Stability of Earth Masses and Slopes

2015 ◽  
pp. 528-588
Keyword(s):  
Cross Sections ◽  
Limit Equilibrium ◽  
Circle Method ◽  
Earth Dam ◽  
Stability Of Slopes ◽  
Solution Of Equations ◽  
Analysis Of Stability ◽  
The Stability ◽  
Cut Slopes ◽  
Type Of Failure

The design of open-cut slopes and embankments, foundations, levees, and earth-dam cross-sections is based primarily on stability considerations. There are many causes and types of earth instability. There are also many ways of analyzing the stability of slopes. The chapter considers the limit equilibrium approach, which aims essentially to determine a factor of safety, F, that would ensure a slope does not fail. The chapter considers the analysis of stability of infinite slopes based on translational type of failure and the analysis of finite slopes using the Swedish Method, Method of Slices, Bishop Simplified Method, Friction Circle Method, and the Translational Method. The solution of equations developed for the analysis of stability of slopes can be tedious and time consuming. A way of reducing the amount of calculation required in slope stability studies is by use of charts based on geometric similarity. The chapter discusses how Taylor (1948) and Janbu (1964) charts are used in stability analysis of slopes. Finally, the chapter discusses ways to reduce the risk of instability in slopes.

scholarly journals Optimal profile for concave slopes under static and seismic conditions

2016 ◽  
Vol 53 (9) ◽  
pp. 1522-1532 ◽  
Author(s):  
Farshid Vahedifard ◽  
Shahriar Shahrokhabadi ◽  
Dov Leshchinsky
Keyword(s):  
Limit Equilibrium ◽  
Stable Configuration ◽  
Preliminary Evaluation ◽  
Construction Technology ◽  
Stability Of Slopes ◽  
Optimal Profile ◽  
Stabilized Soil ◽  
The Stability ◽  
Comparison Of The Results ◽  
The Impact

This study presents a methodology to determine the stability and optimal profile for slopes with concave cross section under static and seismic conditions. Concave profiles are observed in some natural slopes suggesting that such geometry is a more stable configuration. In this study, the profile of a concave slope was idealized by a circular arc defined by a single variable, the mid-chord offset (MCO). The proposed concave profile formulation was incorporated into a limit equilibrium–based log spiral slope stability method. Stability charts are presented to show the stability number, MCO, and mode of failure for homogeneous slopes corresponding to the most stable configuration under static and pseudostatic conditions. It is shown that concave profiles can significantly improve the stability of slopes. Under seismic conditions, the impact of concavity is most pronounced. Good agreement was demonstrated upon comparison of the results from the proposed method against those attended from a rigorous upper bound limit analysis. The proposed methodology, along with recent advances in construction technology, can be employed to use concave profiles in trenches, open mine excavations, earth retaining systems, and naturally cemented and stabilized soil slopes. The results presented provide a useful tool for preliminary evaluation for adopting such concave profiles in practice.

scholarly journals Study of the Stability of a Soil-Rock Road Cutting Slope in a Permafrost Region of Hulunbuir

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Yuxia Zhao ◽  
Jun Feng ◽  
Kangqi Liu ◽  
Hongwei Xu ◽  
Liqun Wang ◽  
...  
Keyword(s):  
High Latitude ◽  
Limit Equilibrium ◽  
Slope Angle ◽  
In Situ Monitoring ◽  
Permafrost Region ◽  
Freeze Thaw ◽  
Stability Of Slopes ◽  
Low Altitude ◽  
The Stability ◽  
Permafrost Regions

Due to the threat of global warming and the accelerated melting of glaciers and permafrost, the stability of slopes in permafrost regions has received an increasing amount of attention from scholars. However, research on the stability of soil-rock road cutting slopes in high-latitude and low-altitude permafrost regions of the Greater Khingan Mountains in the Inner Mongolia Autonomous Region has not been reported. For this reason, a study of the stability of a slope with a high ice content in section K105 + 600 to K105 + 700 of National Highway 332 is conducted. The slope is 20 m high and the slope angle is 45°, and the risk of landslides on this slope under the action of freeze-thaw erosion is very high. Because of this, field in situ monitoring, indoor freeze-thaw tests, thermal parameter tests, and ABAQUS numerical simulation models are used to study the stability of the slope. After collecting the continuous temperature, moisture, settlement, and slope deformation data, it was found that the slope was undergoing dynamic changes. The creep of shallow slopes increased with the number of freeze-thaw cycles. After approximately 150 freeze-thaw cycles, the slope safety factor was less than 1, which means that the slope had reached the limit equilibrium state. Therefore, freeze-thaw erosion greatly reduced the stability of the slope. Hence, the stability of the slope must be protected during its entire life cycle. This study provides a reference for the design and construction of road cutting slopes in the high-latitude and low-altitude permafrost regions of the Greater Khingan Mountains.

