NUMERICAL ANALYSIS OF SEISMIC BEHAVIOUR OF SINGLE PILE IN THREE LAYERED LIQUEFIABLE SOIL

Author(s):  
Adel Javdani Naeeni ◽  
Hossein Matinmanesh ◽  
Amir Hossein Yousefzadeh
Author(s):  
Thejesh Kumar Garala ◽  
Gopal Madabhushi

A series of dynamic centrifuge experiments was conducted on model pile foundations embedded in a two-layered soil profile consisted of soft-clay layer underlain by dense sand. These experiments were specifically designed to investigate the individual effect of kinematic and inertial loads on a single pile and a 3×1 row pile group during model earthquakes. It was observed that the ratio of free-field soil natural frequency to the natural frequency of structure might not govern the phase relationship between the kinematic and inertial loads for pile foundations as reported in some previous research. The phase relationship obtained in this study agrees well with the conventional phase variation between the force and displacement of a viscously damped simple oscillator subjected to a harmonic force. Further, as expected, the pile accelerations and bending moments can be smaller when the kinematic and inertial loads act against each other compared to the case when they act together on the pile foundations. This study also revealed that the peak kinematic pile bending moment will be at the interface of soil layers for both single pile and pile group. However, in the presence of both kinematic and inertial loads, the peak pile bending moment can occur either at the shallower depths or at the interface of soil layers depending on the pile cap rotational constraint.


2011 ◽  
Vol 261-263 ◽  
pp. 1694-1698 ◽  
Author(s):  
Feng Yi Tan ◽  
Xin Zhi Wang

The bearing performance of composite foundation improved by flexible piles was influenced by changes of cushion’s modulus, the modulus ratio between soil on bottom of pile and soil surrounded pile, which was analyzed by the finite element method. Results showed that: 1.For single pile, by increasing of cushion’s modulus, the bearing performance nearby the top of flexible pile increased apparently, and the common tendency of settlement of pile and soil surrounded piles was affected negatively. For multi-piles, the increasing of cushion’s modulus resulted in the increasing of bearing performance and the common tendency of settlement of piles and soil surrounded piles was affected positively. 2.The change of modulus ratio between soil surrounded piles and soil on bottom of piles resulted positively in the change of frictional resistance and end-bearing performance nearby the bottom of single pile and reduced the settlement of composite foundation. But the multi-pile borne absolutely all loading due to the increasing of modulus ratio, and both of piles and soil surrounded piles had the same tendency of settlement.


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