PERMEABILITY AND COMPRESSIBILITY OF MIXED SOIL COMPOSED OF VOLCANIC COHESIVE SOIL AND SHIRASU

本研究的目的是寻找合适的防渗土材料。本课题选择粘性土为Kuroboku土，砂土为Shirasu土。得到的结果如下：1。当白苏的混合比低于50%时，混合土的物理性质与黑龙土相似；当浓度超过70%时，混合型出现与白露相似的现象。其最大干密度随比的增大而增大。剪切特性受初始密度、围压和颗粒破碎的影响。对于这些因素，偏差应力的增量随应变的增加而减小。因此，高围压下的抗剪角值比低围压下的小。含砂率65%的混合土为渗透性系数为10^<-6>cm/sec，黏聚力为0.4 kgf/cm^2，内摩擦角为25度的防渗材料。综上所示，在压缩指数0.2以下，混合比为60%左右的混合材料被认为是最合适的抗渗材料。

The purpose of this research is to find out suitable soil material as an impervious one. Kuroboku soil for a cohesive soil and Shirasu for a sandy soil were chosen in this subject. The results obtained are as follows.1. In case the mix ratio of Shirasu is below 50%, the mixed soil comes to show physical properties similar to Kuroboku soil ; while when it is above 70%, the mixed one comes to show those similar to Shirasu. The maximum dry density of it shows the high value as the ratio increases.2. The shearing characteristics are subjected to the initial density, confining pressure and crushing of grain. For these factors, the increment of deviator stress is reduced with increasing of strain. As a result of it, values of angle of shearing resistance at the high confining pressure are lower than those at low pressure.3. The mixed soil containing the sand fraction of 65% is the impervious material having the coefficient of permeability of 10^<-6>cm/sec, the cohesion of 0.4 kgf/cm^2 and the angle of internal friction of 25 degree.Judging from these results, the mixed material compacted at the mix ratio of about 60% is considered to be the most suitable impervious material below 0.2 of compression index.