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대형 댐의 지진응답특성평가를 위한 원심모형시험 기법 연구대형 댐의 지진응답특성평가를 위한 원심모형시험 기법 연구
김남룡,임정열,임은상 한국지진공학회 2016 한국지진공학회논문집 Vol.20 No.4
Damages of large embankment dams by recent strong earthquakes in the world highlight the importance of seismic security of dams. Some of recent dam construction projects for water storage and hydropower are located in highly seismic zone, hence the seismic performance evaluation is an important issue. While state-of-the-art numerical analysis technology is generally utilized in practice for seismic performance evaluation of large dams, physical modeling is also carried out where new construction technology is involved or numerical analysis technology cannot simulate the behavior appropriately. Geotechnical centrifuge modeling is widely adopted in earthquake engineering to simulate the seismic behavior of large earth structures, but sometimes it can’t be applied for large embankment dams due to various limitations. This study proposes a dynamic centrifuge testing method for large embankment dams and evaluated its applicability. Scaling relations for a case which model scale and g-level are different could be derived considering the stress conditions and predominant period of the structure, which is equivalent to previously suggested scaling relations. The scaling principles and testing method could be verified by modified modeling of models using a model at different acceleration levels. Finally, its applicability was examined by centrifuge tests for an embankment dam in Korea.
김남룡,하익수 대한토목학회 2012 대한토목학회논문집 C Vol.32 No.5
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 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 garget 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 rel 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. 본 연구의 목적은 댐 인접발파로 유발된 진동을 이용하여 사력댐의 고유주가를 산정하는 방법을 제시하고, 산정결과의 실효성을 확인하는 것이다. 이를 위하여 운영 중인 성덕댐에 대하여 국내 최초로 실대규모 근접 발파진동 실험을 수행하였다. 장약량과 발파 시추공심도를 4가지 유형으로 달리한 발파진동을 유발시키고, 각 유형별 발파 시에 댐 정상부에서 가속도를 계측하였다. 계측기록 붕 발파로 인한 주 진동이후 자유진동감쇠에 의한 계측기록만을 발췌하였으며, 이데 대한 주파수응답 특성을 분석하여 대상댐의 고유주기를 산정하였다. 발파진동 실험으로 구한 사력댐의 고유주기는 발파유형에 영향을 받지 않고 일관성 있는 결과를 보여줌을 확인하였다. 발파진동실험에 의한 대상댐의 고유주기 산정결과를 실지진 계측 기록을 분석하는 방법으로 구한 기존의 연구결과와 비교해 본 결과, 그 경향성이 일치함을 확인하였다. 이로부터 지진계가 설치되지 않아 실지진 계측기록을 이용할 수 없는 사력댐의 경우, 인접발파에 따른 발파진동계측기록에 대한 분석으로도 고유주기를 실효성있게 산정할 수 있음을 확인할 수 있었다.