Pseudo-static Analysis Research Articles

Pseudo-static and Dynamic Analysis of Mine Rock Slope Under the Influence of Production Blasting

Pseudo-static and Dynamic Analysis of Mine Rock Slope Under the Influence of Production Blasting

Comparison of stability analysis methods for safe design of volcanic rock slope

The performance of the stability chart (SC), limit equilibrium (LE), and finite element (FE) methods for stability analysis of weathered volcanic rock slopes under static and earthquake loads is not fully understood. This research aimed to evaluate the performance of the SC, LE, and FE methods for slope stability analyses by studying a case of a weathered volcanic rock slope at the Leuwikeris Dam diversion tunnel in Indonesia. Site characterisations were carried out to obtain the input parameters for the static and pseudostatic slope stability analyses. The results showed that using various search methods of failure surface and the suggested optimum number of finite elements, multiple non-circular failure surfaces were predicted from the LE and FE methods that were not anticipated in the initial slope design based on the SC method. The location and shape of the failure surfaces from the LE method agreed with those from the FE method. The difference between the Fs values from the static LE analysis and those from the static FE analyses was less than 14%, but the discrepancy increased up to 78% in the pseudostatic analyses. This study highlights the importance of validating the results from one method with the other methods to prevent slope failures.

Pseudo-static slope stability analysis using explainable machine learning techniques

Pseudo-static slope stability analysis using explainable machine learning techniques

The Geomechanics of the Dangkhar Landslide, Himachal Pradesh, India

The Dangkhar Landslide is an extremely large landslide located in the Spiti Valley of Himachal Pradesh, India. The landslide is situated in a remote high mountain desert within the Tethys Himalaya at elevations between 3400 m and 5600 m. It is amongst the five largest continental landslides on earth, covering an area of approximately 54 km2 and having an estimated volume of 15–20 km3. Geomechanical evaluations based on the block theory indicate that the Dangkhar Landslide formed as a result of unfavorable combinations of structural geological features and complex surface morphology. A massive kinematically removable block is created by a regional synclinal flexure that is crosscut and kinematically liberated by bounding side valleys. Three-dimensional block kinematics are necessary to permit the release of the giant block and its sliding along the synclinal flexure. Pseudostatic slope stability sensitivity analyses incorporating estimates of site seismicity and shear strength parameters suggest that earthquake shaking could have triggered instability if the static factor of safety was less than or in the range of about 1.5–1.9. Considering the glacial history of the region, ice debuttressing represents an additional potential triggering mechanism.

Kinematic response of a pile within a soil slope to SH wave excitation

It is widely recognized that the topography of a slope can significantly enhance the magnitude of seismic waves. Nevertheless, the mechanism behind the topographic amplification on the kinematic response of a pile within a soil slope remains unclear. Consequently, a newly rigorous method is employed to investigate the kinematic response of a pile within a soil slope. The proposed method which combines the Wave Function Expansion (WFE) method and the Beam on Dynamic Winkler Foundation (BDWF) model advances the rigorous theoretical study for the kinematic response of a pile on slope from the pseudo-static analysis to the frequency-domain analysis. The proposed solution well captures the kinematic response of a piles within a slope. The parametric analysis focuses on investigating the influence of slope topographic amplification effects on pile vibration under different incident frequencies, slope gradients, and pile-to-soil modulus ratios. The results indicate that steep slopes and high pile-to-soil modulus ratios lead to higher topographic amplification effects, with specific frequencies significantly amplifying the kinematic response of pile within a slope. Nonetheless, as the pile located beyond twice the length of the slope, the amplification effect notably diminishes.

Improved pseudostatic analysis of pile response to seismic ground movement: Multiple characteristic ground displacement profiles

Piles may be subjected to significant kinematic loading from ground movement under earthquakes. Pseudostatic analysis, which is based on the Winker beam model, traditionally adopts a single ground displacement profile, known as the characteristic ground displacement profile, for assessments of pile response under this loading condition. This study conducts dynamic analyses with different soil, pile-head-fixity, and seismic conditions and generates displacement, moment, and shear force response envelopes to evaluate the appropriateness of the characteristic displacement profiles of four common methods. These methods give inconsistent predictions because the maximum responses at different depths in the pile response envelopes occur at different points in time. To address this issue, we propose using multiple characteristic ground displacement profiles, which are determined by the maximum ground relative deformation or rotation. These multiple profiles, when used in pseudostatic analyses, give consistent predictions with dynamic pile response envelopes in most scenarios, thus overcoming the limitations of conventional single-profile methods.

