Observation of the effect of soil-structure boundaries using transparent soil technology

¹ Department of Civil Engineering, Yokohama National University, Yokohama, Japan
² School of Civil Engineering, Southeast University, Nanjing, China

^* Corresponding author: sai-ei-mx@ynu.ac.jp

Abstract

The predominance of water flow at strata boundaries often triggers dam and levee failures. However, research on the porosity and water flow at soil-structure boundaries is insufficient despite the fact that the fact that their significant influence on water flows through soil is due to high porosity caused by compaction difficulties in the boundary region. Additionally, observing the interior of soil by conventional experimental methods is challenging, making it difficult to precisely determine the exact differences between the boundary area and surrounding grounds. Therefore, transparent soil techniques were employed to investigate the interior of the soil and the impact of soil-structure boundaries on flow path formation. The experiment identified two critical properties at the soil-structure boundary: relatively high porosity and the maximum average velocity of the fluid during permeability, both occurring at the interface. The good connectivity of the pores at the boundary is due to the barrier effect of the flat wall, which causes water to flow vertically upward along the boundary. In contrast, water flows meanderingly upward in the interior area of the soil, resulting in a two-dimensional movement at the boundary compared to a three-dimensional movement in the interior of the soil.