In-Situ Tests of Ground Vibration and the Assessment of Ground Vibration Attenuation in the Tainan Area of Southern Taiwan Science Park
Date Issued
2010
Date
2010
Author(s)
Huang, Tsung-Chen
Abstract
The Taiwan High Speed Rail (THSR) passes through the Tainan Area of Southern Taiwan Science Park (STSP) where the high-tech fabs inside are very sensitive to ground vibrations. In order to characterize the attenuation of ground vibration with distance and characteristics of ground vibration, a series of small-scaled in-situ vibration tests and traffic-induced ground vibration measurements were conducted at sites in STSP. The tests including four drop hammer tests and five shaking tests which were performed on the ground surface, on shallow foundation (footing), on single pile foundation, and on proto-type pile foundation, respectively. For drop hammer tests, hammer weights of 80, 120, 220, 260, 430kN and drop heights of 0.5m~3.0m were adopted to generate different levels of ground vibration. For shaking tests, exciters that can generate harmonic loads up to 100 or 200kN were used for ground vibration tests. As for the traffic-loading induced ground vibration measurements, a total of ten high speed trains running with various speeds and four cases for heavy trucks running were measured.
In this study, results of all drop hammer tests and shaking tests are summarized and compared with those of in-situ measurements of ground vibrations induced by heavy trucks and THSR trains. Analysis results show that the natural frequency of STSP site is about 3.1Hz to 5Hz. The main frequency of drop hammer tests is about 3.1Hz to 10Hz. The heavier the hammer weight and the larger the energy of impact loading, the lower the significant frequency and the smaller the attenuation coefficients will be. The ground vibrations induced by THSR trains will have larger responses in the vertical direction and the THSR route direction. The main frequency of the high speed train running through STSP by the speed of 270km/hr is about 3.1Hz, 6.3Hz, and 10Hz. The larger levels of ground vibrations induced by heavy trucks are found in the vertical direction and the perpendicular direction of route. The main frequency of heavy trucks running is about 10Hz to 12.5Hz. Attenuation coefficient of ground vibration in each direction generally increases with frequency. In addition, the ground vibrations induced by different type of sources will have different characteristics. The ground vibrations induced by high-energy source and line-load source tend to be decayed slower with traveling distance.
From this study, it concludes that the dominant frequency, amplitude, and attenuation coefficients of ground vibration at the test site are influenced by different source types, energy level, foundation type, interface area between soil and foundation, as well as the foundation size and stiffness. Conclusions also show that the levels of ground vibration induced by heavy truck are significant at small distances. Therefore, for the design of high-tech fabs in STSP, both the ground vibrations induced by the THSR and the heavy trucks have to be considered to meet their operational requirements.
Subjects
Southern Taiwan Science Park
Taiwan High Speed Rail(THSR)
truck loading
drop hammer test
shaking test
ground vibration
attenuation coefficient
Type
thesis
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