Seismic Stability Analysis Research Articles

Upper-bound limit analysis on seismic rotational stability of waterfront retaining walls

The seismic rotational stability analysis of waterfront retaining walls can be found in the existing literature, which adopted the limit equilibrium theory and was based on the moment balance of the external force on the wall. However, the application location of the seismic earth pressure still lacks a recognized solution. This paper presented a new methodology for the rotational stability analysis of the waterfront retaining wall under earthquake conditions based on the multi-block upper bound approach. The seismic loads are determined by the pseudo-static method. The wall and soil wedge (not containing water within) are treated as a whole system and build an energy balance equation of this system, then an analytical expression for the seismic yield acceleration coefficient is deduced. Results showed that the water level on the downstream side exceeds 30% of the wall height, the seismic rotational stability of the waterfront retaining wall would decrease significantly. The seismic yield acceleration coefficient is decreasing by about 40% when the water level on the downstream side is increased from 3 m to 4 m. The results from the proposed method compared with those from Choudhury and Ahmad (2007) are slightly different but more reasonable.

Reliability Analysis of Seismic Slope Stability with Uncertain Probability Distributions

Abstract The probability density function or cumulative distribution function of shear strength parameters is commonly unknown, and the first-order reliability method, second-order reliability meth...

Extensions of the dynamic Newmark method for seismic stability analysis of a rock block

AbstractThe Newmark sliding block method combined with block theory (referred to as the dynamic Newmark method) can be used to calculate the dynamic safety factor and the permanent displacement, which provides a quantitative tool to evaluate the dynamic stability of a rock block under seismic action. Frequent changes in the position of a rock block under seismic action may lead to the changes in contact areas and modes of contact between sliding faces. These problems that are not considered in the original dynamic Newmark method are solved to extend the dynamic Newmark method. First, the loop analysis method is introduced to obtain the contact polygonal faces of a sliding surface, and the simplex integration method is used to calculate the contact areas. Second, the reference point method is defined to identify the mode of contact between a structural plane and the surrounding rock mass, and the possible mode of motion of the rock block is determined. Based on these extensions of the dynamic Newmark method, an Extended Newmark Method (ENM) program is developed, and a verification example, three comparison cases, and an application are used to validate the correctness and effectiveness of the extended method. The results show that the ENM program can be used to calculate the effects of the change in contact areas and modes of contact on block motion, which better reflects the dynamic response of a rock block under seismic action compared with the original dynamic Newmark method.

Constant Volume Ring Shear Specimen Trimming and Testing

The constant volume ring shear (CVRS) apparatus can use intact/undisturbed specimens to measure the peak and residual undrained shear strengths to estimate the post-peak strength reduction for seismic stability and permanent deformation analyses. A trimming apparatus and specimen container were fabricated to allow the trimming of an intact annular specimen directly into a container that is used for the shearing phase of the test. This article describes the specimen trimming, recommendations for handling and converting the trimming apparatus to the shearing container, which can be done either by hand or with a specially prepared trimmer holder, and suggestions for maintaining an undrained or constant volume shear condition. CVRS undrained peak and residual shear strengths for soils with different plasticity and clay size fractions are presented, and they are in agreement with peak undrained strength ratios from direct simple shear tests. This article also introduces correlations for peak and residual undrained shear strength ratios as a function of plasticity index for verification of future test results and planning level design.

A simplified nonlinear coupled Newmark displacement model with degrading yield acceleration for seismic slope stability analysis

AbstractThe use of Newmark permanent displacement to preliminarily evaluate the seismic performance of earth slopes has been well accepted in geotechnical community. Essentially, the seismic displacement would cause slope soil shear strength to reduce, thus causing the slope yield acceleration to degrade during the earthquake shaking. This phenomenon is known as degrading effect of yield acceleration, which has not been fully addressed in the literature. In this study, the degrading effect is investigated on the basis of various Newmark's displacement calculation frameworks for infinite slopes. Specifically, the flexible‐deformation‐recoverable soil columns as well as the nonlinear soil dynamic properties including the damping and shear modulus are taken into account to derive the coupled Newmark model. Detailed discussions are made to the possible influence of the degrading effect of yield acceleration in different schemes of Newmark displacement calculation frameworks. The parametric studies show that the seismic displacement calculated by the proposed method reaches peak value at small period ratio, and dramatically drops to zero when the period ratio increases. Furthermore, the possible influence of shear rate on soil shear strength is also discussed.

