Selecting Minimum Factors of Safety for 3D Slope Stability Analyses

Stark, Timothy D.; Ruffing, Daniel

doi:10.1061/9780784480700.025

Cited by 8 publications

(7 citation statements)

References 10 publications

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“…However, there are two important aspects of our study that need to be addressed: (1) despite the very detailed level of investigations, high density of measurements, and homogeneous processing and interpretation of data, the slope stability analysis is affected by different types of uncertainties as well as assumptions and simplifications introduced during the data acquisition and processing. Thus, it is important to understand the main uncertainty sources present in our data and results (e.g., Stark and Ruffing 2017). Additionally, the spatial variability of sediment properties has to be discussed; (2) to verify the applicability of our s u (z) models to other Swiss lakes with similar sedimentation history and sediment composition, they have to be compared with the s u (z) estimates from the other available investigations.…”

Section: Discussionmentioning

confidence: 99%

“…Currently stable areas close to the unstable state (1 ≤ FS < 1.5-2) which require a more detailed and comprehensive investigation. This FS range was selected as a compromise between different approaches to separate between the stable and unstable state of the slope (Kramer 1996;Silva et al 2008;Stark and Ruffing 2017;Herza et al 2018; 1 3 Schnaid et al 2020). Parts of the slopes at St. Niklausen, Weggis, Kastanienbaum, and Muota sites belong to this group (Fig.…”

Section: Static One-dimensional Infinite Slope Stability Analysismentioning

confidence: 99%

“…Additionally, the minimum factor of safety (FS) which is considered a boundary between the stable and unstable states depends on the goals of a study. Generally, it is selected between 1 and 1.5 or even more (Kramer 1996;Silva et al 2008;Duncan et al 2014;Stark and Ruffing 2017;Herza et al 2018;Schnaid et al 2020).…”

Section: Slope Stability Analysismentioning

confidence: 99%

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Geotechnical characterization and stability analysis of subaqueous slopes in Lake Lucerne (Switzerland)

et al. 2022

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Tsunamis occur not only in marine settings but also in lacustrine environments. Most of the lacustrine tsunamis are caused by seismically- or aseismically-triggered mass movements. Therefore, an assessment of the stability of subaqueous slopes is crucial for tsunami hazard assessment in a lake. We selected Lake Lucerne (Switzerland) as a natural laboratory to perform an in-depth geotechnical characterization of its subaqueous slopes. This lake experienced documented tsunamis in 1601 and 1687. Some of its slopes still bear sediment volumes with a potential for tsunamigenic failure. To identify such slopes, we interpreted available reflection seismic data and analyzed the bathymetric map. Then, we performed 152 dynamic Cone Penetration Tests with pore pressure measurement (CPTu) and retrieved 49 sediment cores at different locations in the lake. These data were used to characterize the failure-prone sediments and to evaluate the present-day static stability of subaqueous slopes. Obtained results allowed the definition of three classes of slopes in terms of static stability: unstable slopes, stable slopes close to the unstable state, and stable areas. Non-deltaic slopes with thicker unconsolidated fine-grained sediment drape and moderate-to-high slope gradients (> 5–10°) have the lowest Factor of Safety. In agreement with previous studies, the failure plane for the non-deltaic slopes is embedded within the fine-grained glaciolacustrine sediments. Deltaic slopes with prevailing coarse-grained sediments mostly appear statically stable. Finally, we generalized the measured undrained shear strength profiles $${s}_{u}(z)$$ s u ( z ) into the depth-dependent power-law models. These models define the $${s}_{u}$$ s u of Lake Lucerne’s sediments and can be applied to other lakes with similar sedimentation history.

