A Study on Duplication Method of Undisturbed Natural Clays in Laboratory

研究了高岭土与膨润土混合的人工粘土的物理特性、固结特性、剪切特性与混合条件之间的关系，建立了利用市场材料在实验室复制天然粘土的方法。结果表明，混合土的液限随混合土中膨润土含量的增加呈线性增加，其增加速率随混合水盐度的增加而减小。另一方面，混合粘土的膨润土含量和混合水的盐度对塑性极限几乎没有影响。固结特性研究发现，随着膨润土含量的增加，混合粘土的压缩指数线性增大，固结系数的对数线性减小。在剪切特性上还发现，随着膨润土含量的增加，剪切引起的超孔隙水压力减小，抗剪强度增大，应变硬化程度增大。为了模拟室内的老化效果，将混合粘土从浆料状态进行高温重固结或仅在最后一次重固结阶段的二次压缩进行高温固化。结果表明，高温重固结或固化粘土的固结屈服应力比室温重固结粘土的固结屈服应力大，高温重固结或固化粘土的特性与自然时效粘土相似。这表明高温再固结过程和高温固化过程可以重复时效效果。

Relationships between physical properties, consolidation characteristics and shear characteristics and mixing conditions of artificial clays mixed a kaolin with a bentonite were investigated in order to develop the duplication method of undisturbed natural clays in laboratory by using marketed materials.As the results, it is found on physical properties that the liquid limit of mixed clays linearly increases with an increase of the bentonite content of the mixed clays and that the rate of its increase decreases with an increase of the salinity of the mixing water.On the other hand, the plastic limit is hardly influenced by the bentonite content of the mixed clays or the salinity of the mixing water.It is found on consolidation characteristics that the compression index of the mixed clays linearly increases and the logarithm of the coefficient of consolidation linearly decreases with an increase of the bentonite content of the mixed clays.It is also found on shear characteristics that the excess pore water pressure caused by shearing decreases, shear strength increases and the degree of the strain hardening increases with an increase of the bentonite content of the mixed clays.In order to duplicate the aging effect in laboratory, the mixed clays were reconsolidated at the high temperature from the slurry state or cured at high temperature only during the secondary compression of the last reconsolidation stage.As the results, it is found that the consolidation yield stress of the clay samples reconsolidated or cured at high temperature becomes large than that of the clay samples reconsolidated at room temperature and that the characteristics of the clay samples reconsolidated or cured at high temperature are similar to those of naturally aged clays.This implies that the high temperature reconsolidation procedure and the high temperature curing procedure can duplicate the aging effect.