THE DRIVING OF PILES BY LONGITUDINAL VIBRATIONS.
Engineering Research Series,
PRINCETON UNIV N J DEPT OF CIVIL AND GEOLOGICAL ENGINEERING
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The state of the art of vibratory technology was reviewed. The process of pile driving was examined in a general frame of reference, with emphasis on soil response to driving energy input. A test assembly, consisting of a mechanical oscillator which drives a cylindrical pile completely through a laterally confined cylinder of sand, was used to determine, experimentally, the response of a friction pile to combine static bias force and low frequency less than the quarter-wave natural frequency of the pile longitudinal oscillations. The test results were used to determine those driving parameters which must be included in an equation expressing pile bearing capacity as a function of driving record. It was found that the oscillator frequency, pile acceleration amplitude, static bias force, and pile penetration rate are sufficient to estimate the bearing capacity of friction piles driven by low-frequency longitudinal oscillations. The four driving parameters, bearing capacity and the acceleration of gravity were combined to give three dimensionless variables which enter the pile equation. Deviations of the actual bearing capacity from that estimated by the equation were found to be distributed normally. The properties of the normal distribution were used to evaluate the probability of pile failure under a load equal to any specified fraction of the bearing capacity estimated by the equation. Author
- Soil Mechanics
- Structural Engineering and Building Technology