An analysis of the stability of thawing slopes, Ellesmere Island, Nunavut, Canada

2000 ◽  
Vol 37 (2) ◽  
pp. 449-462 ◽  
Author(s):  
Charles Harris ◽  
Antoni G Lewkowicz
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Active Layer ◽  
Factor Of Safety ◽  
High Arctic ◽  
Ellesmere Island ◽  
Sensitivity Analyses ◽  
Pore Water Pressures ◽  
Hot Weather ◽  
The Stability

Active-layer detachment slides are locally common on Fosheim Peninsula, Ellesmere Island, where permafrost is continuous, the active layer is 0.5-0.75 m thick, and summer temperatures are unusually high in comparison with much of the Canadian High Arctic. In this paper we report pore-water pressures at the base of the active layer, recorded in situ on two slopes in late July and early August 1995. These data form the basis for slope stability analyses based on effective stress conditions. During fieldwork, the factor of safety within an old detachment slide on a slope at Hot Weather Creek was slightly greater than unity. At "Big Slide Creek," on a slope showing no evidence of earlier detachment failures, the factor of safety was less than unity on a steep basal slope section but greater than unity elsewhere. In the upper slope, pore-water pressures were only just subcritical. Sensitivity analyses demonstrate that the stability of the shallow active layer is strongly influenced by changes in soil shear strength. Possible mechanisms for reduction in shear strength through time include weathering of soils and gradual increases in basal active layer ice content. However, we suggest here that soil shearing during annual gelifluction movements is most likely to progressively reduce shear strengths at the base of the active layer from peak values to close to residual, facilitating the triggering of active-layer detachment failures.Key words: detachment slides, Ellesmere Island, pore-water pressures, gelifluction.

A new approach to the stability analysis of thawing slopes

1980 ◽  
Vol 17 (4) ◽  
pp. 607-612 ◽  
Author(s):  
Luis E. Vallejo
Keyword(s):  
Stability Analysis ◽  
Water Content ◽  
Pore Water ◽  
Active Layer ◽  
Necessary Conditions ◽  
Mass Movements ◽  
New Approach ◽  
Pore Water Pressures ◽  
The Stability ◽  
Excess Pore

A new approach to the stability analysis of thawing slopes at shallow depths, taking into consideration their structure (this being a mixture of hard crumbs of soil and a fluid matrix), is presented. The new approach explains shallow mass movements such as skin flows and tongues of bimodal flows, which usually take place on very low slope inclinations independently of excess pore water pressures or increased water content in the active layer, which are necessary conditions in the methods available to date to explain these movements.

A transient analysis of slope stability following drawdown after flooding of a highly plastic clay

1999 ◽  
Vol 36 (6) ◽  
pp. 1151-1171 ◽  
Author(s):  
G J Pauls ◽  
E Karl Sauer ◽  
E A Christiansen ◽  
R A Widger
Keyword(s):  
Stability Analysis ◽  
Pore Water ◽  
Factor Of Safety ◽  
Field Measurements ◽  
Stability Of Slopes ◽  
Pore Water Pressures ◽  
Seepage Model ◽  
Transient Seepage ◽  
The Stability ◽  
Plastic Clays

The stability of slopes at bridge abutments across the Carrot River in east-central Saskatchewan was not influenced significantly by drawdown after flooding in the spring of 1995. Traditional methods of analysis for rapid drawdown predicted the factor of safety of slopes on highly plastic clays of proglacial Lake Agassiz would drop to 0.65 from an initial value of 1.0. Deformation along a well-defined slip plane has persisted at a more or less constant, slow rate since the bridge was constructed in 1975. The river rose approximately 10 m during a flood in the spring of 1995, yet there was only minimal response in piezometers and no measurable increase in the rate of deformation recorded by inclinometers. Pore-water pressures from a steady state seepage model, which was calibrated from piezometer measurements, were integrated into a stability analysis. Changes in pore-water pressures caused by flooding and subsequent drawdown were characterized from a transient seepage model using the flood hydrograph as a flux boundary. The stability analysis integrated with the transient seepage model estimated the factor of safety would drop from 1.0 to 0.91 after drawdown. Field measurements indicated the reduction in factor of safety was even less.

scholarly journals Integrated Simulation Modeling Approach for Investigating Pore Water Pressure Induced Landslides

2022 ◽  
Author(s):  
Sahila Beegum ◽  
P J Jainet ◽  
Dawn Emil ◽  
K P Sudheer ◽  
Saurav Das
Keyword(s):  
Pore Water ◽  
Factor Of Safety ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Simulation Models ◽  
Integrated Simulation ◽  
Hill Slope ◽  
Slope Factor ◽  
The Stability ◽  
The Hill

