Shear Resistance and Stability Study of Embankments Using Different Shear Resistance Parameters of Soft Soils from Laboratory and Field Tests: A Case Study of Hai Phong City, Viet Nam (original) (raw)
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IRJET, 2020
Moisture content is one of the most crucial factors influencing soil strength. This paper deals with the effect of moisture content and density on the shear strength parameters of WOZEKA-GIDOLE road elastic silt (expansive) embankment soil under dry, wet (partially saturated), OMC and saturated conditions in relation to slope stability analysis. The wide distribution of expansive soil in Ethiopia creates problems in many field of construction such as excavation, slope stability and foundation in understanding their engineering characteristics especially the behavioral changes in dry and saturation condition. In this study, samples were collected from a slope construction road site in WOZEKA-GIDOLE, southern Ethiopia. At a constant grading of a soil its effect on strength, swelling pressure and index properties value has been undertaken, as soils are to be used for making road pavement, embankments. The stability of an embankment will greatly be influence by the shear parameters which are depend upon the degree of compaction. So soil specimen were compacted in the laboratory and the optimum moisture content and dry densities were identified. After compaction soil was tested at the dry side of optimum water content at w = 5%, partially saturate of the optimum at 10%, at 15% OMC and at 20% saturation condition at 1.3 gm/cm 3 , 1.4 gm/cm 3 and 1.55 gm/cm 3 (MDD) dry densities. Parameters of shear strength (C) and (ϕ) were obtained from triaxial shear test (UU) and shows the compacted elastic silt soil behaves like a granular soil on the dry side of optimum water content (5% and 10%) and a reduction in angle of friction and an increase in cohesion are observed as the compaction water contents approach the optimum value. Cohesion shows a slight increase as moisture content increases whereas friction angle highly decreases with increasing moisture content at constant density. The shear strength parameters were used for stability analysis with software GEOSLOPE/W 2018 with Limit equilibrium based methods to calculate the factor of safety (FOS) and locate critical failure arc. The slope stability analysis of elastic silt soil has been done and is used in under different conditions to evaluate slope stability. Analysis of embankment at different heights of the slope with Morgenstern-Price's analysis method. In the present study varying the density and moisture has been affect the properties of expansive soil namely elastic silt soil. Finally constant grading of soil is a technique for modification the geotechnical properties and improving slope stability of embankment and increasing the dry density and decreasing height of embankment, the undrained shear parameters (C & Φ) are improved.
Slope Stability of Embankments on Soft Soil Improved with Vertical Drains
Civil Engineering Journal, 2020
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...
Structural behaviour and parametric study of reinforced embankments on soft clays
Computers and Geotechnics, 2001
Geotechnical behaviour of a reinforced embankment on soft ground is studied by a numerical model based on the ®nite element method. Special emphasis is given to the stress states (stress levels and pore pressures), displacements, tensile forces in the geosynthetic and overall stability, during and after construction. The in¯uence of some parameters, namely geosynthetic stiness and viscosity, embankment width and construction sequence, is also analysed. Several conclusions are obtained. #
This paper proposes a method of analysis of the stability of embankments on clay foundations which makes use of a conventional total stress analysis, corrected to take into consideration the preconsolidation pressure and the undrained shear strength profile. Good results are obtained for three well documented cases of embankment failures, the data of which allow a direct application of the proposed method. Many other failure cases, for which the published data are insufficient to allow such a direct application, are analyzed on statistical basis using a relationship between Cu/σp and Ip. Bjerrum‟s correction for total stress analysis and Otoko‟s correction for effective stress analysis appear as particular cases, only statistically applicable, of the proposed method. Based on the data generated in the Niger delta, Nigeria, the results obtained from the new method are compared with those obtained from limit equilibrium methods, Taylor's chart, upper and lower bound limit analyses. While Taylor‟s chart and limit equilibrium methods gave approximately the same results as upper bound limit analysis, the new method gave results between upper and lower bound limit analyses, which is considered to be a great advantage over the other methods. Copyright © IJEATR, all rights reserved. Keywords: Slope stability; Proposed method; Otoko's correction; Bjerrum's correction; Taylor's chart; Limit equilibrium; Limit Analysis
STABILITY ANALYSIS OF REINFORCED AND UNREINFORCED EMBANKMENTS ON SOFT GROUND
General solutions are developed for the rotational stability analysis of an embankment with and without reinforcement constructed on soft ground that has an undrained shear strength varying with depth. The general cases of an embankment having a berm, dry or wet tensile cracks, and multiple layers of reinforcement are considered. The additional friction caused by the reinforcement force normal to the slip plane is incorporated into the solution. The solutions are presented in the form of simple equations. The relationship between the critical slip circles through the embankment with and without reinforcement is expressed explicitly. The analysis procedures and supporting graphs allow the user to obtain the solutions using hand computations. A simple computer program in the form of a worksheet was developed to quickly obtain the final results. Applications and illustrative examples of embankments with one-and two-step berms, and distributed loads are given. The results obtained using the approach presented in this paper compare very well to the solutions obtained from the method of slices using the computer programs SB-SLOPE and PC-STABL6. Telephone: 1/612-222-2508, Telefax: 1/612-222-8215. Geosynthetics International is registered under ISSN 1072-6349.
Slope Stability of Road Embankment on Soft Soil.
