An efficient approach for prediction of subway train-induced ground vibrations considering random track unevenness

2019 ◽  
Vol 455 ◽  
pp. 359-379 ◽  
Author(s):  
Zhihui Zhu ◽  
Lidong Wang ◽  
Pedro Alves Costa ◽  
Yu Bai ◽  
Zhiwu Yu
Author(s):  
Lidong Wang ◽  
Yan Han ◽  
Zhihui Zhu ◽  
Peng Hu ◽  
CS Cai

In this paper, an efficient time–frequency approach is presented for the prediction of subway train-induced tunnel and ground vibrations. The proposed approach involves two steps. In the first step, a time domain simulation of the vehicle–track subsystem is used to determine the track–tunnel interaction forces and, in the second step, the resulting forces are then applied to a 2.5 D FEM–PML model of the tunnel–soil system. There are two main aspects to the novelty and contribution of this work: First, the errors of the linearized Hertzian wheel–rail contact models in the calculation of the track–tunnel interaction forces are quantified by a comparison with the nonlinear Hertzian contact model. The results show that the relative errors are less than 2%. Second, an efficient time–frequency analysis framework is proposed, including the use of a strongly coupled model in the time domain solution and a 2.5 D FEM–PML model in the frequency–wavenumber domain solution. Finally, the accuracy and efficiency of the proposed approach are verified by comparison with a time-dependent 3 D approach, where three types of soil, i.e. soft, medium, and hard, are considered.


AIAA Journal ◽  
1998 ◽  
Vol 36 ◽  
pp. 2005-2012
Author(s):  
L. He ◽  
W. Ning

2020 ◽  
Author(s):  
Lucien Caspers ◽  
Julian Spils ◽  
Mattis Damrath ◽  
Enno Lork ◽  
Boris Nachtsheim

In this article we describe an efficient approach for the synthesis of cyclic diaryliodonium salts. The method is based on benzyl alcohols as starting materials and consists of an Friedel-Crafts-arylation/oxidation sequence. Besides a deep optimization, particluar focusing on the choice and ratios of the utilized Bronsted-acids and oxidants, we explore the substrate scope of this transformation. We also discuss an interesting isomerism of cyclic iodonium salts substituted with aliphatic substituents at the bridge head carbon. <br>


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