This study investigates the seismic response of a reinforced concrete (RC) tunnel using two-dimensional plane strain finite element models calibrated and validated against experimental results. A comprehensive parametric study is then conducted to explore the influence of tunnel-soil flexibility ratio, soil relative density, Arias intensity of the input motion, and ground motion components on the seismic soil-structure interaction (SSI). The results demonstrated that the flexibility ratio and racking coefficient increase with overburden height, while soil deformations decrease. Acceleration amplification factors rise from the bottom soil to the ground surface, with dense soil showing higher amplification especially in the regions at and near the tunnel field. The horizontal amplification factor exhibits greater variability with increasing seismic energy intensity, and the effect of the vertical motion becomes more pronounced near the structure. The vertical amplification factor is lowest for the horizontal component, while the vertical and combined components exhibit higher values influenced by the presence of the tunnel with lower earthquake intensity. Soil relative density significantly influences the vertical and lateral pressures on the tunnel, with dense sand causing maximum vertical pressures on the top slab and walls. The vertical earthquake component has a greater impact on the tunnel's top slab pressure distribution than the horizontal component. Seismic bending moments are influenced by earthquake components, with the vertical component leading to the greatest positive bending moment values in the middle of the roof slab. Vertical soil deformation is significantly affected by the horizontal input motion component, whereas the vertical component minimally affects lateral soil deformation. These findings underscore the importance of capturing stress-strain response under cyclic loading, particularly near the tunnel crown, where complex stress interactions lead to increased variability in behavior.

Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering. They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes. However, no previous studies have assessed the mechanisms underlying seismic failure in rock slopes. In this study, large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration, displacement, and earth pressure responses combined with shattering failure phenomena. The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance, and these mutations may transform into potential sliding surfaces, thereby intensifying the nonlinear seismic response characteristics. Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners, leading to greater permanent displacements at the internal corners. Therefore, the internal corners are identified as the most susceptible parts of the slope. In addition, the concept of baseline offset was utilized to explain the mechanism of earth pressure responses, and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage. Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope, i.e. the formation of tensile cracks at the internal corners of the berm, expansion of tensile cracks and bedding surface dislocation, development of vertical tensile cracks at the rear edge, and rock mass slipping leading to slope instability. Overall, this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

The seismic response characteristics of the Yellow River terrace are crucial, as it is one of the key human activity areas. Seismic response characteristics of Yellow River terrace stations in Ningxia were analyzed using strong-motion earthquake records from seismic observations in the Loess Plateau and corresponding station data, employing the Horizontal-to-Vertical Velocity Response Spectrum Ratio method. The seismic vulnerability coefficient (Kg) was computed, and the bedrock depth was estimated. The results indicate that the spectral ratio curves of the Yellow River terrace can be classified into three types: single-peak, multi-peak, and ambiguous-peak types. The predominant period of the terraces ranges from 0.12 to 1.22 s, and the amplification factor ranges from 2.87 to 10.29. The calculated Kg values range from 2.09 to 63.24, and the bedrock depth ranges from 10.68 to 168.11 m. The site's predominant period, amplification factor, high Kg values, and deep bedrock depths can significantly impact seismic design, potentially leading to greater damage during earthquakes. Based on the predominant period, Kg values, and bedrock depth, the seismic vulnerability of Yinchuan is assessed to be high.

This study investigated the seismic performance and assessed the seismic fragility of an existing pentapod suction-bucket-supported offshore wind turbine, focusing on the amplification of earthquake ground motions. A simplified suction bucket-soil interaction model with nonlinear spring elements was employed within a finite element framework, linking the suction bucket and soil to hypothetical points on the OWT structures at the mudline. Unlike conventional approaches using bedrock earthquake records, this study utilized free-field surface motions as input, derived from bedrock ground motions through one-dimensional wave theory propagation to estimate soil-layer-induced amplification effects. The validity of the simplified model was confirmed, enabling effective assessment of seismic vulnerability through fragility curves. These curves revealed that the amplification effect increases the vulnerability of the OWT system, raising the probability of exceeding damage limit states such as horizontal displacement of the tower top, tower stress, and horizontal displacement at the mudline during small to moderate earthquakes, while decreasing this likelihood during strong earthquakes. Comparisons between the Full Model and the simplified Spring Model reveal that the simplified model reduces computational time by approximately 75%, with similar seismic response accuracy, making it a valuable tool for rapid seismic assessments. This research contributes to enhancing seismic design practices for suction-bucket-supported offshore wind turbines by employing a minimalist finite element model approach.

