Seismic Vibration Research Articles

Model tests on static/seismic behavior of three-hinged multi-arch culvert constructed using different embankment processes

A three-hinged multi-arch (THMA) culvert is a new type of underground structure that is gradually being adopted in practical engineering in Japan as an alternative to elevated bridges. However, there exist reports that THMA culverts were seriously damaged by earthquakes in the past, and research on the behavior of THMA culverts during the embankment process and exposure to post-construction earthquakes is insufficient. Therefore, to carefully investigate the static/seismic mechanical behavior of the THMA culvert, systematic 1 g shaking table model tests were carried out in the current study. THMA culverts were constructed using different embankment procedures in dry/saturated sand ground, and then subjected to seismic loading. The results showed that the different embankment procedures significantly affect the deformation mode of the multi-arch culvert on both dry and wet sand grounds, and the construction sequence involving simultaneous backfilling on both sides of the culvert can reduce the generated bending moments during seismic vibration. Furthermore, in all cases, the bending moments generated during the earthquake were significant on both sidewalls of the culvert in the range of 30°–60° from the ground, and the bending moments in the region near the hinges were smaller, which provided basic data for the optimized design of the culvert.

Pipe vibration attenuation through internal damping and optimal design of vibro-impact systems

Pipelines periodically supported by rack structures (PPRs) are common in chemical and petrochemical plants, among others, and conventional tools such as dampers and hysteretic absorbers are commonly used to mitigate large vibrations in these systems. In this study, we explore two alternative strategies: (i) enhancing the attenuation rate of PPR vibrations through structural internal damping, and (ii) using nonlinear vibro-impact systems (VIS) to reduce seismic vibrations in a PPR. To shed light on the first strategy, we develop analytical dispersion relations for a PPR and show how damping can improve the mitigation capabilities of the periodic system. As for the second strategy, we consider a 9-node beam, i.e., a single span (SS) of a PPR equipped with a VIS, and combine the central composite design (CCD) and Kriging metamodelling to maximize dissipation energy and minimize the number of impacts. This multi-objective optimization problem aims to find the most effective design solution for the VIS in terms of gap and coefficient of restitution (COR). Additionally, we consider the stochastic nature of seismic input and the possible chaotic behavior of the VIS. To account for the sensitive variability of the number of impacts in seismic records, we perform incremental dynamic analyses and calculate fragility functions for various engineering demand parameters, including the number of impacts. We define a 3D surface for selecting the optimal gap-COR pair. When impacts occur, transient results can be chaotic, and we compute the largest Lyapunov exponents of a few representative trajectories.

Comparative seismic performance of building with Cu-Al-Be and Ni-Ti SMARB base isolation system using particle swarm optimization

ABSTRACT This study deals with the optimal performance of a five-storeyed shear frame building, base isolated with shape memory alloy rubber bearing (SMARB), under a set of real earthquake data. Nickel-Titanium (Ni-Ti) as well as Copper-Aluminum-Beryllium (Cu-Al-Be) is used as SMA material, and the responses are compared for both systems. The variations of optimized responses of the building are obtained for changing various structural and isolator parameters. A numerical study is taken where the optimization problem is considered to minimize the top floor acceleration by obtaining the optimal value of normalised forward transformation strength (F S0 ) of SMA using the particle swarm optimization (PSO) algorithm, which is an advanced bio-inspired optimization technique and relies on an intelligent swarm of particles which search for the solution in the problem space. The study shows that Cu-Al-Be-based SMARB system is more efficient than the traditional Ni-Ti-based base isolation system in reducing the top floor acceleration of the building at a marginal cost of isolator displacement. The optimal F S0 is considerably higher for Cu-Al-Be SMA device in practical conditions. Overall this study shows that Cu-Al-Be is a better choice for SMARB isolated buildings for mitigating seismic vibration compared to Ni-Ti SMARB system.

Seismoacoustic Monitoring of a Longwall Face Using Distributed Acoustic Sensing.

