EVALUATION OF POROSITY DISTRIBUTIONS WITHIN PACKED SOIL COLUMNS WITH X-RAY CT BASED 3-D VISUALIZATION

Abstract

 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.