Abstract Soil pore water pressure analysis is crucial for understanding landslide initiation and prediction. However, field-scale transient pore water pressure measurements are complex. This study investigates the integrated application of simulation models (HYDRUS-2D/3D and GeoStudio–Slope/W) to analyze pore water pressure-induced landslides. The proposed methodology is illustrated and validated using a case study (landslide in India, 2018). Model simulated pore water pressure was correlated with the stability of hillslope, and simulation results were found to be co-aligned with the actual landslide that occurred in 2018. Simulations were carried out for natural and modified hill slope geometry in the study area. The volume of water in the hill slope, temporal and spatial evolution of pore water pressure, and factor of safety were analysed. Results indicated higher stability in natural hillslope (factor of safety of 1.243) compared to modified hill slope (factor of safety of 0.946) despite a higher pore water pressure in the natural hillslope. The study demonstrates the integrated applicability of the physics-based models in analyzing the stability of hill slopes under varying pore water pressure and hill slope geometry and its accuracy in predicting future landslides.

Cyclic loading of an Ottawa area Champlain Sea clay

1977 ◽  
Vol 14 (1) ◽  
pp. 52-63 ◽  
Author(s):  
R. J. Mitchell ◽  
R. Douglas King
Keyword(s):  
Shear Strength ◽  
Cyclic Loading ◽  
Pore Water ◽  
Soil Structure ◽  
Shear Failure ◽  
Large Deformations ◽  
Cemented Soil ◽  
Pore Water Pressures ◽  
Excess Pore ◽  
Static Shear

Undrained cyclic loading of triaxial samples of a sensitive Champlain Sea clay at deviatoric stress levels in excess of 50% of the static shear strength is shown to produce large deformations and eventual shear failure. Continued deformation of the clay under repeated loadings is believed to result from a progressive destruction of the cemented soil structure. Effective stress failures result from an increase in the excess pore water pressures within the sample.

Climate, Hydrology and Vegetation Patterns Hot Weather Creek, Ellesmere Island, Arctic Canada

1990 ◽  
Vol 21 (4-5) ◽  
pp. 273-286 ◽  
Author(s):  
Sylvia A. Edlund ◽  
Ming-ko Woo ◽  
Kathy L. Young
Keyword(s):  
Active Layer ◽  
Ellesmere Island ◽  
Vegetation Patterns ◽  
Ground Ice ◽  
Vegetation Growth ◽  
Polar Desert ◽  
Safe Delivery ◽  
Summer Temperatures ◽  
Hot Weather ◽  
Fail Safe

Recent studies at Hot Weather Creek, Ellesmere Island document the climate and vegetation of a major part of the intermontane zone of Ellesmere Island. Summer temperatures in this region are much higher than would be expected for its 80° N location. This enables a variety of arctic species with more moderate temperature tolerances to thrive. The dense and diverse tundra and wetland vegetation in parts of the region, however, does not conform to polar desert or semidesert vegetation expected from the meager amount of precipitation (< 70 mm per year) recorded there. Comparisons between differing biological and geomorphological responses to the summer climatic regimes of 1988 and 1989 suggest a two source supply of moisture to the active layer in summer. Supplementary source of water, from the melting of massive ground ice bodies provides water from the base of the active layer, during the hot, dry summer of 1988. During the wet summer of 1989, a more conventional nival regime was in operation. These two potential sources of moisture in summer provide a fail-safe delivery system to vegetation in areas underlain by massive ground ice, and permit a richer vegetation growth than climate alone could.

Rock slope stability and distributed joint systems

1992 ◽  
Vol 29 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Bruce J. Carter ◽  
Emery Z. Lajtai
Keyword(s):  
Factor Of Safety ◽  
Rock Slope ◽  
Limit Equilibrium ◽  
Slope Angle ◽  
Probability Of Failure ◽  
Cumulative Distribution ◽  
Rock Slope Stability ◽  
Sensitivity Analyses ◽  
The Stability ◽  
Rock Wedge

A deterministic (GEOSLIDE) and a probabilistic (PROSLIDE) microcomputer code are introduced to aid in performing rock wedge analyses based on the limit equilibrium method. The deterministic code evaluates the stability of a single rock wedge formed by discontinuities in rock through three-dimensional vector algebra, GEOSLIDE undertakes a full kinematic analysis (daylighting and obstruction), analyzes both wedge and plane sliding, and provides for anchor designs and sensitivity analyses (cohesion, friction, and water forces). Through multiple stability analyses, PROSLIDE evaluates the probability of failure for a rock slope by examining the distribution of the factors of safety from all the potential sliding wedges formed by the discontinuities of the rock mass. The probability of failure is expressed as the ratio of kinematically free wedges that have a factor of safety less than unity to the total number of wedges, PROSLIDE can form and analyze as many as 2000 different pairs of discontinuities in less than 30 min using a 25 MHz 486 IBM-compatible computer. In a worked example, the probability of failure for a fixed slope strike and loading condition is shown to vary with the slope angle, following the characteristic 'S' shape of a cumulative distribution function. The effect of an anchor force is to spread the distribution over a wider range of the factor of safety (SF), pushing many wedges into a potential upslide situation and splitting the distribution about the failure zone of the stability diagram (−1 < SF < 1). Key words : rock slope, rock wedge, stability analysis, factor of safety, probability of failure, Monte Carlo simulation.

