Search Results (27)

Coal mining can cause the rupture of the overlying strata, and the energy released by large-scale fractures can therefore induce earthquake disasters, which in turn can cause more secondary disasters. In the past 50 years, countless earthquakes induced by coal mining have been reported. In this paper, the main factors relating to the mining-induced seismicity, including the mechanical properties, geometry of the space, excavation advance, and excavation rate, are investigated using both experimental and numerical methods. The sensitivity of these factors behaves differently with regard to the stress distribution and failure mode. Space geometry and excavation advances have the highest impact on the surface settlement and the failure, while the excavation rate in practical engineering projects has the least impact on the failure mode. The numerical study coincides well with the experimental observation. The result indicates that the mechanical properties given by the geological survey report can be effectively used to assess the risk of mining-induced seismicity, and the proper adjustment of the tunnel geometry can largely reduce the surface settlement and improve the safety of mining. Full article

After the 2011 earthquake, lake water depletion has become a widespread issue in Sikkim, especially in regions classified as high to very high seismic zones, where many lakes have turned into seasonal water bodies. This study investigates Chochen Lake in the Barapathing area of Sikkim’s Pakyong district, which is facing severe water seepage and instability. The problem, intensified by the 2011 seismic event and ongoing local construction, is examined through subsurface fracture mapping using Vertical Electrical Sounding (VES) and profiling techniques. A statistical factor method, applied to interpret VES data, helped identify fracture patterns beneath the lake. Results from two sites (VES-1 and VES-2) reveal significant variations in weathered and semi-weathered soil layers, indicating fractures at depths of 17–50 m (VES-1) and 20–55 m (VES-2). Higher fracture density near VES-1 suggests increased settlement risk and ground displacement compared to VES-2. Contrasting resistivity values emphasize the greater instability in this zone and the need for cautious construction practices. The findings highlight the role of seismic-induced fractures in ongoing water depletion and underscore the importance of continuous dewatering to stabilize the swampy terrain. Full article

This study presents a scenario-based, two-dimensional flood modeling approach to assess the potential downstream impacts of a piping-induced dam failure triggered by seismic activity. The case study focuses on the Doğantepe Dam in northwestern Türkiye, located near an active branch of the North Anatolian Fault. Critical deformation zones were previously identified through PLAXIS 2D seismic analyses, which served as the physical basis for a dam break scenario. This scenario was modeled using the HEC-RAS 2D platform, incorporating high-resolution topographic data, reservoir capacity, and spatially varying Manning’s roughness coefficients. The simulation results show that the flood wave reaches downstream settlements within the first 30 min, with water depths exceeding 3.0 m in low-lying areas and flow velocities surpassing 6.0 m/s, reaching up to 7.0 m/s in narrow sections. Inundation extents and hydraulic parameters such as water depth and duration were spatially mapped to assess flood hazards. The study demonstrates that integrating physically based seismic deformation data with hydrodynamic modeling provides a realistic and applicable framework for evaluating flood risks and informing emergency response planning. Full article

The symmetrical Double-O-Tube (DOT) shield tunneling method, first developed in Japan in the 1980s, offers advantages in optimizing cross-sectional area and reducing construction space. While past studies have primarily focused on construction-induced settlement or empirical modeling, this study presents the first comprehensive three-dimensional seismic analysis of Taiwan’s first DOT shield tunnel, part of the CA450A contract of the Taoyuan International Airport MRT. A detailed numerical simulation is conducted using PLAXIS 3D 2024 with the Hardening Soil model, capturing both static and dynamic responses under earthquake loading. Notably, the analysis incorporates full-direction seismic input (3D) using Arias intensity-based filtering and scaling to assess the tunnel’s mechanical behavior under varying seismic intensities. Key structural responses such as displacement, axial force, shear force, and bending moment are evaluated. The findings reveal critical deformation patterns and stress concentrations in the central support structure, offering novel insights for the seismic design of complex multi-cell shield tunnels in high-risk seismic zones. Full article

