Slope stability thresholds for vegetated hillslopes: a composite model

2002 ◽  
Vol 39 (4) ◽  
pp. 849-862 ◽  
Author(s):  
Jagath C Ekanayake ◽  
Christopher J Phillips
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Plant Density ◽  
Composite Model ◽  
Energy Approach ◽  
Water Infiltration ◽  
Wetting Front ◽  
Tree Roots ◽  
Soil Shear Strength ◽  
The Stability

Location of the critical shear plane (CSP) plays a major role in determining landslide-initiation thresholds. Depth to the CSP increases as the soil shear strength increases. Tree roots provide a significant strength contribution to soil shear strength. Our objective is to understand how vegetation can be used to increase landslide-initiation thresholds by changing the location of the CSP. This will enable us to select and compare combinations of plant species and densities to suit any given situation to increase landslide-initiation thresholds and improve slope stability. The CSP location is estimated incorporating available root cross-sectional area – root depth data in the stability analysis in terms of energy. The energy approach has been developed to take into account the contribution of the roots to soil strength. Generalization of the original energy approach is required to enable its use outside our study areas. Once depth to the CSP is found, the time for the wetting front to reach it is found using a soil-water infiltration model. The composite model described may be used as a simple tool to choose the most appropriate plant density to maximize the stability of a given hillslope. A worked example of the model demonstrates how the approximate thresholds for different hillslopes with known plant densities under different climatic conditions are estimated.Key words: slope stability, safety factor, roots, energy, threshold.

scholarly journals Pengujian Geser Limestone Untuk Menghitung Angka Keamanan Terhadap Kelongsoran Di Utama Mandala Pura Uluwatu

2019 ◽  
Vol 24 (1) ◽  
pp. 13
Author(s):  
I Nyoman Ramia ◽  
I Wayan Arya ◽  
I Wayan Wiraga ◽  
I G A G I G A G Suryanegara
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Direct Shear Test ◽  
Shear Test ◽  
Dead Load ◽  
Soil Shear Strength ◽  
Engineering Department ◽  
Sliding Test ◽  
The Stability ◽  
The Temple

The shear strength value is one of the important points in calculation of slope stability. One way to obtain the shear strength value is to do a direct shear test in laboratory. Like the cliff reinforcement study at Utama Mandala Uluwatu temple which is currently experiencing crack, it is necessary to test the shear strength of the limestone material at the cliff of the temple . There is no limestone testing equipment in the laboratory of the Civil Engineering Department, so that innovation is needed on the existing sliding test equipment. In this study innovation was carried out on how to test the soil shear strength so that it could be used to test the limestone shear strength. The test is done by moving two limestone surface that have been formed based on the mold tool which shape is circle. The shear strength slope at Uluwatu temple, which is currently experiencing crack in dry condition is . The shear strength value is used for calculating slope stability at Uluwatu Temple which is currently experiencing crack wich . The calculation used is curved slope stability by only calculate the life load and dead load. From the calculation of the stability of the slope, the safety factor is 1.15.

Stability analysis of soil slope based on rainfall

2020 ◽  
pp. 18-26
Author(s):  
ZONG GANG ◽  
FU JIAJIA ◽  
WANG YAO
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Slope Stability ◽  
Unsaturated Soil ◽  
Heavy Rainfall ◽  
Soil Slope ◽  
Short Term ◽  
Soil Shear Strength ◽  
The Stability

Rainfall is the main cause of landslides, the two are closely related. Based on the theory of saturatedunsaturated seepage and the theory of unsaturated soil shear strength, this paper makes an in-depth comparatve analysis on the infuence of short-term heavy rainfall and long-term weak rainfall on slope stability. The results show: The soil above the slope is more likely to reach saturaton under short-term heavy rainfall, while the infuence of long-term weak rainfall on the slope soil is deeper and the stability is greatly reduced. However, landslides with long periods of weak rainfall are more dangerous. In additon, the method of determining the critcal rainfall of a slope for landslide is obtained, and the safety status of the slope can be directly judged by comparing the actual rainfall with the critcal rainfall, and the classifcaton standard of the safety grade of a specifc slope is further obtained, which can provide reference for landslide preventon and treatment.

