• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5C
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• pp.185-192
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• 2012

The objective of this study is to present and verify a method for evaluating the fundamental period of a rockfill dam using artificially generated vibration from a blasting event. In this study, the artificial blasting vibration tests were carried out at the site adjacent to the existing Seongdeok Dam for the first time in Korea. The artificial vibrations were induced by 4 different types of blasting with the various depths of blasting boreholes and the various explosive charge weight. During the tests, the accelerations time histories were recorded at the crest of the dam. In this acceleration history, only free vibration decay part following the main vibration event was extracted and it was analyzed by frequency domain analysis using Fast Fourier Transform (FFT). From the results of FFT, the fundamental period of the target dam was evaluated. It is found that the effect of different blasting types on the fundamental period of the target dam is negligible and the fundamental period of the target dam can be consistently obtained by blasting vibration tests. Furthermore, it is found that the period of the target dam calculated by the method using blasting vibration test is similar to that obtained by the method of previous researchers using the real earthquake records. Therefore, in case that the earthquake record is not available, the fundamental period of a rockfill dam can be reasonably evaluated if blasting vibration test is allowed at the site adjacent to the dam.

• Journal of the Korean Geotechnical Society
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• v.28 no.3
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• pp.35-43
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• 2012

Following the companion paper (I. Comparisons with Well-known Seismic Code and Site Response Characteristics), several acceleration data recorded during recent earthquake events in Korea were analyzed to verify the suitability of the proposed two-parameters site classification system and the corresponding site coefficients. For all of rock-soil site pairs less than 30 km distant, response spectrums and corresponding site coefficients, $F_a$ and $F_v$, were determined. Unfortunately, some of data have an eccentric error, where the spectral acceleration of rock site is more amplified than that of soil site. The $F_a$ and $F_v$ for all of pairs except the pairs of error were compared with those in the current code and the proposed system. The $F_a$ and $F_v$ from the recorded motions show definitely different trend from that of the current code. In addition, the site coefficients from recorded motions at four 765 kV substation sites, which are several hundred meters distant, have a remarkably similar trend and absolute values to those in proposed two-parameters site classification system. Based on earthquake motions recorded in domestic areas including data from the four 765 kV substation sites, the two-parameters site classification and site coefficients are superior to the results obtained from the current Korean seismic code.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.619-629
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• 2013

The objective of this study is to estimate shear wave velocity of earth dam materials using artificially generated vibration from blasting events and to verify its applicability. In this study, the artificial blasting and vibration monitoring were carried out at the site adjacent to Seongdeok dam, which is the first blasting test for an existing dam in Korea. The vibrations were induced by 4 different types of blasting with various depths of blasting boreholes and explosive charge weights. During the tests, the acceleration time histories were recorded at the bedrock adjacent to the explosion and the crest of the dam. From frequency analyses of acceleration histories measured at the crest, the fundamental frequency of the target dam could be evaluated. Numerical analyses varying shear moduli of earth fill zone were carried out using the acceleration histories measured at the bedrock as input ground motions. From the comparison between the fundamental frequencies calculated by numerical analyses and measured records, the shear wave velocities with depth, which are closely related to shear moduli, could be determined. It is found that the effect of different blasting types on shear wave velocity estimation for the target dam materials is negligible and the shear wave velocity can be consistently evaluated. Furthermore, comparing the shear wave velocity with the previous researchers' empirical relationships, the applicability of suggested method is verified. Therefore, in case that the earthquake record is not available, the shear wave velocity of earth dam materials can be reasonably evaluated if blasting vibration test is allowed at the site adjacent to the dam.