Violent, dynamic failures of rockmasses in underground mines pose significant hazards to workers and operations. Over the past several decades, hardrock mines have widely adopted seismic monitoring to help address such risks. However, coal mines, particularly those employing the longwall mining method, have struggled to implement similar monitoring strategies. This is because typical longwall mines are much larger and mine more rapidly than hardrock mines. Moreover, regulations place significant restrictions on the subsurface use of electronics in coal mines due to potentially explosive atmospheres. We present a new monitoring concept that uses distributed acoustic sensing (DAS) to turn an entire longwall face into a seismoacoustic array. After exploring the acoustic response of our sensors in the laboratory, we deployed the array at an active underground longwall mine for several days. We examine 33 events recorded by both the in-mine DAS array and a surface seismic network. We observed that the array records both seismic vibrations traveling through rock and mining equipment as well as sound waves propagating in the workings. We show that waveform moveouts are clearly visible, and that the standard deviation of the audio recordings is a straightforward yet promising metric that could help quantify burst damage. Although improvements are needed before mines can routinely use this monitoring strategy, DAS-based seismoacoustic arrays may assist in understanding coal-burst mechanisms and managing associated risks in underground longwall mines as well as enable better understanding of damage associated with dynamic failures in other underground environments.

Location and Activity Changes of Slow-Moving Landslides Due to an Earthquake: Perspective from InSAR Observations

Strong earthquakes can not only trigger many landslides in a short period of time but can also change the stability of slopes in the earthquake area, causing them to be active for a long time after the earthquake. Research on the variation of slow-motion slopes before and after earthquakes can help us to better understand the mechanism of earthquake-affected landslides, which is also crucial for assessing the long-term landslide risk in seismically active areas. Here, L-band ALOS-2 PALSAR-2 images are utilized with the SBAS-InSAR algorithm to monitor and assess the location and activity changes of slow-moving landslides in the Iburi region (Hokkaido, Japan) before and after an earthquake occurred on 6 September 2018. Unlike previous studies, which focused on single typical landslides, we tracked all the landslides within a 33 × 55 km region close to the epicenter. According to the results, the majority of the co-seismic landslides that quickly failed during the earthquake are now stable, and a few of them are still moving. In contrast, due to near-field seismic shaking, certain slopes that did not show substantial surface changes during the earthquake period continued to move and eventually developed into slow-moving landslides. In addition, it can be seen from the spatial distribution of slow-moving landslides after the earthquake that this distribution is not only dependent on strong earthquake seismic vibration or the hanging-wall effect. Far-field weak vibrations can also accelerate landslides. Additionally, we discovered that the earthquake made the unstable slopes move more quickly but also tended to stabilize the slopes that were already in motion before the earthquake. The various response modes of slow-moving landslides to seismic events are related not only to the intensity of seismic vibration but also to the geological conditions of the region and to the size of the landslide itself. These findings are extremely valuable for studying the mechanism of earthquake-affected landslides.

Nonlinear dynamic analysis of a seismic vibrator-ground interaction system considering interval uncertainties

Seismic vibrators have wide prospections in geological exploration which can provide useful information of underground conditions for various geotechnical engineering. The enhancement of the exploration performance of the seismic vibrators closely relates to the dynamic response of the vibrator-ground (VG) system. This paper proposes an effective method for the uncertain nonlinear dynamics of the VG system. Firstly, the dynamic model of the VG system with uncertainties is developed based on the solution of the nonlinear soil-baseplate interaction. Then, the fundamental theory of the Chebyshev-based interval method and its implementation in the simulation of the VG dynamics are described. The efficiency and accuracy of the proposed method are validated by comparing with the scanning method. Finally, the effects of the multiple uncertainty parameters, sourced from both the soil conditions and the vibrator structure, on the dynamic response of the VG system are analyzed and discussed in detail. In addition, an interval sensitivity analysis is developed to evaluate and compare the effects of different uncertain parameters. The results indicate that uncertainties greatly influence the dynamics of the VG system, and their effects change with the excitation frequency and also relate to the sources of the uncertainties.

