A method for predicting the factor of safety of an infinite slope based on the depth ratio of the wetting front

Abstract. Most landslides in Korea are classified as shallow landslides with an average depth of less than 2 m. These shallow landslides are associated with the advance of a wetting front in the unsaturated soil due to rainfall infiltration, which results in an increase in water content and a reduction in the matric suction in the soil. Therefore, this study presents a modified equation of infinite slope stability analysis based on the concept of the saturation depth ratio to analyze the slope stability change associated with the rainfall on a slope. A rainfall infiltration test in unsaturated soil was performed using a column to develop an understanding of the effect of the saturation depth ratio following rainfall infiltration. The results indicated that the rainfall infiltration velocity due to the increase in rainfall in the soil layer was faster when the rainfall intensity increased. In addition, the rainfall infiltration velocity tends to decrease with increases in the unit weight of soil. The proposed model was applied to assess its feasibility and to develop a regional landslide susceptibility map using a Geographic Information System (GIS). For that purpose, the spatial databases for input parameters were constructed and landslide locations were obtained. In order to validate the proposed approach, the results of the proposed approach were compared with the landslide inventory using ROC (Receiver Operating Characteristics) graph. In addition, the results of the proposed approach were compared with the previous approach used steady state hydrological model. Consequently, the approach proposed in this study displayed satisfactory performance in classifying landslide susceptibility and showed better performance than the steady state approach.

Download Full-text

A method for predicting the factor of safety of an infinite slope based on the depth ratio of the wetting front induced by rainfall infiltration

Natural Hazards and Earth System Science ◽

10.5194/nhess-15-1835-2015 ◽

2015 ◽

Vol 15 (8) ◽

pp. 1835-1849 ◽

Cited By ~ 19

Author(s):

B.-G. Chae ◽

J.-H. Lee ◽

H.-J. Park ◽

J. Choi

Keyword(s):

Steady State ◽

Slope Stability ◽

Unsaturated Soil ◽

Landslide Susceptibility ◽

Shallow Landslides ◽

Rainfall Infiltration ◽

Wetting Front ◽

Operating Characteristics ◽

Infinite Slope ◽

Depth Ratio

Abstract. Most landslides in Korea are classified as shallow landslides with an average depth of less than 2 m. These shallow landslides are associated with the advance of a wetting front in the unsaturated soil due to rainfall infiltration, which results in an increase in water content and a reduction in the matric suction in the soil. Therefore, this study presents a modified equation of infinite slope stability analysis based on the concept of the saturation depth ratio to analyze the slope stability change associated with the rainfall on a slope. A rainfall infiltration test in unsaturated soil was performed using a column to develop an understanding of the effect of the saturation depth ratio following rainfall infiltration. The results indicated that the rainfall infiltration velocity due to the increase in rainfall in the soil layer was faster when the rainfall intensity increased. In addition, the rainfall infiltration velocity tends to decrease with increases in the unit weight of soil. The proposed model was applied to assess its feasibility and to develop a regional landslide susceptibility map using a geographic information system (GIS). For that purpose, spatial databases for input parameters were constructed and landslide locations were obtained. In order to validate the proposed approach, the results of the proposed approach were compared with the landslide inventory using a ROC (receiver operating characteristics) graph. In addition, the results of the proposed approach were compared with the previous approach used: a steady-state hydrological model. Consequently, the approach proposed in this study displayed satisfactory performance in classifying landslide susceptibility and showed better performance than the steady-state approach.

Download Full-text

Infinite slope stability model and steady-state hydrology-based shallow landslide susceptibility evaluations: The Guneysu catchment area (Rize, Turkey)

CATENA ◽

10.1016/j.catena.2021.105161 ◽

2021 ◽

Vol 200 ◽

pp. 105161

Author(s):

Fatma Keles ◽

Hakan A. Nefeslioglu

Keyword(s):

Steady State ◽

Slope Stability ◽

Landslide Susceptibility ◽

Catchment Area ◽

Shallow Landslide ◽

Infinite Slope ◽

Infinite Slope Stability Model ◽

Stability Model

Download Full-text

Analysis of Slope Stability Considering the Saturation Depth Ratio by Rainfall Infiltration in Unsaturated Soil

