Journal of the Korean GEO-environmental Society (한국지반환경공학회 논문집)

Korean Geo-Environmental Society (한국지반환경공학회)
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Evaluation on Weathering Characterization on Rock Types Using Artificial Weathering Test

인공풍화시험을 이용한 암종별 풍화특성 평가

  • Heo, Yeul (Department of Civil Engineering, Chungbuk National University) ;
  • Kang, Changwoo (Department of Civil Engineering, Chungbuk National University) ;
  • Kwon, Youngcheul (Department of Civil Engineering and Management, Tohoku Institute of Technology) ;
  • Bae, Wooseok (NANO-GEO ENC Co. Ltd.)
  • Received : 2017.06.27
  • Accepted : 2017.07.26
  • Published : 2017.08.01
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Abstract

For exposed slopes, the weathering degree over time has a major effect on the engineering properties of rocks and the slope stability. Rocks are gradually changed by weathering into soil over time, and the resulting physical, chemical and mechanical changes of rocks affect the engineering stability of the slope. However, there are not many ways to objectively evaluate the weathering degree of a slope. In this study, therefore, to investigate the weathering characteristics of rocks, granite, gneiss and shale distributed in the Chungbuk region were sampled by weathering stage and changes in their component minerals and tissues were investigated. Furthermore, artificial weathering was induced using the freezing and thawing test and quantitatively investigated through porosity and absorption rate. In addition, the changes of microcracks due to artificial weathering were evaluated through box fractal dimension ($D_B$). Through mineralogical study the phase change of constituting minerals, the growth of secondary minerals, the development of micro-cracks and the fabric changes due to weathering were observed. The mineralogical, chemical and engineering evaluations of the weathering degree through the experimental results in this study are expected to be useful for analyzing the weathering characteristics and causes by rock type and for proposing a methodology to evaluate the degradation of physical properties comparatively and quantitatively.

노출된 비탈면은 시간에 따른 풍화도가 암반의 공학적인 성질과 비탈면의 안정성에 주요한 영향을 미치게 된다. 풍화는 시간의 경과에 따라 암석을 토양으로 점진적으로 변화시키며, 이로 인한 암석의 물리적, 화학적, 역학적인 변화는 비탈면의 공학적인 안정에 영향을 미친다. 그러나 비탈면의 풍화도를 객관적으로 평가할 수 있는 방법은 많지 않은 것이 현실이다. 따라서 본 연구에서는 암석의 풍화특성을 규명하기 위해 충북지역에 분포하고 있는 화강암과 편마암, 셰일을 대상으로 풍화 단계별로 시료를 채취하고 조성광물과 조직의 변화 등을 조사하였으며, 이들 암석에 대해 동결융해시험을 이용하여 인공풍화를 유발시켜 공극률, 흡수율 등의 변화를 정량적으로 고찰하였다. 또한 박스프랙탈차원($D_B$)을 통해 인공풍화에 따른 미세균열의 변화를 평가하였다. 광물학적분석을 통해 풍화에 기인한 구성광물의 변화상과 2차광물의 생성, 미세균열의 발달을 관찰하였다. 실험결과를 통하여 풍화도에 대한 광물학적, 화학적, 공학적 평가는 암종에 따른 풍화특성과 원인을 분석하고 물성의 저하를 비교적 정량적으로 평가할 수 있는 방법론을 제시하고 규명하는데 활용할 수 있을 것으로 기대된다.

Keywords

References

  1. Bae, W. S., Kim, K. S., Sun, B. I., Lee, B. W. and Ann, B. C. (2010), A case study on weathering sensitivity analysis at sang-ju area, The proceeding of Korean Society of Civil Engineers, Vol. 2010, pp. 2200-2203 (in Korean).
  2. Choi, E. K. (2011), A study on the chemical index of alteration (CIA) and geotechnical properties of igneous rocks by weathering, PhD. dissertation, Pusan University, pp. 1-199 (in Korean).
  3. Crosta, G. (1998), Slake durability vs Ultrasonic treatment for rock durability determinations, International Journal of Rock Mechanics and Mining Sciences, Vol. 35, No. 6, pp. 815-824. https://doi.org/10.1016/S0148-9062(98)00006-0
  4. Goldich, S. S. (1938), A study in rock weathering, Journal of Geology, Vol. 46, pp. 17-58. https://doi.org/10.1086/624619
  5. ISRM (1981), Rock characterization, Testing and Monitoring. In: Brown ET(ed) Suggested methods. Pergamon Press, Oxford, 211p.
  6. Kang, C. W., Kim, B. S., Son, K. R. and Bae, W. S. (2016), Evaluation about weathering characteristics of granite at sangju area, The Journal of Korean Geo-Environmental Society, Vol. 17, No. 5, pp. 17-25 (in Korean).
  7. Kim, Y. H. and Hong, S. H. (1990), A quantitative study on the variational features of rock properties followed by weathering in granites, Journal of korean Instruction mining Geology, Vol. 23, No. 2, pp. 221-232 (in Korean).
  8. Lee, S. B. (2008), Weathering mechanism and degradation of physical property of hallasan trachyte in Jeju island, PhD. dissertation, Pukyung University, pp. 1-205 (in Korean).
  9. Lee, S. G. (1993), Weathering of granite, Journal of the Geological Society of Korea, Vol. 29, No. 4, pp. 396-413 (in Korean).
  10. Park, J. J. (2015), Mechanical characteristics of pohang area mudstone as material for reclamation material, PhD. dissertation, Joongbu University, pp. 1-143 (in Korean).
  11. Pollard, D. D. and Aydin, A. (1988), Progress in understanding jointing over the past century, Geol. Soc. of Am. Bull., 100, pp. 1181-1204. https://doi.org/10.1130/0016-7606(1988)100<1181:PIUJOT>2.3.CO;2
  12. Reiche, P. (1950), A survey of weathering processes and products, University of new mexico press, Albuquerque, pp. 1-95.
  13. Ryu, S. H. and Song, J. J. (2012), Weathering of rock specimens exposed to recurrent freezing and thawing cycles, Vol. 22 No. 4, pp. 276-283 (in Korean). https://doi.org/10.7474/TUS.2012.22.4.276