Seismic Stability Analysis Research Articles

Energy-based seismic stability analysis of single-layer reticulated dome structures

Seismic stability of single-layer dome structures is closely related to both the external seismic ground motions and structural properties. The physical mechanism of seismic instability of single-layer reticulated dome structures is investigated from the perspective of energy, which can take into account both the external excitations and structural properties. First, the energy balance equation is established and the accuracy for calculating each energy component of structures is verified. Then, the energy-based criterion is introduced as a quantitative index for the identification of seismic stability/instability, where the first-passage of the intrinsic energy over the input energy demonstrates the seismic instability of single-layer reticulated dome structures. Besides, some qualitative indices are also employed to further confirm the judgement by the energy-based criterion. By using the proposed criterion, the critical peak ground acceleration for seismic stability of single-layer reticulated dome structures can be identified by using the incremental dynamic analysis. The energy-based criterion is also validated by comparisons with the B-R criterion. Parametric analyses are implemented to investigate the impacts of different structural parameters on seismic stability and characteristic responses of single-layer dome structures. • Seismic stability of single-layer reticulated dome structures relates to both structural parameters and external excitation. • An energy based criterion is introduced to identify the seismic instability. • The proposed criterion is validated by the comparison with the B-R criterion. • Parametric analyses are conducted to investigate the impacts of different parameters.

Seismic finite element analysis of tailings dam in high seismic intensity area

As an important facility for mine exploitation, the safety of tailings dam is very important in high seismic intensity area. In this paper, the seismic stability analysis of tailings dam located in high intensity area was carried out by taking the example of one tailings dam. Three-dimensional finite element model was established, and the calculation results were analyzed and compared under fixed boundary condition and viscous spring boundary condition. The results showed that, (1) Under the static condition, the deformation value is distributed in layers from top to bottom. (2) Under the seismic condition, it can be seen that the Z direction deformation is the largest, followed by the X direction, and the Y direction deformation is the smallest. (3) It is too conservative to evaluate the seismic stability of dam slope with the minimum safety coefficient, while it is more practical to use the minimum average safety factor as the evaluation index.

Finite-element upper-bound analysis of seismic slope stability considering pseudo-dynamic approach

The present study presents a novel procedure to assess the seismic slope stability, using the finite-element upper-bound method combined with the pseudo-dynamic approach. A pioneering work is performed to incorporate the pseudo-dynamic accelerations into the finite-element upper-bound analysis which combines the advantages of upper bound and finite element methods. The finite element method is principally used to discretize the domain of soil mass into finite elements, aiming to construct a kinematically admissible failure mechanism based on which the external and internal rates of work can be expressed. Based on the upper bound theorem, the upper bound formulations are derived from the virtual work rate equation, in the form of slope safety factor and limit surcharge acting on the slope crest. The problem of seeking the optimal upper bound solution is transformed to solve a linear programming problem within numerous kinematically admissible velocity fields, and this is achieved by using the interior-point algorithm implemented into the MATLAB. Pseudo-dynamic solutions are calculated and compared with the pseudo-static, limit equilibrium and FLAC results. The proposed procedure is versatile in considering the homogeneity and non-homogeneity of soil strength properties in seismic slope stability analysis. A benchmark problem with 0.5 m thick weak interlayer is discussed.

Fuzzy-Random Reliability Analysis of loess landslide Stability Under Earthquake

In this paper, the fuzziness of the failure events and the parameters of the random variables is considered. In the reliability analysis of the loess landslide stability, the combination of the randomness and fuzziness is proposed, and the fuzzy random reliability calculation method of the loess landslide stability under the earthquake action is proposed. The established model is applied to the seismic stability analysis of a loess landslide, and the evaluation results show that the loess landslide is in an under stable state under the seismic action.

Seismic Stability Analysis of Loess Landslide Based on Orthogonal Test

A numerical model of a loess landslide is established by using numerical simulation method to simulate the stability of the loess landslide under earthquake load. The results show that the loess landslide is stable before the earthquake and instable under the earthquake. The horizontal displacement and shear strain increment of the front part of the sliding slope increase obviously under the earthquake. At the same time, the sensitivity analysis of the seismic stability of the loess landslide is carried out by using the orthogonal test design method. The results show that the seismic action is the second factor to the internal friction angle of the sliding zone soil. With the increase of the seismic intensity, the decrease trend of the stability coefficient increases.

