• Title/Summary/Keyword: Limestone cavity

Search Result 40, Processing Time 0.038 seconds

A Study on the Dynamic Behavior of Underground Tunnels with a Cavity (주변 공동을 고려한 터널의 동적거동에 관한 연구)

  • 김민규;이종우;이종세
    • Tunnel and Underground Space
    • /
    • v.12 no.3
    • /
    • pp.171-178
    • /
    • 2002
  • A dynamic analysis of a horseshoe_shaped tunnel near to cavity was performed to study the effect of the cavity on the dynamic behavior of the tunnel. In order to obtain the dynamic response of the tunnel embedded in a semi-infinite domain, a hybrid numerical technique was primarily developed. A dynamic fundamental solution in frequency domain for multi-layered half planes was derived and subsequently incorporated in the boundary element method. Coupling of the boundary element method for the far field with the finite element method for the near field is made by imposing compatibility condition of a displacement at the interface. The boundary element method is then coupled with the finite element method, which is utilized to model the near field including the tunnel and the cavity. In order to demonstrate the validity of the proposed technique, dynamic responses of single and multiply-layered semi-infinite structural systems are obtained by using the Kicker waveform and investigated in the limestone layer to find how the being and the location of the cavity affect the dynamic characteristics of the system.

Scoping Analysis of MCCI (Molten Core Concrete Interaction) at Plant Scale Using CORQUENCH Code (CORQUENCH 코드를 사용한 실규모 원자로의 노심용융물과 콘크리트 상호반응 해석)

  • Kim, Hwan-Yeol;Park, Jong-Hwa
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2008.03b
    • /
    • pp.268-271
    • /
    • 2008
  • If a reactor vessel is failed to retain a molten corium in a postulated severe accident, the molten corium is released outside the reactor vessel into a reactor cavity. The molten corium would attack the concrete wall and basemat of the reactor cavity, which may lead to inevitable concrete decompositions and possible radiological releases. In the OECD/MCCI project, a series of tests were performed to secure the data for cooling the molten corium spread out at the reactor cavity and for the long-term CCI (Core Concrete Interaction). Also, a MCCI (Molten Core Concrete Interaction) analysis code, CORQUENCH was upgraded at Argonne National Laboratory with embedding the new models developed for the tests. This paper deals with analyses of MCCI at plant scale under the conditions of top flooding using the upgraded CORQUENCH code. The modeling approach is briefly summarized first, followed by presentation of a validation calculation that illustrates the predicative capability of the modeling tool. With this background in place, the model is then used to carry out a parametric set of scoping calculations that define approximate coolability envelopes for the LCS (Limestone Common Sand) concrete that has been evaluated in the OECD/MCCI project.

  • PDF

Development of the Environmentally Friendly Filling Material for the Underground Cavities using the Rock-dust and an Assessment on Filling and Material Characteristics (석분토를 이용한 지하공동의 친환경적 충전재 개발과 충전 및 재료특성 평가)

  • Ma Sang-Joon;Kim Dong-Min
    • Journal of the Korean Geotechnical Society
    • /
    • v.21 no.9
    • /
    • pp.35-44
    • /
    • 2005
  • Recently, underground cavities such as limestone cavity and abandoned mine give rise to a lot of damage in SOC facilities. But there are many difficult problems such as delay of the working terms and enormous economic losses in finding a new method and changing construction design. In this study, a new filling material for underground cavities was developed using the stone-dust classified as industry waste polluting environment. As a result of test, filling material properties was that a compressive strength was $34{\~}60\;kgf/cm^2$, a change ratio in length was $0.268{\~}0.776\%$ and water absorption was $34.3{\~}46.9\%$. Also as a result of suspended mass test and pH test, it was confirmed that the developed filling material has a characteristic of non-separating in water and it was an environmentally friendly material.

Case Stories of Microgravity Survey for Shallow Subsurface Investigation (고정밀 중력탐사를 이용한 천부 지질구조 조사 사례)

  • Park Yeong-Sue;Rim Hyoungrae;Lim Mutaek;Koo Sung Bon;Kim Hag Soo;Oh Seok Hoon
    • 한국지구물리탐사학회:학술대회논문집
    • /
    • 2005.05a
    • /
    • pp.181-186
    • /
    • 2005
  • Gravity method produces subsurface density distribution, which is direct information of soundness of basement. Therefore, microgravity is one of the most effective method for detections of limestone cavities, abandoned mine-shafts and other tunnels, The paper show the effectiveness of microgravity by three different field cases.

  • PDF

A case histories on the detection of weak zone using electrical resistivity and EM surveys in planned tunnel construction site (터널 건설 예정지구에서의 전기비저항 탐사와 전자탐사의 적용을 통한 연약대 탐지에 대한 사례 연구)

  • 권형석;송윤호;이명종;정호준;오세영;김기석
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2002.03a
    • /
    • pp.63-70
    • /
    • 2002
  • In tunnel construction, the information on the rock quality and the location of fault or fracture are crucial for economical design of support pattern and for safe construction of the tunnel. The grade of rock is commonly estimated through the observation with the naked eye of recovered cores in drilling or from physical parameters obtained by their laboratory test. Since drilling cost is quite expensive and terrains of planned sites for tunnel construction are rough in many cases, however, only limited information could be provided by core drilling Electrical resistivity and EM surveys may be a clue to get over this difficulty. Thus we have investigated electrical resistivity and EM field data providing regional Information of the rock Quality and delineating fault and fracture over a rough terrain. In this paper, we present some case histories using electrical resistivity and EM survey for the site investigation of tunnel construction. Through electrical resistivity and EM survey, the range and depth of coal seam was clearly estimated, cavities were detected in limestone area, and weak zones such as joint, fault and fracture have been delineated.

