Effect of rotated anisotropy of soil shear strength on three-dimensional slope stability: a probabilistic analysis

2021 ◽  
Author(s):  
Zhen Wang ◽  
Huanling Wang ◽  
Weiya Xu
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Probabilistic Analysis ◽  
Three Dimensional ◽  
Soil Shear Strength

Two- and three-dimensional analyses of translational slides in soils with nonlinear failure envelopes

2010 ◽  
Vol 47 (4) ◽  
pp. 388-399 ◽  
Author(s):  
Hisham T. Eid
Keyword(s):  
Shear Strength ◽  
Dimensional Stability ◽  
Three Dimensional ◽  
Shear Resistance ◽  
Fast Method ◽  
Stability Number ◽  
Stability Function ◽  
Case Histories ◽  
Failure Envelopes ◽  
Soil Shear Strength

This paper aims to assess the effect of nonlinearity of the soil shear strength envelope on the sliding mass configurations and the minimum two- and three-dimensional factors of safety for slopes susceptible to translational failure in both static and seismic conditions. An extensive parametric study was conducted using slope models and nonlinear soil strength envelopes that simulate translational failure case histories. Analysis of the results led to the development of stability charts that do not require an iterative procedure when determining the factors of safety. The introduction of a two-dimensional stability number and three-dimensional stability function, the values of which depend on the degrees of nonlinearity of the involved soils’ strength envelopes, has made it possible to develop such charts. These charts give the practicing geotechnical engineer a reliable and fast method to analyze translational failures. Using available software in such an analysis can be complicated if shear resistance along the sliding mass vertical sides and nonlinearity of soil shear strength envelopes are considered. Numerical examples and a case history are given to verify the reliability and illustrate the different applications of these charts.

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.

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.

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 Contribution of Tea Root Reinforcement to Soil Shear Strength on Slope Stability

2018 ◽  
Vol 4 (1) ◽  
pp. 13
Author(s):  
Mukhsin Abubakar
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Tensile Stress ◽  
Soil Condition ◽  
Soil Mass ◽  
Root Diameter ◽  
Root Reinforcement ◽  
Root Branching ◽  
Soil Shear Strength ◽  
Diameter Differentiation

Roots played important role in the process of stabilizing the soil mass. The geo-mechanical and soil-hydrological aspects on the slope are determined by, one of it, the root reinforcement. The role of root branching series with diameter differentiation is greatly determining its tensile stress. The tensile stress from the interaction between the root and the soil, could it contribute to increasing the shear strength of the slope stability. The purpose of this research was to identify the tensile stress on root branching series that interacted with the soil and created additional cohesion as a shear strength contribution to the slope stability. Testing on the root pulling force was conducted on slope prototype with angle 30o to 40o and has been planted with tea vegetation. A tripod that was completed with strain gauge as the recording instrument was used. Testing was conducted on two and three root branching, also on each unit by observing the diameter. This testing method was done in saturated soil condition. The tensile stress result showed that increasing diameter of the tea root, an increase was noticed, and also result in the equation of TFr = 0.089e0.516d. Root diameter increase on two and three root branching to one unit of tea vegetation showed that the stress increase was significant. When observed, in the root diameter differentiation of 4 mm to 6 mm, the stress on two and three root branching and one unit of tea vegetation were respectively 5.94%, 12.30%, and 35.42%. The contribution of additional cohesion caused by root-soil interaction to soil shear strength apparently could increase slope stability.

scholarly journals Shear strength properties of Hong Kong soils for slope stability

2020 ◽  
Vol 27 (1) ◽  
pp. 48-54
Author(s):  
Hong Yau Wong
Keyword(s):  
Shear Strength ◽  
Hong Kong ◽  
Slope Stability ◽  
Triaxial Compression ◽  
Quantitative Relationship ◽  
Site Investigation ◽  
Standard Penetration Test ◽  
Strength Properties ◽  
Triaxial Tests ◽  
Soil Shear Strength

With the recent advancement in technology, the method, accuracy and speed of slope stability analysis have been vastly improved. Nevertheless, the reliability and appropriateness of such analysis can be very much in doubt if the soil behaviour, in particular the shear strength behaviour, is not fully understood. The objective of this paper is therefore to evaluate the shear strength behaviour of various soil types in Hong Kong. This comprises the collection, processing and analysis of the laboratory and field works carried out in the past few decades, in particular the triaxial compression testing in the laboratory and standard penetration test (SPT) in the field. For correlating SPT with soil shear strength, a fairly large number of carefully controlled site investigation works with SPT are carried out both above and below any Mazier sampling. Laboratory triaxial tests are then carried out in these Mazier samples. Finally, it is hoped that a basically quantitative relationship between soil shear strength and SPT can be obtained as this would enable a soil shear strength profile to be established once the corresponding SPT profile has been determined on site by carrying out SPT in adequate number of drill holes.

scholarly journals Evaluation of Undrained Bearing Capacities of Wide-Shallow Bucket Foundation with Honeycomb Bulkheads in Clay

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Qingshan Wang ◽  
Xun Han ◽  
Yunfei Guan ◽  
Yongyong Cao ◽  
Wenxuan Li
Keyword(s):  
Shear Strength ◽  
Three Dimensional ◽  
Offshore Wind ◽  
Combined Loading ◽  
Vertical Load ◽  
Bucket Foundation ◽  
Failure Envelopes ◽  
Soil Shear Strength ◽  
New Type ◽  
The Moment

