【正文】 90 mm 194。 800 mm (width) 194。 800 mm (width) 194。 (b) an elevated side viewof the system showing the sizes and the laminated soil tank。 (e) gap observed in shaking table test (after [11])。 2008 Elsevier Ltd. All rights reserved.1. IntroductionMany big cities in the world are built on ?at lands containing a thick layer of sediment, such as basins, river deltas, or valleys. Tall buildings or important structures in these cities have to be founded on piles to avoid excessive ground settlements. In addition to static load transferred from the dead load of the structures, piles are also subject to dynamic loads. The most monly encountered dynamic loads on a pile–soil–structure system are those due to earthquakes. Past earthquake events demonstrate that damages in piles are monly induced during moderate to strong earthquakes. Mizuno [1] piled the earth quakeinduced damages of piles reported in Japan from 1923 to 1983, including those of the great Kanto earthquake. Damages in pile have been observed during the 1964 Niigata earthquake, the 1964 Alaska earthquake, the 1985 Mexico City earthquake, and the 1989 Loma Prieta earthquake [2]. More recently, severe damages in piles were also reported during the 1995 Kobe earthquake [3–6].The remedial works needed for damaged piles can be very costly. Thus, pile–soil–structure interaction and mechanism forpile damages need to be further examined. For prehensive reviews on theoretical soil–pile–structure interaction (SPSI), we refer to Meymand [2] and Novak [7]. The SPSI problem has also been investigated by using the shaking table test [2,8] and the centrifuge test [9,10]. The present study continues the line of works on shaking table tests on the soil–pile–structure system.The main focus of the present study is to report a newly observed phenomenon in our shaking table tests—pounding between soil and pile when a soil–pile–structure model is subject to seismic excitations. When the soil–pile–structure model is subject to seismic excitations, the soil surrounding the pile may be pressed laterally such that a soil–pile gap separation may develop. Consequently, pounding may appear between soils and piles due to the different dynamic responses of the pile–structure system and the soil. We will show that this pounding may lead to a very large inertia force at the pile cap level, which may lead to cracking in the foundation piles. Finite element analysis is used to explain the unusual large acceleration suffered at the pile cap level.Although soil–pile gaps have been observed in the ?eld after earthquakes and in shaking table tests after soil–pile–structure models are subject to seismic excitations, the pounding between soil and pile has not been recognized and examined. Photographs in Fig. 1 show soil–pile gap separations observed in the ?eld and in the laboratory. For soil–pile gaps observed in the ?eld, Figs. 1(a) and (b) show two photographs of soil–pile gaps observed on the reclaimed Port Island after the 1995 Kobe earthquake, while Figs. 1(c) and (d) show two photographs of soil–pile gaps developed along the Struve Slough Crossing during the 1989 Loma Prieta earthquake. For soil–pile gaps observed in shaking table tests, Figs. 1(e) and (f) are reproduced from Fig. 8 of Wei et al. [11] and Fig. of Meymand [2], respectively. There has been no previous attempt to investigate the possibility of pounding between soil and pile induced by these gaps. Therefore, shaking table tests demonstrating the pounding between soil and pile will be presented here.To simulate the free ?eld response of soil, various soil tank designs have been proposed to minimize the boundary effect of the ?nite soil tank. They include rigid tank with suf?ciently large size [12,13], rigid tank packed with foam at the sides of the tank [14–17], laminated soil tank [18–27], soil tank with walls having a hingedbase [28], and ?exible circular container [2,29,30]. There is no conclusion on which particular soil tank system is better than others. For this study, a rectangular laminated tank system was selected. The results of the present study provide a new potential cause of pile damages observed in the ?eld especially when no liquefaction is observed around the damaged piles [6].2. Experimental setupExperiments on a model of a soil–pile–structure system were performed on an MTS uniaxial seismic shaking table of size 3m3m. Fig. 2(a) shows a photograph of the experimental set up, while schematic diagrams of the laminated soil tank and the crosssections of the members used in constructing the pile, the columns of the structure, and the soil tank are shown in Figs. 2(b) and (c), respectively. A maximumhorizontal acceleration of 1g can be applied at the full load of 10 ton. The working frequency of the able ranges from 1 to 50Hz. The shaking table can simulate motions with displacement, velocity or acceleration control. The displacement control is primarily for low frequency range, velocity control for middle frequency range, and acceleration control for high frequency range. The maximum overturning moment that can be restrained by the bearing of the table is 10 tonm. In our experiment, the total weight of our soil–pile–structure system is close to the limit of 10 ton.Fig. 1. Photographs of soil–pile gap observed in the ?eld and laboratory: (a,b) piles in the reclaimed island of Kobe during the 1995 Kobe earthquake (after Refs. [2,5])。致謝人：2013年6月1日外文資料Oil Dynamics and Earthquake EngineeringNonlinear seismic soil–pile–structure interactions:Shaking table tests and FEM analyses. Chau a, . Shen b, X. Guo ca Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, Chinab Earthquake Engineering Research Test Center, Guangzhou University, Guangzhou, Chinac Institute of Engineering Mechanics, Harbin, ChinaArticle infoArticle history:Received 7 November 2007Received in revised form15 February 2008Accepted 26 February 2008Keywords: