| dc.description.abstract | Taiwan is heavily populated in some restricted area. Engineering civil structures are highly developed in this country. Construction activities are often close to the surrounding living and working environments. Ground vibrations due to construction often caused residents uncomfortable or the precision machinery operation abnormal or, more seriously, the adjacent structures damaged.
First, the various worldwide vibration criteria was collected, compared and analyzed. Then, this investigation performs a series of field measurements of ground vibrations due to various constructions, including dynamic compaction, PC pile driving, vibratory sheet-piling, H steel piling, gravel column piling, tunnel blasting and vibrating machine striking concrete pavement. The triaxial velocity sensors were also installed on the different floors of various structures which located in different distances from the construction sites. The measured vibration data was used to investigate the vibration characteristics of ground and structures. The characteristics include the distance attenuation relation, Fourier and response spectra of vibration record, predominant frequencies of different structures, and the vibration propagation effect from the ground through the building structures. A newly developed method called Hilbert-Huang Transform (HHT) was also used to analyze the three dimensional relation of amplitude-frequency-time for vibration signals. The energy distribution characteristics of construction vibrations in frequency and time domains have been surveyed and discussed in detail.
An empirical method for evaluating the safe construction distance to adjacent building structures was presented based on the attenuation relation and the proposed building vibration criterion. Vibration response spectra were also suggested for use with the spectral analysis method to determine more accurately the safe construction distance. The study also discussed the isolation and barrier effects of the trench and sheet pile on the vibration propagation by the measured data.
Finally, based on the numerical simulation using ABAQUS software (finite element analysis program) and choosing appropriate vibration source, boundary conditions, material properties of hammer, piles and soil, the transient behaviors of ground vibrations induced by dynamic compaction and pile driving in situ are quite reasonably displayed.
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