Unstable sandy soils pose significant challenges for buried pipelines due to soil–infrastructure interaction, leading to settlement that increases the risk of displacement and stress-induced fractures. In earthquake-prone regions, seismic-induced ground deformation further threatens underground infrastructure. Fiber-reinforced polymer (FRP) composites have emerged as a sustainable alternative to conventional piling materials, addressing durability issues in deep foundations. This paper introduces novel explicit models for predicting the maximum settlement of oil pipelines supported by concrete or polymer micropiles under seismic loading. Using genetic programming (GP), this study develops closed-form expressions based on simplified input parameters—micropile dimensions, pile spacing, soil properties, and peak ground acceleration—improving the models’ practicality for engineering applications. The models were evaluated using a dataset of 610 data points and demonstrated good accuracy across different conditions, achieving coefficients of determination (R²) as high as 0.92, among good values for other evaluation metrics. These findings contribute to a robust, practical tool for mitigating seismic risks in pipeline design, highlighting the potential of FRP micropiles for enhancing infrastructure resilience under challenging geotechnical scenarios. Full article

Designing petroleum tanks that are inter-related with pipelines in a founding position containing very compressible soil are a challenging task, particularly when a possible high-water table and considerably high seismicity are also present. Some of the issues that occur are the problems of the time dependence of settlement behavior as well as the earthquake response of the soil–structure interaction system. This work intends to portray the following: (a) an estimation of the foundations and the corresponding consolidation time response and (b) the earthquake-induced geohazard as well as the soil–structure interaction considered for the foundation of the tanks alongside pipelines in a suburban area in Greece, namely Kalochori of Thessaloniki. A numerical analysis considering the dynamic and static behavior and inter-relation among the soil mass and the buried pipeline alongside the system of the foundation type and the soil beneath is performed. Also, the foundation type that was finally chosen as the optimized solution, namely the set of gravel piles and the subsequent prestress loading, is presented and discussed. Taking into account that the soil in the vicinity of the foundation will have its shear strength during an earthquake decreased to almost zero, risk reduction actions may be suggested for large stresses imposed on the pipeline. The methodology for the dimensionality of the gravel pile group as well as the preloading session indicate that a substantial reduction in the displacements of more than 50% is obtained with the combination of the methods, something that would not be feasible if the methods were implemented individually. Full article

Rocking shallow foundations interrupt the seismic transmission path from the base of the structure and possess advantages, such as effective seismic isolation, self-resetting capabilities post-earthquake, and low costs. A numerical model of the rocking shallow foundation was developed in OpenSees (version: Opensees 3.5.0) based on field test data using numerical simulation. The effect of different parameters (column height, foundation sizes, top mass, and soil softness and stiffness) on the seismic response characteristics of rocking shallow foundations is investigated, and the seismic response characteristics of rocking shallow foundations are analyzed under the action of sinusoidal waves of different frequencies and various seismic wave types. The results of the study show that, as the height of the column increases, the bending moment decreases and settlement decreases; as the size of the foundation increases, the bending moment increases and settlement increases; as the mass of the top increases, the bending moment increases and settlement increases; and as the soil becomes softer, the bending moment decreases, and settlement increases. Inputting a sine wave that matches the structure’s natural oscillation frequency may induce resonance. This phenomenon can significantly amplify the structure’s vibrations; thus, it is essential to avoid external excitation frequencies that coincide with the foundation’s natural oscillation frequency. Under seismic loading, the rocking shallow foundation can mitigate the bending moment in the superstructure. When the displacement ratio remains within −0.5 to 0.5 percent, the foundation settlement is minimal. However, when the absolute displacement ratio exceeds 0.5 percent, the soil exhibits plastic deformation characteristics, resulting in increased foundation settlement. This study is an important contribution to the improvement of seismic performance of buildings and an important reference for improving seismic design standards and practices for buildings in earthquake-prone areas. In the future, the seismic response characteristics of rocking shallow foundations under bidirectional seismic action will be investigated. Full article

Unstable sandy soil poses significant challenges for buried pipelines, particularly due to the increased risk of displacement and stress-induced fractures resulting from soil settlement and earthquake-induced ground deformation. These concerns are especially critical in seismically active regions where underground infrastructure is at higher risk. Fiber-reinforced polymer (FRP) composites present a promising and sustainable alternative for deep foundations, offering durability and reduced maintenance costs compared to conventional materials. This study introduces a novel approach to enhancing the seismic performance of pipelines buried in sandy soils by numerically investigating a three-dimensional (3D) multipipe grouting micro anti-slide pile system, utilizing a polyurethane polymer slurry as the grouting material. Key parameters such as pile spacing, diameter, and length, along with the effects of soil wetting and various earthquake intensities, were examined under the influence of surface loads exerted by a fully loaded truck. The results demonstrate that using polymer micropiles significantly reduces soil and pipeline settlement by 15% to 50%, with larger pile diameters and lengths further decreasing settlement and strain on pipelines. While seismic excitation increases settlement, polymer grouting effectively mitigates this impact, leading to substantial reductions in settlement. Full article