  • PDF

Evaluation of Groundwater Flow by Gravel-Filling and Temporary Drainage in Groundwater-saturated Limestone Mine Cavities (지하수 포화 석회석 채굴공동에서의 골재 충전 및 임시배수시 발생하는 지하수 유동 평가)

  • Choi, Woo-Seok;Kang, Byung-Chun;Kim, Eun-Sup;Shin, Dong-Choon
    • Tunnel and Underground Space
    • /
    • v.27 no.4
    • /
    • pp.205-216
    • /
    • 2017
  • Fluctuations in groundwater level are the major cause of ground subsidence in the abandoned limestone mine. In this study, evaluation of groundwater flow under three different cases of natural condition, aggregate-filling, temporary drainage in groundwater-saturated limestone mine cavities was executed by 3-dimensional analysis. In the case of aggregate-filling, although the water level both in the upper ground of mine cavities and an agricultural watershed was elevated, it was lower than the water level fluctuation of an agricultural water use and rainfall and the flow rate was similar to the flow rate of natural condition. In the case of temporary drainage, as the water level in the upper ground of mine cavities and an agricultural watershed decrease rapidly and the flow rate has increased by 25times, so the risk of ground subsidence increased.

Detection of cavities in a karst area by means of a 3D electrical resistivity technique (3차원 전기비저항탐사에 의한 카르스트 지역에서의 공동탐지)

  • Park, Sam-Gyu;Kim, Chang-Ryol;Son, Jung-Sul;Yi, Myeong-Jong;Kim, Jung-Ho
    • Geophysics and Geophysical Exploration
    • /
    • v.12 no.1
    • /
    • pp.27-32
    • /
    • 2009
  • 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.

A Microgravity for Mapping Karstic Cavities at Gaeun (가은지역 석회 공동 탐지를 위한 고정밀 중력탐사)

  • Park, Yeong-Sue;Rim, Hyoung-Rae;Lim, Mu-Taek;Koo, Sung-Bon
    • 한국지구물리탐사학회:학술대회논문집
    • /
    • 2008.10a
    • /
    • pp.167-172
    • /
    • 2008
  • A microgravity survey was applied for detecting and mapping karstic cavities over limestone area at Gaeun. The gravity data were collected at about 1, 100 stations by 4 m interval. The density distribution beneath the profiles was drawn by two dimensional inversion based on the minimum support stabilizing functional, which generated better focused images of density discontinuities. We also imaged three dimensional density distribution by growing body inversion. The density image showed that the cavities were dissolved, enlarged and connected into a cavity network system.

  • PDF

Analysis of Ground Subsidence according to Tunnel Passage in Geological Vulnerable Zone (지질취약구간 터널통과에 따른 지반침하량 분석)

  • Choi, Jung-Youl;Yang, Gyu-Nam;Kim, Tae-Jun;Chung, Jee Seung
    • The Journal of the Convergence on Culture Technology
    • /
    • v.6 no.3
    • /
    • pp.393-399
    • /
    • 2020
  • In this study, the subsidence behavior caused by groundwater ex-flow in a limestone cavity encountered during tunnel excavation was quantified based on numerical analysis and the effect was analyzed. Based on the groundwater level and surface subsidence surveyed at the site, a numerical analysis technique was applied to analyze the characteristics of the subsidence behavior according to the tunnel passage of the geological vulnerabilities. The results of groundwater seepage-coupled analysis were analyzed to reflect the actual ground subsidence behavior. As a result of the study, it was analyzed that the ground subsidence due to the tunnel excavation in the limestone common section(the geological vulnerable zone) was analyzed that the dramatical decrease in groundwater level was the main cause. As a result of numerical analysis, it was analyzed that the long-term cumulative settlement of the asphalt surface after the groundwater ex-flow was 76~118mm due to the reduction of the volume of the soil layer due to the decrease in the groundwater level, and the settlement amount increased as the depth of the soil layer increased.

Stability Analysis on the Substructure of Abutment in Limestone Basin (석회암층 교대 하부 구조물의 안정성 해석)

  • 최성웅;김기석
    • Tunnel and Underground Space
    • /
    • v.12 no.2
    • /
    • pp.120-129
    • /
    • 2002
  • Natural cavitied were found at shallow depth during construction of a huge bridge in Cambro-Ordovician Limestone Basin in the central part or Korea. The distribution patterns of cavities in this area were investigated carefully with a supplementary field job such as a structural geological survey, a geophysical survey, and a rock mechanical test in laboratory or field. A structural geological mapping produced a detail geological map focusing the route of the Proposed highway. It suggested that there were three faults in this wet and these faults had an influence on the mechanism of natural cavities. Among many kinds of geophysical surveys, an electrical resistivity prospecting was applied first on the specific area that was selected by results from the geological survey. Many evidences far cavities were disclosed from this geophysical data. Therefore, a seismic tomography was tested on the target wet which was focused by results from the electrical resistivity Prospecting and was believed to have several large cavities. A distinct element numerical simulation using the UDEC was followed on the target area after completing all of field surveys. Data from field tests were directly dumped or extrapolated to numerical simulations as input data. It was verified from numerical analysis that several natural cavities underneath the foundation of the bridge should be reinforced Based on the project result, finally, most of fecundations far the bridge were re-examined and the cement grouting reinforcement was constructed on several foundations among them.