| Summary: | 碩士 === 國立中央大學 === 土木工程研究所 === 95 === Transportation vehicles pass through viaduct or bridge may cause vibration. This vibration may transmit from pier to pile foundation, and then transmit to the bearing stratum. The wave propagation from the bearing stratum may cause damages to the adjacent structures or high-tech production facilities. This research investigated the transmission behaviors of waves mentioned above and the reducing method of this kind of vibration.
To reduce the vibration that may cause some detrimental effects to the residences, adjacent structures or high-tech production facilities, and considered to prevent too large displacement caused by vibration suppression, this research installed two different shock absorbing devices at the pile head. One is the new-type composite stiffness shock-absorbing spring and spring damping device with oil pressure. A series of model pile tests were carried out in the laboratory to investigate the effect of vibration mitigation in bearing stratum, behaviors of the attenuation of wave propagation around model pile in the soil and the relationships among dynamic displacement, impact acceleration and spring constant.
From the results of experiments, it was revealed that the impact energy is transferred from pile shaft to pile tip, and then transmit the energy to the surrounding soil layers from the pile tip. For the two kinds of model piles with shock-absorbing device set at pile head, the behaviors of attenuation of wave propagation approach are similar and attenuate gradually in proportion with distance. With the function of shock-absorbing spring, the vibration energy generated at the tip of the improved pile is at least 40%. It is also revealed that the new-type composite stiffness shock-absorbing spring can improve the problem of too large displacement caused by vibration suppression.
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