摘要:
通过改变砂样中的粘土矿物的种类和含量,结合咸淡水之间的单一和驱替实验,研究不同粘土矿物的水敏性特征。在单一的咸水和淡水情况下,当砂柱中的粘粒含量≤1.5%(重量比)时,其渗透系数基本不发生改变,即使粘粒含量从1.5%增加10%,其渗透系数也仅下降约一个数量级。各种粘土矿物中,蒙脱石导致含水介质渗透系数的下降最为明显,高岭土和伊利石约是其影响值的一半。咸淡水驱替实验中,加入蒙脱石颗粒的砂柱的渗透系数急剧下降,当蒙脱石含量达3~4%时,渗透系数已经下降的极低,可以看作不透水层,而加入高岭土和伊利石的砂柱的渗透系数没有急剧变化。对于这种现象的解释是:不同类型的粘土颗粒吸附不同数量的水分子,形成数量和大小不同的胶体团,使得介质渗透系数的变化量不同。
Abstract:
By changing the kind and content of clay mineral in the sand,associating with the simplex and replacing experiments for saline and fresh water,the water sensitivity characters of different clay minerals are studied in this paper.For the simplex fluid(saline or fresh water),the hydraulic conductivities of sand columns don’t decrease when the content of any clay mineral is under 1.5%(weight ratio),and only decrease by one digital grade even the content increases to 10% (weight ratio).The hydraulic conductivities of the sand columns containing smectite decrease more obviously than others containing kaoline and illite, whose decreasing extent is about 50% of the former’s.The result of the replacing experiment indicates that the hydraulic conductivities of the sand columns containing smectite decrease sharply,and the hydraulic conductivity is so low that the sand columns can be regarded as an impenetrable layer,but the other columns’ hydraulic conductivity don’t decrease greatly.The reason for this phenomenon is that the different clay minerals adsorb different quantity of water molecules and form to different quantity and size colloid agglomerates which bring on different varieties of the hydraulic conductivity.
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