Seismic stability of coal tailings dams with spatially variable and liquefiable coal tailings using pore pressure plasticity models

Failure of tailings dams can result in significant spill, loss of human lives, and damages to the environment and infrastructure. Cyclic loadings such as earthquakes and blasting are among the main threats to the stability of tailings dams. Seismic stability analyses of tailings dams are further challenged by the uncertainty and variability of tailings properties. In this paper, the influence of input motion characteristics and spatial variability in coal tailings (CT) properties on the seismic stability of a typical upstream-construction CT dam is investigated. Among the input motion characteristics, peak ground acceleration (PGA), equivalent number of cycles (ENC), and frequency content are the focus of this study. First, the applicability of two advanced constitutive plasticity models, PM4Sand and PM4Silt, in simulating the cyclic behavior of CT is evaluated and a suitable model is selected. The undrained shear strength of CT is modeled as a spatially correlated Gaussian random field. Six input motions — one blast and five earthquakes — are selected for the dynamic analyses. The dynamic analyses are conducted in co-seismic and then post-seismic stages. The seismic stability of the CT dam with uniform properties (i.e. uniform models) is compared to the stochastic models under the selected input motions. Post-seismic analysis was found critical for the stochastic models. This study highlights the importance of stochastic modeling and the consideration of spatial variability in seismic stability analysis of CT dams.

Seismic Stability Analysis of Soil Nail Walls Using the Upper Bound Method

Seismic Stability Analysis of Soil Nail Walls Using the Upper Bound Method

Study on Seismic Coefficient Calculation Method of Slope Seismic Stability Analysis

In this paper, a pseudostatic seismic coefficient evaluation method for slope dynamic stability analysis was explored with Yushu Airport Road 3# landslide as a typical engineering case, and the shaking table test and numerical calculation were performed during the exploration. The loading waveform was selected as Yushu wave, and the acceleration time‐history of seismic waves was measured and analyzed, revealing the failure mode of slopes. Based on the rigid‐body limit equilibrium theory, the instantaneous additional seismic forces of each block and the time‐history landslide stability coefficient were calculated. According to the time‐history of the landslide, dynamic stability coefficients were calculated. Subsequently, we proposed a pseudostatic seismic coefficient evaluation method and discussed the seismic coefficient slope dynamic stability analysis. The results showed that as the vibration frequency rose, the average acceleration and the residual displacement of the slope decreased, but the slope grew more dynamically stable. With the proposed method, we calculated the period of slope seismic action to be 0.126 s and the average maximum acceleration to be 0.156 g, which was close to the designed ground motion acceleration of 0.15 g. Besides, we calculated the safety factor of landslides under earthquake to be 0.93∼0.97, which was close to that obtained from the building code method and in accordance with the present seismic deformation and failure mode of landslides. Moreover, the results obtained from the method of nuclear power plant specification were relatively small compared to other specification methods. The research is significant because it provides a new idea for the evaluation of seismic landslide stability in practical engineering.

Upper bound solution of collapse pressure and permanent displacement of 3D tunnel faces using the pseudo-dynamic method and the kinematic approach

This work presents seismic stability analysis of tunnel faces under three-dimensional (3D) conditions. To consider the temporal and spatial features of seismic force, the pseudo-dynamic approach was employed and incorporated into the 'horn-like' mechanism. According to the limit analysis method and the Hoek-Brown strength criterion, analytical solution of collapse pressure on tunnel faces was derived. The permanent displacement of tunnel face was then calculated by virtue of the Newmark method. The effects of the parameters of seismic force and Hoek-Brown strength criterion on collapse pressure and failure range of tunnel faces were analyzed. The relationship between the Hoek-Brown strength criterion parameters, the supporting force, and the yield acceleration was discussed. Moreover, the permanent displacements at the top, center, and bottom of tunnel faces under seismic effect were examined. This paper proposes a new idea for seismic stability analysis of tunnel faces.

