A Study by Field Measurement and Numerical Simulation About Rainfall Seepage Mechanism in Case of Torrential Rainfall

To investigate the mechanism of rainwater infiltration into an unsaturated soil slope during torrential rainfall, we conducted a field measurement and monitoring of the rainfall for a year, pore water pressure, and pore air pressure on a natural slope located in Fukuchiyama city in Kyoto, Japan. In 2013, torrential rainfall was observed at the study site on August 31 and September 15. This study presents the measurement data collected during the two torrential rainfall events and compares them with a saturated–unsaturated flow simulation of fluctuations in water content inside the slope, which was performed using a two-dimensional (2-D) finite element method (FEM). The simulation results and field measurement data are then used to explore the influence of pore air pressure on the rainwater infiltration mechanism at different rain intensities.