Control of Metro Train-Induced Vibrations in a Laboratory Using Periodic Piles
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sustainability Article Control of Metro Train-Induced Vibrations in a Laboratory Using Periodic Piles Meng Ma 1,2,* , Bolong Jiang 3, Weifeng Liu 1,2 and Kuokuo Liu 2 1 Key Laboratory of Urban Underground Engineering of Ministry of Education, Beijing Jiaotong University, Beijing 100044, China; wfl[email protected] 2 School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China; [email protected] 3 Rail Transit Digital Construction and Measurement Technology National Engineering Laboratory, China Railway Design Corporation, Tianjin 300308, China; [email protected] * Correspondence: [email protected] Received: 30 June 2020; Accepted: 20 July 2020; Published: 21 July 2020 Abstract: Laboratories with sensitive instruments need a low-vibration environment. It is a challenge to control the train-induced vibration impact on these instruments when a newly planned metro line is adjacent to a laboratory building. An alternative method of mitigating train-induced ground vibrations involves installing measures along the transmission path. Recent research has highlighted the potential of periodic pile barriers with specifically designed band gaps for controlling environmental vibrations. This study performed in-situ measurements of ambient vibrations inside and outside a laboratory containing various types of sensitive instruments and located adjacent to a newly designed metro line. The vibration transfer function of the laboratory was then obtained. To help design and optimize the band gaps of periodic piles, a novel band gap performance evaluation function was proposed. Finally, numerical analysis was conducted to validate the mitigation effect of the designed periodic piles. The results showed that the band gap performance evaluation function can be used to optimize the mitigation effect of periodic piles. The proposed periodic piles clearly attenuated vibrations between 52.4 and 74.3 Hz, especially those at 63 Hz. A comparison of general vibration criteria (VC) curves revealed that vibration attenuation of one level can be obtained by the designed periodic piles. Keywords: environmental vibration; metro train; sensitive instrument; vibration control; periodic piles; band gap theory 1. Introduction In recent years, the problem of train-induced vibrations have been paid increasing attention due to its potential impacts on the comfort of nearby residents [1,2], the long-term protection of historic buildings [3,4], and the operation of precision instruments [5,6]. For laboratories containing sensitive equipment such as high sensitivity weighing equipment, electronic microscopes, and magnetic resonance imaging instruments, controlling vibrations induced by rail and road traffic is a challenging issue. Previous studies have reported this problem; for example, Wolf [7] introduced a case study of the United States, where the planned Sound Transit Link Light Rail system was due to pass through the University of Washington. In Taiwan, the bullet train was designed to pass through Tainan Industrial Science Park [8]; as such, a honeycomb wave impeding barrier (WIB) was proposed to mitigate the resulting train-induced vibrations [9]. In Beijing, due to the impact of the planned metro line 4 on sensitive microscopes in a physics laboratory of Peking University, Gupta et al. [5] and Liu et al. [10] conducted numerical predictions and experimental analyses. Furthermore, Ding et al. [6] predicted train-induced vibrations in a laboratory in Beijing near metro line 8. Sustainability 2020, 12, 5871; doi:10.3390/su12145871 www.mdpi.com/journal/sustainability Sustainability 2020, 12, 5871 2 of 20 Sustainability 2020, 12, x FOR PEER REVIEW 2 of 22 Sustainability 2020, 12, x FOR PEER REVIEW 2 of 22 Sustainability 2020, 12, x FOR PEER REVIEW 2 of 22 Generally,Generally, itit isis di difficultfficult to to control control vibrations vibrations in in a laboratorya laboratory with with sensitive sensitive instruments, instruments, especially whenespecially theGenerally, laboratory when theit is laboratory isdifficult located isto near located control a rail near vibrations transportation a rail transportation in a laboratory system. system. 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