scholarly journals Reliability Analysis of Expansive Soil Slope Stability Based on the Three-Broken Line Model

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Wenwei Li ◽  
Baotian Wang ◽  
Jinyu Zuo ◽  
Bingsheng Zhou ◽  
Haixia Zhang
Keyword(s):  
Reliability Analysis ◽  
Expansive Soil ◽  
Probability Of Failure ◽  
Rigid Bodies ◽  
Soil Parameters ◽  
Soil Slope ◽  
Safety Factors ◽  
Line Model ◽  
Stability Of Slopes ◽  
Weathered Layer

Based on the characteristics of an expansive soil slope, the slip mass can be simplified to a simpler model with three-broken line rigid bodies. A solution was formulated to calculate the safety factors of the slope, and the results are similar to those based on the strength reduction method. However, similar to conventional methods to analyze the stability of slopes, the deterministic method to obtain the safety factors only calculates the safety factor using deterministic values without considering the randomness of soil parameters, which leads to unstable results. To improve the rationality of the calculated results, this paper aims to construct a reliability analysis method based on the simplified three-broken line model of a landslide. The reliability is calculated with the response surface method in a spreadsheet with efficiency and convenience. The designed program considers the changes in the strength of the shallow soil and the depth of the strongly weathered layer for different stages of the wetting-drying cycles and solves for the probability of failure of the sliding surface at the interface between the strong and weak weathered layers. Considering an expansive soil slope as an example, the reliability of the slope was analyzed based on laboratory test data and the proposed formula. The results show that multiple wetting-drying cycles significantly increase the probability of failure of an expansive soil slope and that the slope typically becomes unstable after six wetting-drying cycles. Slope cutting helps alleviate the adverse effects of wetting-drying cycles.

scholarly journals Deterministic and Probabilistic Analysis of Dasdhunga Soil Slope along Narayangarh-Mugling Road Section

2021 ◽  
Vol 6 ◽  
pp. 187-198
Author(s):  
Saurav Shrestha ◽  
Indra Prasad Acharya ◽  
Ranjan Kumar Dahal
Keyword(s):  
Limit Equilibrium ◽  
Water Pressure ◽  
Slope Angle ◽  
Friction Angle ◽  
Probability Of Failure ◽  
Soil Slope ◽  
Extrinsic Factors ◽  
Stability Of Slopes ◽  
Road Section ◽  
Truncated Normal

Instability of slopes is usually governed by a combination of intrinsic and extrinsic factors. The inherent variability of parameters make the problem probabilistic rather than a deterministic one. This research deals with evaluation of stability of slopes with the calculation of the factor of safety of Dasdhunga soil slope along Narayangarh- Mugling road section under different rainfall conditions through the use of coupled finite element and limit equilibrium method in GeoStudio and the determination of probability of failure by sliding, modeled as infinite slopes by using Monte Carlo simulation in R-Studio. Mean, standard deviation, minimum and maximum values of the parameters like- friction angle, cohesion and unit weight were computed from eight samples of the slope. The pore water pressure developed and its corresponding statistical data for different rainfall conditions were computed from FEM based SEEP/W simulation. The above parameters are assumed to follow truncated normal probability distribution function and the geometric parameters like height and slope angle are regarded as constant parameters. It was observed that the safety factors for theslopeis low in high intensity-low duration rainfalls and the probability of failure is high. The tendency to fail increases as the return period of rainfall increases and viceversa. Sensitivity analysis performed in both deterministic and probabilistic methods showed that friction angle is the most sensitive.

