scholarly journals Slope Stability Analysis of Unsaturated Soil in Debris-Flow Occurrence Slopes

2012 ◽  
Vol 28 (9) ◽  
pp. 23-30
Author(s):  
Cheol-Soo Kwak ◽  
Byung-Soo Park ◽  
Nam-Jae Yoo
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Debris Flow ◽  
Unsaturated Soil ◽  
Slope Stability Analysis

scholarly journals Landslide and debris flow susceptibility zonation using TRIGRS for the 2011 Seoul landslide event

2013 ◽  
Vol 1 (3) ◽  
pp. 2547-2587 ◽  
Author(s):  
D. W. Park ◽  
N. V. Nikhil ◽  
S. R. Lee
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Debris Flow ◽  
Slope Stability Analysis ◽  
Flow Paths ◽  
Infinite Slope ◽  
Erosion Rates ◽  
Landslide Event ◽  
Physically Based ◽  
Pore Pressure Response

Abstract. This paper presents the results from application of a regional, physically-based stability model: Transient Rainfall Infiltration and Grid-based Regional Slope-stability analysis (TRIGRS) for a catchment on Woomyeon Mountain, Seoul, Korea. This model couples an infinite-slope stability analysis with a one-dimensional analytical solution to predict the transient pore pressure response to the infiltration of rainfall. TRIGRS also adopts the Geographic Information Systems (GIS) framework for determining the whole behaviour of a slope. In this paper, we suggest an index for evaluating the results produced by the model. Particular attention is devoted to the prediction of routes of debris flow, using a runoff module. In this context, the paper compares observed landslide and debris flow events with those predicted by the TRIGRS model. The TRIGRS model, originally developed to predict shallow landslides, has been extended in this study for application to debris flows. The results predicted by the TRIGRS model are presented as safety factor (FS) maps corresponding to transient rainfall events, and in terms of debris flow paths using methods proposed by several researchers in hydrology. In order to quantify the accuracy of the model, we proposed an index called LRclass (landslide ratio for each predicted FS class). The LRclass index is mainly applied in regions where the landslide scar area is not well defined (or is unknown), in order to avoid over-estimation of the model results. The use of the TRIGRS routing module was proposed to predict the paths of debris flow, especially in areas where the rheological properties and erosion rates of the materials are difficult to obtain. Although an improvement in accuracy is needed, this module is very useful for preliminary spatiotemporal assessment over wide areas. In summary, the TRIGRS model is a powerful tool of use to decision makers for susceptibility mapping, particularly when linked with various advanced applications using GIS spatial functions.

Slope Stability Analysis on Unsaturated Soil by Probable Rainfall Intensity

2017 ◽  
Vol 17 (2) ◽  
pp. 495-500
Author(s):  
Sunhak Kim ◽  
◽  
Young-il Kim ◽  
Jaehong Kim ◽  
◽  
...  
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Unsaturated Soil ◽  
Rainfall Intensity ◽  
Slope Stability Analysis

A Slope Stability Analysis Method Based on Unsaturated Seepage of Slope and its Comparison with Geo-Seep Software

2014 ◽  
Vol 540 ◽  
pp. 177-180 ◽  
Author(s):  
Dong Fang Tian
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Rigid Body ◽  
Unsaturated Soil ◽  
Limit Equilibrium ◽  
Fem Analysis ◽  
Slope Stability Analysis ◽  
Analysis Method ◽  
The Impact ◽  
Unsaturated Seepage

Based on the FEM analysis of unsaturated slope seepage and strength of unsaturated soil, and adopted the assumption of rigid body limit equilibrium to calculate safe coefficient of landslides, a new slope stability analysis method is promoted and the calculation program called USSP is composed and verified. The method could consider the impact of rainfall and water change to slope stability. Compared with GeoSlope package, it is more practical in rainfall or variation of ground water level condition.

scholarly journals Landslide and debris flow susceptibility zonation using TRIGRS for the 2011 Seoul landslide event

2013 ◽  
Vol 13 (11) ◽  
pp. 2833-2849 ◽  
Author(s):  
D. W. Park ◽  
N. V. Nikhil ◽  
S. R. Lee
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Debris Flow ◽  
Slope Stability Analysis ◽  
Flow Paths ◽  
Erosion Rates ◽  
Landslide Event ◽  
Physically Based ◽  
Spatio Temporal ◽  
Pore Pressure Response

