有明粘土

Several studies have reported that quick clay can be formed artificially by salt-leaching treatment on undisturbed Ariake clay. In the present study, however, artificial salt-leaching on the undisturbed clay taken from a site in Shiroishi-cho of Saga Prefecture failed to produce quick clay. To identify the cause, pore-water chemistry of the clay was assessed and the predominance of divalent cation in pore water was found to be responsible for the poor development of quick clay. Assuming that cation composition in pore water controls the development of quick clay, the undisturbed Ariake clay was saturated with seawater followed by artificial salt-leaching, resulting in the formation of quick clay. Based on these findings, how cation composition in pore water is related to whether quick clay develops or not is described in the present paper. Pore water of the original undisturbed Ariake clay after sampling was occupied with as much as 78% divalent cation, which was almost maintained after salt-leaching. Because of this, the remolded strength of the clay was not changed due to salt-leaching, leading to unchanged sensitivity as well. On the other hand, pore water of the seawater-saturated clay was dominated with sodium and divalent cation percentage was only 6%, which was maintained at 3% after salt-leaching. The remolded strength of the seawater-saturated clay dropped dramatically due to salt-leaching, resulting in an increase in the sensitivity of the clay up to the level of 790 to 1500.