Study on the Reliability of Loess Cutting Slope Considering the Variability of Soil-Water Characteristic Parameters

2012 ◽  
Vol 446-449 ◽  
pp. 1967-1972
Author(s):  
Yan Liang ◽  
Li Juan Huang ◽  
Xian Li Xing ◽  
Ping Li ◽  
Tong Lu Li
Keyword(s):  
Slope Stability ◽  
Soil Water ◽  
Failure Probability ◽  
Reliability Index ◽  
Factor Of Safety ◽  
Stability Calculation ◽  
Malan Loess ◽  
Cutting Slope ◽  
Geological Conditions ◽  
The Mean

The complexity of the geological conditions and the non-uniformity of geotechnical material make the study of slope stability with big uncertainties, so it is necessary to analyze the reliability of slope. In this paper, firstly, the matrix suction of Malan loess in Gansu Province is measured by tension meter, and a fitted soil-water characteristic curve (SWCC) is obtained according to the empirical formula; then SWCC parameters of Malan loess such as a, n and θs (saturation volumetric water content) are thought as random variables, the method of simplified Bishop is used to calculate of slope stability, and the reliability of cutting slope of Malan loess is analyzed according to Rosenbleuth method. Through calculating, obtain mean factor of safety, failure probability and reliability index of the slope. After analyzing the relations between mean factor of safety, failure probability, reliability index and variability of parameters, the results show that, the factor of safety is 1.005 and it is stable when the variability of SWCC parameters are not considered. When variation coefficients of a, n and θs are all 0.3, the average factor of safety is 1.051, the reliability index is 10.94 and failure probability is 29.81%. It is obvious that variability of SWCC parameters has certain influence on stability of the slope. In parameters of SWCC, comparing with a and θs, the variability of n has the most important influence on the mean factor of safety and failure probability. But the corresponding reliability index is minimum (the change ratios of the mean factor of safety， failure probability and reliability index with variation coefficient of n are 0.37，3.247 and 282.0 respectively). So variation level of n should be specially taken into account in reliability analysis of the slope. This research provides an important basis for the determination of the SWCC parameters of Malan loess, the stability calculation, stability estimation and prevention sliding of loess cutting slope caused by rainfall.

Non-Probabilistic Reliability and Slope Stability Analysis

2014 ◽  
Vol 578-579 ◽  
pp. 1538-1541
Author(s):  
Huan Sheng Mu
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Reliability Index ◽  
Mean Value ◽  
Slope Stability Analysis ◽  
Performance Function ◽  
Interval Variables ◽  
Reliability Method ◽  
The Mean ◽  
The Difference

In the present paper, a non-probabilistic reliability method is proposed for slope stability analysis. Soil properties involved in non-probabilistic reliability analysis are viewed as random variables and represented by interval variables. The performance function for slope stability analysis is expressed as the difference between anti-sliding moment and driving moment. The non-probabilistic reliability index is defined as the ratio of the mean value of performance function to deviate. Three examples have illustrated the simplicity and applicability of the method. This method provides a new means for slope stability analysis.

scholarly journals Slope stability analysis considering seepage and stress coupling under water level fluctuation

2021 ◽  
Vol 276 ◽  
pp. 01028
Author(s):  
Zhou YiLiang ◽  
Li Ming ◽  
Li ZiLong
Keyword(s):  
Slope Stability ◽  
Water Level ◽  
Factor Of Safety ◽  
Coupling Effect ◽  
Water Pressure ◽  
Water Level Fluctuation ◽  
Level Fluctuation ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Stability Calculation

The reservoir water level fluctuation is an important factor inducing the reaction of pore-water pressure, seepage and at last resulting in instability and failure of the slope. A typical homogeneous slope is conducted as an example in this paper, the seepage and stress coupling effect is considered, and the slope stability calculation and analysis are carried out by using the finite element stress method. The results demonstrate that the factor of safety increases with the reservoir water level rises, and then gradually changes from decrease to stabilization. It should be noted that the factor of safety decreases slightly during the initial stage of water level rising at the speed of 0.2 m/d, which the slope will probably lose its stability. On the other, the factor of safety changes from decrease to increase along with the reservoir water level drawdown, and then gradually tends to stabilization. There is a minimum factor of safety when the water level is at about 1/4 of the slope height, and the minimum factor of safety decreases with increasing drawdown speed, just as the factor of safety decreases from 0.83 to 0.73 when the drawdown speed is increased from 0.20 m/d to 5.0 m/d.

