Soil Liquefaction Effects on R.C.C. Piles (original) (raw)
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Earthquakes - From Tectonics to Buildings, 2021
This chapter presents a concise overview of the mechanics of failure, analysis and requalification procedures of pile foundations in liquefiable soils during earthquakes. The aim is to build a strong conceptual and technical interpretation in order to gain insight into the mechanisms governing the failure of structures in liquefaction and specify effective requalification techniques. In this regard, several most common failure mechanisms of piles during seismic liquefaction such as bending (flexural), buckling instability and dynamic failure of the pile are introduced. Furthermore, the dynamic response commentary is provided by critically reviewing experimental investigations carried out using a shaking table and centrifuge modelling procedures. The emphasis is placed on delineating the concept of seismic design loads and important aspects of the dynamic behaviour of piles in liquefiable soils. In this context, using Winkler foundation approach with the proposed p–y curves and finit...
Buckling and bending response of slender piles in liquefiable soils during earthquakes
Geomechanics and Geoengineering, 2008
Design of pile foundations in seismically liquefiable soils involves identifying the appropriate failure mechanisms. Piles in liquefiable soils are conventionally designed against bending failure due to lateral loads arising from inertia and/or lateral spreading. This is strong evidence that there is another mechanism, which the code does not consider, that may govern the failure of these foundations. In this paper, the response of a single end bearing pile in liquefied soil with and without the effect of axial load has been presented. The effect of liquefaction is incorporated in the pile–soil interaction through nonlinear analysis using the finite difference program Fast Lagrangian Analysis of Continua (FLAC). The method of analysis is carried out using the well documented failure of Showa Bridge piles which failed during the 1964 Niigata earthquake. The response of the pile is also evaluated using dynamic analysis. The need for proper identification of failure mechanisms as well as design guidelines is highlighted.
A critical review of methods for pile design in seismically liquefiable soils
Bulletin of Earthquake Engineering, 2008
Collapse and/or severe damage to pile-supported structures are still observed in liquefiable soils after most major earthquakes. Poor performance of pile foundations remains a great concern to the earthquake engineering community. This review paper compares and contrasts the two plausible theories on pile failure in liquefiable soils. The well established theory of pile failure is based on a flexural mechanism; where the lateral loads on the pile (due to inertia and/or lateral spreading) induce bending failure. This theory is well researched in the recent past and assumes that piles are laterally loaded beams. A more recent theory based on buckling instability treats the piles as laterally unsupported slender columns in liquefiable soils and investigates the buckling instability (bifurcation). The objective of this paper is to investigate the implications to practical pile foundation design that flow from both these theories. Provisions for design made by major international codes of practice for pile design including the Japanese Highway Code (JRA) will be considered. The necessity for such codes to consider alternative forms of failure mechanisms such as the buckling instability of piles in liquefied ground will be discussed.
Analysis of Pile Foundations for Liquefaction
Poor performance of pile foundations in liquefiable soils after major earthquakes remains a great concern to the earthquake engineering community. The current understanding of the pile failure in liquefiable soils considers either bending or buckling as a probable cause of failure. However, in reality, the two mechanisms interact. Hence, the pile foundations designed with these mechanisms separately might become un-conservative when the mechanisms interact. This paper compares and contrasts the two plausible theories on pile failure in liquefiable soils under seismic conditions. By using STADD Pro V8i software, a detailed analysis of pile behaviour under vertical load and lateral load separately is carried out and then the pile behaviour is analyzed by applying the loads simultaneously. Based on the deflection pattern charts are provided for all the analysed end conditions to arrive the length and diameter of the pile in a simple way, if the force acting at any point on the pile is known. The possible field observed failure mechanisms are analysed and the recommendations on % increase in diameter of the pile to withstand the bending-buckling interaction is provided.