Soil water balance model for precipitation-induced shallow landslides
- PDF / 854,639 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 59 Downloads / 196 Views
ORIGINAL ARTICLE
Soil water balance model for precipitation-induced shallow landslides Hsin-Fu Yeh • Cheng-Haw Lee
Received: 23 April 2012 / Accepted: 9 February 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract Precipitation infiltration is one of the most significant triggering factors for slope failure occurrence in many places around the world. Knowledge of the mechanisms leading to precipitation-induced slope failures is of great importance to the management of landslide hazard. In this study, a soil water balance model is developed to estimate soil water flux during the process of infiltration from rainfall data, with consideration of storm periods and non-storm periods. Two important assumptions in this study are given: (1) instantaneous uniform distribution of the degree of saturation and (2) a linear relationship between evapotranspiration and the related degree of saturation. For storm periods, the Brooks and Corey model estimates both the soil water retention curve and soil water parameters. The infiltration partition is employed by an infinite-series solution of Philip in conjunction with the time compression approximation. For none-storm periods, evapotranspiration can be derived for the moisture depletion of soil water. This study presents a procedure for calculating the safety factor for an unsaturated slope suffering from precipitation infiltration. The process of infiltration into a slope due to rainfall and its effect on soil slope behavior are examined using modified Mohr–Coulomb failure criterion in conjunction with a soil water balance model. The results indicate that the matric suction, which is closely related to slope stability, is affected by the degree of saturation controlled by rainfall events. Keywords Soil water balance Soil water retention curve Matric suction Landslide H.-F. Yeh C.-H. Lee (&) Department of Resources Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC e-mail: [email protected]
Introduction Shallow landslides are landslides in which the sliding surface is located in the soil mantle or regolith typically to a depth of a few centimeters to a few meters (Sidle and Ochiai 2006; Godt et al. 2009). Shallow slope failures may occur within the vadose zone under partly saturated soil conditions (Lu and Godt 2008). According to recent studies, about half of the 40 most destructive landslide disasters worldwide in the past century resulted from long-term or heavy rainfall (Sidle and Ochiai 2006). Most of the annual precipitation (2,500 mm) in Taiwan comes from typhoons and convection rain. Due to the landform and monsoons, the distribution of precipitation is not uniform either in time or space. Generally speaking, the amount of precipitation in the mountains is higher than that in the plains and higher on the eastern coast than it is on the western coast. The precipitation is 1,500–2,000 mm in the western plains and hills and more than 3,000 mm in the mountains (Yeh 2008). Slope stability problems are receiving increasing attention in Taiwa
Data Loading...
