Railway train induced ground vibrations in a low V S soil layer overlying a high V S bedrock in eastern Canada D. Motazedian a,n , J.A. Hunter b , S. Sivathayalan c , A. Pugin b , S. Pullan b , H. Crow b,c , K. Khaheshi Banab c a Earth Sciences Dept., Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6 b Terrain Geophysics Section, Northern Division, Geological Survey of Canada, 601 Booth St. Ottawa, Ontario, Canada K1A 0E8 c Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6 article info Article history: Received 5 September 2010 Received in revised form 7 January 2011 Accepted 9 February 2011 abstract Railway trains were used as a seismic source to observe the differences in behavior of seismic ground motions at different types of soil and rock sites. Observations indicate that the durations and amplitudes of the train induced seismic waves at the soil sites increased dramatically compared to the reference bedrock site. The very high site effect for railway train induced vibration may be due to the fact that the speed of train was close to the Rayleigh wave velocity of the soil. On the other hand, very large soil amplifications have been observed based on local earthquakes recordings, with a very different source mechanism than train induced seismic waves. Combining these two effects may lead to unusual soil amplification, at least for weak motion, especially when a train is moving at a speed close to the velocity of Rayleigh waves. These findings can be utilized in early warning systems in eastern Canada by mapping the potential railway train induced vibrations and the velocity of Rayleigh waves along railway transportation corridors. & 2011 Elsevier Ltd. All rights reserved. 1. Introduction The importance of site response is well known; it has been recognized for years by both seismologists and engineers (see Aki [1], Field et al. [2], Field and Jacob[3], Gao et al.[4], Boore and Joyner [5], Riepl et al. [6], Boore [7], Atkinson and Cassidy [8], Bard and Riepl Thomas [9], Ch  avez-Garcia et al. [10], Olsen [11], Field[12], Ch  avez-Garcia et al.[13], Finn and Wightman [14], Kawase [15], Boore [16], Adams [17], Motazedian and Hunter [18], Hunter et al. [19,20], Khaheshi Banab and Motazedian [21], and Motazedian et al. [22]) that seismic waves are amplified, some- times by factors as large as ten, due to variations in near-surface material properties. Carleton University, in collaboration with the Geological Survey of Canada, has begun ‘‘microzonation’’ studies within the city of Ottawa. Different seismic methods have been used extensively to evaluate the soil characteristics in the city of Ottawa. The seismic methods applied were downhole measurements at 15 borehole sites, seismic refrac- tion/reflection at 686 sites, high-resolution shear wave reflection ‘‘Landstreamer’’ profiling for a total of 25 line-kilometers, multi- channel analysis of surface waves (MASW) measurements at 36 sites, and horizontal-to-vertical spectral ratio (HVSR) of ambient seismic noise, in order to evaluate the fundamental frequency for  400 sites. These methods are described in Motazedian and Hunter [18], Hunter et al. [19], Khaheshi Banab and Motazedian [21], Hunter et al. [20], and Motazedian et al. [22]. In this work, we designed an experiment to observe railway train induced ground vibrations at different site conditions in Ottawa area. Free vibrations of soil along railways have been studied by researchers involved in the evaluation of ground vibration as part of the ‘‘noise problem’’ in urban areas (see Kaynia et al. [23], Kim and Lee [24], Madshus and Kaynia [25], Degraande [26], Degraande and Schillemans [27], Kogut et al. [28], Lombaert et al. [29], and With et al. [30]). Railway companies, mainly in Europe (France, Germany, Great Britain and Holland, Swiss), have been investing in the in-situ measurements of railway induced ground vibrations and investigating the dynamic interaction between the train and the ground (see Dieterman and Metri- kine [31] and Wolfert et al. [32]). Train induced vibration is generated by moving loads. Usually, the embankment is considered to be a seismic source, the length of which corresponds to the train length. A train is generally modeled as a line source, if the distance of the receiver is less than 1/pi times the source length. Different theoretical and numerical models have been studied for railway induced ground vibrations, propagation and response of structures [24,25,27,29,30]. The vibrations measured at near-railway distances are combina- tions of various vibrations that occur at different locations with different phases. Train induced vibrations contain three-directional Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/soildyn Soil Dynamics and Earthquake Engineering 0267-7261/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.soildyn.2011.02.008 n Corresponding author. Tel.: 613 520 2600x8536; fax: 613 520 5613. E-mail address: Dariush_Motazedian@Carleton.ca (D. Motazedian). URL: http://www.carleton.ca/ dariush (D. Motazedian). Please cite this article as: Motazedian D, et al. Railway train induced ground vibrations in a low V S soil layer overlying a high V S bedrock in eastern Canada. Soil Dyn Earthquake Eng (2011), doi:10.1016/j.soildyn.2011.02.008 Soil Dynamics and Earthquake Engineering ] (]]]]) ]]]–]]]