This study evaluates the earthquake-induced movement of mechanically stabilized earth (MSE) walls. A thorough investigation was conducted on an MSE wall model, utilizing a comprehensive finite element (FE) analysis. This research focuses on investigating and designing MSE walls made of reinforcement concrete and hollow precast concrete panels. It also involves comparative studies such as on the vertical pressure of the wall, horizontal pressure of the wall, lateral pressure of the wall, settlement of the wall, settlement of the backfill reinforcement, vertical pressure of the backfill, horizontal pressure of the backfill, lateral pressure of the backfill, vertical settlement of the foundation, and settlements of soil layers across the height of the MSE walls. The FE simulations used a three-dimensional (3D) nonlinear dynamic FE model of full-scale MSE walls. The seismic performance of MSE walls has also been examined in terms of wall height. It was found that the seismic motion significantly impacts the height of the walls. In addition, the validity of the proposed study model was assessed by comparing it to the reinforcement concrete wall and ASSHTO guidelines using finite element (FE) simulation results. Based on the findings, the hollow prefabricated MSE wall was the most practical alternative due to its lower displacement and settlement. The specifics of the modeling approach used in this study and the lessons learned serve as benchmarks for future comparable lines of inquiry and practitioners, especially as the computational power of desktop computers continues to rise. Full article

In engineering practice, properly characterizing the spatial distribution of soil liquefaction potential and induced surface settlement is essential for seismic hazard assessment and mitigation. However, geotechnical site investigations (e.g., cone penetration test (CPT)) usually provide limited and sparse data with high accuracy. Geophysical surveys provide abundant two-dimensional (2D) data, yet their accuracy is lower than that of geotechnical investigations. Moreover, correlating geotechnical and geophysical data can effectively reduce site investigation costs. This study proposes a data-driven adaptive fusion sampling strategy that automatically develops an assessment model of the spatial distribution of soil liquefaction potential from spatially sparse geotechnical data, performs monitoring of liquefaction-induced settlement, and integrates spatiotemporally unconstrained geophysical data to update the model systematically and quantitatively. The proposed strategy is illustrated using real data, and the results indicate that the proposed strategy overcomes the difficulty of generating high-resolution spatial distributions of liquefaction potential from sparse geotechnical data, enables more accurate judgment of settlement variations in local areas, and is an effective tool for site liquefaction hazard analysis. Full article

In recent times, induced joints have been set along the length of subway stations in order to avoid disordered cracking of the main structures occurring due to temperature stress, concrete shrinkage, creep, or uneven foundation settlement. At present, the use of induced joints in subway station structures is mainly based on engineering experience. The seismic response of induced joints has not yet been well explained, much less mastered. In this study, a 3-D numerical model of a subway station incorporating certain sorts of induced joints is established systematically. Then, the seismic response of those induced joints applied in different positions and various forms has been studied under different seismic waves by varying the spectral characteristics and peak acceleration values of the waves. The results show that the horizontal relative sliding displacement of the structures on both sides of an induced joint increases gradually from bottom to top along the structure of the subway station. While the vertical sliding displacements that occur along the section width are larger at both ends of the induced joints than in the middle. What is more, with an increase in seismic intensity, the horizontal relative sliding displacement becomes larger, while the vertical displacement becomes even smaller. In addition, the relative sliding displacement can be reduced by increasing the residual longitudinal reinforcement ratio of the induced joint. Furthermore, it is discovered that the setting of key grooves at the bottom plate of the induced joint section has a certain effect on controlling the horizontal relative sliding displacement, as well as a significant effect on preventing the vertical relative dislocation of the structures on both sides of the induced joint. Full article