Estimating sliding displacement of slopes induced by earthquake sequences based on the finite element method

After shocks trigger or worsen landslides by exacerbating damage to slopes. In this study, slope sliding displacements induced by seismic sequences were calculated. The combined effects of mainshocks and aftershocks on slope sliding were examined in this study using 273 ground motion records from real seismic sequences. A three-layer clayey slope was modeled in OpenSees. The ground motions were input for dynamic analysis to calculate the corresponding sliding displacements. More than 20% of the seismic sequences caused slope instability. The Arias intensity (Ia) of the mainshock had the strongest correlation with sliding displacements. The strength reduction technique was used for the pseudo-static stability analysis of the slope whose yield acceleration (ky ) value was 0.23g. The Newmark method computed smaller displacements compared to the finite element method which calculated the dynamic behavior of the slope more accurately when Ts/Tm > 0.1. The Ia of the mainshock was the optimal parameter. An empirical model based on finite element numerical analysis was proposed for predicting slope sliding displacements induced by seismic sequences. The predictive model, unlike the traditional rigid sliding block method, prevented some unrealistic assumptions. The proposed model was more conservative than numerical algorithm-based predictive models that compute only the mainshock effect.

Pseudo-static Winkler springs for longitudinal underground structures subjected to shear waves

ABSTRACT Shear waves in underground longitudinal structures impose deformations that need to be accounted for in structural design. Simplified approaches for such structures typically consider the Winkler foundation model, assuming Euler-Bernoulli beam theory, which neglects shearing-induced distortions, especially significant when shear waves are a dominant component of the seismic motion. In order to overcome these limitations, Timoshenko beam models have been proposed in the literature. These approaches however depend on an appropriate determination of the ground springs. Existing analytical formulations often assume plane-strain conditions, inadequate for representing low frequencies and thus are not directly applicable for pseudo-static interaction analyses. The present paper develops analytical solutions to determine transverse and rotation Winkler springs for structures subjected shear waves. The proposed springs overcome the drawbacks of plane-strain models and can be construed as a generalisation of them. The springs are obtained as a function of the seismic wavelength and the ground-structure stiffness contrast. Results obtained are validated against solutions from the literature and numerical results from a full 3D finite-element model. A non-dimensional parametric study is also presented, that allow an expedited evaluation of ground springs for practical applications.

Pseudo-static analysis of 3D unsaturated bench slopes stabilized by multiple rows of piles

Bench slopes incorporated with multiple rows of anti-slide piles remain an effective technique in landslide disaster preventions and are widely employed in the design of new subgrades and embankments. To provide more realistic results for engineering guidance, the three-dimensional (3D) effect and suction in soils require explicit considerations. Employing the upper bound limit analysis method, a 3D limit analysis of bench slopes stabilized by multiple rows of piles is performed in this paper. The upper bound solutions of several illustrative slopes are optimized and compared with the published ones, indicating the validity of the optimization program and the proposed method. A series of parameter analyses are conducted regarding the roles of suction and anti-slide piles in slope safety assessments. The results show that the suction effect and pile reinforcement increase continually as the pile location increases and the influence of bench width can be ignored. The stability of bench slopes stabilized by multiple rows of piles differ with that of slopes stabilized by single row of piles dramatically. The maximum pile reinforcement reaches 70% for sandy soil slopes but only 30% for clayey soil slopes. The influences of surcharge load and seismic load on the pile reinforcement can nearly be neglected.