Low-cement content gravity dam as an alternative for Pskem HPP

In this paper, we consider the numerical justification of the possibility to construct a low-cement content concrete gravity dam as an alternative to the traditional solution with a rockfill dam in a Pskem HPP canyon on the river Pskem in Uzbekistan Republic. The calculation studies were performed using the finite element method (FEM), considering the non-linear (elastoplastic) behavior of concrete and foundation rock in the ANSYS software package. Seismic stability of structure was ascertained by means of time-dependent transient dynamic analysis in accordance with the implicit temporal scheme, since such approach allows to trace the development of plastic deformations in the structure and foundation during dynamic loading as well as to evaluate the possible adverse effects. Maximum design earthquake bicomponent accelerogram was involved as an input data for seismic stability analysis. According to the results of the study the conclusions were made about the possibility of construction of a high low-cement content concrete dam in geotechnical, hydrological and climatic conditions of the Pskem HPP site on the Pskem River as well as on the other HPPs of the Chirchik-Bozsu cascade in Uzbekistan Republic, which are now under design. The reported study was funded by RFBR, project number 20-38-90160.

Seismic stability analysis for a two-stage slope

This paper adopts the kinematic theorem of limit analysis to assess the seismic stability of a two-stage slope. The seismic effect is taken into account by using the pseudo-static approach. The failure mechanism for the slope is extended to include below-toe failure, toe failure and face failure. Validation of this approach is conducted by comparing the factor of safety with the data in the existing literatures. The stability charts are presented based on the graphical method for reading the factor of safety readily. Parametric study involving the effect of slope geometry, internal friction angle, seismic effect as well as depth coefficient on the stability of a two-stage slope is carried out. The critical failure surfaces with various parameters are plotted. The results obtained reveal the significant influence of slope geometry on the failure mechanism of a two-stage slope under static and seismic condition.

A method for seismic stability analysis of jointed rock slopes using Barton-Bandis failure criterion

Earthquakes are the main cause of slope failure in seismic active regions. In this study, we present a method for analyzing the seismic stability of a plane jointed rock slope with two blocks. In this analysis, the Barton-Bandis failure criterion is applied, considering the nonlinear characteristics of rock joints. Based on the limit equilibrium principle, we derived the safety factor of a jointed rock slope subjected to the modified pseudo-dynamic seismic forces. In addition, the analytical method developed in this study explains the interaction force between two blocks. Hence, it can effectively analyze the stability of a jointed rock slope and distinguish the failure modes. Further, a parametric study was conducted to investigate the effects of geometric and material properties on the safety factor of a hypothetical slope. The results show that the slope stability is significantly influenced by the geometry of the slope and the parameters including the joint roughness coefficient JRC, the horizontal seismic acceleration coefficient kh, the joint compressive strength JCS, and the basic friction angle of the structural plane ϕb. Moreover, the accuracy of the derivation is verified by the universal distinct element code UDEC 6.0. A parametric sensitivity analysis is used to determine the key parameters affecting slope stability. Finally, a set of seismic stability design charts is produced for preliminary design.

System reliability analysis of seismic pseudo-static stability of rock wedge based on nonlinear Barton—Bandis criterion

Based on the nonlinear Barton-Bandis (B–B) failure criterion, this study considers the system reliability of rock wedge stability under the pseudo-static seismic load. The failure probability (Pf) of the system is calculated based on the Monte–Carlo method when considering parameter correlation and variability. Parameter analysis and sensitivity analysis are carried out to explore the influence of parameters on reliability. The relationships among the failure probability, safety factor (Fs), and variation coefficient are explored, and then stability probability curves of the rock wedge under the pseudo-static seismic load are drawn. The results show that the parameter correlation of the B–B failure criterion has a significant influence on the failure probability, but correlation increases system reliability or decreases system reliability affected by other parameters. Under the pseudo-static seismic action, sliding on both planes is the main failure mode of wedge system. In addition, the parameters with relatively high sensitivity are two angles related to the joint dip. When the coefficient of variation is consistent, the probability of system failure is a function of the safety factor.

Seismic Slope Stability Analysis of a Hydraulic Fill Dam

Abstract This paper presents a seismic slope stability assessment study of an inherently heterogeneous hydraulic fill dam in Texas. Extensive cone penetration soundings conducted at the dam site we...