Математическое моделирование воздействия слабых низкочастотных сейсмических волн на ледниковый массив

Introduction. The Kolka glacial massif repeatedly broke off from the freezing surface and thereby formed powerful glacial mudflows that caused great material damage to the Republic of the Republic of Alania with numerous human casualties. In the work of Muzaev I. D. and Sozanov V. G., the first step was taken in mathematical modeling of seismic vibrations of the glacial massif and the statement was proved that weak earthquakes of 3-3.5 MSK points can provoke bending and shear stresses several times higher than the destructive stresses of ice on the underlying surface of the glacial massif. The considered mathematical model proposed in the article has been amended, significantly clarifying the scientific results. The purpose of the work is to formulate and solve an initial boundary value problem that resembles the problems of mathematical physics and simulates the fluctuations of a glacial massif. The oscillation of the array is caused by the freezing of a weak traveling harmonic seismic wave with an intensity of 3-3.5 MSK points falling on it and on its underlying surface. Materials and methods. Due to the fact that the longitudinal dimensions of glacial massifs are an order of magnitude larger than their transverse dimensions, the article assumes that the mechanics of such massifs are most adequately modeled if their geometric configurations are considered as girder bodies with their physical and mechanical characteristics. The losses of mechanical energy due to internal resistance in the array material are taken into account in accordance with the hypothesis of S. A. Sorokin. The elastic rebound force from a seismically oscillating base is taken into account in accordance with Winkler’s hypothesis. Due to the fact that the coefficient of the differential equation of vibrations of the beam array is complex, the equation splits into a system of two fourth-order differential equations with real coefficients, where the desired functions are the real and imaginary parts of the originally sought complex function. The initial boundary value problem is solved analytically. Results. On the example of the Kolka glacier (North Caucasus Highlands), which collapsed in 2002 and claimed 126 human lives, computer experiments were performed to calculate induced stresses. Discussion. Comparative computational experiments have proved the claims that the seismic stresses caused by the Winkler elastic rebuff of the seismically oscillating surface of the base: a) are significantly greater than the stresses from the bending component of the vibrations of the array; b) can significantly exceed all the values of the destructive stresses of the ice. Conclusion. It is proved that the superiority of the Winkler stress over the destructive stress of ice can also occur in weak earthquakes with an intensity of 3-3.5 MSK points. Such superiority can play the role of a trigger for the breakaway of the glacial massif from the freezing surface and thereby the formation of a powerful glacial mudflow, as happened on the Kolka glacier. Suggestions for practical application and directions for future research. The paper presents a method for directly determining the cause of the breakaway of the glacial massif from the freezing surface. In the future, it is desirable to check the effect of a sharp induced maximum stress for steels intended for mechanical engineering purposes. It is desirable to study in detail the time dependence of the effect of inducing maximum stresses in arrays using low-intensity waves.

Studying the high frequency seismic signals for enhanced knowledge of the shallow Earth structure and soil investigation

The Earth acts like a low-pass filter to earthquake energy so that frequencies higher than 10 Hz are rapidly attenuated. This intrigues seismologists about the seismic waves in the frequency domain 1–10 Hz, which is crucial to correctly assess the impact of seismic shaking on structures. However, not much attention has been paid to higher frequencies, probably due to its low significance and structural damage. The Earth has high frequency seismic signal (HFSS) in the audible frequency range 20–20,000 Hz and maybe higher (Gamal et al., 2020). These seismic signals result from the transformation of any energy into HFSS energy which is propagated inside the Earth, this energy may be winds, the crustal structure movement, movement due to gravitational force or any mechanical energy transformed into high frequency seismic vibrations. Fifteen different geological environments were tested in Egypt, to monitor the high frequency seismic signals (HFSS) of the subsurface soil. The present study used very high digitising frequency seismographs, not less than 8,000 to 16,000 sample per second, and a set of horizontal and vertical geophones of natural frequencies in the ranges of 4 Hz to 100 Hz. It was found that consolidated rocks have high-pitch that may reach 4,000 Hz, while weak fractured soils sound have a low-pitch, in the frequency range of 20–70 Hz. Speech and audio processing methods have been used to differentiate between these HFSS preserved inside soils and to produce the “unified HFSS map”. The “Soil HFSS map” was considered as avail science could be used in the future to give deep insight on the shallow Earth's interiors.