The Journal of Engineering Geology ◽

10.9720/kseg.2012.3.343 ◽

2012 ◽

Vol 22 (3) ◽

pp. 343-351 ◽

Cited By ~ 6

Author(s):

Byung-Gon Chae ◽

Kyu-Bo Park ◽

Hyuck-Jin Park ◽

Jung-Hae Choi ◽

Man-Il Kim

Keyword(s):

Slope Stability ◽

Unsaturated Soil ◽

Rainfall Infiltration ◽

Depth Ratio

Download Full-text

Determination Critical Rainfall Threshold for the Initiation of Landslides Using Rainfall-Infiltration Model and Infinite Slope Stability Model

Springer Geography - Geoinformatics for Sustainable Development in Asian Cities ◽

10.1007/978-3-030-33900-5_8 ◽

2019 ◽

pp. 75-84

Author(s):

Thapthai Chaithong

Keyword(s):

Slope Stability ◽

Rainfall Threshold ◽

Rainfall Infiltration ◽

Infinite Slope ◽

Infiltration Model ◽

Infinite Slope Stability Model ◽

Stability Model ◽

Critical Rainfall

Download Full-text

Probabilistic landslide susceptibility analysis in tropical mountainous terrain using the physically based r.slope.stability model

10.5194/nhess-2019-223 ◽

2019 ◽

Author(s):

Johnnatan Palacio Cordoba ◽

Martin Mergili ◽

Edier Aristizábal

Keyword(s):

Slope Stability ◽

Landslide Susceptibility ◽

Confusion Matrix ◽

Hazard Mapping ◽

Infinite Slope ◽

Susceptibility Analysis ◽

Colombian Andes ◽

Infinite Slope Stability Model ◽

Stability Model ◽

Physically Based

Abstract. Landslides triggered by rainfall are very common phenomena in complex tropical environments such as the Colombian Andes, one of the regions most affected by landslides every year. Currently in Colombia, physically based methods for landslide hazard mapping are mandatory for land use planning in urban areas. In this work, we perform probabilistic analyses with r.slope.stability, a spatially distributed, physically based model for landslide susceptibility analysis, available as an open-source tool coupled to GRASS GIS. This model considers alternatively the infinite slope stability model or the 2.5D geometry of shallow planar and deep-seated landslides with ellipsoidal or truncated failure surfaces. We test the model in the La Arenosa catchment, northern Colombian Andes. The results are compared to those yielded with the corresponding deterministic analyses and with other physically based models applied in the same catchment. Finally, the model results are evaluated against a landslide inventory using a confusion matrix and Receiver Operating Characteristic (ROC) analysis. The model performs reasonably well, the infinite slope stability model showing a better performance. The outcomes are, however, rather conservative, pointing to possible challenges with regard to the geotechnical and geo-hydraulic parameterization. The results also highlight the importance to perform probabilistic instead of – or in addition to – deterministic slope stability analyses.

Download Full-text

Infinite Slope Stability under Transient Rainfall Infiltration Conditions

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.501-504.395 ◽

2014 ◽

Vol 501-504 ◽

pp. 395-398 ◽

Cited By ~ 1

Author(s):

Yu Fei Kong ◽

Jian Liu ◽

Hong Gang Shi ◽

Long Ying Zhang ◽

Heng Zhao ◽

...

Keyword(s):

Stability Analysis ◽

Slope Stability ◽

Safety Factor ◽

Underground Water ◽

Rainfall Infiltration ◽

Infiltration Process ◽

Infinite Slope ◽

Seepage Analysis ◽

Infiltration Model ◽

Two Stages

The infiltration process of infinite slopes was studied with modified Green-Ampt infiltration model. The process was divided into two stages, in which the depth of the wetting zone and underground water was calculated. Stability analysis considering different sliding patterns was conducted on the basis of seepage analysis. The safety factor of infinite slopes at different time stages has been derived. Equations in this paper could be used for predicting rain-induced landslides with limited parameters available.