scholarly journals Assessing Submarine Slope Stability through Deterministic and Probabilistic Approaches: A Case Study on the West-Central Scotia Slope

Geosciences ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 18
Author(s):  
Kevin MacKillop ◽  
Gordon Fenton ◽  
David Mosher ◽  
Valerie Latour ◽  
Perry Mitchelmore
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Factor Of Safety ◽  
Slope Instability ◽  
Spatial And Temporal Variability ◽  
Submarine Slope ◽  
Geostatistical Approach ◽  
Mean And Variance ◽  
The Mean ◽  
Static Conditions

A simplified geostatistical approach was adopted to assess the effect of spatial variability of soil properties on slope stability analysis in order to understand continental margin geologic processes and potential geohazards for an area of the central Scotian Slope, offshore Nova Scotia, Canada. The analyses are conducted on piston core samples, thus are restricted to ~12 m sub-seabed; however, the approach provides insight into the general effects of spatial and temporal variability. Data processing using geostatistics and assessment of spatial correlation are used to characterize the current dataset. A deterministic assessment was performed for both non-spatially averaged and spatially averaged core sections. The results indicate that the estimated factor of safety increased by about 30% when spatially averaged values were used. A probabilistic model is introduced to assess reliability of the slope. The approach makes use of estimates of both the mean and variance of input random variables (e.g., Su and γb). The model uses an exact probabilistic formulation for the total stress stability analysis and a Taylor series approximation for the effective stress stability analysis. In both cases, the mean and variance of the factor of safety are computed, leading to estimates of failure probability. The results suggest that the deterministic analysis is conservative with respect to slope reliability, although they do not lead to an estimate of the probability of failure. While these results indicate sediment instability is largely unlikely under static conditions, the reality is that many examples of submarine slope failure are observed in the geologic record. These results suggest that cyclic loading (earthquakes) or pre-conditioning factors (elevation of pore pressures) are critical for slope instability on the Scotian Slope.

scholarly journals Slope stability estimation of the «earth bed – road dressing» system with disturbed structure

2020 ◽  
Vol 7 (4) ◽  
Author(s):  
Aleksey Kamenchukov ◽  
Gamilia Nikolaeva ◽  
Nikolay Gorshkov ◽  
Alexander Lovtsov
Keyword(s):  
Slope Stability ◽  
Field Research ◽  
System Stability ◽  
Permafrost Soil ◽  
Stability Calculation ◽  
Research Results ◽  
Embankment Slope ◽  
The Earth ◽  
Geological Conditions ◽  
Soil Slopes

Off-standard soil-geological systems stability assessing issues under complex conditions is being discussed in this article. Modern methods and tools analytical review for assessing the embankment slope stability was performed here. Embankment work peculiarities in the areas of the permafrost soil spread were discussed in this paper. Special attention is paid to the embankments stability issue on a thawed foundation. The design features of the embankments on permafrost soils with the frozen soils preservation or partial thawing have been studied here. Two variations of sliding surface design-level static circuit are presented in this paper: base – earth bed and base – earth bed – road dressing. The main reasons that lead to the soil slopes stability loss of soil slopes are presented here. Based on the field research results, the embankment soil stress-related characteristics and the earth bed base were determined. Those results became the basis for embankment slope stability mathematical modeling and assessment. In software packages, GeoStab (demo) and Geo5 (educational license), based on the finite element method and the field research results, digital embankment models were built on a weak foundation. The «earth bed – road dressing» system stability calculation under the standard uniformly distributed load has been performed. Two system strengthening options are proposed to increase its stability: reinforcement with soil anchors and geosynthetic materials. The hypothesis sufficiency about the influence of the pavement road dressing state on the embankment stability was also tested here. Two models of the system and the base – earth bed – road dressing are discussed: without cracks on the track and with cracks on the track. It has been elucidated that coating imperfection affects the system stability only in the presence of medium or larger strength earthquakes. Recommendations for strengthening the embankment slopes operating in difficult soil-geological conditions were given in this article.

