한국도로학회논문집 제20권 제6호 (p.41-50)

휴대용 소형루프 전자기탐사법을 이용한 지반하부 동공탐사

Exploration of Underground Cavity Using Portable Small-loop Electromagnetic Method
키워드 :
Small-loop Electromagnetic,Cavity Detection,Electrical Conductivity,Electrical Resistivity,Inverse Analysis

목차

ABSTRACT
1. 서론
2. 비파괴 탐사기술의 분류 및 특징
3. 소형루프 전자기탐사법의 기본원리
4. 동공탐사 시험
  4.1. 테스트베드 구축
  4.2. 탐사방법
5. 탐사결과 분석
REFERENCES

초록

PURPOSES: The purpose of this study is to verity the applicability of a portable small-loop electromagnetic survey method to underground cavity detection.
METHODS: In order to evaluate applicability of the method, a test bed comprised of four sections was constructed. The two sizes of the four cavities artificially formed at two depths were contained in the test bed. Each cavity was positioned at center of each 6 m long section. Four types of pavement materials such as unpaved ground, bricks, asphalt, and concrete were used at every section. The portable small-loop electromagnetic device measured electrical conductivity as an exploration signal that varied according to the electrical properties underground. The electrical conductivity was converted into two-dimensional electrical resistivity distribution sections using an inverse analysis program.
RESULTS : The results showed that the electrical resistivity of the non-cavity area was lower than that of the cavity area. The electrical resistivity increased as the measurement device moved closer to the cavity position. It was also found that the electrical resistivity values were not significantly affected by pavement type. The small cavity with diameter of 35 cm could be detected up to 1.2 m depth.
CONCLUSIONS: Therefore, it was verified that the portable small-loop electromagnetic survey method is applicable to the detection of cavities in sections where ground subsidence is expected. This method can be effectively used for small-scale roads such as sidewalks, parkways, and side streets where large exploration equipment cannot enter.