• 한국터널지하공간학회 논문집
• /
• 제6권2호
• /
• pp.151-160
• /
• 2004

본 연구는 국내 재래식 철도 터널에서 발생한 아치부 종방향 균열 부위에 대하여 각종 현장조사를 실시하여 터널의 변상상태를 파악한 것이다. 현장 외관조사 및 각종 비파괴 조사를 통하여 균열 부위에 대한 상세한 조사를 실시하였으며 현장조사 결과를 토대로 균열의 발생 원인을 추정하였다. 아울러 현장여건을 고려한 안전성 해석을 실시하여 터널 구조물의 균열 발생 가능성을 검토하였다.

• KIEE International Transactions on Electrophysics and Applications
• /
• 제11C권2호
• /
• pp.12-17
• /
• 2001

In this work, the correlation between the PD Patterns and the electrical tree propagation has been investigated by use of the specimen removed from the insulation of the real 154 kV XLPE underground power cables. As a result, it could be deduced that the PD pattern regarding electrical trees depends on their type which could be classified into three different distinct groups such as branch-bush mixed. Considering the results of our investigation, if the partial discharge magnitude is only considered for the diagnosis of the cable system, it is possible to draw a wrong decision. Therefore, it is possible to propose that the time characteristics of PD pattern should be taken into account for the diagnosis of the cable system in addition to the conventional $\Phi$-q-n characteristics.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1999년도 지반조사 세미나
• /
• pp.169-180
• /
• 1999

Ground penetrating radar(GPR) uses radio waves to detect buried objects in any non-metallic material. Initially it was used to detect structures in ice. GPR has evolved to include the penetration of soils, rocks and man-made structures. GPR uses a sensitive detector to record weak radio waves reflected from objects embedded in the material under investigation. In this study, the GPR is applied to outside plant telecommunication facilities such as cable tunnels, manholes and underground conduits and model experiments to obtain radar characteristics. The thickness and soundness of tunnel lining can be evaluated, and the location of rebars and steel ribs can also be found effectively. The location of underground conduits as well as manholes can be found and the results of GPR give good coincidence with design drawings. In order to investigate the tunnel lining, the GPR mounted vehicle is developed and it is proved that the vehicle can save time and manpower.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 전기설비
• /
• pp.61-63
• /
• 2005

In present, most of underground metallic structures, especially gas pipeline, have adopted in order to protect against a corrosion. If a coating defect is be on the surface of gas pipeline, the pitting corrosion is occur normally. So, in the corrosion field, investigation of coating defect is very important activity. In this paper, DCVG(Direct Current Voltage Gradient) method which is can detect a coating defect of gas pipeline is introduced. And also, the assesment of coating defect position according to the position of temporary anode of ICCP(Impresed Current Cathodic Protection) system is presented.

• 한국지구물리탐사학회:학술대회논문집
• /
• 한국지구물리탐사학회 1999년도 제2회 학술발표회
• /
• pp.65-91
• /
• 1999

GPR이 국내에 소개된지 6년 이상이 지났으며 그 동안 GPR이 가지는 다양한 적용 분야 및 그 방법의 편의성과 경제성에 의해 많은 건설현장에서 수많은 이용 사례들이 축적되었다. 따라서 본 논문에서는 이들 실제 사례들을 중심으로 GPR이 가지는 특성 및 제한을 살펴보고자 하였다.

• 터널과지하공간
• /
• 제6권1호
• /
• pp.10-18
• /
• 1996

Arched openings are generally excavated in underground construction works. Since stress distribution around openings depends on geological structure in rock mass, any shape of arched openings fully conformed with in-situ stress condition should be recommended to maintain mechanical safety of structures. Shape of arched openings is specified by both roof curvature and height-width ratio, and especially this report presents deformation behaviors related with roof curvature. Scale model tests and numerical studies of various shaped openings are conducted, where rectangular opening shows the greatest convergence. Through the anlayses of various arched opengings, as radius of roof curvature is increased, roof lowering and sidewall closure are remarkably increased, whereas floor heaving is increased little by little. By the way, it is useful that displacements of openings are roughly estimated in the stage of preliminary investigation. To find out elastic displacements of arched openings with any roof curvature, regressional formula and charts by least square method are represented. In addition elastoplastic deformation behavoirs of arched openings concerning associated adn non-associated flow rule are discussed.

