Abstract:

Irrigation-induced loess landslides are common geological disasters in the Loess Plateau region, and its essence is the groundwater rising which caused loess matric suction falling and intensity decreasing, eventually leading to the instability process of loess slope. In this paper, taking Heifang platform typical slope for example, we studied the variation of seepage field internal the loess slope which caused by the groundwater level rising, and investigated the affect that the groundwater level changes on slope stability, which both based on the characteristics test of unsaturated soil and the saturated-unsaturated seepage analysis. The results show that the groundwater level rises which has an obvious effect on pore pressure distribution internal slope and results in the saturation region increasing and matric suction reducing in unsaturated zone. There is a linear relationship between decreasing of matric suction internal slope and groundwater level. We made unsaturated limit equilibrium analysis in the typical slope, based on seepage analysis. The results show that there is approximate linear relationship between groundwater level rising and stability coefficient decreasing. Slope instability occurs, while groundwater level in loess layer of about 21 m, 100 m from the top of the hill.

Key words: irrigation, matric suction, seepage field, slope, stability