Technical safety of buildings around polish quarries against harmful seismic vibrations caused by rock blasting

This paper presents the results of measurements of the elliptical distribution of seismic vibrations generated during rock blasting.The technical safety of a building in the area of seismic vibrations is determined by the vibration velocity that does not exceed the line B included in zone II of the scale of dynamic influences [SWD]. The hypothesis proved in the paper is that for both elliptical and circular distributions of the vibration velocity in rock mining with blasting material [BM] there is a directionality of the horizontal radial component Vx and the tangential component Vy of the vibration velocity.The magnitude of the components Vx and Vy of the vibration velocity at the same distance from the vibration source depends on the directional angle "α" between the line of the blast holes and the line connecting the centre of the surface of the rock block being mined with [BM] and the place of measurement. The elliptical shapes of the graphs Vx and Vy obtained during the mining of the BM of the basalt deposit, which depend on the value of the directional angle, were compared with the shape of the circular velocity graphs Vx and Vy. New correlations are given that take into account the directional angle when calculating the maximum vibration velocity values needed to determine the damage caused to a bulding by the SWD.A dynamic impact scale [SWD] for the assessment of building damage as the vibration velocity acting on the building increases is given and discussed. Vibration velocity diagrams measured during the excavation of BM rock are presented for circular distributions in accordance with theoretical predictions. A vibration velocity diagram for an elliptical distribution, inconsistent with a circular distribution, measured during the excavation of BM rock is presented. It is shown that the directionality of the horizontal radial and tangential components of vibration velocity exists for both circular and elliptical distribution of vibration velocity in rock excavation with BM. In the conclusions, for the elliptical velocity field of the vibrations, the conditions to be observed in order to be able to direct the smallest vibrations towards the built up area are given.

Low-frequency noise mitigation and bandgap engineering using seismic metamaterials for terrestrial gravitational wave observatories

AbstractGravitational waves have become one of the most important observational methods for studying the Universe since their first detection. However, ground-based observatories have an inherent barrier to their detection frequency band due to the seismic and gravity gradient noises near the perturbation of the surroundings. A recent intriguing development of artificial structures for media called metamaterial is opening a new branch of wave mechanics and its application in various fields, in particular suggesting a novel way of mitigating noises by controlling the media structure for propagating waves. In this paper, we propose a novel framework for handling noises in ground-based gravitational wave detectors by using wave mechanics under metamaterial media. Specifically, we suggest an application of the bandgap engineering technique for mitigating the underground effects of acoustic noises resulting from seismic vibration in the KAGRA gravitational wave observatory.

The optimum design of particle tuned mass damper for structural seismic control considering soil-structure interaction

Particle tuned mass damper has received considerable attention on mitigating structural seismic responses recently. However, soil-structure interaction effects have not been considered for the optimization design of particle tuned mass damper in the previous studies yet, which may play significant roles in particle tuned mass damper’s effectiveness. This paper investigates the seismic control performance of particle tuned mass damper for tall buildings considering SSI effects. A 40-story benchmark structure is adopted as the primary structure, and different soil conditions including soft, medium, dense soil, and the fixed-base case are considered. Based on the Cuckoo Search algorithm, an optimum design approach for the particle tuned mass damper implemented in SSI system under earthquake excitations is proposed, and the optimum parameters of particle tuned mass damper are obtained from the optimum design process. The optimum results indicate that the optimized particle tuned mass damper can effectively decrease the displacement response without the increase of peak acceleration, and the reduction rates could exceed 30% in some cases. Compared with other soil type cases, under soft soil condition, the optimum parameters of particle tuned mass damper are especially different, and the mitigation effects of the optimized particle tuned mass damper on maximum displacement weaken. Hence, it is necessary to consider the SSI effects for particle tuned mass damper’s seismic design. Furthermore, the interaction effects between the primary structure and particle tuned mass damper in SSI system are also evaluated through energy analysis. The results show that considering SSI effects, the optimized particle tuned mass damper device dissipates the overwhelming majority of the input energy, and it greatly decreases the structural energy, displaying excellent energy dissipation performance on seismic vibration control of structure.

STABILITY ANALYSIS OF THE SLOPE SUBJECTED TO THE DYNAMIC LOADING

This paper presents the results of a stability analysis of a slope located in the immediate vicinity of a railway line. The plans for the extension of this railway track include the construction of another line, which would run parallel to the existing one, within a few metres distance. It is expected that intensive goods train traffic will generate both static and dynamic forces in the underlying subsoil. Consequently, seismic vibrations will be generated in the subsoil, propagating mainly not only in the horizontal direction but also in the vertical direction. The method of seismic coefficient of the earthquake intensity determined by a pseudo-static method and horizontal component of acceleration is appropriate and recommended because it is simple, and the safety factor of the slope is calculated in the same way as in conventional stability calculations.