Pseudo-static stability analysis of a laterally confined dip slope investigated by dynamic centrifugal models

Pseudo-static stability analysis of a laterally confined dip slope investigated by dynamic centrifugal models

Assessing the stability of the reservoir rim in moraine deposits for a mega RCC dam

<abstract> <p>Diamer Basha Dam is an under-construction, 272-meter-high, roller compacted concrete (RCC) dam on the Indus River in Pakistan. Once constructed, it will be the world's highest RCC gravity dam with a 105-kilometer-long reservoir. Most of the reservoir lies in unstable moraine deposits with steep slopes. Events like saturation during reservoir filling, alternate wetting, drawdown during reservoir operation, or a seismic event could trigger a large mass movement of these slopes into the reservoir to disrupt the dam functionality. This work identified the 15 most vulnerable slide areas using digital slope maps, elevation maps, and satellite imagery. Deterministic slope stability analysis was carried out on the identified sections under various stages of reservoir operation for static and seismic loading, using pseudo-static and dynamic analysis approaches. Probabilistic analysis was then performed using Monte Carlo simulation. The findings showed that most moraine deposits would collapse under reservoir filling, rapid drawdown, or seismic activity. Following the assessments, landslide susceptibility maps were generated, and an assessment of potential impacts, including the generation of dynamic waves, reservoir blockage, increased sediment loads, and reduced reservoir storage capacity, was also performed.</p> </abstract>

Road cut slope stability analysis for static and dynamic (pseudo-static analysis) loading conditions

Abstract Slope instability has been identified as one of the most natural and man-made disasters that can lead to the life of humans in danger and enormous loss of capital. The roads which pass on the hilly and mountainous terrains are frequently affected by slope failures since hilly and mountainous areas are characterized by variable topographical, geological, hydrological, and land-use conditions. Slope stability analysis was carried out using FEM (plaxis 2D) and LEM (slide software). The stability analysis covers both static and dynamic (in pseudo-static analysis) loading conditions on soil and rock material along selected critical slope sections. Two soil-critical slope sections and two rock-critical slope sections are analyzed in this study. The strength reduction method and method of the slice with Mohr–Coulomb model were used in FEM and LEM, respectively. The slope stability analysis was carried out for both dry and wet states of the soil and rock material along the critical slope sections (i.e., static dry, dynamic dry, static wet, and dynamic wet). The analysis result shows that the total displacement of the slope along soil critical slope section one is (0.58703, 0.58755, 2.35, and 2.38 m), along soil critical slope section two is (0.6574, 0.6621, 1.2841, and 1.2872 m), along rock-critical slope section one is (4.8624, 4.8672, 17.8463, and 17.8512 m) and total displacement along rock-critical slope section two is (3.8365, 3.8391, 11.437, and 11.6275 m) during static dry, dynamic dry, static wet, and dynamic wet loading conditions, respectively. In general, the result shows soil critical slope sections one and two are stable in dry conditions and unstable in wet conditions. Rock-critical slope sections are stable during the dry and wet states of the slope.

Polynomial response surface-based transformation function for the performance improvement of low-fidelity models for concrete gravity dams

The behavior of concrete gravity dams under seismic loading is a complex engineering problem dependent on a wide range of variables. Probabilistic methods can be used to evaluate the capacity of an individual or a portfolio of dams to withstand seismic events. However, due to the high number of re-evaluations required by such methods, simplified models that may not fully capture the complexity of the problem are frequently adopted in the evaluations. For a portfolio of dams that requires geometric uncertainty to be included in the list of controlled variables, the number of re-evaluations increases even further. This is a common engineering problem, where the cost-performance trade-off must be evaluated for every project. To address this issue, this study proposes a machine learning-based transformation function that improves the results obtained with a simplified method by converting low-fidelity data into high-fidelity data. The proposed procedure is applied to analyze the seismic response of a dam-reservoir-foundation system considering three approaches for geometric uncertainty, with increasing complexity. The final function takes as input low-fidelity observations, as well as geometric, material and seismic parameters, and outputs improved observations, with accuracy levels comparable to those obtained with a high-fidelity model but at a much lower cost. The sliding factor of safety resulting from a pseudostatic analysis is taken as the low-fidelity observation, and the sliding displacement from a nonlinear finite element analysis is selected as the high-fidelity observation. The resulting transformation function is then used to generate fragility curves for a well-documented case study dam, and the results using the proposed methodology and from a traditional fragility analysis are compared. It is observed that the proposed methodology to generate transformation functions is capable of correlating methods with radically different hypotheses, precision levels and even different outputs.