Download Full-text

Soil moisture storage and hillslope stability

Natural Hazards and Earth System Science ◽

10.5194/nhess-7-523-2007 ◽

2007 ◽

Vol 7 (5) ◽

pp. 523-534 ◽

Cited By ~ 27

Author(s):

A. Talebi ◽

R. Uijlenhoet ◽

P. A. Troch

Keyword(s):

Soil Moisture ◽

Steady State ◽

Slope Stability ◽

Safety Factor ◽

Unsaturated Zone ◽

Soil Depth ◽

Critical Role ◽

Infinite Slope ◽

Stability Model ◽

Hillslope Stability

Abstract. Recently, we presented a steady-state analytical hillslope stability model to study rain-induced shallow landslides. This model is based on kinematic wave dynamics of saturated subsurface storage and the infinite slope stability assumption. Here we apply the model to investigate the effect of neglecting the unsaturated storage on the assessment of slope stability in the steady-state hydrology. For that purpose we extend the hydrological model to compute the soil pore pressure distribution over the entire flow domain. We also apply this model for hillslopes with non-constant soil depth to compare the stability of different hillslopes and to find the critical slip surface in hillslopes with different geometric characteristics. In order to do this, we incorporate more complex approaches to compute slope stability (Janbu's non-circular method and Bishop's simplified method) in the steady-state analytical hillslope stability model. We compare the safety factor (FS) derived from the infinite slope stability method and the more complex approach for two cases: with and without the soil moisture profile in the unsaturated zone. We apply this extended hillslope stability model to nine characteristic hillslope types with three different profile curvatures (concave, straight, convex) and three different plan shapes (convergent, parallel, divergent). Overall, we find that unsaturated zone storage does not play a critical role in determining the factor of safety for shallow and deep landslides. As a result, the effect of the unsaturated zone storage on slope stability can be neglected in the steady-state hydrology and one can assume the same bulk specific weight below and above the water table. We find that steep slopes with concave profile and convergent plan shape have the least stability. We also demonstrate that in hillslopes with non-constant soil depth (possible deep landslides), the ones with convex profiles and convergent plan shapes have slip surfaces with the minimum safety factor near the outlet region. In general, when plan shape changes from divergent to convergent, stability decreases for all length profiles. Finally, we show that the applied slope stability methods and steady-state hydrology model based on the relative saturated storage can be used safely to investigate the relation between hillslope geometry and hillslope stability.

Download Full-text

A strategy for GIS-based 3-D slope stability modelling over large areas

Geoscientific Model Development Discussions ◽

10.5194/gmdd-7-5407-2014 ◽

2014 ◽

Vol 7 (4) ◽

pp. 5407-5445 ◽

Cited By ~ 3

Author(s):

M. Mergili ◽

I. Marchesini ◽

M. Alvioli ◽

M. Metz ◽

B. Schneider-Muntau ◽

...

Keyword(s):

Slope Stability ◽

Landslide Susceptibility ◽

Slope Failure ◽

Computing Time ◽

Central Italy ◽

Shallow Landslides ◽

Landslide Susceptibility Mapping ◽

Deterministic Models ◽

Average Value ◽

Slip Surfaces

Abstract. GIS-based deterministic models may be used for landslide susceptibility mapping over large areas. However, such efforts require specific strategies to (i) keep computing time at an acceptable level, and (ii) parameterize the geotechnical data. We test and optimize the performance of the GIS-based, 3-D slope stability model r.slope.stability in terms of computing time and model results. The model was developed as a C- and Python-based raster module of the open source software GRASS GIS and considers the 3-D geometry of the sliding surface. It calculates the factor of safety (FoS) and the probability of slope failure (Pf) for a number of randomly selected potential slip surfaces, ellipsoidal or truncated in shape. Model input consists of a DEM, ranges of geotechnical parameter values derived from laboratory tests, and a range of possible soil depths estimated in the field. Probability density functions are exploited to assign Pf to each ellipsoid. The model calculates for each pixel multiple values of FoS and Pf corresponding to different sliding surfaces. The minimum value of FoS and the maximum value of Pf for each pixel give an estimate of the landslide susceptibility in the study area. Optionally, r.slope.stability is able to split the study area into a defined number of tiles, allowing parallel processing of the model on the given area. Focusing on shallow landslides, we show how multi-core processing allows to reduce computing times by a factor larger than 20 in the study area. We further demonstrate how the number of random slip surfaces and the sampling of parameters influence the average value of Pf and the capacity of r.slope.stability to predict the observed patterns of shallow landslides in the 89.5 km2 Collazzone area in Umbria, central Italy.

Download Full-text