Shake‐table investigation of scoured RC pile‐group‐supported bridges in liquefiable and nonliquefiable soils

Abstract

Summary This paper presents results of one‐g shake‐table tests on scoured pile‐group‐supported bridge models in saturated (liquefiable) and dry (nonliquefiable) sands. The primary objective is to reveal the influence of liquefaction on seismic demands and failure mechanism of scoured bridges. To this end, two identical models, each consisting of a 2 × 2 reinforced concrete pile‐group with a center‐to‐center spacing of 3 times pile diameter, a cap and a single pier with a lumped iron block, were constructed and embedded into saturated and dry sands, respectively, with the same scour depth of 4 times pile diameter. Typical test results, including excess pore pressure, acceleration and displacement demands are interpreted first, followed by the focus on curvature demands and associated seismic failure mechanism identification. Finally, inertial and kinematic effects on pile curvature demands are estimated using cross‐correlation analyses. Results show that near‐pile liquefied soils exhibit more remarkable dilation tendency as compared to far field. For bridges under the given scour depth, soil liquefaction tends to significantly affect the failure modes via transferring damage positions from pier bottom to pile head and meanwhile from underground pile to pile head. In addition, pile group effects appear to be significant in nonliquefiable soils while to be relatively inessential in liquefied soils. Moreover, the inertial effect is more prominent in nonliquefiable soils, while the kinematic effect itself generally appears to be more significant in liquefiable soils. The test results can be used to validate numerical models for future studies.

Response of a scale‐model pile group for a jacket foundation of an offshore wind turbine in liquefiable ground during shaking table tests

“…Large‐scale shaking table tests were conducted on a reinforced concrete (RC) bridge pier model supported by pile group in a liquefiable ground to examine the soil–pile group–superstructure interaction via comparing the acceleration of the ground, the pier, and the pile as well as the bending moment along the pile 9 . Shaking table tests were performed on a scoured RC bridge pier model in liquefiable and nonliquefiable soils respectively to demonstrate the difference in ground response, system dynamic characteristics, and curvature distribution of the pile 10 …”

“…9 Shaking table tests were performed on a scoured RC bridge pier model in liquefiable and nonliquefiable soils respectively to demonstrate the difference in ground response, system dynamic characteristics, and curvature distribution of the pile. 10 The soil container is important for geotechnical physical model tests, including tests on the pile foundation because it should be able to reasonably simulate the characteristics of the ground. To this end, the laminar shear box was used in many of the mentioned shaking table tests.…”

Evaluation on influences of inertial mass on seismic responses and structure-soil interactions of pile-soil-piers

“…In the past, many tests have studied the SSI effects and seismic behavior of pile-supported piers with a concentrated oscillation mass or even neglecting an oscillation mass in different soils (Makris et al 1997, Yao et al 2004, Rollins et al 2005, Tokimatsu et al 2005, Cubrinovski et al 2006, Dungca et al 2006, Chau et al 2009, Motamed and Towhata 2010, Gao et al 2011, Haeri et al 2012, Chang and Hutchinson 2013, Motamed et al 2013, Goit and Saitoh 2014, Durante et al 2015, Wang et al 2015, Durante et al 2016, Su et al 2016, Durante et al 2017, Liu et al 2017, Wang et al 2019). The research work validated experimentally the Winkler foundation model using the displacement transfer function and strain spectrum of a SDOF superstructure supported by a single pile (Makris et al 1997).…”

“…Liu et al (2017) presented test results of a 2×2 pile-group behind a quay wall that evident pile group effects were observed by comparing the bending moment between piles. Wang et al (2019) investigated the inertial and kinematic effects on the curvature of the pile using shaking table tests on pile-soil-pier models in liquefiable and dry sand. Results indicated the near pile in liquefiable sand behaving more significant dilation tendency compared to the far-field.…”

Experimental Study of Local Scour around Caissons under Unidirectional and Tidal Currents

“…Compared with the land environment [2], coastal and offshore bridge foundations can obstruct current flow in the offshore environment [3], which can induce a downward flow and create complex vortexes [4] and finally result in local scour of sediments around the foundations [5]. Local scour reduces not only the embedded depth, but also the stability and vibration frequency of bridge foundations, and hence affects the safety of structures [6][7][8].…”