Seismic Coefficients for Simplified Deepwater Slope Stability Assessment Under Earthquake Loading

2021 ◽  
Author(s):  
Aurelian C. Trandafir

Abstract Pseudostatic limit-equilibrium based slope stability analyses are carried out on a routine basis to evaluate stability of submarine slopes under earthquake loading. For slopes in deepwater settings, a major challenge in performing pseudostatic slope stability analyses is selection of an appropriate seismic coefficient. Most published displacement-based methodologies for seismic coefficient selection were developed using simplified sliding block models for seismic slope performance evaluation that are unable to capture the complex deformation mechanism of deepwater slopes during earthquakes. To address this challenge, this study employs two-dimensional dynamic finite-element based deformation analysis to investigate the earthquake response of submarine clay slopes characterized by morphology, stratigraphic architecture and geotechnical properties representative for the deepwater environment. Finite-element computed seismic slope performance indicators, including horizontal peak ground acceleration at the seafloor and earthquake-induced maximum shear strain within the slope, along with horizontal seismic coefficients required to trigger slope instability in limit-equilibrium based pseudostatic stability analyses are used to develop a rational shear strain-based correlation relationship for deepwater slope seismic coefficient selection.

2012 ◽  
Vol 548 ◽  
pp. 363-366
Author(s):  
Mao Hu Wang ◽  
Zhen Liang Xu

This article simulates an open pit slope stability using the ANSYS software, which is based on the finite element strength reduction theory, three kinds of slope instability criterion of the strength reduction method are applied to judge whether the slope is on the limit equilibrium state, the incremental search method is used to search the safety factor of the slope stability, and the results show that, the slope body damages when the plastic zone developed from the top to the bottom, in the numerical simulation the finite element iteration calculation didn’t just converge, the corresponding former level of reduction factor is the safety factor, This article can have a guiding significance on the safety production of the open-pit mine.


2012 ◽  
Vol 256-259 ◽  
pp. 157-162
Author(s):  
Lai Gui Wang ◽  
Guo Chao Zhao ◽  
Feng He

In order to search for the control factors of slope stability containing weak layers, combining with the methods of the finite element and the limit equilibrium to simulate the slope stability problems. From the numerical simulation results, the stress field distribution and displacement field distribution internal the slope could be got. According to the finite element analysis results and the safety factor of slope stability got with the limit equilibrium method, evaluate the slope stability. By the simulation analysis of slope which contains a number of weak structural surfaces, the conclusion we got is that the existence of weak structural plane like weak layers and faults are the main factors of slope instability.


2021 ◽  
Author(s):  
Legesse Asfaw ◽  
Matebie Meten

Abstract Arjo Didesa dam is an earth and rock fill dam which is under construction on the Didesa River in western Ethiopia. However, the dam encountered engineering geological problems that affected the water tightness and slope stability of the dam abutments and reservoir area. To solve these problems, different methods such as discontinuity survey, packer test, sampling and laboratory tests were applied to evaluate the engineering geological conditions of materials along the dam abutments and reservoir area on slope stability and water tightness. Slope stability analyses were performed by kinematic, limit equilibrium and finite element methods using laboratory and in-situ tests. Kinematic analyses revealed that both the left abutment slope 1(LAS1) and the right abutment slope 1(RAS1) sections were unstable for planar mode of failures. Further stability analyses using deterministic methods indicated that both sections were unstable only during saturated conditions. Similarly, stability analysis using limit equilibrium and finite element method revealed that both the left abutment slope 2(LAS2) and the right abutment slope 2(RAS2) sections were unstable under saturated conditions. This study also analyzed the permeability of soils and rock masses and the result showed that the permeability values range from 2.693*10− 7cm/s − 6.687*10− 5cm/s and 3.19*10− 5cm/s − 1.3*10+ 1cm/s for soils and rock masses respectively. Integration of surface hydraulic conductivity and subsurface packer permeability tests showed the presence of potential leakage through the dam abutments. Remedial measures such as rock bolts, anchors and shotcrete for slope stabilization and grouting and clay blanketing are recommended to control this leakage.


2021 ◽  
Author(s):  
Muhammad Salman Babar ◽  
Jahanzaib Israr ◽  
Umair Ali ◽  
Gang Zhang

Abstract This study presents a framework for semi-empirical slope stability analysis of Mohmand dam, an important ongoing mega concrete faced rockfill dam hydropower project in Pakistan. The project comprises of 213 m high hybrid dam that will produce 800 megawatt of clean hydropower energy in addition to an effective flood mitigation. Also, it will supply water for both irrigation and drinking to the provincial capital city, Peshawar. In this study, finite element and limit equilibrium methods have been used for slope stability analysis and factors of safety have been computed for all anticipated loading conditions including earthquake loading. The rockfill samples of main dam were obtained from the construction material site of Mohmand dam and the input parameters for slope stability analysis were obtained both empirically and through laboratory testing. Results of both limit equilibrium and finite element analyses have been compared and it was observed that the latter is more conservative than the former except for earthquake loading. The implications of current findings have been demonstrated using an important case study of an independent dam site that would boost the confidence of practitioners.


2012 ◽  
Vol 170-173 ◽  
pp. 1064-1067
Author(s):  
Shong Loong Chen ◽  
Chun Fu Lin

This study simulates the slope stability at Jiu-Fen, using the limit equilibrium method and the finite element method. The limit equilibrium method can find potential slide surfaces and safety factors rapidly. The advantage of the finite element method is that it utilizes more reasonable soil behavior and boundary conditions. A critical slide surface obtained by the limit equilibrium method can be compared with the displacement vector, stress field and location of plastic zone obtained by the finite element method. Furthermore, we can compare the safety factors produced by the two methods. This study shows that the safety factor from the limit equilibrium method is higher than that from the finite element method. The displacement analysis by the finite element method agrees well with the progressive slope failure. So, if we combine the two methods using monitored data in the field, we can analyze slope stability clearly.


2019 ◽  
Vol 270 ◽  
pp. 02004
Author(s):  
Kongkit Yingchaloenkitkhajorn

This paper presented the analysis of embankment slope stability by considering the problem of embankment slope stability with special effects that it was filled with sand and was placed on purely cohesive clay. The finite element limit analysis of two-dimensional plane strain was employed to analyze the stability of this problem. The embankment slope height (H), the depth factors (d/H) and the embankment slope angle (β) for the finite element limit analysis of sand was modeled as a volume element with the properties of Mohr-Coulomb material in drained condition. And the clay was modeled as a volume element with the properties of Tresca material in undrained condition where the parameters were soil unit weight (γ), undrained shear strength (su) and friction angle (φ′). Parametric studies consisted of three dimensionless variables including depth factors (d/H), friction angle (φ′) and embankment slope angle (β). Results were summarized in the form of the dimensionless stability number (su/γH(FS)) and the design chart and application were presented. In addition, the comparison of the solution of stability number with the limit equilibrium methods and the failure mechanisms were also proposed in this paper.


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