Seismic stability analysis of tunnel face in purely cohesive soil by a pseudo-dynamic approach

To give a solution for seismic stability of tunnel faces subjected to earthquake ground shakings, the pseudo-dynamic approach is originally introduced to analyze tunnel face stability in this study. In the light of the upper-bound theorem of limit analysis, an advanced three-dimensional mechanism combined with pseudo-dynamic approach is proposed. Based on this mechanism, the required support pressure on tunnel face can be obtained by equaling external work rates to the internal energy dissipation and implementing an optimization searching procedure related to time. Both time and space feature of seismic waves are properly accounted for in the proposed mechanism. For this reason, the proposed mechanism can better represent the actual influence of seismic motion and has a remarkable advantage in evaluating the effects of vertical seismic acceleration, soil amplification factor, seismic wave period and initial phase difference on tunnel face stability. Furthermore, the pseudo-dynamic approach is compared with the pseudo-static approach. The difference between them is illustrated from a new but understandable perspective. The comparison demonstrates that the pseudo-static approach is a conservative method but still could provide precise enough results as the pseudo-dynamic approach if the value of seismic wavelengths is large or the height of soil structures is small.

Notes on the behaviour of trajectories of polynomial dynamic systems

Dynamic systems play a key role in various directions of modern science and engineering, such as the mathematical modeling of physical processes, the broad spectrum of complicated and pressing problems of civil engineering, for example, in the analysis of seismic stability of constructions and buildings, in the fundamental studies of computing and producing systems, of biological and sociological events. A researcher uses a dynamic system as a mathematical apparatus to study some phenomena and conditions, under which any statistical events are not important and may be disregarded. The main task of the theory of dynamic systems is to study curves, which differential equations of this system define. During such a research, firstly we need to split a dynamic system’s phase space into trajectories. Secondly, we investigate a limit behavior of trajectories. This research stage is to reveal equilibrium positions and make their classification. Also, here we find and investigate sinks and sources of the system’s phase flow. As a result, we obtain a full set of phase portraits, possible for a taken family of differential dynamic systems, which describe a behavior of some process. Namely polynomial dynamic systems often play a role of practical mathematical models hence their investigation has significant interest. This paper represents the original study of a broad family of differential dynamic systems having reciprocal polynomial right parts, and describes especially developed research methods, useful for a wide spectrum of applications.

Seismic fragility functions for slope stability analysis with multiple vulnerability states

The seismic performance and stability analysis of slopes are important in predicating damage and mitigating potential losses in landslide-prone areas. Fragility functions can give results of slope performance assessment that are more comprehensive and richer. This study presents a procedure of constructing seismic fragility functions for slope stability analysis with various vulnerability states based on incremental dynamic analysis (IDA). IDA is a performance-based earthquake engineering analysis based on a series of dynamic time history analyses conducted for suitable multiple-scaled seismic records. IDA not only estimates the seismic demand and capacity of systems but also provides basic data for the estimation of fragility functions. Firstly, an ensemble of seismic records meeting the requirements of specific site conditions of a slope is selected to consider the randomness of ground motion. A series of seismic stability analyses of the slope are performed to obtain the dynamic safety factor time history of the slope. Each minimum safety factor and corresponding seismic intensity measure is then extracted to develop a set of IDA curves. On the basis of IDA results, analytical seismic fragility functions of a slope are developed considering the prescribed various vulnerability states of the slope in terms of the safety factor. The failure probabilities of exceeding different specific vulnerability states for a given intensity measure of the earthquake are finally obtained.

Probabilistic seismic slope stability analysis and design

Deterministic seismic slope stability design charts for cohesive–frictional ([Formula: see text]) soils are traditionally used by geotechnical engineers to include the effects of earthquakes on slopes. These charts identify the critical seismic load event that is sufficient to bring the slope to a state of limit equilibrium, but they do not specify the probability of this event. In this paper, the probabilistic seismic stability of slopes, modeled using a two-dimensional spatially random [Formula: see text] soil, is examined for the first time using the random finite element method (RFEM). Slope stability design aids for seismic loading, which consider spatial variability of the soil, are provided to allow informed geotechnical seismic design decisions in the face of geotechnical uncertainties. The paper also provides estimates of the probability of slope failure without requiring computer simulations. How the design aids may be used is demonstrated with an example of slope remediation cost analysis and risk-based design.

Three-dimensional internal stability analysis of geosynthetic-reinforced earth structures considering seismic loading

The seismic internal stability analysis of geosynthetic-reinforced earth structures (GRESs) is typically conducted under idealized two-dimensional conditions. Though this assumption simplifies the analysis and design procedure, GRESs are three-dimensional in nature. In addition, existing seismic internal stability analyses of three-dimensional GRESs focus on the required strength of reinforcement, ignoring potential pullout failure of reinforcement. This may result in potentially underconservative design as the required length of reinforcement is a vital part of the internal stability analysis of GRESs. In this study, both the required strength and length of reinforcement of three-dimensional GRESs are calculated considering pseudostatic seismic loading. The results are compared with idealized two-dimensional solutions and presented in the form of stability charts for illustrative purposes and ease of application. It shows that seismic loads amplify the effects stemming from consideration of three-dimensional conditions.

