This paper presents experimental results obtained from silty sand slope models subjected to an artificial rainfall. Four models were constructed to evaluate the effect of initial water content and rainfall intensity on the hydraulic behavior and failure mechanisms of the slopes. The models were instrumented with volumetric water content sensors to monitor the advance of the water front, and inclinometers to measure lateral movements of the slope. The models were subjected to rainfall intensities ranging from 25 to 50 mm/h, and durations from 19 to 152 minutes. The influence of low intensity rainfall events before a high intensity rainfall is discussed herein. The results showed that the time the slope models required to reach failure was influenced by the soil initial water content, being shorter at high initial water contents. These results are useful to understand the behavior of unsaturated natural slopes and embankments exposed to rainfall infiltration, and to complement the existing laboratory database existing in this subject.

This paper presents experimental results obtained from tests on unsaturated soil in one-dimensional columns simulating a rainfall infiltration process. Six columns composed of compacted Silty Sand were prepared to study the effects of the initial water content and rainfall intensity on the downward infiltration process. The advance of the water front was monitored using sensors to measure pore water pressure and volumetric water content installed at different locations along the height of the Silty Sand column. The test results show that the lag time, defined as the time difference from the beginning of the test to a sudden increase in the volumetric water content readings, was influenced by the soil initial water content and rainfall intensity; it is observed that the lag time is shorter at higher initial water contents and greater rainfall intensities. The results provide insights to understand the hydraulic behavior of unsaturated slopes and embankments exposed to rainfall infiltration. RESUMEN:En este artículo se presentan los resultados experimentales obtenidos a partir de ensayos en suelo parcialmente saturado en columnas unidimensionales, simulando un proceso de infiltración de lluvia. Se prepararon seis columnas de arena limosa compactada para estudiar los efectos del contenido inicial de agua y de la intensidad de la lluvia en el proceso de infiltración descendente. El avance del agua fue monitoreado usando sensores para medir la presión de poros y de contenido volumétrico de agua instalados a diferentes alturas de la columna de arena limosa. Los resultados de los ensayos muestran que el tiempo de retraso, definido como la diferencia de tiempo desde el inicio del ensayo hasta el aumento súbito en las lecturas del contenido volumétrico de agua, fue influenciado por el contenido inicial de agua en el suelo y la intensidad de la lluvia; se observa que el tiempo de retraso es más corto a mayores contenidos iniciales de agua y mayores intensidades de lluvia. Estos resultados proveen información para comprender el comportamiento hidráulico de taludes y terraplenes parcialmente saturados expuestos a la infiltración de lluvias.