程度上加强了煤样渗透率的滞后效应,热冷冲击的滞后效果大于冷冲击。

The permeability of coal samples under the condition of confining pressure and unloading were studied by experiments.The nonlinear fitting of the test results was conducted,it is concluded that there is a negative exponential relationship between permeability and confining pressure.The impact of temperature affects the permeability of the coal is sensitive to confining pressure,coal samples after cold shock and hot and cold shock treatment,the maximum coal permeability damage rate increase by2.88%and10.64%,the damage rate of permeability increase by18.35%and21.60%,the hot and cold shock stress sensitivity has greater impact on the coal,and hot and cold shock on the permeability of coal sample is larger than the impact of cold damage on permeability of coal samples.In the unloading process,the permeability of the recovery has obvious stress hysteresis effect,resulting in plastic deformation,damage caused by the loading process can not completely eliminate the damage.The hysteresis effect of coal sample permeability is enhanced by both cold and thermal shock,and the hysteresis effect of the thermal shock is greater than that of the cold shock.