Investigation on strong vertical permeability and micro-pore characteristics of Jinan red clay using X-ray micro-tomography

Abstract

Due to the peculiarity of the spring domain strata in Jinan, the phenomenon of serious water seepage appears in the process of excavation. The macro permeability of soil is closely correlated with its microstructure. In this study, by using the X-ray micro-tomography (micro-CT) system and a self-designed soil seepage device, the internal pore structure of Jinan red clay and the water ow inside the sample under different seepage stages were observed. The microstructure of water phase and air phase in the sample was segmented by the watershed algorithm. Calculation and comparison of pore and throat size distributions at different seepage stages were conducted by establishing Pore Network Model (PNM). Meanwhile, the seepage experiment simulations were conducted based on the 3D pore structure of red clay. The results show that the preferentially ow of Jinan red clay is obvious due to the existence of the vertically developed macropore channel. The ne particles (mainly silt particles) are washed away during seepage, thereby expanding the pore channels. The maximum pore radius and pore connectivity have important in uence on seepage characteristics of Jinan red clay, but the correlation between porosity is small.

Numerical Study of the Influence of Horizontal Spatial Distribution of Macropores on Water Infiltration

“…The macropore position can affect the water and solute transport capacity of soil [30], and the existing parameters describing the spatial characteristics of macropores (such as macroporosity, number, pore size, connectivity, tortuosity, hydraulic radius, path number, mean angle, etc. [62][63][64]) are difficult to use to characterize the macropore position. Therefore, this study establishes two two-dimensional statistical parameters to characterize the position relationships among macropores and between the macropores and the observation area, which can be combined to characterize the macropore position to a certain extent.…”