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Section: Discussionmentioning

confidence: 99%

Section: Static One-dimensional Infinite Slope Stability Analysismentioning

confidence: 99%

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Geotechnical characterization and stability analysis of subaqueous slopes in Lake Lucerne (Switzerland)

et al. 2022

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“…In the literature, it has been observed that for a static two-dimensional (2D) a minimum factor of safety of 1.3 is acceptable for temporary or low-risk slopes and 1.5 for permanent slopes (Stark and Ruffing, 2017). However, in most cases, when a factor of safety is below 1 then is considered a total embankment failure.…”

Section: Figure 8 Instantaneous Drawdown; (A) Embankment (B) Graph Of...mentioning

confidence: 99%

Stability analysis of an old earth Samarkand Dam in Kazakhstan under rapid drawdown conditions

Zhussupbekov

Mkilima

2022

EnvEng-IO

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Despite being potential historical sites, old embankment dams are subjected to many stability challenges due to many factors, including a lack of sufficient stability assessment tools by the time the dam was built and changes in embankment material properties induced by natural and human activities. Therefore, with the current advancement in technology is of great importance to investigate the state of old embankment dams under different potential loading conditions. The stability challenges become of more significant concern when the embankment is subjected to a rapid drawdown loading scenario. In this study, the Samarkand dam located in Karaganda province in Kazakhstan which was put into operation in 1941 is investigated in terms of seepage and slope stability with the help of numerical modelling. Both steady and transient (rapid drawdown) flow conditions are taken into consideration. e finite element method-based modelling is achieved using SEEP/W and SLOPE/W of the GeoStudio software. From the analysis results, it was observed that the old dam can be subjected to a potential failure under rapid drawdown conditions as the minimum factor of safety values were decreasing with the increase in the drawdown rates. For instance, the minimum factor of safety from the instantaneous drawdown rate was equivalent to 32.85% less than the factor of safety retrieved from the long-term steady-state conditions. Also, from Analysis of Variance (ANOVA), a p-value of 9.97× 10-29 was obtained after subjecting the factor of safety values from instantaneous, 5 days, 10 days, and 1 m per day drawdown rates to ANOVA, indicating that the factor of safety differences among the analyzed drawdown rates were statistically significant.

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“…This was because the final effect for the estimated factor of safety was not included. In addition, landslide analysis using the 3-D method is recommended for performing back analysis [10]. Several studies are being increasingly conducted on the soil and rock slope stabilities, using a 3-dimensional approach that was initially introduced by Anagnosti (1969).…”

Section: Introductionmentioning

confidence: 99%

Comparison of safety factor and geosyntetic reinforcement requirement for slope stability using 2-D and 3-D analysis method

2022

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The analysis of landslide slope stability since 1960s is the development of a 2-D structure proposed by various experts, through the 3-D method. Most of these previous studies stated that the ratio of 3-D and 2-D safety factors was more than one for cohesive and less than one for non-cohesive soils. These were because several required slope reinforcements were affected by the safety factors, with the analytical differences of the 2-D and 3-D methods causing a distinction in the requirements. These differences further cause problems by underestimating or overestimating the design. Therefore, this study aims to determine a comparative analysis of 2-D and 3-D slope stability on several required reinforcements. The analyses of the 2-D and 3-D structures were carried out using the LEM proposed by Fellenius and Hovland, respectively. The comparison of the several required reinforcements was also conducted using geotextile with Tult = 200 kN/m. The results showed that the reinforcements required with geotextile between 2-D and 3-D analysis were relatively similar on homogeneous soils. Meanwhile, the geotextile reinforcement needs were different for heterogeneous soils. Under different certain conditions, the need for 2-D reinforcement was greater and lesser than 3-D. In addition, the difference in the reinforcement required for the analysis of these structures was between 1-8 layers of geotextile, depending on soil parameters, slope, and length of the landslide field.

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Selecting Minimum Factors of Safety for 3D Slope Stability Analyses

Cited by 8 publications

References 10 publications

Geotechnical characterization and stability analysis of subaqueous slopes in Lake Lucerne (Switzerland)

Geotechnical characterization and stability analysis of subaqueous slopes in Lake Lucerne (Switzerland)

Stability analysis of an old earth Samarkand Dam in Kazakhstan under rapid drawdown conditions

Comparison of safety factor and geosyntetic reinforcement requirement for slope stability using 2-D and 3-D analysis method

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