Research on Technology of Abandoned Quarry Complex Rock Slope Stability Calculation

2014 ◽  
Vol 638-640 ◽  
pp. 542-548
Author(s):  
Yuan Liang Liu ◽  
Xiao Feng Xie
Keyword(s):  
Rock Mass ◽  
Slope Stability ◽  
3D Modeling ◽  
Rock Slope ◽  
Technical Problem ◽  
Rock Slope Stability ◽  
Rock Mass Structure ◽  
Stability Calculation ◽  
Geological Body ◽  
Geological Conditions

For the abandoned quarry complex rock slope project, the slope stability calculation is always the key technical problem, but due to the complex geological conditions and other factors, it makes the calculation of 3D modeling and the stability of the slope geological body and structure of the division, rock unit has always been the difficult problems in the field. This paper proposes a new method based on the rock mass structure combined with the degree of rock mass element, and then FLAC 3D, Midas GTS three-dimensional numerical calculation software are used, structure and surface topography in the slope, the slope surface fault, soft interlayer, complex geological 3D modeling, overcomes the problem of modeling of complex geological body, and the factors of rainfall, earthquake effect of the slope are consider for stability calculation, the calculation result is consistent with the reality, it has certain directive significance to the abandoned quarry re-greening slope stability analysis.

Effects of anisotropy in correlation structure on reliability-based slope stability analysis of a landfill

2020 ◽  
pp. 0734242X2094636
Author(s):  
Mohammad Javad Mehdizadeh ◽  
Nader Shariatmadari ◽  
Mehran Karimpour-Fard
Keyword(s):  
Slope Stability ◽  
Safety Factor ◽  
Failure Probability ◽  
Random Variables ◽  
Unit Weight ◽  
Distribution Fitting ◽  
Correlation Lengths ◽  
Isotropic Structure ◽  
The Mean ◽  
Factor Data

In this study, a reliability-based analysis of slope stability in a landfill considering the spatial variability of shear strength (c and φ) and unit weight ( γ) of municipal solid waste was performed using the random finite difference method. The effect of the anisotropic correlation (AC) structure of random variables including c, φ, and γ on mean and coefficient of variation (CoV) of safety factor values was investigated using Monte Carlo simulation. Also, probability of failure was determined through probability distribution fitting to a series of safety factor data. The results showed that the AC of the random variables has a significant effect on the stochastic safety factor of landfill slope. In general, the mean of the stochastic safety factor decreases with increasing horizontal and vertical correlation lengths (CLs). Also, the CoV of the safety factor increased with increase in horizontal or vertical CLs or both. Moreover, it was found that failure probability increases with an increase in the horizontal and vertical CLs and assuming isotropic structure for the correlation of random variables leads to the underestimation of failure probability. Overall, the results indicate that assuming an AC structure results in different failure mechanisms in the landfill slope, which are different from the deterministic cases.

A global meta-analysis reveals a significant offset in δ2H between plant water and its sources

2021 ◽  
Author(s):  
Javier de la Casa ◽  
Adrià Barbeta ◽  
Asun Rodriguez-Uña ◽  
Lisa Wingate ◽  
Jérôme Ogeé ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Soil Water ◽  
Meta Analysis ◽  
Water Evaporation ◽  
Source Water ◽  
Plant Water ◽  
Water Line ◽  
Plant Source ◽  
Sampling Campaign ◽  
The Mean

<p> </p><p>Long-standing ecological theory establishes that the isotopic composition of the plant water reflects that of the root-accessed sources, at least in non-saline or non-xeric environments. However, a growing number of studies challenge this assumption by reporting plant-source offsets in water isotopic composition, for a wide range of ecosystems. We conducted a global meta-analysis to systematically quantify the magnitude of this plant-source offset in water isotopic composition and its potential explanatory factors. We compiled 108 studies reporting dual water isotopic composition (δ<sup>2</sup>H and δ<sup>18</sup>O) of plant and source water. From these studies, we extracted the δ<sup>2</sup>H and δ<sup>18</sup>O of both plant and source waters for 223 plant species from artic to tropical biomes. For each species and sampling campaign, within each study, we calculated the mean line conditioned excess (LC-excess), with the slope and intercept of the local meteoric water line, and the mean soil water line conditioned excess (SWL-excess), from the slope and intercept of the soil water evaporation line. For each study site and sampling campaign, we obtained land surface temperature and volumetric soil water from the ERA5 database. For each study species, we recorded the functional type, leaf habit and for those available wood density. We found, on average, a significantly negative SWL-excess: plant water was systematically more depleted in δ<sup>2</sup>H than soil water. In > 90% of the cases with significantly negative SWL-excess, we also found negative LC-excess values, meaning that access to sources alternative to soil water was unlikely to explain negative SWL-excess values. </p><p>Calculated SWL-excess was affected by temperature and humidity: there were larger mismatches between plant and source water in isotopic composition in colder and wetter sites. Angiosperms, broadleaved and deciduous species exhibited more negative SWL-excess values than gymnosperms, narrow-leaved and evergreen species. Our results suggest that when using the dual isotopic approach, potential biases in the adscription of plant water sources are more likely in broadleaved forests in humid, and cold regions. Potential underlying mechanism for these isotopic mismatches will be discussed.</p><p> </p>

scholarly journals Yield, water use efficiency, and yield response factor in carrot crop under different irrigation depths

