Journal of Conservation Science (보존과학회지)

The Korean Society Of Conservation Science For Cultural Heritage (한국문화재보존과학회)
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A Study on Evaluation of Slope Stability and Range of Rockfall Hazard of Daljeon-ri Columnar Joint in Pohang, Korea

천연기념물 제415호 포항 달전리 주상절리의 사면안정성 평가 및 낙석 위험 범위 설정

  • Kim, Jae Hwan (Natural Heritage, National Research Institute of Cultural Heritage) ;
  • Kang, Mu Hwan (Geochang Granite Research Center) ;
  • Kong, Dal-Yong (International Cooperation Division, Cultural Heritage Administration) ;
  • Jwa, Yong-Joo (Department of Geology, Gyeongsang National University)
  • 김재환 (국립문화재연구소 자연문화재연구실) ;
  • 강무환 (거창화강석 연구센터) ;
  • 공달용 (문화재청, 국제협력과) ;
  • 좌용주 (경상국립대학교 지질과학과)
  • Received : 2021.08.04
  • Accepted : 2021.09.23
  • Published : 2021.10.20
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Abstract

In this study, we evaluated the slope stability of the Pohang Daljeon-ri columnar joint (Natural Monuments # 415) and calculated the maximum energy, jumping height and moving distance of rockfalls using a simulation. Based on the results, we established the range of rockfall risk. The slopes of the Pohang Daljeon-ri columnar joint have dip directions of 93.79°, 131.99°, 165.54° and 259.84° from left (SW) to right (NE). Furthermore, they have a fan-like shape. The Pohang Daljeon-ri columnar joints are divided into four sections depending on the dip direction. The measurement results of the discontinuous face show that zone 1 is 125, zone 2 is 261, zone 3 is 262, zone 4 is 43. The results of slope stability analyses for each section using a stereographic projection method correspond to the range of planar and toppling failure. Although it is difficult to diagnose the type of failure, risk evaluation of currently falling rocks requires further focus. The maximum movement distance of a rockfall in the simulation was approximately 66 m and the rockfall risk range was the entire area under slope. In addition, it is difficult to forecast where a rock will fall as it rolls in various directions due to topographic factors. Thus, the installation of measures to prevent falling is suggested to secure the stability based on the results of the rockfall simulations and its probabilistic analysis.

포항 달전리 주상절리(천연기념물 제415호, 이하 주상절리)에 대한 사면안정성 평가 및 낙석 시뮬레이션을 통하여 낙석의 최대 에너지, 도약높이, 이동거리를 산출하였으며, 낙석 위험 범위를 설정하였다. 주상절리가 분포하는 사면의 경우 왼쪽(SW)에서 오른쪽(NE)에 이르기까지 93.79°, 131.99°, 165.54°, 259.84°의 경사방향을 가지며 전체적으로 부채꼴의 형상을 하고 있다. 이러한 사면의 경사방향을 따라 4구간으로 구분하였으며, 각 구간별 노출되어 있는 주상절리의 단면에서 개별적인 불연속면의 방향성을 측정한 결과 1구간은 125개, 2구간은 261개, 3구간은 262개, 4구간은 43개로 확인된다. 평사투영법을 이용한 각 구간별 사면 안정성 평가 결과, 평면 및 전도파괴 영역에 해당되나 이는 노출된 주상절리면의 개별 방향성에 대한 해석 결과로 주상절리에 대하여 평면 및 전도파괴의 가능성을 진단하기 어렵기 때문에 현재에도 발생되고 있는 낙석으로부터 위험 가능성을 평가하는 것이 바람직한 것으로 판단된다. 또한 낙석 시뮬레이션을 통해 측정된 낙석의 최대 이동거리는 약 66 m이며, 낙석 위험 범위는 사면 아래 전 영역이 해당됨을 알 수 있다. 따라서 이러한 낙석의 거동은 지형학적 요인에 의해 다양한 방향으로 굴러떨어져 낙하지점을 예측하기 힘들기 때문에 낙석으로부터 안정성 확보를 위한 낙석 방지시설 설치를 제안하고자 한다.

Keywords

Acknowledgement

이 연구를 위해 현지조사에 많은 도움을 주신 포항시청과 포항시청 김진규 선생님께 감사드립니다. 그리고 심도 깊은 논문이 될 수 있도록 유익한 조언을 해주신 익명의 심사위원님께도 감사드립니다.

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