Abstract. This paper presents the results from the application of a regional, physically based stability model: Transient Rainfall Infiltration and Grid-based Regional Slope-stability analysis (TRIGRS) for a region on Woomyeon Mountain, Seoul, South Korea. This model couples an infinite-slope stability analysis with a one-dimensional analytical solution to predict the transient pore pressure response to the infiltration of rainfall. TRIGRS also adopts the geographic information system (GIS) framework for determining the whole behaviour of a slope. In this paper, we suggest an index for evaluating the results produced by the model. Particular attention is devoted to the prediction of routes of debris flow, using a runoff module. In this context, the paper compares observed landslide and debris flow events with those predicted by the TRIGRS model. The TRIGRS model, originally developed to predict shallow landslides, has been extended in this study for application to debris flows. The results predicted by the TRIGRS model are presented as safety factor (FS) maps corresponding to transient rainfall events, and in terms of debris flow paths using methods proposed by several researchers in hydrology. In order to quantify the effectiveness of the model, we proposed an index called LRclass (landslide ratio for each predicted FS class). The LRclass index is mainly applied in regions where the landslide scar area is not well defined (or is unknown), in order to avoid overestimation of the model results. The use of the TRIGRS routing module was proposed to predict the paths of debris flow, especially in areas where the rheological properties and erosion rates of the materials are difficult to obtain. Although an improvement in accuracy is needed, this module is very useful for preliminary spatio-temporal assessment over wide areas. In summary, the TRIGRS model is a powerful tool of use to decision makers for susceptibility mapping, particularly when linked with various advanced applications using GIS spatial functions.

Modeling the unsaturated soil zone in slope stability analysis

2014 ◽  
Vol 51 (12) ◽  
pp. 1384-1398 ◽  
Author(s):  
L. L. Zhang ◽  
Delwyn G. Fredlund ◽  
Murray D. Fredlund ◽  
G. Ward Wilson
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Slope Stability ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Matric Suction ◽  
Slope Stability Analysis ◽  
Engineering Practice ◽  
Rate Of Increase ◽  
Nonlinear Shear

The linear form of the extended Mohr–Coulomb shear strength equation uses a [Formula: see text] parameter to quantify the rate of increase in shear strength relative to matric suction. When the [Formula: see text] value is unknown, a [Formula: see text] equal to 15° is sometimes used in the slope stability study to assess the influence of matric suction on the stability of a slope. In many cases, however, a [Formula: see text] value of zero is used, signifying that the effect of matric suction is ignored. Experiment results have shown that the relationship between the shear strength of an unsaturated soil and matric suction is nonlinear. Several semi-empirical estimation equations have been proposed relating the unsaturated shear strength to the soil-water characteristic curve. In this paper, the results of a study using two-dimensional slope stability analysis along with an estimated nonlinear shear strength equations is presented. The effects of using an estimated nonlinear shear strength equation for the unsaturated soils are illustrated using three example problems. Several recommendations are made for engineering practice based on the results of the example problems. If the air-entry value (AEV) of a soil is smaller than 1 kPa, the effect of matric suction on the calculated factor of safety is trivial and the [Formula: see text] value can be assumed to be zero. If the AEV of a soil is between 1 and 20 kPa, the nonlinear equations of unsaturated shear strength should be adopted. For soils with an AEV value between 20 and 200 kPa, an assumed [Formula: see text] value of 15° provides a reasonable estimation of the effects of unsaturated shear strength in most cases. For soils with an AEV greater than 200 kPa, [Formula: see text] can generally be assumed to be equal to the effective angle of internal friction, [Formula: see text], in applications where geotechnical structures have matric suctions around 100 kPa.

scholarly journals A Non-Linear, Time-Variant Approach to Simulate the Rainfall-Induced Slope Failure of an Unsaturated Soil Slope: A Case Study in Sapa, Vietnam

2021 ◽  
Vol 16 (4) ◽  
pp. 512-520
Author(s):  
The Viet Tran ◽  
Hoang Viet Hung ◽  
Huy Dung Pham ◽  
Go Sato ◽  
Hoang Hiep Vu ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Unsaturated Soil ◽  
Slope Failure ◽  
The United States ◽  
Slope Stability Analysis ◽  
Rainfall Infiltration ◽  
Landslide Event ◽  
Non Linear ◽  
The Stability

In this study, the Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Analysis (TRIGRS), v2.1 program, and module SLOPE/W in the Geostudio package were adopted for assessing rainfall-induced slope failure. TRIGRS was developed by the United States Geological Survey to determine the time-varying groundwater table at the regional scale under rainfall infiltration. The program employs partial differential equations represented by one-dimensional vertical flow in homogeneous materials for unsaturated conditions. With the application of a simple runoff routing scheme combined with the mass balance between rainfall, infiltration, and runoff over the study area, the distribution of the transient pore-water pressures within the entire landscape was simulated considering both the surface and subsurface flow. Additionally, compared to the traditional two-dimensional approach, the topographical conditions were also considered during the groundwater simulation. For conducting the slope stability analysis, a typical cross-section was constructed based on the site description. The predicted water-tables at the observed time of failure of the typical section were extracted and used in SLOPE/W to conduct the time-dependent modelling of rainfall-induced slope failures. In this study, the non-linear method was employed for simulating unsaturated soil shear strength, and the stability of the slope was evaluated using Bishop’s simplified method. We applied the approach to the landslide event that occurred on August 5, 2019, in Sapa district, Lao Cai province, Vietnam. The event resulted in severe damage and blocked the road for days. The predicted results on the stability of the slope as the factor of safety were compared with the actual slope failure during the event. The results showed that, by inputting accurate data, the applied approach could provide valuable evidence about the time of the slope failure.

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