Application of Partial Safety Factors for Fitness-for-Service Assessment of Pressure Equipment With Local Metal Loss

2017 ◽  
Author(s):  
Takuyo Kaida ◽  
Shinsuke Sakai
Keyword(s):  
Reliability Analysis ◽  
Limit State ◽  
Probability Of Failure ◽  
Pressure Vessels ◽  
Metal Loss ◽  
State Function ◽  
Safety Factors ◽  
Loss Assessment ◽  
Reliability Method ◽  
Partial Safety Factors

Reliability analysis considering data uncertainties can be used to make a rational decision as to whether to run or repair a pressure equipment that contains a flaw. Especially, partial safety factors (PSF) method is one of the most useful reliability analysis procedure and considered in a Level 3 assessment of a crack-like flaw in API 579-1/ASME FFS-1:2016. High Pressure Institute of Japan (HPI) formed a committee to develop a HPI FFS standard including PSF method. To apply the PSF method effectively, the safety factors for each dominant variable should be prepared before the assessment. In this paper, PSF for metal loss assessment of typical pressure vessels are derived based on first order reliability method (FORM). First, a limit state function and stochastic properties of random variables are defined. The properties of a typical pressure vessel are based on actual data of towers in petroleum and petrochemical plants. Second, probability of failure in several cases are studied by Hasofer-Lind method. Finally, PSF’s in each target probability of failure are proposed. HPI published a new technical report, HPIS Z 109 TR:2016, that provide metal loss assessment procedures based on FORM and the proposed PSF’s described in this paper.

Effects Analysis of Expansive Soil Slope Reinforced with Geogrid Considering Long Term Weathering

2011 ◽  
Vol 261-263 ◽  
pp. 1319-1323
Author(s):  
Ji Zhu Sun ◽  
Wen Hui Xiao
Keyword(s):  
Safety Factor ◽  
Slip Surface ◽  
Expansive Soil ◽  
Vertical Direction ◽  
Soil Slope ◽  
Soil Stress ◽  
Vertical Grid ◽  
Weathered Layer ◽  
Weathering Effects

Considering the long-term atmospheric weathering effects on expansive soil strength, geogrid reinforcement effects of expansive soil slope are analyzed with FLAC3D. The research in this paper shows that: (1) when the reinforcement is deeper than the weathered layer, the inhibition effect of soil stress and displacement increases with increasing length of geogrid, in this case a critical slip arc moves away from the slope surface, and the maximum safety factor of slope stability increases approximately 50 percent; the grid stress decreases with the increasing height of grid location; (2) when the reinforcement depth exceeds the weathered layer 1 m, the denser geogrid in the vertical direction, the smaller shear stress and horizontal deformation in reinforced region, so that the slope safety factor increase and the critical slip arc moves towards the slope back. However,if the geogrid length exceeds the weathered layer more than 3 m, the vertical grid distance change has no significant influence on the safety factor and the location of critical slip surface.

Analysis of shallow landslide mechanism of expansive soil slope under rainfall: a case study

2021 ◽  
Vol 14 (7) ◽  
Author(s):  
Chao Liang ◽  
Zhijian Wu ◽  
Xinfu Liu ◽  
Zhaomei Xiong ◽  
Tao Li
Keyword(s):  
Expansive Soil ◽  
Shallow Landslide ◽  
Soil Slope ◽  
Landslide Mechanism

Research on the Ecological Protection Mechanism and Applied of Expansive Soil Slope

2014 ◽  
Vol 501-504 ◽  
pp. 359-367
Author(s):  
Feng Zhou ◽  
Kai Zhang ◽  
Ying Chun Tang
Keyword(s):  
Slope Failure ◽  
Expansive Soil ◽  
Treatment Method ◽  
Engineering Properties ◽  
Soil Slope ◽  
Protection Mechanism ◽  
Temperature Changes ◽  
Ecological Protection ◽  
Slope Treatment ◽  
Vegetation Formation

This paper summarizes and analyzes the basic concepts and ecological protection mechanism for expansion geotechnical slope failure mechanism and the resulting impact on the shallow, traction engineering properties such as analysis, proposed ecological slope of expansive soil slope mechanism of action: vegetation system by improving internal slope soil moisture and temperature changes affect the atmosphere and thus effectively reduce the depth. Vegetation root through reinforced anchoring, delay time and improving soil hydration ductility such as the role played good strength enhancement. Vegetation formation can effectively improve the damaged outer slope interface morphology, to restore the ecological environment and landscape effect. Integrating the past experience on expansive soil slope treatment, this paper provide a slope treatment method used in Nanning metro Tunli section, these will provide reference for the expansive soil slope ecological management.

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