Economical Design of Reinforced Slope Using Geosynthetics

Slope failures triggered by earthquakes are one of the most important geotechnical earthquake hazards that can cause severe damage to road/rail embankments, bridge abutments and dams. In the present paper, a road embankment of height 5 m is designed for Roorkee region using locally available soil as per the Indian Standards Specifications. Seismic slope stability analysis is also carried out to ensure the safety of the constructed or designed embankment under seismic loading appropriate to the considered region. The factor of safety obtained is unsatisfactory and hence there was need of reinforcement. Geosynthetics used for reinforcement include geotextiles and geogrids. Geosynthetics aims to ensure strength, stability and serviceability over its intented life span. To assess slope stability of reinforced slope, a single soil slope was analysed using Geostudio 2004 to estimate factor of safety under static and dynamic conditions. This study proposes a geotechnical stable slope embankment and also, the economical design using geosynthetics in both static and dynamic loading conditions which can be of great help in practical applications of geotechnical earthquake engineering.

Seismic rotational stability analysis of reinforced soil retaining walls

Reinforced soil retaining walls have been widely constructed all over the world. Although the limit equilibrium (LE) method is common practice in design, a growing body of experimental and analytical evidence has demonstrated that it could lead to overly conservative (and hence, uneconomical) design. In this paper, a kinematic limit analysis method, combined with a pseudo-dynamic method of analysis, is developed for rotational stability analysis of reinforced soil retaining walls based on the log-spiral failure mechanism. The proposed analysis method is validated against the results from different pseudo-static methods. However, the rotational stability and the corresponding yield acceleration coefficients from the proposed method are shown to vary with time, and with factors such as the backfill shear modulus and the frequency of ground motion. Parametric analyses are also conducted to study the influences that pseudo-dynamic analysis parameters, reinforcement properties, wall height, and soil strength have on rotational stability and failure geometry of reinforced soil retaining walls. Results indicate that optimum value of ultimate reinforcement strength is greater when the reinforcement is more widely spaced. Additionally, the cross-sectional area of the rotational failure mass is smaller for walls with lower-strength reinforcement and larger vertical spacing.

Kinematic analysis of seismic slope stability with discretisation technique and pseudo-dynamic approach: a new perspective

Kinematic analysis of seismic slope stability with discretisation technique and pseudo-dynamic approach: a new perspective

Discussion of “New Perspective on Seismic Slope Stability Analysis” by Changbing Qin and Siau Chen Chian

Discussion of “New Perspective on Seismic Slope Stability Analysis” by Changbing Qin and Siau Chen Chian

Implementation of a large deformation finite element modelling technique for seismic slope stability analyses

Post-slide investigations show large displacement of failed soil mass in many earthquake-triggered landslides. An Eulerian-based finite-element modelling (FEM) of large deformation of soil, for pseudostatic and dynamic loadings, is presented in this study. The Eulerian FEM is compared with Lagrangian-based explicit and implicit finite-element (FE) modelling approaches. The dynamic FE modelling of two hypothetical slopes for eight earthquake acceleration–time histories show that the failure surfaces develop progressively, which cannot be modelled using the traditional limit equilibrium method (LEM). A large plastic shear strain concentration (i.e. shear band formation) occurs when the strain-softening behaviour of soil is considered. The similarities and differences between the results of dynamic and pseudostatic FE analyses based on estimated pseudostatic coefficient from acceleration–time records are presented. The duration of an earthquake influences the failure process and displacement of the failed soil mass. The displacement of the toe obtained from FEM is compared with Newmark's simplified approach. The developed Eulerian-based FE modelling technique has been used to simulate large-scale landslides in sensitive clays due to earthquake loading [1].

Two-dimensional dynamic analysis of seismic slope stability using DEM coupling with strength reduction technique

The seismic stability of earth slopes attracts more attentions. In this study, the two-dimensional dynamic analyses of slope stability subjected to earthquakes are conducted by DEM. In order to prevent boundary effect in dynamic analysis, the quiet boundary is applied in the model, which can fully absorb seismic waves. The progressive failures are clearly observed. The obtained slip surface is in good agreement with that determined by pseudo-static method. In order to calculate the factor of safety using DEM, the strength reduction technique is adopted. A numerical example regarding the instability of the soil slope induced by earthquake shows the validation of the strength reduction technique. In the procedure, several failure criteria are proposed to determine the global instability of the slope. The factor of safety is defined and then compared with the results from other methods. It demonstrates that the discrete element method with strength reduction technique is a promising and feasible method for assess the seismic slope stability.