Erzurum province is located close to two important faults, namely the North Anatolian Fault Zone and the East Anatolian Fault Zone. Additionally, numerous local faults such as the A & scedil;kale, Ba & scedil;k & ouml;y-Kandilli, Erzurum-Dumlu, Paland & ouml;ken, and Horasan-Narman Fault Zones could potentially trigger devastating earthquakes for Erzurum province. All these seismic hazard sources require a well-understanding of the soil dynamic properties in Erzurum province. The single-station microtremor method were carried out at 45 points to determine the Atat & uuml;rk University Central Campus-Erzurum soil dynamic parameters with this motivation. Seismic vulnerability index and seismic bedrock depth values were calculated with the help of empirical relations using the soil dominant frequency and soil amplification factor values calculated from the horizontal/ vertical spectral ratio method. The south-eastern region of the study area exhibits characteristics such as low soil dominant frequency values, high soil amplification factor values, elevated Kg values, and considerable engineering bedrock depth. This area is particularly vulnerable to potential earthquake damage due to its high sediment thickness and susceptibility to site effects. Notably, points three and four also demonstrate low soil dominant frequency values, coinciding with the locations of hospitals and administrative units. Therefore, it is imperative to intensify site effect investigations, especially using active sources of geophysical methods in these specific areas.

This article examines the effects of slope topography, soil non-linearity and soil-structure interaction (SSI) in hilly areas, where severe damage to hill buildings during past earthquakes were observed. Two-dimensional finite element analysis is carried out to simulate seismic response of hill buildings situated on the center of the slopes for three earthquake time histories. The influence of topographic amplification and SSI as a function of frequency of ground motion and site condition are examined. The present study shows significant ground motion amplification near the crest. It was found that the Seismic-Slope Topographic Amplification Factor (S-STAF) indicating the effect of slope on the seismic response, increases with the increase of slope angle and peak ground acceleration. However, S-STAF was increased by a margin as much as 30% when the non-linearity of the soil is considered. The effects of structural irregularity are also investigated by considering two types of buildings, (i) stepback and (ii) stepback and setback. Relative displacement of each story normalized with its height is reported as a drift ratio for two different slopes. The inter-story drift ratio of stepback building is slightly smaller than that of stepback and setback building. The seismic displacement of the slope increases significantly due to the presence of the building. The significant effect of SSI is observed with the increase of slope angle and this effect is much dependent on the earthquake characteristics. Further, period lengthening characteristics, seismic displacement, rocking and stress distribution of the footings of a stepback building on slopes are also investigated.

The accumulated water within the drainage layer of a final cover system of municipal solid waste (MSW) landfills is the foremost reason for the failure of final covers. This study adopts a pseudodynamic (PD) method to assess the seismic stability of landfill cover systems against direct sliding failure (DSF) and uplifted floating failure (UFF). The novelty of this study lies in consideration of the simultaneous action of hydrostatic, hydrodynamic, and seismic forces on the cover soil layer. The factors of safety (FS) against DSF (FSds) and UFF (FSuf) failures are evaluated by incorporating the effects of shear and primary (P) wave velocities, the phase difference between the seismic waves, soil amplification, time duration, and frequency of the earthquake. The influence of phase change on FSds and FSuf is examined, and the results are compared with those obtained by the pseudostatic (PS) method. The results show that the PD method yields a 29.11% increase in FSds and a 23.29% reduction in FSuf values compared with the PS method. The effects of horizontal seismic acceleration coefficient, slope angle, stability number, cover soil layer thickness, and height of landfill on FSds and FSuf are observed for different conditions of immersion ratio (Ir). Consideration of the soil amplification factor reduces the values of FSds and FSuf by 12.48% and 18.46%, respectively. The cover soil thickness (h) should be chosen between 0.047H and 0.067H, where the height of the landfill is H, to maintain safety against DSF and UFF modes for Ir = 0.3. Further, design charts are presented to compute the optimum thickness of the cover soil under earthquake loading conditions by targeting FSds and FSuf >= 1.15. Pseudodynamic (PD) stability analysis of veneer cover systems with accumulated water in the drainage layers is useful to model the behavior of landfill covers when subjected to various external loading conditions, which include earthquakes, heavy rain, and other environmental factors. The results of the analysis could be used to optimize the design of landfill covers to ensure their stability over time. The analysis could help engineers determine the appropriate thickness of the clogged drainage layer and other design parameters that ensure the long-term stability of the landfill cover. It could help assess the risks associated with earthquake loading or heavy rain and determine the probability of failure of the landfill cover system. These results could be used to plan and implement risk mitigation measures to reduce the potential for damage or environmental harm. In addition, it could be used to monitor the performance of landfill covers against direct sliding failure (DSF) and uplifted floating failure (UFF). This study proposed design charts that could facilitate practicing engineers to achieve safe, cost-effective, and reliable design of final covers of municipal solid waste (MSW) landfills. The findings of this study could be beneficial when standardizing the international design codes for the seismic stability of veneer cover systems.