• 터널과지하공간
• /
• 제6권1호
• /
• pp.30-38
• /
• 1996

A two dimensional analysis program for groundwater flow in fractured network was developed to analyze the influence of discontinuity characteristics on groundwater flow. This program involves the generation of discontinuities and also connectivity analysis. The discontinuities were generated by the probabilistic density function(P.D.F.) reflecting the characteristics of discontinuities. And the fracture network model was completed through the connectivity analysis. This program also involves the analysis of groundwater flow through the discontinuity network. The result of numerical experiment shows that the equivalent hydraulic conductivity increased and became closer to isotropic as the density and trace length increased. And hydraulic head decreased along the fracture zone because of much water-flow. The grouting increased the groundwater head around cavern. An analysis of groundwater flow through discontinuity network was performed around underground oil storage cavern which is now under construction. The probabilistic density functions(P.D.F) were obtained from the investigation of the discontinuity trace map. When the anisotropic hydraulic conductivity is used, the flow rate into the cavern was below the acceptable value to maintain the hydraulic containment. But when the isotropic hydraulic conductivity is used, the flow rate was above the acceptable value.

• 자연, 터널 그리고 지하공간
• /
• 제13권6호
• /
• pp.68-80
• /
• 2011

해저터널은 태풍, 폭우 등과 같은 악천후에도 안정적으로 자국내 도서지역 및 인접국가간 교통 및 물류수송체계 운용을 가능하게 하는 주요 사회기반시설로서 활용되어왔다. 이러한 해저터널 프로젝트를 안전하고 경제적으로 수행하기 위해서는 해저터널의 공학적 특성을 정확하게 이해하는 것이 매우 중요하다. 이에 해저터널의 지반조사를 중심으로 전반적으로 언급하였다. 해저터널은 육상터널과는 달리 조사, 설계 및 시공단계에 있어 많은 불확실성과 위험성을 가지고 있으므로, 프로젝트의 특성에 맞는 정밀하고 정확한 조사는 해저터널의 성공여부를 좌우할 수 있다. 따라서 계획단계에서 철저한 문헌조사 연구 및 해저지형, 지질구조 등에 대한 이해를 기반으로 해저지반 조사계획을 수립 및 수행하여야 한다. 또한 해저터널의 특성상 완벽한 지반조사는 불가능하므로 광범위한 조사에도 불구하고 사전에 예상치 못한 불량한 지반조건을 마주칠 가능성이 크므로, 불확실성과 위험성을 염두에 두고 설계 및 시공에 임하여야 한다.

• Geomechanics and Engineering
• /
• 제37권5호
• /
• pp.467-474
• /
• 2024

Monitoring and managing the condition of underground utilities is crucial for ground stability. This study aims to determine whether images obtained using ground penetrating radar (GPR) accurately reflect the characteristics of buried pipelines through image analysis. The investigation focuses on pipelines made from different materials, namely concrete and steel, with concrete pipes tested under various diameters to assess detectability under differing conditions. A total of 400 images are acquired at locations with pipelines, and for comparison, an additional 100 data points are collected from areas without pipelines. The study employs GPR at frequencies of 200 MHz and 600 MHz, and image analysis is performed using machine learning-based convolutional neural network (CNN) techniques. The analysis results demonstrate high classification reliability based on the training data, especially in distinguishing between pipes of the same material but of different diameters. The findings suggest that the integration of GPR and CNN algorithms can offer satisfactory performance in exploring the ground's interior characteristics.

• 한국터널지하공간학회 논문집
• /
• 제18권2호
• /
• pp.143-154
• /
• 2016

최근 국내 빈번하게 발생되고 있는 지반함몰 현상의 원인, 현황, 대책에 대하여 지반공학적인 접근 방법으로 조사하였다. 국내 발생된 지반함몰은 대부분 터널 굴착 공사와 지중매설관의 손상에 의한 것으로 나타났다. 용산역과 석촌 지하차도 지반함몰 사례와 같이, 굴착 공사 중 지반함몰은 지하수와 토사의 과다 유출이 주된 원인으로 나타났다. 특히, 충적층과 같은 연약지반에서의 기계식 굴착 시, TBM 굴착이 멈춘 지점에서 지반함몰 위험이 큰 것으로 나타났다. 서울시에서 발생된 지중매설관 손상으로 인한 지반함몰 사고를 종합하였을 때, 시공 시의 부주의, 노후화, 연약지반에서의 관의 부등침하 등이 지반함몰의 원인으로 나타났다. 터널 굴착 공사에 의한 지반함몰은 공사 시 발생되는 지하수, 토사의 이동에 대한 모니터링을 통해 대비할 수 있다. 지중매설관 손상으로 인한 지반함몰은 지중매설관의 생애주기 분석 및 유지관리 혹은 관 상부의 토압 분산 및 토압 지지력 증대를 통하여 대비할 수 있을 것으로 판단된다.