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摘要: 以颗粒状钠基膨润土防水毯为研究对象，采用改造的GDS全自动环境岩土渗透仪开展渗透试验，研究温度和压力对渗透系数的影响。研究表明：低围压下膨润土防水毯的渗透系数随温度的增加而减小，温度较高时趋于平缓或略有增大；围压增为100 kPa时，渗透系数随温度的增加而增大。固有渗透率随温度的增加而减小；低围压下固有渗透率减小更显著，仅考虑流体物理性质变化的渗透系数估算值与实测值有很大差异。膨润土吸附结合水量随温度的升高而减小，不能解释膨润土防水毯渗透系数和固有渗透率随温度的变化规律。当温度升高时，粒间孔隙减小且颗粒状膨润土分解成凝胶态蒙脱石颗粒，在低围压下凝胶态蒙脱石颗粒层间距离减小，是渗透系数和固有渗透率随温度的升高而减小的主要原因。Abstract: The hydraulic tests were conducted on geosynthetic clay liners (GCL) containing granular Na-bentonite under different temperatures and pressures, using the GDS geoenvironmental permeameter. Under low pressures, the hydraulic conductivity decreases with the temperature, and will be gentle or slightly increases when the temperature is over 50-60 ℃. Nevertheless, the hydraulic conductivity decreases with the temperature under the pressure of 100 kPa. The intrinsic permeability decreases with the temperature, which is more significantly under low pressures. Therefore, a great difference exists between the estimated and the measured hydraulic conductivities when only considering the change in physical properties of the fluid with temperature. The adsorbed water content of bentonite decreases with the temperature, resulting in the estimated hydraulic conductivity less than the measured value and intrinsic permeability increasing with temperature, which cannot explain the permeability of GCL. With the increasing temperature, the granular bentonite will transform into the montmorillonite gel. Under low pressure, the distance between montmorillonite in intraparticle pore decreases with temperature, resulting in the decrease in hydraulic conductivity and intrinsic permeability.
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