Slope Stability Analysis in Anisotropic Winnipeg Clays

1974 ◽  
Vol 11 (1) ◽  
pp. 59-71 ◽  
Author(s):  
W. S. Freeman ◽  
Hugh B. Sutherland
Keyword(s):  
Shear Strength ◽  
Cross Sections ◽  
Strength Properties ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Residual Shear Strength ◽  
Lower Shear ◽  
The Stability ◽  
Mechanism Of Failure ◽  
Cut Slopes

Two major aspects of an investigation dealing with the stability of natural and cut slopes in the Winnipeg area are described. The first concerns an experimental investigation of the anisotropic shear strength characteristics of the layered Lake Agassiz clays and the second is a study of the mechanism of failure for slopes in these layered clays.Four main types of clay were investigated and it was found that the effective shear strength parameters were greater for failure across the layers than for failure along the layers. Residual shear strength parameters were also determined.Stability analyses were carried out for representative slope cross sections using circular and noncircular failure surfaces, taking into account the anisotropic shear strength effects measured in the laboratory tests.Factors of safety were found for the conventional method of analysis assuming circular arc failure surfaces and isotropic shear strength properties. These factors of safety were found to be up to 0.5 greater than those obtained from noncircular failure surfaces which partially passed along the layers and so mobilized the lower shear strength properties of these layers.

scholarly journals Influence of parameters of retaining walls and loose soils on the stability of slopes in the new construction of residential complexes

2020 ◽  
pp. 65-75
Author(s):  
Liudmyla Skochko ◽  
Viktor Nosenko ◽  
Vasyl Pidlutskyi ◽  
Oleksandr Gavryliuk
Keyword(s):  
Finite Element ◽  
Slope Stability ◽  
Cross Sections ◽  
Retaining Wall ◽  
Retaining Walls ◽  
Natural State ◽  
Soil Parameters ◽  
Stability Of Slopes ◽  
The Stability ◽  
Stage 1

The stability of the slope in the existing and design provisions is investigated, the constructive decisions of retaining walls on protection of the territory of construction of a residential complex in a zone of a slope are substantiated. The stability of the slope when using rational landslide structures is estimated. The results of the calculation of the slope stability for five characteristic sections on the basis of engineering-geological survey are analyzed. For each of the given sections the finite-element scheme according to the last data on change of a relief is created. The slope was formed artificially by filling the existing ravine with construction debris from the demolition of old houses and from the excavation of ditches for the first houses of the complex. Five sections along the slope are considered and its stability in the natural state and design positions is determined. Also the constructive decisions of retaining walls on protection of the territory of construction of a residential complex as along the slope there are bulk soils with various difference of heights are substantiated. This requires a separate approach to the choice of parameters of retaining walls, namely the dimensions of the piles and their mutual placement, as well as the choice of the angle of the bulk soil along the slope. The calculations were performed using numerical simulation of the stress-strain state of the system "slope soils-retaining wall" using the finite element method. An elastic-plastic model of soil deformation with a change in soil parameters (deformation module) depending on the level of stresses in the soil is adopted. Hardening soil model (HSM) used. Calculations of slope stability involve taking into account the technological sequence of erection of retaining walls and modeling of the phased development of the pit. The simulation was performed in several stages: Stage 1 - determination of stresses from the own shaft, Stage 2 - assessment of slope stability before construction, Stage 3 - installation of retaining wall piles, Stage 4 - assessment of slope stability after landslides. Based on these studies, practical recommendations were developed for the design of each section of the retaining wall in accordance with the characteristic cross-sections.

scholarly journals Deformation structures in central Nepal and their engineering geological significance