Seismic dynamic stability analysis of landslide based on unbalanced thrust method

The unbalanced thrust method is one of the main research methods for the stability evaluation of the geological hazard of the landslide caused by the earthquake. When the traditional unbalanced thrust method is used to calculate the safety factor of the seismic downhill slope, all the soil strips use the same seismic acceleration. This treatment does not consider the propagation process of seismic waves in the landslide body. In this paper, the peak acceleration of the seismic center of each soil strip is obtained by numerical simulation, considering the temporal and spatial variation of seismic waves in soil strip, forming an imbalance considering multi-point seismic action thrust method. Based on this, taking the landslide formed by the K92 roadbed excavation of a highway in Yunnan as an example, the unbalanced thrust and safety factor under different seismic intensities are analyzed, and the engineering reinforcement effect is studied. Analysis shows that: sliding surface has obvious sliding section and anti-slip section, and the sliding section is distributed in the soil block with large inclination angle at the trailing edge of the landslide,and the anti-slip section is distributed in the lower part of the landslide; the landslide is in an unstable state after excavation, which is consistent with the scene.After comprehensive measures such as slope reduction, anti-slide pile reinforcement and prestressed anchor cable reinforcement, the landslide meets the requirements of earthquake resistance against IX. The research results provide an effective method for the evaluation of dynamic stability of landslides caused by earthquakes.

Seismic stability analysis of a pre-cracked natural slope: a case study of Aomar slope in Algeria

ABSTRACT This paper presents and analyses the results of a series of seismic stability calculations performed on a pre-cracked natural slope located at Aomar city in Bouira Province, Algeria, whose collapse caused significant damages to the slope and surrounding structures. Among the calculation methods used to determine the potential slip surface of the slope (limit equilibrium method, yield design theory, plasticity calculation and limit analysis theory), the limit equilibrium method and the yield design theory seem best suited for this type of problem. The instability causes of the slope can be multiple and the cracks present upstream of it have probably been the catalyst. In addition to the probable seismic action, the potential instability factors of the slope considered in this study are the shear strength loss of the soil mass, the pore water pressure generated by the water table fluctuations, a possible excessive overloading upstream and an eventual unloading downstream. Stability calculations performed on assumed uncracked and cracked slope confirm the overall collapse mode observed in the field. They also show that it is a slight seismic action combined with some of these negative factors that caused the collapse of the slope.

Reliability analysis for seismic stability of tunnel faces in soft rock masses based on a 3D stochastic collapse model

A new horn failure mechanism was constructed for tunnel faces in the soft rock mass by means of the logarithmic spiral curve. The seismic action was incorporated into the horn failure mechanism using the pseudo-static method. Considering the randomness of rock mass parameters and loads, a three-dimensional (3D) stochastic collapse model was established. Reliability analysis of seismic stability of tunnel faces was presented via the kinematical approach and the response surface method. The results show that, the reliability of tunnel faces is significantly affected by the supporting pressure, geological strength index, uniaxial compressive strength, rock bulk density and seismic forces. It is worth noting that, if the effect of seismic force was not considered, the stability of tunnel faces would be obviously overestimated. However, the correlation between horizontal and vertical seismic forces can be ignored under the condition of low calculation accuracy.

Seismic Stability Sensitivity and Uncertainty Analysis of a High Arch Dam-Foundation System

Parameter uncertainty associated with concrete arch dams always arises from modeling assumptions and the lack of knowledge or information of the engineering geological situations, especially in the seismic stability analysis of arch dams. In this research, a high arch dam is selected as a case study for probabilistic analysis of the seismic stability performance. The arch dam abutment and the dam are coupled as a system. A comprehensive approach considering contraction joints, boundaries of the probable sliding rock mass and the dam-foundation interface is presented. The contact nonlinearity is solved by using the dynamic contact model with Lagrange multiplier method. The main parameters of the probable sliding block are considered as random variables containing the friction coefficients and cohesions. Both the slippage and sliding area ratio are chosen as the engineering demand parameters (EDP). The sensitivity analysis is performed to reveal the relative influence of each parameter separately by the approximate incremental dynamic analysis (IDA) method. The friction coefficients are shown to be more crucial than the cohesions on the dam’s resistance to seismic instability. The sliding area ratio can be better used for unveiling the sliding process of the arch dam of concern, while the slippage is useful for one to judging the stability of the arch dam under seismic hazards. The Latin hypercube sampling (LHS) with approximate moment estimation is used to investigate the parameter uncertainty to the seismic stability performance of the high arch dam. The results provide a useful reference for using the median/mean-parameter model to accurately estimate the median/mean response of the dam.