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Many examples of earthquake damage show that liquefied lateral spreading is the main cause of pile foundation failure. Rigid drainage piles (RDPs), with two drainage grooves and plastic drainage plates, are a new type of liquefaction-resistant pile that can take into account the bearing capacity and drainage function. A series of 1g shaking table tests was carried out to analyse the seismic response of an RDP–superstructure–quay wall system subjected to lateral spreading. Three levels of earthquake intensities – small (peak ground acceleration (PGA) of 0.05g), moderate (PGA = 0.1g) and large (PGA = 0.2g) – were investigated. The improvement in the anti-liquefaction performance using RDPs was analysed. The influences of far-field (FF) and near-field (NF) ground motions were also examined. The experimental results showed that RDPs can effectively reduce the liquefaction degree and the horizontal flow of the sand stratum. In addition, the internal force and displacement of the superstructure built on RDPs were small. The seismic response due to NF ground motion was found to be more significant than that of the FF ground motion, but the effects of FF ground motion cannot be disregarded. The results of the tests could provide useful information for the design of RDP groups in a typical pile–superstructure–quay wall system. [ABSTRACT FROM AUTHOR]

Many instances of severe damage to pile foundations and pile-supported infrastructures have been caused by liquefaction-induced lateral spreading during major earthquakes, particularly in coastal areas. The current study conducted a series of shaking table experiments to determine the differences between the responses of a free- and a fixed-head group pile under lateral spreading in the presence of finned and circular protection piles. The results indicated that the maximum bending moment tolerated by nonprotected free-head piles was more than that by fixed-head piles. Also, reductions in bending moments were more significant in free-head piles in the presence of protection piles than in fixed-head piles. The bending moments of front and rear piles under restricted pile head conditions were reduced by about 31% and 21%, respectively, when finned piles were used as protection piles, while they were 34% and 42%, respectively, under free-head conditions. Furthermore, modification factors of recommended lateral pressure distribution along a pile per the current design code were determined for the protected and nonprotected free- and fixed-head pile groups of the current study and it was observed that this modification factor (CL) was highly dependent on the location of piles in a group, pile head conditions, and the presence of protection piles in the lateral spreading analysis. [ABSTRACT FROM AUTHOR]

Shake table experiments are conducted to assess the potential of the polymer injection technique as a liquefaction countermeasure. A large 2.9 m high (10 ft) laminar soil container on a 3.9×1.85 m (13×6 ft) shake table is employed. Mitigation of liquefaction-induced settlement for a shallow foundation is explored. In a series of two shake table experiments, the system response is studied first without (baseline) and subsequently with polymer injected into the liquefiable stratum. Each test is densely instrumented to provide insights into the dynamic response of the soil and foundation system. Furthermore, cone penetration tests (CPTs) are performed pre- and postinjection to assess the extent of soil improvement. Strong base excitation is imparted by the shake table, resulting in liquefaction and excessive foundation settlement in the original baseline test. In the second test, with the polymer injection countermeasure, a significant reduction is observed in the tendency for liquefaction and the resulting foundation settlement. After this test, careful excavation provided additional insights into the polymer's configuration within the deposit, increasing overall soil relative density, confinement and creating solidified paths for the shallow foundation load toward the lower, more competent stratum. As such, these mechanisms have the potential to allow for: (1) an increase in soil resistance to liquefaction, and (2) a significant reduction in settlement of overlying shallow foundations. [ABSTRACT FROM AUTHOR]

Destructive damages to deep foundations due to liquefaction-induced lateral spreading during or after major earthquakes in gently sloping or level grounds with a free end have been observed in many earthquakes. The pile foundations supporting structures located in or near the ports and harbors, and also bridge piers, are the most vulnerable structures in this respect, as have been observed in various events in earthquake-prone areas all around the world for decades. Many physical and numerical modeling studies have been carried out to study and understand the insight into different aspects of this phenomenon. In this regard, 1g shake table and Ng centrifuge tests using both rigid and laminar shear boxes have been utilized to physically model the problem and measure the crucial parameters that may play an important role in the effects of lateral spreading on deep foundations. A number of countermeasures have also been examined for tackling this problem. In this paper, the authors describe shortly the physical modeling studies conducted by the first author and his coworkers including the second author on this subject during the last decade. In addition, the various parameters that are involved in physical modeling for studying the behavior of deep foundations subjected to liquefaction-induced lateral spreading are discussed herein. The limitations involved in such physical modeling are also mentioned and some solutions to the involved challenges are discussed as well. • Shake table experiments were conducted to study the responses of piles to lateral spreading. • Different parameters (configurations of piles, soil profiles and superstructure weights) have been investigated. • Several shake table experiments were also conducted to assess the mitigation methods against lateral spreading. • Rigid and laminar shear boxes were constructed and used to investigate the effects of boundary condition. • A number of limitations involved in 1g physical modeling are mentioned and discussed. [ABSTRACT FROM AUTHOR]