矿井火灾对矿山充填膏体劣化规律试验研究

Experimental Study on Deterioration Law of Filling Paste by Mine Fire

为研究矿井火灾对充填膏体抗压强度的影响,分别设置4个高温(200℃,400℃,600℃,800℃)和4个受热时间(60 min,100 min,140 min,180 min)模拟矿井火灾产生的温度和火灾持续的时间,以喷水冷却和自然冷却来模拟火灾的熄灭方式,对高温后充填膏体进行了单轴压缩实验,系统研究了高温后充填膏体剩余抗压强度与受热温度、受热时间的关系,通过扫描电子显微镜(SEM)分析充填膏体内部微观结构。结果表明:受热温度和受热时间对充填膏体强度均存在影响,充填膏体在受热温度较低、受热时间较短时抗压强度出现小幅度增长,随试验进行,强度陡然下降,其损失最高达到50%,当温度到达800℃左右,强度下降幅度趋于平缓;充填膏体内部的自由水蒸发,结晶水、石英晶体和水泥水化产物的分解是影响充填膏体抗压强度的主要因素。喷水冷却相比自然冷却下对充填膏体强度影响较大,通过SEM分析充填膏体在高温作用下呈现"较疏松-密实-疏松-开裂"的过程演化。

In order to study the effect of mine fire on the compressive strength of the filling paste,four high temperatures(200 ℃,400 ℃,600 ℃,800 ℃)and heating time(60 min,100 min,140 min,180 min)were set to simulate the temperature generated by the mine fire and the firing duration. The water cooling and natural cooling were used to simulate the extinguishing mode of the fire. The uniaxial compression experiment was carried out on the filling paste after high temperature.The relationship of residual compressive strength and the heating temperature,heating time of the filling paste after high temperature was systematically studied. The scanning electron microscopy(SEM)was adopted to analyze the internal microstructure of the filling paste. The results show that the heating temperature and heating time have an effect on the strength of the filling paste. When the heating temperature is low and the heating time is short,the compressive strength of the filling paste increases slightly,and then drops sharply with maximum loss of 50%. When the temperature reaches about 800 ℃,the intensity decreases gently again;The evaporation of free water inside the filling paste,and the decomposition of crystal water,quartz crystal and cement hydration product are the main factors affecting the compressive strength of the filling paste. The water cooling has a greater influence on the strength of the filling paste than that the natural cooling. The SEM analysis shows that the filling paste exhibits a process of "more loose-dense-loose-cracking" under high temperature.