細粒分を含む締固めた砂質土の土粒子流出特性に関する実験的研究

摘要

Since the ground surface above the damaged conduits might cave in, and it is difficult to estimate where and when it would occur because vast amounts of conduit are buried in the ground, it is useful to know priorities to the improvements based on the resistance characteristics of the soils. Concerned with this issue, the model tests to investigate the mechanisms and the searching technology for the existing caves were conducted and reported, but research from view point of soil characteristics related to the resistance against effluence is insufficient. In this paper, a series of model tests was conducted to cause soil particle effluence from an opening of the damaged pipe using several kinds of materials including either plastic or non-plastic fines in order to know the influence of both amount and plasticity index of fines on the resistance against effluence. It is proved that the combination of fine's content and plasticity index determine the resistance against effluence. Further, for the soil used in this study having a fine of rather large plasticity index, the resistance against effluence was larger when compacted under the condition of having a little more water content than the optimum water content.