1998 ◽  
Vol 18 ◽  
Author(s):  
Indra Raj Humagain ◽  
K. Schetelig ◽  
M. P. Sharma ◽  
B. N. Upreti ◽  
M. Langer
Keyword(s):  
Cross Sections ◽  
Decisive Role ◽  
Tectonic Deformation ◽  
Deformation Structures ◽  
Central Nepal ◽  
Discontinuous Deformation ◽  
The Stability ◽  
Air Photo ◽  
Cut Slopes ◽  
Different Order

Geological maps of the Helambu-Kathmandu area and Kathmandu-Hetauda area with their suitable cross-sections are presented. On the basis of the deformation history, the deformation structures recorded from the field study as well as from the air photo interpretations are classified as continuous and discontinuous deformation structures. All types of discontinuous deformation structures are considered as discontinuities. Discontinuities play decisive role in engineering geology breaking the continuity of the mechanical behaviour of the rockmass at different scales. On the basis of spacing, width, mineral fill and extent, the discontinuities are classified into seven orders. Such classification is essential and appropriate for rockmasses, which are heavily affected by intense tectonic deformation in the Himalaya, the Alps or corresponding orogens. The study area within central Nepal is having many engineering geological problems. Stability of the rock slopes and underground excavations are two major engineering geological problems to deal here with. Significance of the different order of discontinuities in the light of these engineering geological problems are discussed. Orientation of different order of discontinuities is an important parameter affecting blasting, span width, roof support and ground water flow and related problems in the proposed tunnels in the study area. Such structures are also important factor for the stability of the natural slopes and cut slopes.

scholarly journals Examining the Effects of Suction and Nonlinear Strength Envelopes on the Stability of a High Plasticity Clay Slope

Geosciences ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 449
Author(s):  
Mengwei Xuan ◽  
Jack Montgomery ◽  
J. Brian Anderson
Keyword(s):  
Limit Equilibrium ◽  
Friction Angle ◽  
Stability Factor ◽  
High Plasticity ◽  
Slope Failures ◽  
Clay Deposits ◽  
Ring Shear ◽  
High Plasticity Clay ◽  
The Stability ◽  
Cut Slopes

Slope failures in high plasticity clay deposits are common occurrences in many parts of the world. In western and central Alabama, expansive Prairie clays are commonly found, and shallow slope failures have occurred in both fill and cut slopes containing these high plasticity clays. The objective of this study was to examine the effects of suction and the use of nonlinear strength envelopes on the embankment stability of a section of highway AL-5. The testing program consisted of fifteen ring shear tests performed using a Bromhead Ring Shear Device. The results of the tests were used to develop both linear and nonlinear fully softened and residual strength envelopes. The saturated strength envelopes are then used in a limit equilibrium slope stability analysis with and without the effects of suction. The results show stability (factor of safety >1) for all cases except the residual friction angle without suction. Given these results, large slope failures are unlikely to occur in this area, but surficial failures and deformations due to creep may be possible. These results demonstrate the importance of considering the effects of suction and nonlinear strength envelopes when examining the potential for shallow slope failures in high plasticity clays.

Stability Analysis of Earth Dam under Unsaturated Seepage

2008 ◽  
Vol 33-37 ◽  
pp. 1129-1134
Author(s):  
Zheng Hua Xiao ◽  
Bo Han ◽  
Akenjiang Tuohuti ◽  
Hong Jian Liao
Keyword(s):  
Stability Analysis ◽  
Unsaturated Soil ◽  
Limit Equilibrium ◽  
Earth Dam ◽  
Hydraulic Pressure ◽  
Earth Dams ◽  
Seepage Analysis ◽  
Unknown Quantity ◽  
The Stability ◽  
Unsaturated Seepage

This paper is mainly concerned with the saturated-unsaturated seepage analysis of earth dams based on unsaturated soil theory and the stability analysis of earth dams based on conception of slices. At first, beginning basic seepage theory, thesis introduce the saturated-unsaturated and steady-unsteady seepage differential equation of porous media and the FEM regarding hydraulic pressure head as basic unknown quantity. Then considering the shear strength of unsaturated soil, the method of analysis of general limit equilibrium has been approved and it can be used in the analysis of the stability of saturated-unsaturated slopes. Through an example it is respectively discussed effects of seepage flow when water head is changed in earth dam and the effects of percolation in the stability of the earth dam slope. Some helpful conclusions are gained. This can be making the best of the tow methods and the results can be used in engineering for reference.

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