Slope Stability Analysis under the Condition of Seepage

2012 ◽  
Vol 204-208 ◽  
pp. 241-245
Author(s):  
Yang Jin
Keyword(s):  
Finite Element Method ◽  
Shear Strength ◽  
Slope Stability ◽  
Negative Impact ◽  
Strength Reduction ◽  
Soil Slope ◽  
Failure State ◽  
Calculation Results ◽  
The Stability ◽  
Shear Strength Reduction

The stability of soil slope under seepage is calculated and analyzed by using finite element method based on the technique of shear strength reduction. When the condition of seepage or not is considered respectively, the critical failure state of slopes and corresponding safety coefficients can be determined by the numerical analysis and calculation. Besides, through analyzing and comparing the calculation results, it shows that seepage has a negative impact on slope stability.

scholarly journals Brasília municipal solid waste landfill: a case study on flow and slope stability

2021 ◽  
Vol 44 (3) ◽  
pp. 1-13
Author(s):  
José Fernando Jucá ◽  
Alison Norberto ◽  
José Ivan Santos Júnior ◽  
Fernando Marinho
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Limit Equilibrium ◽  
Drainage System ◽  
Equilibrium Analysis ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Cause Of Failure ◽  
Leachate Level ◽  
The Stability

For geotechnical and environmental reasons, landfills are positioned above the regional water table and thus are formed in unsaturated conditions. This condition can be different if the drainage system and the rain regime of the site are such that they create a level of internal liquid in the landfill. During January and February 2019, excessive movements occurred in the slopes of the Brasília sanitary landfill. A geotechnical investigation indicated that the raised leachate level caused by the clogging of the drainage system contributed to the landfilled waste movements. The limit equilibrium analysis was used to predict the relationship between leachate level and slope stability. In order to understand the process that led to the rupture, flow and stability analysis by limit equilibrium were performed. The parameters associated with flow, water retention capacity, and shear strength were obtained based on literature evaluations. In addition, data from tests were used, which allowed to define more accurately the distribution of pore pressures of liquid that led to the failure. This study allowed to define the cause of failure and also to establish the role of the drainage system in maintaining the stability of the landfill. The studies indicated that although the gain of shear strength of landfill due to the unsaturated condition is negligible, the process of flow in unsaturated medium, associated with climatic aspects, are fundamental for a medium- and long-term analysis.

Application of a rock buttress in the design of slopes of a strip coal mine adjacent to a highway

1993 ◽  
Vol 30 (3) ◽  
pp. 391-408 ◽  
Author(s):  
R. Ulusay ◽  
M.F. Yolerì ◽  
V. Doyuran
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Back Analysis ◽  
Bedding Plane ◽  
Open Pit ◽  
State Highway ◽  
Planar Surfaces ◽  
Thermal Coal ◽  
Basal Sliding ◽  
The Stability

Eskihisar open pit mine, located at Yatagan, southwest Turkey, produces thermal coal for a power generating plant. As mining of strips advanced southwards, instability appeared to be highly critical due to the movements in the southeast wall slopes adjacent to the state highway running parallel to the pit boundary. This situation called for an immediate response to initiate a detailed geotechnical investigation program and to redesign the pit slopes. This paper outlines the most probable mode and mechanism of instability along the southeast wall, as well as field and laboratory studies, results of back analysis, discussion of the data requirements, and results of slope stability analyses performed to ensure adequate overall stability. The studies revealed that the most critical failures may occur along two or three planar surfaces, by combination of fault, bedding plane, and localized strata steepening adjacent to the fault, in multiplanar failure mode controlled by faulted blocks. The stability is sensitive to changes in length of the lower part of the basal sliding surface, as well as to the configuration and shear strength of black and highly plastic underclay. The effects of a buttress of intact rock and slope flattening on the stability are compared and discussed. Key words : back analysis, multiplanar failure, shear strength, slope stability, toe buttressing.

scholarly journals Strength Characteristics and Slope Stability of Expansive Soil from Pingdingshan, China

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ju-yun Zhai ◽  
Xiang-yong Cai
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Expansive Soil ◽  
Friction Angle ◽  
Natural Soil ◽  
Soil Slope ◽  
The Finite Element Method ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
The Stability

By analyzing the characteristics of expansive soil from Pingdingshan, China, the shear strength parameters at different water contents, dry densities, and dry-wet cycles of expansive soil are obtained. It is found that, at higher soil-water content, the internal friction angle is 0° and the shallow layer of expansive soil slope will collapse and destroy; this has nothing to do with the height of the slope and the size of the slope. The parameters of soil influenced by atmosphere are the ones which have gone through dry-wet cycles, and the parameters of soil without atmospheric influence are the same as those of natural soil. In the analysis of slope stability, the shear strength parameters of soil can be determined by using the finite element method, and the stability coefficient of the expansive soil slope can be calculated.

scholarly journals Slope Stability Analysis of Kattery Watershed in Nilgiris District

2019 ◽  
Vol 12 (6) ◽  
pp. 163-169
Author(s):  
C. Rajakumar ◽  
P. Kodanda Rama Rao
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Internal Friction ◽  
Slope Stability ◽  
Factor Of Safety ◽  
Slope Stability Analysis ◽  
Strength Parameter ◽  
Angle Of Internal Friction ◽  
Shear Strength Parameter ◽  
The Stability

