X線CTを用いた三次元間隙構造可視化による土壌充填カラムにおける間隙率分布の評価  [in Japanese] EVALUATION OF POROSITY DISTRIBUTIONS WITHIN PACKED SOIL COLUMNS WITH X-RAY CT BASED 3-D VISUALIZATION  [in Japanese]

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Abstract

異なる方法でカラム試験用カラムに充填した土壌試料の通水前後の間隙率分布をX線CTを用いて可視化し,間隙率分布によってどのような流体流動が生じうるかを考察した.水締め法で充填した土壌中の間隙率分布は均質であり,通水後の変化も顕著でなかったことから,このような均質な間隙率分布における流体流動は安定した一様なものであることが示唆された.一方,自由落下法で充填した土壌中の通水前の間隙率分布は,間隙率の大きな部分と小さい部分が層状に存在し,不均質であることが示された.不均質な間隙率分布では,流体流動はらせん状に生じ,さらに流量が時間とともに変化することが示唆された.その間隙率分布に起因して生じる流体流動‐輸送‐反応の連成現象を理解することが,必要不可欠なことであると考えられる.

 The purpose of this paper is to examine the soil structure and flow path in order to standardize an upflow column test using an X-ray CT based numerical analysis. The soil structure and flow path are visualized of a porosity distribution by the X-ray CT. Methods of filling sample to the inside column were used ‘Free fall method’ and ‘Water tightening method’. Porosity of the Water tightening method, sample was maintained 35%-40% before and after in wet condition. And the porosity distribution is confirmed that uniforms and not to change removable with water flow. It is suggested that fluid flux in porosity distributions is stabile in the column. On the other hand, Porosity of the Free fall method, sample was observed that is increased 5% before and after water flow and the chap is occurred before water flow between layers. The porosity distribution is confirmed unevenness forms which have layers and part of large and small pores in the column. These unequal porosity distribution are thought that fluid flux has become spiro-flow and changed flow variation with time. It is revealed that the porosity distribution is significantly different due to differences in the soil filling method even same soil sample. It is considered that most important for standardization and generalization of column test methods and results is understood phenomenon (fluid flux, transport and response) resulting due to porosity distribution and consolidated reproducible test method for radical soil porosity distribute in the column.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. C (Geosphere Engineering)

    Journal of Japan Society of Civil Engineers, Ser. C (Geosphere Engineering) 72(2), 190-195, 2016

    Japan Society of Civil Engineers

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