Acquisition and near-surface impacts on VSP mini-batch FWI and RTM imaging in desert environment

The SEG Advanced Modeling (SEAM) Arid benchmark model was designed to simulate an extremely heterogeneous low-velocity near surface (NS), which is typical of desert environments and typically not well characterized or imaged. Imaging of land seismic data is highly sensitive to errors in the NS velocity model. Vertical seismic profiling (VSP) partly alleviates the impact of the NS as the receivers are located at depth in the borehole. Deep learning (DL) offers a flexible optimization framework for full-waveform inversion (FWI), often outperforming typically used optimization methods. We investigate the quality of images that can be obtained from SEAM Arid VSP data by acoustic mini-batch reverse time migration (RTM) and full-waveform imaging. First, we focus on the effects of seismic vibrator and receiver array positioning and imperfect knowledge of the NS model when inverting 2D acoustic data. FWI imaging expectedly and consistently outperforms RTM in our tests. We find that the acquisition density is critical for RTM imaging and less so for FWI, while NS model accuracy is critical for FWI and has less effect on RTM imaging. Distributed acoustic sensing along the full length of the well provides noticeable improvement over a limited aperture array of geophones in imaging deep targets in both RTM and FWI imaging scenarios. Finally, we compare DL-based FWI imaging with inverse scattering RTM using the upgoing wavefield from the original SEAM data. Use of significantly more realistic 3D elastic physics for the simulated data generation and simple 2D acoustic inversion engine makes our inverse problem more realistic. We observe that FWI imaging in this case produces an image with fewer artifacts.

Effect of seismic vibration amplitudes and frequencies in dislodging an entrapped fluid in a pore model

Effect of seismic vibration amplitudes and frequencies in dislodging an entrapped fluid in a pore model

Study on Seismic Response and Vibration Reduction of Shield Tunnel Lining in Coastal Areas

The construction of subway tunnels in the coastal section is affected by special soil quality, with complex construction conditions of unstable soil and vulnerability to groundwater corrosion. The design difficulty of subway tunnels is greatly increased, and the safety performance in the event of an earthquake is greatly reduced. To study the changes in shield tunnel lining structure under earthquake and propose damping measures, ANSYS software is used to conduct tunnel soil numerical simulation. Firstly, static analysis and modal analysis are carried out, and it is found that the maximum displacement deformation occurs at 3.8 cm of the arch crown, and the maximum stress occurs at 2.6 × 107 Pa of the left and right wall corners, 8 easily deformed points are obtained at the same time. Input EI_Centro EW forward 19 s seismic wave is used to analyze the displacement, acceleration and stress vibration characteristics of tunnel lining. The upper part of the lining is more vulnerable to earthquake, and the right arch waist is subject to the maximum stress, reaching 1.37 × 10−4 Pa, the maximum displacement deformation point is 3.65 × 10−10 m at the right wall. To reduce the impact of earthquakes on tunnel lining, the damping scheme of adding an isolation layer is adopted. Using foam concrete isolation material can reduce the stress of the arch waist by 74.6%, and rubber isolation material can reduce the stress by 80%. In consideration of groundwater corrosion and subsequent engineering construction, it is recommended to use foam concrete as the material for the isolation layer. This study can provide a theoretical basis for the design of metro tunnels in offshore areas.

