DOI QR코드

DOI QR Code

Assessment and Calibration of Ultrasonic Velocity Measurement for Estimating the Weathering Index of Stone Cultural Heritage

석조문화재의 풍화지수 산정을 위한 초음파속도의 평가 및 보정

  • Received : 2012.02.28
  • Accepted : 2012.04.04
  • Published : 2012.04.30

Abstract

Ultrasonic method is widely used for the evaluation of weathering index and of degree of deterioration because it is easily applicable $in$ $situ$. The basic idea of the method is that the ultrasonic velocity decreases as a rock is being weathered. Thus, the difference of ultrasonic velocities between fresh rock and weathered rock indicates the degree of weathering. In this method, the ultrasonic velocity of fresh rock is assumed to be 5,000 m/s. However, this assumption can cause significant errors in estimating weathering index, especially in case that those rocks of the same type have a wide range of ultrasonic velocities such as in Korea. Therefore, we obtained twenty rock specimens and sixty core samples commonly used for stone cultural heritages in Korea, and measured ultrasonic velocities. From the results, we found that the ultrasonic velocities of the same rock type, granite samples range from 3,118 to 5,380 m/s, and that the estimated weathering index can be highly biased if we use the fixed value of 5,000 m/s. We created a database (DB) by combining the measurement data and reported it. We also measured ultrasonic velocities by direct and indirect methods to quantify the calibration coefficient for each sampling site. We found that the calibration coefficients vary widely from site to site (1.31-1.76). Other factors, such as operator bias and temperature did not show any significant effect on errors in ultrasonic velocity measurements. Lastly, we applied our ultrasonic velocity DB and calibration coefficients to a stone cultural heritage, Bonghwang-ri Buddha statue. Our estimation of the weathering index was 0.3, 0.1 smaller than that by conventional method. The degree of deterioration was also different, "moderately weathered", while conventional method gave "highly weathered". Since other independent studies reported that the degree of deterioration of the Buddha statue was "moderately weathered", our estimation seems to be more accurate. Thus our method can help accurately evaluate the weathering index and the conservation planning for a stone cultural heritage.

Keywords

stone cultural heritage;ultrasonic velocity;database;measurement errors;calibration coefficient

References

  1. 국립문화재연구소, 2002, 석조문화재 보존관리 연구: 광주, 전남북 및 제주지역 석조문화재 현황조사. 한국문화재보존과학회, 1825 p.
  2. 국립문화재연구소, 2003, 석조문화재 보존관리 연구: 서울, 충청남.북도지역 석조문화재 현황조사. 한국문화재보존과학회, 1714 p.
  3. 국립문화재연구소, 2004, 석조문화재 보존관리 연구: 경남, 울산, 부산 및 대구지역 석조문화재 현황조사. 한국문화재보존과학회, 1245 p.
  4. 국립문화재연구소, 2005, 석조문화재 보존관리 연구: 강원도, 경기도, 추가지정 및 누락분 석조문화재 현황조사. 한국문화재보존과학회, 1417 p.
  5. 국립문화재연구소, 2011, 석조문화재 풍화훼손도 통합적 평가기술 개발 연구. 국립문화재연구소 연구보고서, 578 p.
  6. 김수진, 2001, 한국의 석조문화재 보존, 문화재 보존에 있어서의 지질학의 역할(서만철 편집). 대한지질학회.대한자원환경지질학회, 제 17차 학술강연회 논문집, 16-26.
  7. 김지영, 박선미, 이찬희, 2009, 논산 개태사지석불입상의 손상도와 보호각 내부의 미기후 환경. 보존과학회지, 25, 179-196.
  8. 양희재, 한민수, 최석원, 이찬희, 2008, 익산 미륵사지석탑 화강암의 풍화에 의한 물리화학적 특성변화. 보존과학회지, 23, 11-24.
  9. 윤석봉, 곽연천, 박성미, 이정은, 이찬희, 최석원, 2006, 논산 관촉사 석조미륵보살입상의 암석학적 특성과 풍화훼손도. 자원환경지질, 39, 629-641.
  10. 이명성, 2007, 경주 불국사 및 감은사지 석탑의 재질특성과 보존과학적 손상 평가. 공주대학교 이학박사학위논문, 315 p.
  11. 이재성, 2009, 화강암의 속도분석과 풍화도 산정에 미치는 영향. 공주대학교 이학석사학위논문, 49 p.
  12. 이종명, 2001, 문화재 복원을 위한 레이저 세정기술. 보존과학회지, 10, 10-20.
  13. 이찬희, 이명성, 서만철, 최석원, 2004, 영주 가흥리 마애삼존불상의 암석학적 분석과 안전 진단. 한국문화재보존과학회 제 19회 학술대회 발표논문집, 64-70.
  14. 이찬희, 조영훈, 전유근, 2009, 석조문화재 풍화도 평가를 위한 초음파 측정의 설정과 직접-간접전달방법의 상관 관계. 보존과학회지, 25, 233-244.
  15. 전유근, 이찬희, 조성남, 조영훈, 박기정, 양필승, 2008, 운현궁수조의 손상평가와 초음파속도를 이용한 풍화도 및 균열심도 측정. 보존과학회지, 24, 1-11.
  16. 조영훈, 이찬희, 2009, 석조문화재 디지털복원 및 구조안정성 평가를 위한 3차원 영상분석: 마곡사 오층석탑. 보존과학회지, 25, 115-130.
  17. 조지현, 조영훈, 전유근, 최준현, 이찬희, 2010, 봉화 북지리마애여래좌상의 비파괴 정밀진단과 사면안정성 분석. 보존과학회지, 26, 121-132.
  18. De Vallejo, L.G. and Ferrer, Mercedes., 2011, Geological engineering. CRC Press, London, UK, 700 p.
  19. Iliev, I.G., 1967, An attempt to estimate the degree of weathering of intrusive rocks from their physicomechanical properties. Proceedings of 1st Congress of International Society of Rock Mechanics, 109-114.
  20. ISRM (International Society for Rock Mechanics), 1979, Suggested methods for determining the uniaxial compressive strength and deformability of rock materials. International Journal of Rock Mechanics and Mining Sciences, 16, 135-140.
  21. Mavko, G., Mukerji, T., and Dvorkin, J., 2009, Rock physics handbook: Tools for seismic analysis of porous media. 2nd ed., Cambridge University Press, New York, USA, 511 p.
  22. National Research Institute of Cultural Heritage, 2009, Development on evaluation technology for weathering degree of stone cultural properties. NRICH Research Report, 874 p.

Cited by

  1. Establishment of Ultrasonic Measurement Method for Stone Cultural Heritage Considering Water Content and Anisotropy vol.30, pp.4, 2014, https://doi.org/10.12654/JCS.2014.30.4.15
  2. A Study on Selection of Ultrasonic Transducer and Contact Material for Surface Irregularities of Stone Cultural Heritage vol.31, pp.3, 2015, https://doi.org/10.12654/JCS.2015.31.3.07
  3. A Study on Weathering Processes of Tafoni in Mt. Cheonsaeng, Gumi, the Republic of Korea: Interpretation of Water Content Data using GIS Interpolation Analysis vol.36, pp.6, 2015, https://doi.org/10.5467/JKESS.2015.36.6.543
  4. Characterization of Surface Deterioration for Stone Property around the Hyeonleung (Royal Tomb of Joseon Dynasty) in Guri, Korea vol.32, pp.3, 2016, https://doi.org/10.12654/JCS.2016.32.3.06

Acknowledgement

Supported by : 국립문화재연구소