压实膨润土在盐溶液中的膨胀变形特性

SWELLING BEHAVIOR OF COMPACTED BENTONITE UNDER OSMOTIC SUCTION

采用蒸馏水以及浓度不同的NaCl溶液作为浸泡溶液,对商用膨润土进行了膨胀变形试验。结果表明在相同的荷载作用下,膨胀变形随浸泡溶液浓度的增加而减小。这是因为浸泡溶液的浓度越大,溶液的渗透吸力π也越大,渗透吸力的增加将引起施加在黏土颗粒上有效应力的增加,使得在外部施加荷载相同时膨润土的膨胀变形随溶液浓度的增加而减小。当压实膨润土在盐溶液中膨胀时,其有效应力pe可分为两部分,即施加荷载部分p和渗透吸力部分pπ。对于浸泡于蒸馏水和NaCl溶液中的膨润土试样,其膨胀后的蒙脱石孔隙比em与有效应力pe之间的关系可采用同一关系曲线表示,此时施加于黏土颗粒上的有效应力的渗透吸力部分pπ=(p/π)^(0.66)·π。

Swelling deformation tests of a commercial bentonite are performed in distilled water and Na Cl solution with different concentrations. The results show the swelling characteristics decrease with the increase of solution concentration. Study on the results finds that the greater concentration of inundation solution exerts greater osmotic suction π. Increase in osmotic suction apparently acts as an equivalent effective stress that favors a reduction in swell potential of the compacted bentonite specimens. It means that,the effective stress includes the part of applied loads p and the part of osmotic suction pπ. The relationship between montmorillonite void ratio emand effective stress pecan be represented by a unified curve for bentonite in salt solution with different concentration and distilled water,and the part of osmotic suction pπ=( p / π)^(0. 66)·π.