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.

scholarly journals Parametric evaluation of shear strength parameters on the stability of cut slope: a case study from Mahabaleshwar road section, India

2016 ◽  
Vol 51 ◽  
pp. 73-76
Author(s):  
Suman Panthee
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Shear Strength ◽  
Internal Friction ◽  
Factor Of Safety ◽  
Slope Failure ◽  
Cut Slope ◽  
Stability Of Slopes ◽  
Proportional Relation ◽  
The Stability

Stability of rock cut slopes depends upon the type of material, discontinuity attributes and geometry present in any location. Although, gravity remains the constant important factor in dictating the slope failure but other parameters like shear strength and available shear stress along the slope also decides the stability of the slopes to great extent. The strength of the material comes from the internal bonding between the mineral grains, contact between the particles and the ability of the material to respond to the stress conditions. Variation of these material attributes fluctuate the cohesion and angle of internal friction that constitutes the most important properties in defining the strength of any material. Rock resists shear stress by these two internal mechanisms. Numerical simulation by Finite Element Method technique is attempted for assessing the stability cut slope. An attempt has been made in this study to document the behavior of strength of the material in terms of stability of slopes by parametric study of cohesion and internal friction. This study carried to understand how the factor of safety changes with reference to change in cut slope height, cohesion and internal friction of the discontinuities that attributes the shear strength of discontinuities. The study is based on Finite Element Modeling (FEM). From the study it is found that factor of safety has strongly proportional relation with cohesion and internal friction but shown inversely proportional relation with height of cut slope.

Stability of swelling clay embankments

1979 ◽  
Vol 16 (1) ◽  
pp. 140-151 ◽  
Author(s):  
R. A. Widger ◽  
D. G. Fredlund
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Back Analysis ◽  
Triaxial Tests ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Total Strength ◽  
Swelling Soils ◽  
Pore Water Pressures ◽  
Matrix Suction

A common occurrence in cuts or fills of swelling soils is their reduction in strength with time. At the time of compaction, the clay generally has a high matrix suction. Correspondingly, it has a high strength and will stand at relatively steep side slopes. With time, the soil generally tends towards saturation and the matrix suction reduces towards zero. There is a reduction in total strength and if the gravitational forces are too large, the slope fails.During the past several years, numerous cut and fill slopes have been observed in the Regina area of Saskatchewan. Many of these slopes have remained stable for 4–6 years and then failed. There has been a 20 year history of observations on the Belle Plaine overpass west of Regina. Field and laboratory investigations have been conducted.With a knowledge of the geometry of the slope and failure plane, the simplified Bishop method of stability analysis was used to perform a 'back-analysis' to assess the shear strength parameters. The shear strength parameters from the laboratory program are compared with those calculated from the stability analyses. The analyses indicate that the peak shear strength parameters from triaxial tests on the softened Regina clay (i.e., c' = 5 kPa and [Formula: see text]), with the appropriate pore water pressures, give a factor of safety of 1 for the failed surface. The effect of spring thawing appears to be to produce the condition of most serious pore water pressures.

scholarly journals Toe drain size and slope stability of homogeneous embankment dam under rapid drawdown.

Technobius ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 0001
Author(s):  
Timoth Mkilima
Keyword(s):  
Numerical Modeling ◽  
Slope Stability ◽  
Pore Water ◽  
Factor Of Safety ◽  
Potential Effect ◽  
Upstream Face ◽  
Design Team ◽  
Potential Influence ◽  
Embankment Dam ◽  
Pore Water Pressures

The slope stability of an embankment dam has been always a serious concern of any design team. Unfortunately, the information on the potential influence of a toe drain size on the slope stability of an embankment dam under rapid drawdown conditions is still scarce. This study investigated the potential effect of a toe drain size on the slope stability of a homogeneous embankment dam under rapid drawdown conditions. Three different sizes (5m, 10m, and 15m) of the toe drain were investigated under instantaneous (worst scenario) and 5 days (more realistic) drawdown rates with the help of numerical modeling in GeoStudio. From the results, it was observed that the pore-water pressures at the upstream face of the embankment decreased with the increase in the toe drain size, while the pore-water pressures at the downstream toe were increasing with the increase in the toe drain size. The factor of safety values were also observed to be affected by the changes in the toe drain size.

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