2016 ◽  
Vol 46 (7) ◽  
pp. 1145-1150 ◽  
Author(s):  
Daniel Fonseca de Carvalho ◽  
Dionizio Honório de Oliveira Neto ◽  
Luiz Fernando Felix ◽  
José Guilherme Marinho Guerra ◽  
Conan Ayade Salvador
Keyword(s):  
Water Use Efficiency ◽  
Soil Water ◽  
Water Use ◽  
Block Design ◽  
Time Domain Reflectometry ◽  
Yield Response ◽  
Response Factor ◽  
Use Efficiency ◽  
The Mean ◽  
Yield Response Factor

ABSTRACT: The aim of the present study was to evaluate the effect of different irrigation depths on the yield, water use efficiency (WUE), and yield response factor (Ky) of carrot (cv. 'Brasília') in the edaphoclimatic conditions of Baixada Fluminense, RJ, Brazil. Field trials were conducted in a Red-Yellow Argisol in the 2010-2011period. A randomized block design was used, with 5 treatments (depths) and 4 replicates. Depths were applied by drippers with different flow rates, and the irrigation was managed by time domain reflectometry (TDR) technique. The reference (ETo) and crop (ETc) evapotranspiration depths reached 286.3 and 264.1mm in 2010, and 336.0 and 329.9mm in 2011, respectively. The root yield varied from 30.4 to 68.9t ha-1 as a response to treatments without irrigation and 100% replacement of the soil water depth, respectively. Values for WUE in the carrot crop varied from 15 to 31kg m-3 and the mean Ky value was 0.82. The mean values for Kc were obtained in the initial (0.76), intermediate (1.02), and final (0.96) stages. Carrot crop was influenced by different water depths (treatments) applied, and the highest value for WUE was obtained for 63.4% of soil water replacement.

Some difficulties associated with the limit equilibrium method of slices

1983 ◽  
Vol 20 (4) ◽  
pp. 661-672 ◽  
Author(s):  
R. K. H. Ching ◽  
D. G. Fredlund
Keyword(s):  
Slope Stability ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Stability Limit ◽  
Limit Equilibrium Method ◽  
Soil Conditions ◽  
Side Force ◽  
Limit Equilibrium Methods ◽  
Equilibrium Method ◽  
The Stability

Several commonly encountered problems associated with the limit equilibrium methods of slices are discussed. These problems are primarily related to the assumptions used to render the inherently indeterminate analysis determinate. When these problems occur in the stability computations, unreasonable solutions are often obtained. It appears that problems occur mainly in situations where the assumption to render the analysis determinate seriously departs from realistic soil conditions. These problems should not, in general, discourage the use of the method of slices. Example problems are presented to illustrate these difficulties and suggestions are proposed to resolve these problems. Keywords: slope stability, limit equilibrium, method of slices, factor of safety, side force function.

Analysis of Rainfall Effect to Slope Stability in Ulu Klang, Malaysia

2015 ◽  
Vol 72 (3) ◽  
Author(s):  
Muhammad Mukhlisin ◽  
Siti Jahara Matlan ◽  
Mohamad Jaykhan Ahlan ◽  
Mohd Raihan Taha
Keyword(s):  
Slope Stability ◽  
Soil Water ◽  
Rainfall Threshold ◽  
Critical Threshold ◽  
Water Index ◽  
Triggering Factors ◽  
Landslide Event ◽  
Tropical Climates ◽  
Fatal Landslides

Malaysia is a country that is located near the equator line with tropical climates which receives high abundant rainfall, averaging 2,400mm annually. This makes Malaysia prone to the landslide events as rainfall is one of the main triggering factors that can cause landslide. Landslides in Malaysia are mainly attributed to frequent and prolonged rainfalls, in many cases associated with monsoon rainfalls. Of these, Ulu Klang area has received the most exposure. The area has constantly hit by fatal landslides since December 1993. This paper is aimed to investigate the correlation between the effective working rainfall and soil water index (SWI) methods with the landslide events in Ulu Klang, Malaysia. In this study 15 landslide events that occurred in Ulu Klang areas between years 1993 to 2012 were investigated and analyzed using rainfall threshold based on effective working rainfall and soil water index (SWI) methods. The analysis results showed that these methods are significant tools that can be used to identify the rainfall critical threshold of landslide event.  

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