Probabilistic Slope Stability Analysis Using Approximative FORM

Huber, Maximilian; Krogt, M. van der; Kanning, W.

doi:10.1007/978-3-319-47886-9_21

Cited by 4 publications

(3 citation statements)

References 3 publications

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“…Additionally, extending the traditional LEM of slices to a probabilistic approach enables the assessment of spatial variation in soil strength parameters [31]. Random FEM has also been employed to capture soil variability [32]. The literature provides an overview of soil heterogeneity [33], with a specific focus on spatial variability in soil stiffness and strength [34].…”

Section: Mathematical Formulationmentioning

confidence: 99%

Stochastic Finite Element Analysis of Root-Reinforcement Effects in Long and Steep Slopes

Tiwari,

Bhandary

2023

Geotechnics

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This article introduces a novel numerical scheme within the finite element method (FEM) to study soil heterogeneity, specifically focusing on the root–soil matrix in fracture treatments. Material properties, such as Young’s modulus of elasticity, cohesion, and the friction angle, are considered as randomly distributed variables. To address the inherent uncertainty associated with these distributions, a Monte Carlo simulation is employed. By incorporating the uncertainties related to material properties, particularly the root component that contributes to soil heterogeneity, this article provides a reliable estimation of the factor of safety, failure surface, and slope deformation, all of which demonstrate a progressive behavior. The probability distribution curve for the factor of safety (FOS) reveals that an increase in the root area ratio (RAR) results in a narrower range and greater certainty in the population mean, indicating reduced material variation. Moreover, as the slope angle increases, the sample mean falls within a wider range of the probability density curve, indicating an enhanced level of material heterogeneity. This heterogeneity amplifies the level of uncertainty when predicting the factor of safety, highlighting the crucial importance of accurate information regarding heterogeneity to enhancing prediction accuracy.

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Section: Mathematical Formulationmentioning

confidence: 99%

Stochastic Finite Element Analysis of Root-Reinforcement Effects in Long and Steep Slopes

Tiwari,

Bhandary

2023

Geotechnics

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“…The reliability is calculated for a fixed slip plane, which is iteratively selected by searching for the most critical slip plane in the probabilistic design point, see the procedure described in Huber et al (2017). The Uplift-Van model (Van, 2001) was used for the slope stability calculation to account for long-shaped slip planes with strength loss due to uplifting of relatively thin clay blanket layers (with a particle swarm search algorithm to determine the most critical slip circle).…”

Section: Stability Model Setup and Parametersmentioning

confidence: 99%

“…Since the transition to safety standards in terms of acceptable probabilities of flooding, many parameters related to dike slope stability are now being assessed in a probabilistic manner. The uncertainty related to these parameters, most strikingly geotechnical material properties such as angle of internal friction or shear strength increase exponent, is thus considered (Huber et al, 2017). In addition, uncertainty in geological architecture is taken into account as 1D scenarios over depth (Hijma and Lam, 2015).…”

Section: Towards a Better Incorporation Of Uncertainty In Groundwater...mentioning

confidence: 99%

Improving Dike Slope Failure Assessments related to Groundwater Hydrology

van Woerkom

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Dikes and dunes protect over 9 million in the Netherlands from floods due to extreme river water levels and coastal storms. According to the 2017 river flood protection assessment, all 3500 km of primary flood defenses must meet a new safety standard by 2050. Currently, 1500 km needs reinforcement. This evaluation aims to meet the new safety rules. Dike failure probability is seen as a mix of mechanisms, with dike slope instability being a key one – soil movement due to increased groundwater pressure. High water levels lead to heightened groundwater pressure through direct infiltration and subsurface flow. The current dike safety assessment uses an analytical approach for groundwater conditions, neglecting parameters like hydrological attributes, subsurface variability, and flood hydrograph shape. The diverse subsurface in the Rhine-Meuse delta impacts groundwater flow. Ignoring these parameters causes inaccurate safety estimates. The research's primary goal is to assess parameters affecting dike failure uncertainty due to groundwater variation in deltas. A groundwater model linked with a geomechanical model assessed dike slope stability, varying parameters that influence it via groundwater conditions. The significance of subsurface and geometry for dike slope stability under steady-state groundwater conditions was explored through a sensitivity analysis involving fifteen parameters related to geometry, drainage, and material properties. Dike slope and subsurface material type were pivotal factors, with complex connections influencing stability directly through geomechanical traits and indirectly through groundwater conditions. However, this assumes pressure conditions stabilize during high water events, which isn't always accurate. The significance of subsurface and geometry for dike slope stability was studied using a sensitivity analysis. Among fifteen parameters related to geometry, drainage, and materials, the dike slope and subsurface material had the greatest impact. Complex connections influence stability through geomechanical properties and groundwater conditions. Yet, this relies on pressure reaching equilibrium during high water events, which may not be consistent. Another uncertainty source is the heterogeneity in human-made river dikes and the natural subsurface. DETRIS, an object-based and process-based model, replicates material patterns in river dikes with historical cores. Incorporating heterogeneous DETRIS-simulated dikes into simulations yields a probabilistic assessment that accounts for internal dike heterogeneity. This approach reduces uncertainty by factoring in permeable layers or weak zones. In lowland deltas like the Rhine-Meuse delta, the natural subsurface's complexity includes sandy channel belts and clayey floodplain deposits. Current groundwater estimation practices oversimplify to two dimensions, but 2D models can underestimate when the river channel connects in three dimensions. A 2D groundwater model may underestimate dike slope stability compared to a 3D model. These uncertain factors merge to influence dike stability. The dike's interior composition significantly affects phreatic levels and heterogeneity. Material composition of the cover layer determines subsurface pressure. None of the factors – flood wave shape, dike interior, subsurface material, or groundwater model dimension – show a significantly greater impact on dike slope safety. Given climate change's potential extreme conditions and groundwater's role in dike failure, comprehensive guidelines for including groundwater uncertainty in safety assessments are advised.

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Improving dike reliability estimates by incorporating construction survival

Krogt

Schweckendiek

Kok

2021

Engineering Geology

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During construction of a dike, slope stability often reaches critical levels, due to the excess pore water pressures in the foundation. The loading condition during construction has similarities with the design conditions during flood loading. Not only in terms of the pore water pressures as the main driving force, but also in terms of criticality of the stability. This paper examines how the information of survival of the construction stage can be used to improve the reliability estimate for a dike in flood conditions, using Bayesian updating. The approach is exemplified for a range of typical dikes and for a case study of a full-scale test embankment. The main result is that the reliability can increase significantly by including the information of construction survival and the uncertainty reduction involved, especially for dikes on soft soil blankets. For the investigated cases, the posterior failure probability was up to several orders of magnitude lower than the prior failure probability. The main factors influencing the degree of reliability update, were the ground conditions and the degree of criticality of the slope stability during construction. In conclusion, using the information of the survived construction leads to improved reliability-based safety assessments of dikes, and consequently to more targeted and cost-effective flood protection.

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Probabilistic Slope Stability Analysis Using Approximative FORM

Cited by 4 publications

References 3 publications

Stochastic Finite Element Analysis of Root-Reinforcement Effects in Long and Steep Slopes

Stochastic Finite Element Analysis of Root-Reinforcement Effects in Long and Steep Slopes

Improving Dike Slope Failure Assessments related to Groundwater Hydrology

Improving dike reliability estimates by incorporating construction survival

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