The slope stability analysis is always under severe threats in many parts of nilgiris district, causing disruption, loss of human life and economy. The stability of slopes depends on the soil shear strength parameters such as Cohesion, Angle of internal friction, Unit weight of soil and Slope geometry. The stability of a slope is measured by its factor of safety using geometric and shear strength parameter based on infinite slopes. In this research, investigation was carried out at 5 locations in Kattery watershed in nilgiris district. The factor of safety of the slope determined by Mohr Coulomb theory based on shear strength parameter calculated from direct shear test which is a conventional procedure for this study. Artificial. Neural Network (ANN) Model is used to predict the factor of safety. The input parameters for the (ANN) are chosen as Cohesion, Angle of internal friction, Density and Slope angle and the factor of safety as output. The results obtained in ANN method were compared with that of conventional method and observed a good agreement between these two methods.

Strength of tree roots and landslides on Prince of Wales Island, Alaska

1979 ◽  
Vol 16 (1) ◽  
pp. 19-33 ◽  
Author(s):  
Tien H. Wu ◽  
William P. McKinnell III ◽  
Douglas N. Swanston
Keyword(s):  
Shear Strength ◽  
Root System ◽  
Forest Cover ◽  
Safety Factors ◽  
In Situ Tests ◽  
Tree Roots ◽  
Stability Of Slopes ◽  
Before And After ◽  
The Stability

The stability of slopes before and after removal of forest cover was investigated. Porewater pressures and shear strengths were measured and the soil properties were determined by laboratory and in situ tests. A model of the soil–root system was developed to evaluate the contribution of tree roots to shear strength. The computed safety factors are in general agreement with observed behaviors of the slopes. Decay of tree roots subsequent to logging was found to cause a reduction in the shear strength of the soil–root system.

Soil movements on permafrost slopes near Fairbanks, Alaska

1984 ◽  
Vol 21 (4) ◽  
pp. 699-709 ◽  
Author(s):  
Tien H. Wu
Keyword(s):  
Slope Stability ◽  
Direct Shear ◽  
Shear Tests ◽  
Tree Roots ◽  
Direct Shear Tests ◽  
Pore Pressures ◽  
Tension Tests ◽  
Moss Layer ◽  
The Stability ◽  
Soil Movements

Many north-facing slopes in the Yukon–Tanana Uplands of Alaska show signs of downhill movements in the form of hummocky surface and leaning trees. Measurements of movements and pore pressures were made at several sites in the Caribou–Poker Creek Research Watershed. It was found that, on slopes with inclinations near 30°, most of the movements occurred immediately after thaw when pore pressures were high.To evaluate the slope stability, the soil strength was measured by direct shear tests. The strength of the moss layer and tree roots was evaluated by performing tension tests on the roots and the moss–root complex. Results of stability analyses show that local failures involving individual wedges are likely. The displacements associated with a wedge slide would result in a hummock or step. The strength of the moss–root complex was found to be a significant factor in the stability of the wedge and of the step. Key words: moss, roots, permafrost, pore pressure, shear strength, slope stability, thaw.

scholarly journals The Effects of Seismic Coefficient Uncertainty on Pseudo-Static Slope Stability: A Probabilistic Sensitivity Analysis

2021 ◽  
Vol 13 (15) ◽  
pp. 8647
Author(s):  
Dongli Li ◽  
Miaojun Sun ◽  
Echuan Yan ◽  
Tao Yang
Keyword(s):  
Sensitivity Analysis ◽  
Shear Strength ◽  
Slope Stability ◽  
Static Analysis ◽  
Probabilistic Sensitivity Analysis ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Seismic Coefficient ◽  
Soil Shear Strength ◽  
Critical Slope

The method of pseudo-static analysis has been widely used to perform seismic slope stability, in which a seismic coefficient is used to represent the earthquake shaking effect. However, it is important but difficult to select the magnitude of seismic coefficients, which are inevitably subjected to different levels of uncertainties. This paper aimed to study the influences of seismic coefficient uncertainties on pseudo-static slope stability from the perspective of probabilistic sensitivity analysis. The deterministic critical slope height was estimated by the method of upper-bound limit analysis with the method of pseudo-static analysis. The soil shear strength parameters, the slope geometrical parameters (including slope inclinations, slope heights, and the slope widths), the horizontal seismic acceleration coefficient, and the unit weight of soil masses were considered as random variables. The influences of their uncertainty degrees, the correlation relations, and the distribution types of random variables on probabilistic density functions, failure probabilities, and sensitivity analysis were discussed. It was shown that the uncertainty degrees greatly impact the probability density distributions of critical slope heights, the computed failure probabilities, and Sobol’ index, and the horizontal seismic coefficient was the second most important variable compared to the soil shear strength parameters.

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