Influence of seismic motions on behavior of piles in liquefied soils

Abstract

Summary In the present study an analytical procedure based on finite element technique is proposed to investigate the influence of vertical load on deflection and bending moment of a laterally loaded pile embedded in liquefiable soil, subjected to permanent ground displacement. The degradation of subgrade modulus due to soil liquefaction and effect of nonlinearity are also considered. A free headed vertical concrete elastic nonyielding pile with a floating tip subjected to vertical compressive loading, lateral load, and permanent ground displacement due to earthquake motions, in liquefiable soil underlain by nonliquefiable stratum, is considered. The input seismic motions, having varying range of ground motion parameters, considered here include 1989 Loma Gilroy, 1995 Kobe, 2001 Bhuj, and 2011 Sikkim motions. It is calculated that maximum bending moment occurred at the interface of liquefiable and nonliquefiable soil layers and when thickness of liquefiable soil layer is around 60% of total pile length. Maximum bending moment of 1210 kNm and pile head deflection of 110 cm is observed because of 1995 Kobe motion, while 2001 Bhuj and 2011 Sikkim motions amplify the pile head deflection by 14.2 and 14.4 times and bending moment approximately by 4 times, when compared to nonliquefiable soil. Further, the presence of inertial load at the pile head increases bending moment and deflection by approximately 52% when subjected to 1995 Kobe motion. Thus, it is necessary to have a proper assessment of both kinematic and inertial interactions due to free field seismic motions and vertical loads for evaluating pile response in liquefiable soil.

Effects of axial loading on dynamic response of laterally loaded single piles in liquefiable layered soil of Kolkata city considering nonlinearity of soil

“…The effects of axial loading in addition to the input earthquake motion on dynamic response of laterally loaded single piles in liquefiable layered soil of Kolkata city considering nonlinearity of soil is evaluated in the present study using finite-element based program OpenSeesPL. The properties of pile section [49,77] considered in this study are presented in Table 7. A circular pile of total length 21 m with free head length of 1 m and embedded length of 20 m is selected for the study.…”

“…IS 2911[47] recommends depth of fixity method which is based on bending failure mechanism for evaluating the flexural response of earthquake -induced laterally loaded pile foundations. The response of pile foundations in liquefiable soil considering both inertial and kinematic interaction effects have been studied by several investigators [48][49][50][51][52]. Recently, Bhattacharya [53], Knappett and Madabhusi [54] and Kimura and Tokimatsu [55] established an alternative theory of possible pile failure in liquefiable soil based on buckling mechanism.…”

“…Chatterjee et al [60] conducted dynamic field testing and numerical study using FLAC3D at three different places of Kolkata city for determination of net pile displacement and ultimate pile capacity. Chatterjee and Choudhury [49] proposed an analytical procedure to evaluate the influence of combined loading on pile response considering typical soil profile of Kolkata city using pseudo-static approach. Chatterjee [61] performed pseudo-static analysis using results obtained from equivalent linear ground response analysis for seismic response of pile foundations in Kolkata city considering both inertial and kinematic effects.…”

Vertical dynamic interaction and group efficiency factor for floating pile group in layered soil

“…Pile foundations are widely used for supporting superstructures such as bridge piers, high-rise buildings, transmission towers because of their merits of high capacity and good serviceability in various geological environments. [1][2][3][4][5][6] Estimating the dynamic performance under the loads from traffic vehicles, 7 earthquake action, 8 vibrating machine, wind, and flood is often a challenging task due to its complex frequency-dependency. [9][10][11][12] In addition to the engineering design, dynamic impedance knowledge of piles is also fundamental to the scour detection of bridges using vibration-based method.…”

Vertical vibration of piles with square cross‐section

“…Pile foundations are often subjected to dynamic loads such as vibrating machines, traffic vehicles, earthquakes, wind, and etc 1–10 . The complex dynamic impedance of a pile shaft is defined by the ratio of the external dynamic load acting on the pile head to the induced displacement, which is a critical physical quality estimation of its dynamic performances 11,12 .…”