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

本研究利用软X射线体视照相技术和图像处理技术，对土壤中主要控制水分和溶质运移的大孔隙结构进行了观测。从而定量地确定了大孔隙的三维坐标。在此基础上，开发了土壤水分运动或排水的可视化系统，研究了土壤水分运动与孔隙结构的关系。主要结果如下：1.通过对土壤大孔隙水分运动的观测，发现水分沿沿着根源孔隙快速流动，并随水力梯度的变化而改变流动路径; 2.对饱和土壤排水过程的可视化研究表明，土壤大孔隙的排水过程是按孔隙在孔隙网络中的位置依次进行的; 3.利用FFT方法，在频率维上对土壤大孔隙的方向分布进行了定量统计; 4.利用软X射线孔隙立体图，建立了土壤大孔隙三维坐标识别系统，利用金属丝制成的准孔隙模型对该方法的可靠性和实用性进行了验证，并对大孔隙的三维结构进行了分析，得到了大孔隙的直径和方向分布。

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.