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In metropolitan cities, underground railway lines of Mass Rapid Transit Systems are the lifeline to the daily commuters. However, these underground lines cause vibrations while trains move. This ground-borne vibrations may cause damage to heritage buildings and fa & ccedil;ade elements. Humans can feel this vibration, and the comfort of people living nearby is compromised if vibrations cross threshold limit. In the current study, a two-stage coupled analysis is conducted to assess ground-borne vibrations in the free field generated by moving trains in a circular shaped tunnel. Two sub-models are generated-(a) train-track sub-model and (b) tunnel-soil coupling sub-model. The preceding model is a closed-form analytical solution which calculates the quasi-static effect of dynamic interactions between the train wheel and the railway track. The follower model is a 2D FE model to calculate the transfer of dynamic forces from track-tunnel interface to the ground surface through the soil medium. It is found that the computed results fairly match with experimental results for both amplitude and frequency content of the vibration. It is observed that ground vibrations reduce with distance from tunnel and any structure or residents staying beyond 30 m distance would not be affected by vibration as only 25% of vibration is present at this distance. The vibration is found to increase with velocity of train and at soft ground conditions to limit vibration, the velocity of train can be restricted. It is found that the frequency content of vibration is in interference range of human life and critical zone of frequency of structures. Therefore, careful assessment of vibration is required during finalization of the metro project particularly if the ground has shear wave velocity of less than 400 m/s.

期刊论文 2025-04-01 DOI: 10.1007/s40098-024-00961-2 ISSN: 0971-9555

Large-scale cooling towers in inland nuclear power plants (NPPs) may collapse under extreme conditions. The collapse-induced ground vibrations threat the safety operations of the adjacent nuclear related facilities. Therefore, prediction and possible mitigation of the ground vibrations are significant in the NPP planning. This study proposed a novel method to arrange a water pool as a cushion underneath the cooling tower to mitigate the ground vibrations. The planar dimension of the water pool is determined by the debris distribution of the collapsed cooling tower. To achieve this, first, the mitigation effect was tested using a steel ball impacting on a concrete pedestal. Then, to obtain the complete debris distribution, a technique was developed to reproduce the disappearing elements in the finite element method-based simulation, and was validated against the tests of vase debris. Finally, the cooling tower-water pool cushion-soil models were established to demonstrate the vibration mitigation using the water pool cushion. For the concerned case with the water pool of 6 m depth, the vibration reduced by 56 % and 59 % for the maximum and average of the ground peak accelerations in the horizontal direction, as well as by 65 % and 60 % for those in the vertical direction, respectively.

期刊论文 2025-03-01 DOI: 10.1016/j.net.2024.10.007 ISSN: 1738-5733

Rockfill columns, also known as stone columns, were installed in a riverbank for slope stabilization measures. The goal of this fieldwork was to prevent slope instability of the riverbank while protecting an in-service aqueduct buried in the riverbank. At this site, rockfill columns were installed with the aid of steel casings (sleeves), which were later removed with a vibrodriver. Peak particle velocities were determined at select locations to monitor the ground vibrations during installation of rockfill columns and during extraction of the steel casings. Instrumentation and monitoring were implemented because there was uncertainty about the potential for structural damage to the nearby aqueduct due to ground vibrations during the stabilization works. In this case study, numerical modeling, calibrated versus field measurements in the ground and on the aqueduct, was used to simulate the ground vibrations due to the installation of three rockfill columns close to the aqueduct. Once calibrated, the numerical models were used to evaluate the effects of vibrations in terms of particle velocities in the ground, displacements of the aqueduct, and frequency spectra on the aqueduct walls. The numerical results showed that the highest particle velocities on the aqueduct were from the rockfill columns that had the steel casings located in the same soil layer as the aqueduct. Based solely on the response in terms of particle velocity, damage to the aqueduct is unlikely. However, the numerical results also showed that the aqueduct moves slightly, both vertically and laterally due to the vibration generated while removing the steel casings; and the frequency range of the waves in the ground are within the natural frequency of the soil, which could impose additional movement to the aqueduct if allowed to move freely with the soil. Numerical results and field data also show that even pulling the steel casings without vibration generated propagation of waves in the ground.

期刊论文 2024-08-01 DOI: 10.1061/JGGEFK.GTENG-12000 ISSN: 1090-0241

Underground train-induced vibrations can cause nearby residents discomfort, damage to buildings, and disturbance for equipment. One of the most effective ways to reduce vibrations is using wave barriers along the propagation path of the waves. Many parameters are involved in determining the efficiency of these barriers: the barrier's dimension, distance from the source of vibration, and material property, to name a few. Simultaneous study of these parameters is complex since numerical analysis of alternatives is time-consuming. Therefore, in this study, by coupling the three-dimensional finite element method and an optimization algorithm, an attempt is made to provide a comprehensive solution to find the optimal wave barriers for Tehran metro line 4 as a case study. The current study evaluates two strategies: using in-filled trenches and topology-optimized barriers. In the first strategy, results show that soft-material trenches with maximum depth close to the observation point have the best performance. Further investigations on jet grout trenches show better performance in stiffer soil and lower train speed. Using dual trenches improves performance only up to 2%, so it does not provide a suitable option. For various practical reasons, there may be no tendency to use soft-material trenches, which perform well in vibration reduction. Therefore, in the second strategy, the improvement of a hard trench (jet grout) performance by topology optimization is investigated. According to this study, topology optimization is an effective method for improving barrier performance.

期刊论文 2024-01-01 DOI: 10.1007/s11356-023-31218-9 ISSN: 0944-1344

Ground-borne vibrations resulting from construction activity or road traffic may set vibrations in buildings. The effects of these induced vibrations on buildings may range from no effect to minor cosmetic damage to serious damage, depending on factors such as the amplitude and time-dependence of the vibration, the building structure and the type of soil it rests on, and the duration of exposure. Various codes and standards from various countries set recommendations regarding the exposure of buildings to soil-induced vibrations with emphasis on the characteristics of the vibration signals for limiting their effects on the building structure and for not reducing the comfort of their tenants. These facts are shortly reviewed in this presentation in conjunction with the effects of vibrations on the human body.

期刊论文 2024-01-01 DOI: 10.1007/978-981-99-5922-8_42 ISSN: 2195-4356
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