Seismic slope stability and failure process analysis using explicit finite element method

Earthquake is one of the primary factors that triggers the failure of slopes and the landslides in the mountainous area. In this study, an efficient method for the seismic slope stability analysis and seismic failure process simulation is proposed. The seismic slope stability and the failure process of a two-dimensional slope model are analyzed via the explicit finite element method with the influence of the dynamic mechanical behavior of soil and the frictional resistance characteristic of the slope rupture surface. A dynamic visco-elasto-plastic constituted model for soil is established and written in FORTRAN as a user subroutine of the finite element method code of ABAQUS. The validation of the visco-elasto-plastic constituted model and the explicit finite element method are compared with the experimental results and the implicit method. The seismic factor of safety and the sliding distance of the soil slopes under the natural earthquake conditions are calculated via the dynamic visco-elasto-plastic constituted model and the explicit finite element method. The influence of the ground motion characteristics on the seismic slope stability is analyzed in this study via the specified elastic response acceleration spectrum. The analysis results of this paper suggest that the seismic slope stability analysis and the progressive failure process of the slope under the seismic condition can be analyzed by the explicit finite element method efficiently. The results show that the dynamic mechanical behavior of soil and the ground motion characteristics are both critical influence factors for the seismic slope stability. The frictional resistance characteristic of the slope rupture surface is the principal influence factor for the sliding distance of the slope, and it also has more influence on the sliding distance of a high slope than that of the small slope.

Seismic stability and failure process analysis of earth-filled dam

Earthquake is one of the primary influence factors for the stability and safety of the earth-filled dam. An efficient way for the seismic stability and failure process analysis of the earth-filled dam is proposed in this paper. In this study, taking the dynamic mechanical behavior of soil and the ground motion characteristics into account, the seismic stability, and failure process of a two-dimensional earth-filled dam is analyzed via the explicit finite element method. A dynamic visco-elasto-plastic constituted model for soil is established and written in FORTRAN as a user subroutine of the finite element method code ABAQUS. The seismic response, residual deformation, and failure process of the earth-filled dam under natural earthquake conditions are analyzed using the dynamic visco-elasto-plastic constituted model and the explicit finite element method. Moreover, the influence of the ground motion characteristics on the seismic stability of the earth-filled dam is analyzed via the specified elastic response acceleration spectrum. The analysis results of this paper suggest that the seismic stability and the progressive failure process analysis of the earth-filled dam under the seismic condition can be analyzed efficiently by explicit finite element method. The dynamic mechanical behavior of soil and the ground motion characteristics are both critical influence factors for the seismic stability analysis of the earth-filled dam. The research work of this study is helpful for the analysis of the failure process of the earth-filled dam collapse.

Seismic stability analysis of nailed vertical cut using modified pseudo-dynamic method

The maximum tensile supporting force requirement and the distribution of the same in a system of nails with respect to depth to maintain the stability of vertical nailed cut subjected to seismic loading has been studied along with critical failure surface inclination. The modified pseudo-dynamic approach in the framework of limit equilibrium technique was employed. Novel closed-form solutions have been produced to predict nail forces, vertical and horizontal inertial forces distribution, which can serve as essential inputs in analysis and design of nailed vertical cuts. Based on the calculus approach, a novel procedure was introduced to obtain peak individual nail force demands. Influence of input parameters pertaining to soil, geometry of cut, seismic excitation was investigated. Higher nail force demand and larger failure wedge were predicted for smaller damping ratios, higher horizontal base acceleration amplitudes, lower shear strength parameters and at resonant frequencies. The ratio of height of slope to wavelength of S-wave proved to be a critical parameter and it predicted the maximum nail forces mobilizing the most substantial failure wedge at a value of 0.25 for a chosen range of parameters.

Reply to the discussion by Huang on “Probabilistic seismic slope stability analysis and design”

Reply to the discussion by Huang on “Probabilistic seismic slope stability analysis and design”

Discussion of “Probabilistic seismic slope stability analysis and design”

Discussion of “Probabilistic seismic slope stability analysis and design”

Discussion of “Probabilistic seismic slope stability analysis and design”

Discussion of “Probabilistic seismic slope stability analysis and design”