Study on Development of Visualization System using Soft X-ray for Macro Pores in Soils and Water Movement in them

本文采用软x射线立体成像技术和图像处理技术，对土壤中主要支配水分和溶质运动的大孔隙结构进行了观察。从而定量地确定了大孔隙的三维坐标。在此基础上，开发了土壤中水分运动或排水的可视化系统，并对水分运动与孔隙结构之间的关系进行了研究。主要研究结果如下：1。水在土壤大孔隙中的运动观测表明，快速的水流沿着根状孔隙流动，水流路径因水力梯度而改变。饱和土排水过程的可视化表明，孔隙是按其在孔隙网络中的位置顺序逐渐排水的。利用FFT方法可以在频率维度上定量和统计地处理大孔隙方向的分布。利用孔隙软x射线立体成像技术，建立了土体大孔隙三维坐标识别系统，并利用金属丝制成的准孔隙验证了该系统的可靠性和实用性。对大孔的三维结构进行了分析，得到了大孔的直径和方向分布。

In this study, structure of macro-pores in soil, which mainly dominate water and solute movement, were observed using the soft X-ray stereography and the image processing thechnology. So, the three dimensional coordinates of the macro-pores were identified quantitatively. Then, visualization system for water movement or drainage in soil has been developed and relation between water movement and pore structures was examined. The main results are as followings :1.Observation of water movement through the macro-pores in soil shows that fast water flows run along root-originated pores and routes are changed by hydraulic gradient.2.Visualization of drainage process in saturated soil make clear that pores are drained gradually in order according to their position in the pore networks.3.Distribution of macro-pore directions can be dealt quantitatively and statistically in the frequency dimension using the FFT method.4.The system for identification of three dimensional coordinates of soil macro-pores was developed using the soft X-ray Stereography of pores, which reliability and utility was examined using the quasi pores made of wire.Three dimensional structure of macro-pores was analyzed to get the distribution of their diameters and directions.