Pseudo-static slope stability analysis and numerical settlement assessment of rubble mound breakwater under hydrodynamic conditions

This research focuses on the slope stability analysis of rubble mound breakwaters using the Bishop method, with a specific application to the Chamkhaleh Port in the Caspian Sea region. The study emphasizes the criticality of slope stability in coastal engineering to protect shorelines from erosion and damage caused by waves and currents. The Bishop method is employed in the analysis, allowing a comprehensive assessment of breakwater stability by considering soil properties, slope geometry, and external forces. Sensitivity analysis is conducted to evaluate the impact of various parameters on breakwater stability, enabling optimization of the design and identification of potential failure mechanisms. Additionally, the research addresses numerical settlement analysis using the finite element method. The finite element method proves effective in handling complex geometries and boundary conditions, accurately capturing deformational changes caused by breakwater construction under short-term and long-term conditions. The settlement analysis results indicate acceptable maximum settlements within the project area. To ensure the reliability of the breakwater, geotechnical investigations are conducted to determine the minimum channel slope and allowable distance from the breakwater edge, crucial parameters for achieving acceptable static and pseudo-static safety coefficients. The breakwater's overall stability is assessed, and the factor of safety is quantified to evaluate the probability of slope failure and associated risks. The findings demonstrate the satisfactory stability and settlement performance of the Chamkhaleh breakwater project, affirming its effectiveness in providing coastal protection for the port.

Research on Seismic Performance and Reinforcement Methods for Self-Centering Rocking Steel Bridge Piers

To study the seismic performance of self-centering circular-section rocking steel bridge piers whose functions can be restored after an earthquake, a high-precision finite element (FE) analysis model of such a bridge piers was established. The hysteresis behavior of concrete-infilled and hollow rocking steel bridge piers was compared. In response to the characteristics of the local deformation of the wall plates and elliptical deformation of the bottom surface, two reinforcement methods for the pier bottom, namely thickening the wall plate and adding longitudinal stiffeners in the plastic zone of the pier bottom, were proposed. The pseudo static analysis of bridge piers was carried out considering the effects of overall design parameters and reinforcement parameters of the pier bottom. The results indicate that the FE model used in this paper can obtain accurate horizontal load-displacement curves of rocking steel bridge piers. The hysteresis curves of the rocking steel bridge piers and infilled concrete rocking steel bridge piers is close, and directly using hollow steel bridge piers can improve the economic efficiency of the design. Compared to adding longitudinal stiffeners, the reinforcement form of thickened wall plates at the pier bottom has a better effect in improving the seismic performance of bridge piers. The reinforcement of the pier bottom has little effect on the energy dissipation capacity of the bridge pier, but it helps to reduce residual displacement and improve lateral stiffness.

Static and Pseudo Static Analysis of Embankment Slope Stability of Bener Dam, Purworejo Regency, Central Java

The Bener Dam is considered as one of the largest rock-fill dams in Indonesia. This dam will impact the inundation area of three main villages in the Wonosobo and Purworejo regency. Since this zoned embankment dam consists of rock-fill and the core material, the stability of the dam slope has to be done to ensure that the dam is stable against any failures including the seismic effects. Moreover, the seismic coefficient in the study area in the seismic analysis of the large dam slope is needed to be used in the analysis which is not yet done from the previous studies. This paper presents the analysis of the embankment slope stability of the Bener dam under static condition and pseudo static condition. The analysis takes into account the end stage of construction, the steady-state stage, and rapid drawdown stage. The results of utilizing the Finite Element Method to analyse the slope stability demonstrates that the dam embankment slopes are stable under static and seismic stress conditions in all the reservoir condition stages. After applying the seismic loading, the result of safety factor of slope stability is reduced while the rapid drawdown stage has the lowest safety factor.

