scholarly journals Distribution Property of Shear Strength Parameters of Q2 and Q3 Loess in Northwest China and Its Application in Reliability Analysis of Natural and Filled Slopes

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xueyan Wang ◽  
Yi-li Yuan ◽  
Changming Hu ◽  
Yuan Mei
Keyword(s):  
Shear Strength ◽  
Reliability Analysis ◽  
Reliability Index ◽  
Northwest China ◽  
Shaanxi Province ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Engineering Project ◽  
Loess Area ◽  
Fill Slope

Geological materials have randomness in nature. Statistical analysis can help revealing the variation pattern of the material parameters and the reliability of the slope. In this paper, the probability distribution and variability of shear strength parameters of typical Q2 and Q3 loess in Northwest China were statistically analysed using the collected geological survey data in Yan`an, Shaanxi Province. Resulting probability properties were applied to the reliability analysis for the natural and fill slope in loess area using the Monte Carlo Method. Finally, an optimization analysis was carried out for the fill slope in the background engineering project. Research results show that normal distribution and lognormal distribution can be used to describe the statistical properties of c and φ of Q2 and Q3 loess. Variance of c is large while the variability of φ is relatively small. The influence of the variability of φ on the reliability index of loess natural slope is generally larger than that of c. On the contrary, influence of the variability of c on the reliability index of the fill slope is generally greater than that of φ, which is related to the structural and uniformity of the soil. Finally, relation between slope height and minimum gradient coefficient is linear when the failure probability of fill slope is less than 10%. Results in this study can be used as a reference for the slope design and construction for the cut and fill engineering in loess area.

scholarly journals Copula-Based Slope Reliability Analysis Using the Failure Domain Defined by theg-Line

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Xiaoliang Xu ◽  
Jianlin Li ◽  
Jiawei Gong ◽  
Huafeng Deng ◽  
Liangpeng Wan
Keyword(s):  
Shear Strength ◽  
Reliability Analysis ◽  
Slope Failure ◽  
Limit State ◽  
Probability Of Failure ◽  
Function Approach ◽  
State Function ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Reliability Method

The estimation of the cross-correlation of shear strength parameters (i.e., cohesion and internal friction angle) and the subsequent determination of the probability of failure have long been challenges in slope reliability analysis. Here, a copula-based approach is proposed to calculate the probability of failure by integrating the copula-based joint probability density function (PDF) on the slope failure domain delimited with theg-line. Here, copulas are used to construct the joint PDF of shear strength parameters with specific marginal distributions and correlation structure. In the paper a failure (limit state) function approach is applied to investigate a system characterized by a homogeneous slope. The results show that the values obtained by using the failure function approach are similar to those calculated by means of conventional methods, such as the first-order reliability method (FORM) and Monte Carlo simulations (MC). In addition, an entropy weight (EW) copula is proposed to address the discrepancies of the results calculated by different copulas to avoid over- or underestimating the slope reliability.

scholarly journals Optimal Estimation of Shear Strength Parameters Based on Copula Theory Coupling Information Diffusion Technique

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Xinlong Zhou ◽  
Guang Zhang ◽  
Shaohua Hu ◽  
Junzhe Li
Keyword(s):  
Shear Strength ◽  
Reliability Analysis ◽  
Information Diffusion ◽  
Gaussian Copula ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Distribution Models ◽  
Marginal Distributions ◽  
Copula Theory ◽  
Diffusion Technique

In geotechnical reliability analysis, random volatility in marginal distributions of shear strength parameters has been rarely considered. Unfortunately, conventional marginal distribution models cannot characterize real probability distribution accurately, leading to considerable dispersion with incomplete probabilistic information. In this paper, an estimation methodology is proposed based on copula theory coupling information diffusion technique. Firstly, information diffusion distribution is extended to represent one-dimensional marginal distributions of shear strength parameters. Secondly, copula theory is employed to characterize the dependence structures among the parameters. Eventually, equivalent sample is yielded by information diffusion distribution that has been already established. A case study in Singapore is implemented to enunciate and validate the competence of the proposed method. The performances of the candidate copulas coupling different marginal distributions are further discussed. Results indicate that information diffusion distribution can efficiently capture the random volatility of real distributions of shear strength parameters and hold remarkable superiority in modeling marginal distributions. The equivalent sample, estimated by information diffusion technique in conjunction with Gaussian copula, has considerable consistency with original data. The proposed method can provide a reference to reliability analysis in geotechnical engineering.

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