Stability of Road Embankments in Soft Clay

1974 ◽  
Vol 11 (1) ◽  
pp. 72-88 ◽  
Author(s):  
Kaare Flaate ◽  
Terje Preber
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Factor Of Safety ◽  
Soft Clay ◽  
Total Stress ◽  
Routine Procedure ◽  
The One ◽  
Marine Clays

Slides in soft marine clays frequently occur during construction of road embankments in Norway. This paper outlines the routine procedure used for a stability analysis of such embankments, based on a total stress concept. Using these procedures, eight slides were investigated, and it was found that the minimum factor of safety obtained could give a too conservative picture of the actual conditions. The minimum factor of safety, which is the one normally used, varied between 0.73 and 1.10. Taking all uncertainties into consideration, an analysis based on a total stress concept as outlined herein must be considered acceptable. The study gives no basis for evaluating the accuracy of the measured shear strength values.

Stochastic stability analysis of a test excavation involving spatially variable subsoil

2006 ◽  
Vol 43 (10) ◽  
pp. 1074-1087 ◽  
Author(s):  
Yu-Jie Wang ◽  
Paul Chiasson
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Slope Stability ◽  
Spatial Variability ◽  
Progressive Failure ◽  
Soft Clay ◽  
Stochastic Modelling ◽  
Undrained Shear Strength ◽  
Slope Stability Analysis ◽  
Undrained Shear

A stochastic slope stability analysis method is proposed to investigate the short-term stability of unsupported excavation works in a soft clay deposit having spatially variable properties. Spatial variability of undrained shear strength is modelled by a stochastic model that is the sum of a trend component and a fluctuation component. The undrained shear strength trend, which is also spatially variable, is modelled by kriging or a random function. Slope stability analyses are performed on the stochastic soft clay model to investigate the contribution of spatial variability of undrained shear strength to a disagreement among high factors of safety computed from deterministic methods for slopes that have failed. Probabilities of failure as computed from the stochastic analyses give a better assessment of failure potential. Probability of failure values also correlate with time delay before failure. This phenomenon may be related to progressive failure or creep and to pore pressure dissipation with time.Key words: slope stability analysis, failure probability, spatial variability, stochastic modelling, geostatistics, vane tests, sensitive clay.

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 Slope Stability of Embankments on Soft Soil Improved with Vertical Drains

2020 ◽  
Vol 6 (1) ◽  
pp. 164-173 ◽  
Author(s):  
F. Kassou ◽  
J. Ben Bouziyane ◽  
A. Ghafiri ◽  
A. Sabihi
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Slope Stability ◽  
Factor Of Safety ◽  
Field Measurements ◽  
Undrained Shear Strength ◽  
Slope Stability Analysis ◽  
Soft Ground ◽  
Soft Soils ◽  
Undrained Shear

The overloads of structures or embankments built on clayey soft ground are generally applied gradually, respecting a specific phasing. This phasing on construction allows the undrained shear strength of clay increasing over consolidation in order to avoid the risk of collapse during loading. In this work, the undrained shear strength of clay over the consolidation was estimated following SHANSEP method of which parameters proposed by eight researchers have been employed, as well as the slope stability analysis of embankments on soft soils during staged construction. Assessment of factor of safety for slope stability was conducted basing on the Bishop method. Additionally, the variations of undrained shear strength and factor of safety were presented. In order to validate the methods discussed in this study, slope stability analysis of five embankments constructed on clayey soft soils improved by the vertical drain technique in a high-speed railway construction project in Morocco was performed. For these embankments, field measurements about lateral displacement are presented.  It was found that some of the adopted methods is in a good agreement with field measurements. Hence, generalization of these methods to many soft ground cases can be proposed.

The stability of stage-constructed embankments on soft clays

1978 ◽  
Vol 15 (2) ◽  
pp. 283-305 ◽  
Author(s):  
F. Tavenas ◽  
R. Blanchet ◽  
R. Garneau ◽  
S. Leroueil
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Text Analysis ◽  
Factor Of Safety ◽  
Initial Period ◽  
Stability Conditions ◽  
Soft Clays ◽  
North Shore ◽  
The North ◽  
The Stability

The stage construction of seven high embankments on soft clays on the north shore of the St. Lawrence Valley has provided an excellent opportunity to check the applicability of the concepts of limit and critical states to the analysis of the behaviour of clay foundations.The construction pore pressures have confirmed the development of a significant consolidation in the initial period of construction.The consequences of this consolidation on the behaviour of the clay, in particular in terms of available strength, and on the method of stability analysis have been found entirely consistent with the general model proposed by Leroueil, Tavenas, Mieussens and Peignaud.It is suggested that the so-called [Formula: see text] analysis based on the vane shear strength corrected according to Bjerrum gives the minimum factor of safety and may be too conservative during stage construction. Effective stress analyses are shown to be more representative of the true stability conditions, and they have been successfully used to accelerate the construction of the embankments.

scholarly journals Slope Stability Analysis to Correlate Shear Strength with Slope Angle and Shear Stress by Considering Saturated and Unsaturated Seismic Conditions

2021 ◽  
Vol 11 (10) ◽  
pp. 4568
Author(s):  
Muhammad Israr Khan ◽  
Shuhong Wang
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Stability Analysis ◽  
Slope Stability ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Slope Angle ◽  
Slope Stability Analysis ◽  
Soil Slope

Assessment and analysis of soil slope stability is an important part of geotechnical engineering at all times. This paper examines the assessment of soil slope stability in fine-grained soils. The effect of change in shear strength (τ), shear stress (σ) and slope angle (β) on the factor of safety has been studied. It correlates shear strength with slope angle and shear stress by considering the horizontal seismic coefficients in both saturated and unsaturated conditions. The slope failure surface was considered a circular slip surface. Statistical package for social sciences (SPSS) and Slide, numerical modeling software and limit equilibrium slope stability analysis software, respectively, are used to find out the correlations between the three basic parameters. The slope angle varied from 70 to 88 degrees, which are the most critical values for slope angles, and a total of 200 analyses were performed. τ, β and σ are correlated, and the correlations are provided in the results section. The results indicate that the correlations developed between the parameters have a very close relationship. The applicability of the developed equations is above 99%. These correlations are applicable in any type of soil slope stability analysis, where the value of shear strength and factor of safety is required with the variation of slope angle and shear stress.

Contrôle de la stabilité des remblais par la mesure des déplacements horizontaux

1974 ◽  
Vol 11 (1) ◽  
pp. 182-201 ◽  
Author(s):  
René Marche ◽  
Robert Chapuis
Keyword(s):  
Factor Of Safety ◽  
Soft Clay ◽  
Ground Surface ◽  
Soft Layer ◽  
The Stability ◽  
Horizontal Displacements

The horizontal displacements measured at the toe of eight embankments are analyzed as a function of the factor of safety. The embankments are built on layers of soft clay. Only the undrained stage is studied.When the factor of safety of the embankments is higher than about 1.4, the horizontal displacements on the ground surface, at the toe of the embankment seem to follow an elastic law which is highly dependent on the ratio of the thickness of the soft layer to the width of the embankment. When the factor of safety is lower than about 1.4, the horizontal displacements do not follow an elastic law, they increase considerably. Consequently, it is suggested that the horizontal displacements be precisely measured at the toe of embankments during construction. These measurements are simple and sensitive to the approach of failure, they can be efficiently used to control the stability of embankments. This study also gives some information concerning the variation of horizontal displacements versus depth.

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.

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