The major part of this paper is on the challenges in predicting the slope stability in highway embankment on the soft soil. By height variation of highway embankment on soft soil, conducted analysis to determine the stability of the embankment. The fundamentals of preloading techniques without and with prefabrication vertical drain (PVD) as ground improvement measures are included. The analysis will perform by comparing the slope stability without PVD and with PVD where the soil subgrade under embankment has been experiencing an increase in bearing capacity. The increases in bearing capacity correlation are using the empirical formula developed by the expert recent study. The Embankment stability analysis conducted by using a factor of safety based on the moment equilibrium methods developed by Bishop. Finally, the latter part of the paper is devoted to determine the influence in subgrade improvement on the stability of embankment using PVD. Another result is to determine the difference between the developed formulas which increase the bearing capacity of soil under embankment. The main result of this study is to obtain the stability standard of highway embankment with vary empirical formula, vary height of embankment and vary soil properties.
IJERT-Stability Analysis of Different Soilfil on Embankment Subgrade using Plaxis-2d
International Journal of Engineering Research and Technology (IJERT), 2021
https://www.ijert.org/stability-analysis-of-different-soilfil-on-embankment-subgrade-using-plaxis-2d https://www.ijert.org/research/stability-analysis-of-different-soilfil-on-embankment-subgrade-using-plaxis-2d-IJERTCONV9IS09009.pdf Slope stability analysis is one of the most important topic in geotechnical engineering. For the construction of railways, embankments, canal, road Embankments, earth dams etc. we go for different slopes with different geometric conditions. If the slope is naturally made, the kind of problem is to check the sustainability of slope. If it is manmade type, the problem of choosing soils to build and other conditions which required for stable. The clear idea of this topic is to know the best suitability of locally available fill materials. For this particular analysis done in latest version of plaxis 2D. Evaluation of the stability analysis for road embankment is not only a problem but also a challenge or Geotechnical Engineering. In manmade slope, the problem of choosing soil is an important role for stability condition. The main purpose on this study is to determine the stability of road fill Embankment according to the factor of safety and deformation. In this study, the stability of slope was modelled in scenarios (different fills, different inclination and various level of water table). Finite Element Method by Plaxis 2D was used in numerical analysis of slope. The result of this study showed the suitability of fill soil in embankment construction according to the comparative study of deformations, factors of safety. In collected fill soils, Clayey sand is most suitable for road fill embankment.
Behaviour of two reinforced test embankments on soft clay
Geosynthetics International, 2009
The paper presents the behaviour of two reinforced test embankments built on a normally consolidated soft clay deposit underlying a top sand layer. The embankments were constructed close to undrained conditions in about 60 days. The embankments were well instrumented, including measurements of tension forces in the reinforcement. The mobilised tension forces in the reinforcements were shown to increase with embankment height and larger values of tension forces were measured in the embankment built on a shallower clay layer. The critical failure surfaces obtained in limit equilibrium stability analyses were close to the observed field failure surfaces. These analyses used measured reinforcement forces and resulted in Bjerrum correction factors around ì ¼ 0.60 for the two embankments. These analyses considered the measured reinforcement forces and three-dimensional effects. Consistent correlations were obtained between embankment loadings, factors of safety, measured reinforcement forces and inclinometer readings.
IRJET, 2020
Moisture content is one of the most crucial factors influencing soil strength. This paper deals with the effect of moisture content and density on the shear strength parameters of WOZEKA-GIDOLE road elastic silt (expansive) embankment soil under dry, wet (partially saturated), OMC and saturated conditions in relation to slope stability analysis. The wide distribution of expansive soil in Ethiopia creates problems in many field of construction such as excavation, slope stability and foundation in understanding their engineering characteristics especially the behavioral changes in dry and saturation condition. In this study, samples were collected from a slope construction road site in WOZEKA-GIDOLE, southern Ethiopia. At a constant grading of a soil its effect on strength, swelling pressure and index properties value has been undertaken, as soils are to be used for making road pavement, embankments. The stability of an embankment will greatly be influence by the shear parameters which are depend upon the degree of compaction. So soil specimen were compacted in the laboratory and the optimum moisture content and dry densities were identified. After compaction soil was tested at the dry side of optimum water content at w = 5%, partially saturate of the optimum at 10%, at 15% OMC and at 20% saturation condition at 1.3 gm/cm 3 , 1.4 gm/cm 3 and 1.55 gm/cm 3 (MDD) dry densities. Parameters of shear strength (C) and (ϕ) were obtained from triaxial shear test (UU) and shows the compacted elastic silt soil behaves like a granular soil on the dry side of optimum water content (5% and 10%) and a reduction in angle of friction and an increase in cohesion are observed as the compaction water contents approach the optimum value. Cohesion shows a slight increase as moisture content increases whereas friction angle highly decreases with increasing moisture content at constant density. The shear strength parameters were used for stability analysis with software GEOSLOPE/W 2018 with Limit equilibrium based methods to calculate the factor of safety (FOS) and locate critical failure arc. The slope stability analysis of elastic silt soil has been done and is used in under different conditions to evaluate slope stability. Analysis of embankment at different heights of the slope with Morgenstern-Price's analysis method. In the present study varying the density and moisture has been affect the properties of expansive soil namely elastic silt soil. Finally constant grading of soil is a technique for modification the geotechnical properties and improving slope stability of embankment and increasing the dry density and decreasing height of embankment, the undrained shear parameters (C & Φ) are improved.