Abstract
The authors found that an employment of crushed shells in the lower layer instead of gravel greatly helps to reduce the transport of the finer particles in the upper layer into the lower layer, and to provide an effective function of capillary barriers. In this study, the diversion lengths are measured in the field experiments using crushed shells instead of gravel in the lower layer, and compared it with the estimations calculated by the theoretical equation proposed by Steenhuis, et al. In addition, we compared it with the diversion lengths which were measured in the field experiments using a sand layer underlain by a gravel layer. As the result, the authors make clearly the application of the theoretical equation proposed by Steenhuis, et al. in estimating the divergence length of the capillary barrier.