Investigation of vibration performance of pure active single and multi-feedback controls for a tall RC building

Structural control methods are applied to eliminate the structural damages caused by the vibrations in the buildings and to improve their dynamic behavior of them under dynamic lateral loads. In this paper, the pure active control performance of a tall building under the influence of earthquake records, in which the effective time duration is determined by considering the ARIAS energy distribution, is presented. The building's pure active control performance in the period when the earthquake records have the maximum effect on the structure is examined. Eleven earthquake records are selected to better evaluate the effect of vibration control performance. A genetic algorithm is used to determine the parameters of single and multi-feedback controllers, and its effect on the vibration eliminations at the top and all floors is studied. Also, the effect of displacement and velocity feedback on seismic vibration control is evaluated. To carry out the vibration control studies of the building, the mathematical model is extracted from the finite element model created in ANSYS and verified with finite element analysis. It is observed that the displacement value at a reference location on the building is reduced from 0.735 m to 0.019 m, 0.004 m, and 0.002 m, respectively, by the Proportional-Integral-Derivative, Direct Velocity Feedback, and Optimal controllers. The results show that the multi-feedback control is more effective than the single-feedback control application in reducing the vibration amplitudes at all floors in the pure active control system.

Solution of the External Pochhammer–Chree Problem and Bending Seismic Vibrations of the Pipeline in Infinite Elastic Continuum

Solution of the External Pochhammer–Chree Problem and Bending Seismic Vibrations of the Pipeline in Infinite Elastic Continuum

Broadband Rayleigh wave attenuation utilizing an inertant seismic metamaterial

In this work, a concept of constructing inertant seismic metamaterials for Rayleigh wave attenuation using inerter-based vibration absorbers (IDVAs) is proposed. The dynamic behaviors of the vibration absorbers are controlled by an inertant mechanical network, while three typical oscillator configurations are considered in the design of the proposed inertant seismic metamaterial. An expanded effective medium method is developed to obtain the dispersion of Rayleigh waves, which is separated into three branches by two broad Rayleigh wave band gaps at low frequencies. The influences of the inertance-to-mass ratio as well as the stiffness ratio on the Rayleigh wave propagation are thoroughly discussed. The results show that the multiple-resonance IDVAs can efficiently open low frequency band gaps of the inertant seismic metamaterial without having to increase the mass of the resonators. Band gaps of the low-frequency Rayleigh waves can be further merged to form an extra wide one by adding dissipative mechanisms, which further enhance the attenuation of the Rayleigh waves. Specifically, by analyzing the corresponding displacement fields, it is observed that the seismic energy propagating as Rayleigh surface waves is converted to that propagating as bulk waves not concentrated to the surface, which offers a protected area behind the inertant seismic metamaterials for the facilities located at the surface of the half space. This work provides a new approach for seismic vibration isolations utilizing inertant seismic metamaterials that can be applied in protecting large infrastructures or civil engineering architectures.

Study on viscoelastic materials at micro scale pondering supramolecular interaction impacts with DMA tests and fractional derivative modeling

AbstractViscoelastic materials are commonly utilized in seismic vibration suppression of building structures. Supramolecular modification can extend the effective damping temperature range and improve the damping performance of viscoelastic materials. In present work, the mechanical behaviors of the nitrile rubber viscoelastic material are investigated by dynamic thermomechanical analyzer (DMA) with different strain amplitudes, excitation frequencies and environmental temperatures. The supramolecular interaction and molecular structures modified fractional Kelvin (SMF Kelvin) model taking into account the temperature and frequency impacts is proposed and verified with the DMA test results of the nitrile rubber viscoelastic material. The test results of the viscoelastic damper with different temperatures are employed to further prove the effectiveness of the new proposed SMF Kelvin model.

Dynamic properties of recycled polyurethane-coated rubber-soil mixtures

A large quantity of end-of-life tire (ELT) rubber is being blended with thermoplastic polyurethane to provide a durable and ecologically friendly material for flexible surfaces, while a significant quantity of thermoplastic elastomeric waste (left-over and cut-outs) is also generated. These waste materials can be used efficiently for seismic isolation and vibration damping at a minimal cost, a process known as frugal innovation. In this regard, waste thermoplastic elastomeric (TPE) material, which is also known as polyurethane-coated rubber (PUcR), obtained from the tire rubber recycling industry, is explored in this study. Herein, we targeted to evaluate the stiffness and energy dissipation capabilities of waste TPE or PU-coated rubber, which, to the best of our knowledge, has never been reported before. To that end, a series of cyclic triaxial tests were carried out on PU-coated rubber-soil mixtures. In comparison to untreated rubber-soil mixtures, the shear modulus of PU-coated rubber-soil mixtures reduces by 5.5–12.7%, while the damping ratio increases by up to 12.6%.