The physical and mechanical properties of sea-bottom sediments in the Eastern Margin of Japan Sea by MD179

on the sediment mineral composition. Conversely, the grain heat capacity and grain specific heat showed hardly any dependency on the mineral composition. We propose empirical formulae for the relationships between: thermal diffusivity and thermal conductivity, and heat capacity and thermal conductivity for the sediment in the Joetsu Basin. These relationships are different from those for mud-dominant sediment in the eastern flank of the Juan de Fuca Ridge presented in previous work, suggesting a difference in mineral composition, probably mainly in the amount of quartz, between the sediments in that area and the Joetsu Basin. Similar studies in several areas of sediments with various mineral compositions would enhance knowledge of the influence of mineral composition.

No abstract

Recently, mixtures of low-quality soil together with solidification materials, such as cement or steel slag, have been used for earthmoving construction. Solidification materials can improve consistency, shear strength, stiffness, and other parameters of low-quality soil by generating bonding forces between soil particles and changing grain size gradation. However, these solidification materials also contain chemical agents. In this study, simulations of rainfall infiltration into embankment constructed with the soil-solidification material mixture are conducted using the soil/water/air/soluble material coupled finite element analysis code, DACSAR-MP_ad. This analysis code can express not only deformation and seepage for an unsaturated earth structure but can also concurrently model the dispersing behaviour of soluble material. Herein, permeability and rainfall intensity conditions are provided and their effects investigated. Consequently, this study succeeds in expressing different distributions of soluble materials within embankment under different rainfall conditions.

バイカル湖表層型メタンハイドレート賦存堆積土の地盤工学的性質 片岡 沙都紀1 ，山下 聡 2 ，南 尚嗣 3 ，西尾 伸也 4 ， 安部 透 4 ，横山 幸也 5 ，兵動 正幸 6 ，Mikhail Grachev 写真4 観察されたメタンハイドレート粘土（褐色） 20cm06-K2 GC.5 06-K2-R GC.12 06-Malen-R GC.1 AbstractThe site investigation of the shallow type methane hydrate-bearing ground was performed on the Lake Baikal, Russia, in 2005 and 2006, and the geotechnical properties of the bottom sediment were examined. In the investigation, sediments with methane hydrates were sampled, and several kinds of tests (cone penetration, vane shear, bender element, uniaxial compression tests) were performed on the board. At the same time, samples were also retrieved from the grounds without methane hydrates. Then, the soil strengths and physical properties for both samples were compared. As a result, it was found that the soil strengths of surface sediments with methane hydrates were lower than those without methane hydrates regardless of the depth. It would seem that this is because the effect of the disturbance by emission of gas and water and pressure release during the sampling.