现场测试固废填埋场压实黄土覆盖层的气相渗透系数（英文）

目的：我国西北地区黄土分布广泛，黄土作为当地固废填埋场的覆盖土料具有广泛的应用前景。现场尺度测试压实黄土覆盖层的气相渗透系数，从而可用于评估其填埋气减排性能。方法：1．在西安固废填埋场建立压实黄土覆盖层试验基地（图2）；2．在试验基地的膜内核心测试区域布置通气试验系统，包括空气压缩机、通气管网、气压测试装置、含水率测试装置、温度传感器和静态箱（图3，5～7）；3．在覆盖层表面裸露时和植草后分别进行通气试验测试压实黄土覆盖层的气相渗透系数。结论：1．当饱和度低于85％时，干密度为1．45Mg／m3压实黄土的气相渗透系数随含水率增加而降低，但并不明显；但是当饱和度高于85％时，气相渗透系数随含水率增加而显著减小；2．黄土层和碎石层之间的毛细阻滞作用使得上部黄土层储存更多水分，并显著降低其气相渗透系数，这有利于降低填埋气的排放；3．裸露条件下，当压实黄土的体积含水率从36％增加至46％时，其气相渗透系数从3．67×10-12m2降低至5．73×10-14m2；4．植草后压实黄土的气相渗透系数比裸露条件下小近一个数量级，这主要是因为植被根系占据了压实黄土的大孔隙；5．现场尺度的压实黄土气相渗透系数比室内试验的结果高1至2个数量级，这主要是因为现场所用黄土含有大的结团，结团会增加黄土的孔隙直径以及减小孔隙的曲折度。

A method of determining the permeability coefficient of coal seam based on the permeability of loaded coal

This study developed the equipment for thermo-fluid–solid coupling of methane-containing coal, and investigated the seepage character of loaded coal under different working conditions. Regarding the effective pressure as a variable, the variation characteristics of the gas permeability of loaded methane-containing coal has been studied under the conditions of different confining pressures and pore pressures. The qualitative and quantitative relationship between effective stress and permeability of loaded methane-containing coal has been established, considering the adsorption of deformation, amount of pore gas compression and temperature variation. The results show that the permeability of coal samples decreases along with the increasing effective stress. Based on the Darcy law, the correlation equation between the effective stress and permeability coefficient of coal seam has been established by combining the permeability coefficient of loaded coal and effective stress. On the basis of experimental data, this equation is used for calculation, and the results are in accordance with the measured gas permeability coefficient of coal seam. In conclusion, this method can be accurate and convenient to determine the gas permeability coefficient of coal seam, and provide evidence for forecasting that of the deep coal seam.