dc.description.abstract | With the cramped spaces and the high population in Taiwan, the structures near the construction site are probably damaged by constructing vibration or the ground deformation. In the various kinds of constructing vibration, the vibration of pile driving is the most important one and has a conspicuous effect to the nearby structures. That’s the reason why a lot of researches focused on this issue. The vibration records of pile driving in the hydraulically reclaimed and alluvial grounds were collected and analyzed to derive the vibration attenuation relations and the response spectra. Based on the criterion and relations, we obtain the safe pile driving distances for the various structures. Incorporating the structural damage criteria for vertical and horizontal vibration directions, the design response spectra and the attenuation relations, a response spectral analysis method was proposed to more accurately determine the safe pile driving distances.
The numerical analysis is another choice to understand the ground vibration caused by pile driving in addition to the rare data of full-scale vibration measurement. The analysis tool we use is ABAQUS, which is a finite-elements program. By using this program, the pile driving vibration, which is caused by the vertical impact loading exerted on the top a single pile, propagating to nearby ground is simulated. Therefore, the problem can be simplified to a 2D axis-symmetric dynamic analysis model to reduce the computing work. After choosing appropriate boundary conditions and material properties of piles and soil, the behaviors of ground vibrations are reasonably displayed.
The analysis results of ground vibration caused by pile driving are that the vibration energy obviously focuses on some frequency bands when driving pile at near distance and at deeper depth. It means that in these cases, predominant frequency is more significant, and the frequency range is within 10~20 Hz. From the normalized response spectrum, we know that the peak value of spectrum value for pile driving occurs at shorter period. The result is the same that measured at field site. This causes a greater damage potential to lower structures and walls that have shorter fundamental vibration periods. | en_US |