Characterization of pile driving induced ground motions
Pile installation is a complicated, energy intensive process where codes and regulatory standards provide some guidance, but little is understood about coupling and transmission of pile driving energy into and through the ground in the form of vibrations. These vibrations can cause direct structural damage and damage due to settlement of granular soils. This study presents results that give insight to concepts that are still in question concerning pile driving induced vibrations using impact hammers. These results are the outcome of an innovative research comprised of three different components: (1) full-scale ground monitoring during impact driving of H-piles in the field, (2) small scale pile driving testing in a controlled laboratory environment and (3) numerical analysis of the impact pile driving process using 3D finite element analysis.
Field pile driving vibration data were monitored from five project sites. The mechanisms of energy propagation during impact pile driving were evaluated by installing sensors in the ground, starting very close from the pile (0.5 ft) and moving away at different radial distances and depths, generating the first data set of its kind. Analysis of the data reinforces the hypothesis of the wave propagation field generated by impact driven piles. Attenuation of the peak particle velocity and increase of the shear wave velocity at increasing distances from the pile is also confirmed. A process to evaluate the potential for a granular soil to undergo shakedown settlement is presented, based on the field measurements from the tested sites.
Small-scale physical experiments of pile driving were conducted in the laboratory. The controlled environment of a homogeneous and properly characterized soil profile allowed for investigation of the mechanisms of energy transfer from pile to soil without the complexities encountered in the field. Finally, the pile driving induced vibration field was modeled using a 3D finite element dynamic analysis.
Cochairs: Adda Athanasopoulos-Zekkos and Richard D. Woods