Holocene Deposits in Saga Plain: Leaching Mechanism and Soil Sensitivity
Holocene Deposits in Saga Plain: Leaching Mechanism and Soil Sensitivity
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DOI：
10.1007/s10706-017-0231-y
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发表时间：
2017-04
影响因子：
1.7
通讯作者：
J. Chai;T. Hino;S. Shen;J. Carter
中科院分区：
文献类型：
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作者：
J. Chai;T. Hino;S. Shen;J. Carter
日本佐贺平原含有10-30 m厚的全新世粘土沉积物，天然含水量一般超过100%，流动性指数（IL）大于1.0。其中大部分是被称为有明粘土地层的海洋沉积物。以该矿床孔隙水中的盐度为指标，研究了有明粘土地层沉积后盐度淋滤的机理。这是通过当前对沉积物中的盐度分布和下面的更新世砾石砂层中的地下水流速的测量以及平流扩散分析来实现的。这表明扩散以及可能的降雨渗透和/或更新世砾石砂层的向上渗流是导致盐度淋滤的主要机制。对四个钻孔测试结果的详细分析表明，对于粘土矿物活性小于 1.25 的位置，盐度淋滤可能是观察到的重塑土壤样品的低不排水剪切强度（<0.5 kPa）、高灵敏度（St）值以及快速粘土形成的原因。
The Saga Plain in Japan contains a 10–30 m thick Holocene clayey soil deposit with a natural water content generally more than 100% and a liquidity index (IL) larger than 1.0. Most of this is a marine deposit known as the Ariake clay formation. Using salinity in the pore water of this deposit as an index, the mechanism of post-depositional salinity leaching from the Ariake clay formation has been investigated. This has been achieved using current measurements of the salinity distribution in the deposit and the groundwater flow velocity in an underlying Pleistocene gravelly sand layer, together with advection–diffusion analyses. It is suggested that diffusion together with possible rainfall percolation and/or upward seepage flow from the Pleistocene gravelly sand layer was the main mechanism causing salinity leaching. Detailed analysis of the test results from four boreholes indicates that for the locations where the activity of the clay minerals was less than 1.25, salinity leaching probably accounts for the observed low undrained shear strength (<0.5 kPa) of remoulded soil samples, high values of the sensitivity (St), and the formation of a quick clay.