Estimation of Shallow Landslide Susceptibility Incorporating the Impacts of Vegetation on Slope Stability

This study aimed to develop a physical-based approach for predicting the spatial likelihood of shallow landslides at the regional scale in a transition zone with extreme topography. Shallow landslide susceptibility study in an area with diverse vegetation types as well as distinctive geographic factors (such as steep terrain, fractured rocks, and joints) that dominate the occurrence of shallow landslides is challenging. This article presents a novel methodology for comprehensively assessing shallow landslide susceptibility, taking into account both the positive and negative impacts of plants. This includes considering the positive effects of vegetation canopy interception and plant root reinforcement, as well as the negative effects of plant gravity loading and preferential flow of root systems. This approach was applied to simulate the regional-scale shallow landslide susceptibility in the Dadu River Basin, a transition zone with rapidly changing terrain, uplifting from the Sichuan Plain to the Qinghai–Tibet Plateau. The research findings suggest that: (1) The proposed methodology is effective and capable of assessing shallow landslide susceptibility in the study area; (2) the proposed model performs better than the traditional pseudo-static analysis method (TPSA) model, with 9.93% higher accuracy and 5.59% higher area under the curve; and (3) when the ratio of vegetation weight loads to unstable soil mass weight is high, an increase in vegetation biomass tends to be advantageous for slope stability. The study also mapped the spatial distribution of shallow landslide susceptibility in the study area, which can be used in disaster prevention, mitigation, and risk management.

Evaluation of the dynamic behavior of pile groups considering the kinematic force of the slope using centrifuge model tests

In this study, dynamic centrifugal model tests were performed by installing a pile group on the slope to examine the effect of the kinematic force of the slope on the pile. Based on the results of this experiment, a method for calculating the slope kinematic force applicable to the pile foundation was derived, and the pseudo-static analysis was performed. The results showed that the moment difference from the experiment occurred at the top of the pile by 14-49% in the analysis model without ground kinematic force, but decreased to 3-35% when the ground kinematic force was considered. In particular, in the lead pile, which is most affected by the ground kinematic force, the moment difference was less than 20% when the ground kinematic force was considered, indicating that the pile moment by depth was most appropriately simulated.

Seismic displacement prediction methods, procedure, comparison and application

The methodology in the seismic design of slopes has evolved with technological advancement and the development of geotechnical engineering. Since methods with great limitations such as pseudo-static analysis to rigorous methods that require a lot of information for a better understanding of the behavior of the soil such as the dynamic analysis.
 This article develops the procedure, comparison, and application of methods for estimating seismic displacements, which are the Newmark (1965), Sarma (1975), Makdisi & Seed (1978) and Bray, Macedo & Travasarou (2018). Each of these methods considering the criteria of each one to obtain permanent displacements, such as yield acceleration, degraded period, spectral acceleration, magnitude, etc.
 As an applicative case, a rockfill dam and core central 50 m high placed in sandstone strata and moraine deposits interspersed with shale intrusions is shown, as seismic scenarios the Lima 1974 earthquake, the Attic 2001 earthquake and the earthquake were used. of Pisco 2007, considering both NS and EW directions. Likewise, the response spectrum on the base of the failure surface, resulting from a nonlinear seismic response analysis from 3 columns in the dam, is considered as information. The methods of Newmark (1965), Sarma (1975), Makdisi & Seed (1978), and Bray, Macedo & Travasarou (2018) were applied, obtaining deformation results between 1 to 30 cm that according to their order of magnitude represent a stable condition for the dam.

Stability Analysis of Toll Road Embankment Induced by Liquefaction In Klaten Regency Based On FEM Numerical Simulation

The construction of toll roads in Klaten Regency supports community connectivity in increasing economic growth and accessibility to tourist areas around the southern part of Java Island. The location of this study is in Polanharjo District, Klaten Regency. The study area has geological conditions, sandy volcanic ash, and shallow groundwater levels and is accompanied by a history of earthquakes that have occurred greater than Mw. 5.0. These three things are triggers for liquefaction. This study discusses the stability analysis of toll road embankments at the STA. 10+724 on the construction of the Solo - Yogyakarta - YIA Kulon Progo Toll Road due to the potential for liquefaction reaching 14 meters. The road embankment construction is placed on the ground surface, which has the potential for liquefaction with a height of up to 5 meters. Calculate the safety factor using the numerical simulation finite element (Plaxis v.8.2 software) with static and pseudostatic analysis. Numerical calculations show that the stability analysis of toll road embankments placed on the ground with the liquefaction potential is still safe for construction with a safety factor on the static analysis (SF: 1.989 > 1.5) and pseudostatic analysis (SF: 1.912 > 1.1).