이 연구는 한국 남서쪽에 위치한 무안군 용월리의 카르스트 지역에서 지하 공동 탐지를 위하여 3차원전기비저항탐사의 적용성을 시험한 것이다. 현장 조사지역은 과거에 지반침하가 발생하였으며, 지하 공동은 충적층 하부에 분포하고 있는 석회암내에서 발견된다. 석회암 공동은 대부분 지하수와 점성토로 충진 되어 있기 때문에 주변의 기반암에 비하여 전기비저항이 상대적으로 낮게 나타난다. 이 연구 결과에 의하면 시추공에서 인식되고 있는 공동 분포대가 저비저항대와 일치하고 있으며, 이로부터 3차원 전기비저항탐사가 카르스트 지역에서의 지하 공동을 탐지하고 영상화 하는데 매우 유용함을 입증했다.
이 연구는 한국 남서쪽에 위치한 무안군 용월리의 카르스트 지역에서 지하 공동 탐지를 위하여 3차원 전기비저항탐사의 적용성을 시험한 것이다. 현장 조사지역은 과거에 지반침하가 발생하였으며, 지하 공동은 충적층 하부에 분포하고 있는 석회암내에서 발견된다. 석회암 공동은 대부분 지하수와 점성토로 충진 되어 있기 때문에 주변의 기반암에 비하여 전기비저항이 상대적으로 낮게 나타난다. 이 연구 결과에 의하면 시추공에서 인식되고 있는 공동 분포대가 저비저항대와 일치하고 있으며, 이로부터 3차원 전기비저항탐사가 카르스트 지역에서의 지하 공동을 탐지하고 영상화 하는데 매우 유용함을 입증했다.
In this study, we examined the applicability of a 3D electrical resistivity technique for the probing of underground cavities at a field test site in a karst area in Yongweol-ri, Muan-gun, in the south-western part of the Korean peninsula. At the test site, where the ground has subsided in the past,...
In this study, we examined the applicability of a 3D electrical resistivity technique for the probing of underground cavities at a field test site in a karst area in Yongweol-ri, Muan-gun, in the south-western part of the Korean peninsula. At the test site, where the ground has subsided in the past, underground cavities are commonly found in the limestone bedrock, which is overlain with alluvial deposits. The limestone cavities at the test site are mostly filled with groundwater and clay; hence, they show levels of electrical resistivity that are significantly lower than those of the surrounding host bedrock. The results of this study demonstrate that the zones of low resistivity correspond to the zones of the cavities identified in the boreholes at the site, and that our 3D electrical resistivity survey is a very effective tool for detecting and mapping underground cavities in a karst area.
In this study, we examined the applicability of a 3D electrical resistivity technique for the probing of underground cavities at a field test site in a karst area in Yongweol-ri, Muan-gun, in the south-western part of the Korean peninsula. At the test site, where the ground has subsided in the past, underground cavities are commonly found in the limestone bedrock, which is overlain with alluvial deposits. The limestone cavities at the test site are mostly filled with groundwater and clay; hence, they show levels of electrical resistivity that are significantly lower than those of the surrounding host bedrock. The results of this study demonstrate that the zones of low resistivity correspond to the zones of the cavities identified in the boreholes at the site, and that our 3D electrical resistivity survey is a very effective tool for detecting and mapping underground cavities in a karst area.
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문제 정의
m or less). This survey was based on the results of the 2D electrical resistivity survey. Figure 7 shows the area of the 3D electrical resistivity survey lines.
가설 설정
1) Karst areas may have thousands of underground cavities due to limestone dissolution by groundwater.
3) The limestone cavities in the study area have low-resistivity zones of 50 Ω or less.
제안 방법
A dense pattern of survey lines was laid out in a longitudinal direction (E–W) and a transverse (N–S) direction to collect resistivity data that would be appropriate for performing a 3D resistivity inversion.
New detection strategies and techniques are therefore required for 3D investigation of the distribution of underground cavities. For this study, the field test site was a karst area with underground cavities, and we tested the area with 2D and 3D electrical resistivity surveys. The spatial distribution of the limestone cavities was visualised by means of 3D inversion of the resistivity data obtained from the site.
In this study, we examined the applicability of 2D and 3D electrical resistivity surveys for detecting and mapping limestone cavities in an area of ground subsidence. The major findings of the study are summarised as follows:
To form an image of the limestone cavities, we conducted 2D and 3D electrical resistivity surveys of the field site. The results of 2D electrical resistivity survey give a rough estimate of how the limestone cavities are distributed at the field site.
대상 데이터
The longitudinal lines are 205 m to 255 m long and the transverse lines are 145 m to 475 m long. The electrode space is 5 m, and the maximum penetration depth of the survey is 25 m. For the electrode layouts, we used dipole-dipole and modified pole-pole configuration systems.
The field test site is located at Yongweol-ri, Muan-gun, in the south-western part of the Korean peninsula. The site is located near a large fault zone called the Kwang-ju Fault.
이론/모형
, 2003). In this automatic analysis method, a forward modelling subroutine was used to calculate the apparent resistivity values, and a non-linear least-squares optimisation technique was used for the 2D inversion routine.
성능/효과
2) The limestone cavities identified in the boreholes of the study site have abnormally low values of resistivity because the cavities are mostly filled with groundwater and clayey soils.
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