Effect of vertical seismic coefficient on cohesive-frictional soil slope under generalised seismic conditions

Sahoo, Pragyan Pradatta; Shukla, Sanjay Kumar

doi:10.1080/19386362.2020.1711553

Cited by 5 publications

(4 citation statements)

References 40 publications

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“…While determining CFS and the associated minimum FS of any slope, the effects of surcharge load (q, kN/m 2 ) and pore-water pressure (μ) over the sliding mass have been considered in this work. The impact of earthquake loading is simulated through equivalent static loading of the amount k h W in the horizontal direction and k v W in the vertical direction [41]. The coefficients k h and k v are called seismic coefficients acting toward horizontal and vertical directions, respectively.…”

Section: Methodsmentioning

confidence: 99%

A Generalized Limit Equilibrium-Based Platform Incorporating Simplified Bishop, Janbu and Morgenstern–Price Methods for Soil Slope Stability Problems

Alok,

Burman,

Samui

et al. 2024

Advances in Civil Engineering

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Limit equilibrium (LE) method is the most widely used method for slope stability analysis. Different methods based on the LE technique for the analysis of the stability of the slope have been developed. Some are based on satisfying the force equilibrium condition of the failing mass (Janbu’s method), while some focus on satisfying the moment equilibrium condition (Bishop’s method). Among these methods, the most accurate result is provided by the Morgenstern–Price method as it not only satisfies both moments as well as a force equilibrium condition but also considers the interslice shear forces (Vi) and interslice normal forces (Ei), which are neglected by most of the LE methods to avoid the condition of indeterminacy. To accommodate these forces, Morgenstern–Price (MP) gave a relation between the Vi and Ei which depends upon a scaling multiplier (λ). Thus, it becomes necessary to evaluate λ value along with the factor of safety (FS). There is barely any work discussing the detailed methodology of evaluation of λ along with FS. Method for obtaining λ along with FS have been developed and elaborated in details here. While calculating FS (MP method), evaluation of Ei is a must which is dependent upon the values of normal force at the base of each slice (Ni) and FS, which itself is dependent upon the value of Ei, making it a loop of interdependent variables. To avoid this interdependency of above stated variables, a separate formulation of Ei is given which reduces the calculations (run-time) involved. A VBA code-based platform has also been developed incorporating the generalized LE method, including Bishop’s, Janbu’s, and Morgenstern–Price methods which are represented in the form of flowcharts in this work.

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Section: Methodsmentioning

confidence: 99%

A Generalized Limit Equilibrium-Based Platform Incorporating Simplified Bishop, Janbu and Morgenstern–Price Methods for Soil Slope Stability Problems

Alok,

Burman,

Samui

et al. 2024

Advances in Civil Engineering

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“…Regarding materials with both cohesive and frictional components (c-ϕ' slope), Sahoo and Shukla (2021) found that the application of k v in the upward direction results in a lower FoS. However, Shukha and Baker (2008) found that for very steep c-ϕ' slopes, the critical condition is when k v is applied in the upward direction and for a gentle slope, this occurs when k v is applied in the downward direction.…”

Section: 25-33mentioning

confidence: 99%

The impact of considering the vertical seismic coefficient kv on the pseudostatic slope stability analysis of downstream tailings sand dams

Morales¹,

Bard²,

Palma³

2022

obrasypro

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In Chile, the limit equilibrium analysis under pseudostatic conditions is compulsory according to the Supreme Decree 248 (DS248, 2007), which establishes a minimum factor of safety (FoS) of 1.2 for stability analysis. In Chilean geotechnical practice, it is usually considered just the horizontal seismic coefficient (kh) for the analyses. However, there is a constant discussion about the necessity of applying both horizontal and vertical seismic coefficient (kv) into the analyses. In addition, there is uncertainty about what kv/kh should be considered and the effect that the sense of application (upward or downward) could have on the FoS. This paper presents an analysis of the effect of considering different |kv|/kh from 0 to 1 on both analysis directions for generic downstream tailings sand dam. Based on this, different dam heights, beach lengths and seepage conditions are also analysed. The obtained results show that when both kh and kv are applied, the FoS increase if kv acts downward and decrease when it acts upward. In addition, the effect for |kv|/kh ≤ 0.5 is almost neglectable, especially for kh ≤ 0.15. Furthermore, although a short beach length significantly impacts the FoS, the influence of applying both kh and kv seems to be independent of the beach length

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“…For instance, the traditional Newmark displacement approach assumes that the direction of seismic movement is downward along the sliding surface, ignoring the fact that both vertical and horizontal seismic forces alternate in direction, and their magnitude also change with the excitation. Some previous studies show that the vertical ground motion can have an important influence on the seismic stability of soil slopes 16–20 . Zhang et al 21 .…”

Section: Introductionmentioning

confidence: 99%

“…Some previous studies show that the vertical ground motion can have an important influence on the seismic stability of soil slopes. [16][17][18][19][20] Zhang et al 21 analyzed the effect of vertical ground motion on the Wenchuan earthquake landslides by FLAC modeling and concluded that calculated slope displacements are greater when both vertical and horizontal ground motions acted simultaneously than when only horizontal ground motion is considered. Korzec and Jankowski 22 conducted shaking table tests under bidirectional cyclic loads for thirty-five European seismic records, showing that the underestimation of permanent displacement can reach up to 19% if the vertical excitation is neglected.…”

Section: Introductionmentioning

confidence: 99%

Seismic displacement of earth slopes incorporating co‐seismic accumulation of dynamic pore water pressure

Zhang

et al. 2023

Earthq Engng Struct Dyn

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The earthquake-induced displacement of sloping soil mass is an important indicator of co-seismic landslide initiation. In this paper, an improved Newmark displacement model that considers the accumulation of dynamic pore water pressure (DPWP) in the soil caused by both vertical and horizontal ground motions is proposed. The model can quantitatively describe the dynamic changes of the seismic yield acceleration of near-saturated infinite soil slopes. Three different types of ground motion time histories are selected to compare the performance of the proposed Newmark displacement model, and the influence of DPWP accumulation on the slope yield acceleration and on the seismic displacement is obtained. The seismic slope displacement analyses indicate that the weakening effect of slope yield acceleration caused by bidirectional earthquake excitation-induced DPWP is more obvious than when only considering the horizontal ground motion, when the slip surface soils are in near-saturated state.The effect of initial saturation (S r0 ) on the DPWP accumulation caused by vertical ground motion is also investigated. Furthermore, the accumulated seismic displacement can be reasonably explained by the frequency distribution characteristics of the ground motions. Finally, the numerical results of this paper show that the seismic displacement model seldomly considering the effect of DPWP, or only considering the DPWP induced by horizontal ground motion, can significantly underestimate the displacement value when the slip surface soils are in a near-saturated state.

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Effect of vertical seismic coefficient on cohesive-frictional soil slope under generalised seismic conditions

Cited by 5 publications

References 40 publications

A Generalized Limit Equilibrium-Based Platform Incorporating Simplified Bishop, Janbu and Morgenstern–Price Methods for Soil Slope Stability Problems

A Generalized Limit Equilibrium-Based Platform Incorporating Simplified Bishop, Janbu and Morgenstern–Price Methods for Soil Slope Stability Problems

The impact of considering the vertical seismic coefficient kv on the pseudostatic slope stability analysis of downstream tailings sand dams

Seismic displacement of earth slopes incorporating co‐seismic accumulation of dynamic pore water pressure

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