Abstract
A simple soil layer system which is composed of a finer soil layer underlain by a coarser soil layer provides an excellent property of capillary barrier. In order to realize the best performance of the capillary barrier function effectively, it is necessary to make larger the gap of particle diameter of sand and gravel material. The functional deterioration of capillary barriers in service for dozens of years is of concern because of the transport of sand particles to the lower gravel layer due to an earthquake et al. The authors found that using crushed shells instead of gravel in the lower layer greatly helps reduce the infiltration of sand particles into the lower layer as well as provides the function of capillary barriers.
In this study, the diversion lengths are measured in the laboratory soil box tests using crushed shells instead of gravel in the lower layer, and compared well with the estimations calculated by the theoretical equation proposed by Steenhuis, et al. In addition, we compared it with the diversion lengths are measured in the laboratory soil box tests using a sand layer underlain by a gravel layer by Morii, et al. As the result, the authors make clear the applicability of the theoretical equation proposed by Steenhuis, et al.