As a new type of offshore wind foundation, the wide-shallow bucket foundation with honeycomb bulkheads mainly bears vertical, horizontal, and moment loads. As yet, no systematic study has been conducted regarding the effects of honeycomb bulkheads on the undrained bearing capacities of the wide-shallow bucket foundation. In this study, a large number of three-dimensional (3D) finite element (FE) analyses were performed to investigate the undrained bearing capacities of the wide-shallow bucket foundations with and without honeycomb bulkheads, thereby evaluating the influence of honeycomb bulkheads on the bearing capacities under different conditions. The results show that under uniaxial loading, the uniaxial bearing capacities of the wide-shallow bucket foundation are basically unaffected by the honeycomb bulkheads in homogeneous clay. For nonhomogeneous clay, the moment bearing capacity will be considerably enhanced with the increase in soil shear strength heterogeneity. Under combined loading, the honeycomb bulkheads will enhance the combined bearing capacities only in nonhomogeneous clay. The enhancement effects will increase with the increase in soil shear strength heterogeneity but decrease with the increase in vertical load. Besides, the simplified equations for calculating the uniaxial bearing capacities of the wide-shallow bucket foundation with honeycomb bulkheads are also proposed considering the influence of embedment ratio and soil shear strength heterogeneity. At last, the parameters of an approximating expression are fitted to predict the failure envelopes of this foundation under combined loading.

scholarly journals Modifying Soil Shear Strength Parameters Using Additives in Laboratory Condition

2015 ◽  
Vol 10 (Special-Issue1) ◽  
pp. 120-130 ◽  
Author(s):  
Marjan Sadrjamali ◽  
Seyed Athar ◽  
Alireza Negahdar
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Slope Stability ◽  
Slope Stability Analysis ◽  
Nano Particles ◽  
Direct Shear ◽  
Shear Strength Parameters ◽  
Nano Silica ◽  
Strength Parameters ◽  
Soil Shear Strength

Mechanical and chemical processes and/or reinforcing materials are used in order to increase soil shear strength. Necessity for reinforcing and strengthening of soil in geotechnical and civil engineering projects requires use of new materials and reinforces. In recent years, although researchers have used new chemical compounds, however, nano-particles have not found their suitable situation. In this study, we have tried to increase soil shear strength parameters using different additives. Clay minerals are considered as problematic soils due to their engineering features. So, it is essential to reclaim them. In this research, clay with low plasticity property has been studied. Soil shear strength is an important factor for any analysis associated with stability including slope stability analysis. Slope stability analysis is used in earth dams and trenches. In this study, we have tried to increase soil shear strength parameters, i.e. cohesion coefficient (C) and internal friction angle (φ) using different additives. Direct shear test has been used for obtaining shear strength parameters as well as Mohr-Coulomb theory has been utilized for calculating of them. Although direct shear machine has its defects and its accuracy is low in comparison with tri-axial machine, however in this study it has been selected due to its simplicity and cheapness. Since this investigation aims to compare various additives and all tests have been done at same condition by direct shear machine, its deficiencies have been neglected. Additives used in present research include: Nano-silica in various percentage, Micro-silica, cement, lime (Cao) and these materials’ combination with together. The reason to choose Nano-silica is that it is a very active super-pozzolanic additive. This additive increases strength of sample significantly through chemical actions. Using silica in soil stabilization depends on type and size of silica particles so that the more finely the more continuous gradation, so property of being finer leads to decrease pores among particles and results to increase strength while light gradation has been achieved. Silica is one of the most popular materials which play a significant role in cohesion and filling. Results of experiments have shown significant effect of these additives in increase of soil shear strength parameters. The lime leads to modify behavioral features of fine-grained soils containing clay (properties such as swelling, shear strength, water absorption ability and plasticity properties) but it should not be in vicinity of sulphate ions.Since, in this condition, presence of lime not only doesn’t play an effective role but also it results to decrease in strength as well as increase in swelling. With regard to this reason, Calcium sulfate (gypsum) was added to soils containing lime in order to study swelling of soils stabilized with lime and nano-silica. Nano-silica increases Soil shear strength parameters while it is efficient in increasing of soil swelling, too.

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.

Three-dimensional numerical analysis for rock slope stability using shear strength reduction method

2014 ◽  
Vol 51 (2) ◽  
pp. 164-172 ◽  
Author(s):  
Jiayi Shen ◽  
Murat Karakus
Keyword(s):  
Shear Strength ◽  
Rock Mass ◽  
Slope Stability ◽  
Rock Slope ◽  
Three Dimensional ◽  
Strength Reduction ◽  
Rock Slope Stability ◽  
Convergence Criterion ◽  
Slope Modeling ◽  
Shear Strength Reduction

Existing numerical modeling of three-dimensional (3D) slopes is performed mainly by using the shear strength reduction (SSR) technique based on the linear Mohr–Coulomb (MC) criterion, whereas the nonlinear failure criterion for rock slope stability is seldom used in slope modeling. However, it is known that rock mass strength is a nonlinear stress function and that, therefore, the linear MC criterion does not agree with the rock mass failure envelope very well. In this research, a nonlinear SSR technique is proposed that can use the Hoek–Brown (HB) criterion to represent the nonlinear behavior of a rock mass in the FLAC3D program to analyze 3D slope stability. Extensive case studies are carried out to investigate the influence of the convergence criterion and boundary conditions on the 3D slope modeling. Results show that the convergence criterion used in the 3D model plays an important role, not only in terms of calculation of the factor of safety (FOS), but also in terms of the shape of the failure surface. The case studies also demonstrate that the value of the FOS for a given slope will be significantly influenced by the boundary condition when the slope angle is less than 50°.

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