ORCID Profile
0000-0002-8189-5584
Current Organisation
Iran University of Science and Technology
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Publisher: American Society of Civil Engineers (ASCE)
Date: 2017
Publisher: Informa UK Limited
Date: 21-09-2017
Publisher: World Scientific Pub Co Pte Lt
Date: 25-08-2016
DOI: 10.1142/S0219455415500406
Abstract: In this paper, a new algorithm for solving the vehicle/track dynamic interaction problem is developed, aimed at reducing the computational cost. The algorithm called Advanced Solver Algorithm (ASA) uses the full Newton–Raphson incremental-iterative method in conjunction with the Newmark integration scheme to solve the equilibrium equations of the coupled vehicle/track system in time domain. Considering the track as a beam resting on a viscoelastic foundation and each vehicle as a wagon with ten degrees of freedom, the governing differential equations of motion of the vehicle/track system were derived. The wheel/rail contact was considered as a nonlinear Hertz spring and consequently the vehicle/track nonlinear dynamic interaction problem was solved. A comparison between the results of the ASA and those of the most advanced algorithm available was made to evaluate the efficiency of the ASA. It is confirmed that using the ASA can result in 40–70 % of reduction in computational cost.
Publisher: SAGE Publications
Date: 29-05-2021
DOI: 10.1177/09544097211020603
Abstract: Transition zones between railway tracks and bridge decks can cause higher dynamic impacts. A solution is smoothly changing the track stiffness by gradually mixing steel furnace slag into the stone ballast. A nominated bridge transition zone is ided into 5 blocks of 7 meters long, with the mixing percentages of 0%, 25%, 50%, 75% and 100%. The mechanical behaviors of furnace slag-ballast combinations (FS-BCs) were studied using experiments of shear strength test, Los Angles abrasion index and plate load test. Furthermore, the dynamic behavior of bridge transition zone with FS-BCs blocks was investigated using a field validated FEM model. Results show that the 100%, 75%, 50% and 25% furnace slag by weight of ballast can increase the shear strength and ballast layer bending modulus by 13%, 12%, 9% and 7% at speed of 300 km/h compared with those of the stone ballast. The FEM study shows that rail deflections are reduced about 20%, 14%, 21% and 16% at speed of 300 km/h corresponding to 100%, 75%, 50% and 25% FS-BCs and accelerations are significantly reduced as well as increasing FS content of each block in bridge transition zone so that a smooth bridge transition zone can be achieved.
Publisher: SciTech Solutions
Date: 08-2017
Publisher: Thomas Telford Ltd.
Date: 02-2014
Abstract: This paper investigates the response of railway track to train loads while rested on an embankment. For this purpose, track structure was ided into two parts, in one of which the rail was modelled as a continuous Euler–Bernoulli beam and in another sleeper, ballast and embankment were considered as an integrated lumped masses system. To obtain the mass and stiffness of embankment, the ‘ballast pyramid model' was developed and, consequently, the response of the whole track system was investigated. The vehicle was assumed to be a ten-degree-of-freedom lumped masses system. The dynamic equilibrium equations of the vehicle-track coupling system were solved in the time domain and the track response was evaluated against applied dynamic loads. As a part of the study, a sensitivity analysis was undertaken on embankment parameters, namely embankment height, stiffness and d ing. The results of numerical modelling and sensitivity analysis reveal that, among the aforementioned parameters, embankment height had a remarkable effect on the track dynamic response.
Publisher: SAGE Publications
Date: 25-04-2022
DOI: 10.1177/09544097221089417
Abstract: As a practical countermeasure against generally destructive subway-induced vibrations, the injection of a continuous thin layer of soft materials into the soil under adjacent receivers is investigated in this paper for the first time. To this aim, simulations were carried out using a finite/infinite element model of a railway track, tunnel, and surrounding soil. A straightforward analytical approach was implemented to model the dynamic excitation of the moving train. In addition, the effect of a soft V-shaped grouted layer on vibration mitigation on the ground was evaluated via a parametric analysis that determined the impacts of soil type, grout specifications, and train speed. The obtained results clearly indicated that a softer isolator (i.e., the grouted layer) in combination with a stiffer soil provides the best configuration for attenuating the subway-induced vibrations. Furthermore, the injection angle and train speed were shown to have minimal impacts on the isolator performance. Other contributions of the present paper include developing a simple equation to estimate the grouted layer effectiveness and describing how the isolator works in layered soils.
Publisher: Hindawi Limited
Date: 13-08-2019
DOI: 10.1002/STC.2444
Publisher: Elsevier BV
Date: 07-2016
Publisher: Elsevier BV
Date: 10-2017
Publisher: Informa UK Limited
Date: 09-04-2018
Publisher: American Society of Civil Engineers (ASCE)
Date: 04-2016
Publisher: Springer Science and Business Media LLC
Date: 23-11-2019
DOI: 10.1007/S40534-019-00201-X
Abstract: In this paper, the use of recycled tire-derived aggregates (TDA) mixed with ballast material is evaluated in order to reduce the train-induced ground-borne vibrations. For this purpose, a series of field vibration measurements has been carried out at an executed pilot track. The prepared ballast layer was mixed with different percentages of TDA in three sections. Moreover, another test section with pure ballast is considered as a reference. The vibrations generated by a motor-powered draisine at two different speeds are then recorded. Records of vibration data are provided using four seismometers placed once longitudinally and once transversely beside different sections. The outputs are then processed in both velocity–time and velocity–frequency domains. To verify the vibration mitigation performance of TDA in real operation conditions, field measurements under the passage of two planned passenger and freight trains are finally arranged. Results show that the best TDA mixture ratio, i.e., 10% by weight, can reduce the transmitted vibrations up to 12 dB for frequencies above 31.5 Hz. According to the obtained efficiency and the very low cost of the recycled materials, this solution can be considered as a competitive vibration countermeasure.
Location: Iran (Islamic Republic of)
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