The negative skin friction (NSF) of pile foundations is one of the most important factors in triggering building subsidence. To study the mechanism and development of the NSF over time, four methods have been used: theoretical calculations, field tests, model tests, and numerical modeling. To address the difficulty of sampling prototype soft soils in model tests, this study uses a dynamic triaxial instrument to select a similar material ratio that can effectively simulate the dynamic properties of the prototype soft soil as a soft soil layer, and input sine waves with different frequencies and peak ground acceleration (PGA) for shaking table tests to investigate the effects of frequency and PGA on the development of the distribution of NSF and the location of the neutral point of the pile foundation. The test results show that the pile NSF is mainly distributed in the upper part of the pile under horizontal sine wave loading, increases rapidly from 0 to 5 s, and stabilizes after 5 s. Its magnitude is influenced by the sine wave frequency and PGA, and the effect of PGA on the NSF is more significant. In addition, the pile neutral point position shifts downwards with increasing sine wave frequency and PGA, but the downwards shift is not significant. Full article

Urban settlements located in high-seismicity areas should benefit from comprehensive vulnerability analyses, which are essential for the proper implementation of vulnerability modelling actions. Alas, many developing countries face a shortage of knowledge on seismic vulnerability, particularly concerning its systemic component, as a consequence of a combination of data scarcity and a lack of interest from authorities. This paper aims to identify primary time-independent spatial patterns of earthquake systemic vulnerability based on the accessibility of key emergency management facilities (e.g., medical units, fire stations), focusing on the urban settlements located in the high-seismicity area nearby the Vrancea Seismogenic Zone in Romania. The proposed methodological framework relies on open source data extracted from OpenStreetMap, which are processed via GIS techniques and tools (i.e., Network Analyst, Weighted Overlay Analysis), to compute the service areas of emergency management centres, and to map earthquake systemic vulnerability levels. The analysis shows that accessibility and systemic vulnerability patterns are significantly impacted by a synergy of factors deeply rooted in the urban spatial layout. Although the overall accessibility was estimated to be medium-high, and the overall systemic vulnerability to be low-medium, higher systemic vulnerability levels in certain cities (e.g., Bacău, Onești, Tecuci, Urziceni). The presented findings have multi-scalar utility: they aid in the development of improved, locally tailored seismic vulnerability reduction plans, as well as the allocation of financial and human resources required to manage earthquake-induced crises at regional scale. Further to that, the paper provides a transparent methodological framework that can be replicated to put cities in high-seismicity areas on the map of systemic vulnerability assessments, laying the groundwork for positive change in countries where the challenges associated with high-level seismic risk are often overlooked. Full article

Searching for unknown earthquakes in Slovenia in the first millennium, we performed archaeoseismological analysis of Roman settlements. The Mesto pod mestom museum in Celje exhibits a paved Roman road, which suffered severe deformation. Built on fine gravel and sand from the Savinja River, the road displays a bulge and trench, pop-up structures, and pavement slabs tilted up to 40°. The city wall was built over the deformed road in Late Roman times, supported by a foundation containing recycled material (spolia) from public buildings, including an emperor’s statue. We hypothesize that a severe earthquake hit the town before 350 AD, causing widespread destruction. Seismic-induced liquefaction caused differential subsidence, deforming the road. One of the nearby faults from the strike-slip Periadriatic fault system was the seismic source of this event. Full article

Chile is exposed to the occurrence of medium- and large-magnitude earthquakes. As a result, national and international design codes have been developed, whose objectives are to grant an ideal behavior to the structures. However, in Chile, many of these structures do not comply with the design and construction standards of current regulations. Therefore, we propose to carry out a historical compilation that allows establishing the components that present the seismic vulnerability in bridges built from 1920 to 2010. We explored information gathered from the Government of Chile. We analyzed 553 bridges out of a total of 6835, considering superstructure and infrastructure components and seismic design evolution. The analysis emphasizes the elements that help improve the seismic performance of a bridge when natural or induced dynamic forces act on it, such as the length support, elastomeric bearing, seismic hold-down bars, transverse girders, seismic stoppers, bracing, and expansion joints. We identified that the most significant problems in bridges are the lack of seismic stoppers, both interior and exterior; lack of development length in the support tables; use of deficient expansion joints; and the inefficient construction of cross girders and baring support; in addition to the presence of differential settlements in elements of the infrastructure. Full article