• Title/Summary/Keyword: concrete lining

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A study on the optimum condition of FRP coarse-sand coating by using a new testing method for shear bearing capacity of FRP-concrete interface (새로운 FRP-콘크리트 전단부착성능 평가법을 활용한 최적 FRP 규사코팅 조건에 관한 연구)

  • Lee, Gyu-Phil;Shin, Hyu-Soung;Kim, Seung-Han
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.13 no.3
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    • pp.277-289
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    • 2011
  • This study proposes a new testing method for shear bearing capacity of FRP-concrete interface, which could well consider a loading condition corresponding to a tunnel lining undergoing axial compression and could be easily carried out with a simply specified specimen. A parametric study is carried out for capturing an optimized condition of coarse-sand coating of FRP, which governs shear bearing capacity of FRP-concrete interface, by using the proposed testing manner in this study. From the parametric study, it is shown that the proposed testing method is reasonably feasible in comparison with the existing testing methods. An optimum condition of coated sand size and sand density is given for the shearing capacity of FRP-concrete interface.

Measurement of Air Tightness of Concrete Block and its Construction Joint from a Model Experiment (모형실험을 통한 콘크리트 블록 및 시공이음부의 기밀성 측정)

  • Kim, Hyung-Mok;Ryu, Dong-Woo;Synn, Joong-Ho;Song, Won-Kyong
    • Tunnel and Underground Space
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    • v.20 no.6
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    • pp.434-445
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    • 2010
  • Underground compressed air energy storage (CAES) system in a lined rock cavern is considered one of the promising large-scale energy storage technologies. In this study, permeabilities of concrete lining block and its construction joint, which are the major components of an air tightness system of the undeground CAES, were measured from a model experiment. From the experiment, it was found that intrinsic permeability of construction joint was larger than that of concrete block by the order scale of $10^1{\sim}10^4$, so that it would be very important to control the quality of construction joints in-situ in order to secure air tightness of storage system. And the permeability of construction joint could be decreased as low as that of the concrete block by pasting an acryl-type adhesive on bonding surfaces. Higher degrees of water saturation of the concrete block resulted in the lower permeability, which is more preferable in the viewpoint of air tightness of storage cavern.

Strength Characteristics of Recycled Concrete by Recycled Aggregate in Incheon Area Waste Concrete (인천지역의 콘크리트 폐기물을 재생골재로 활용한 재생콘크리트의 강도특성)

  • Jang, Jea-Young;Jin, Jung-Hoon;Cho, Gyu-Tae;Nam, Young-Kug;Jeon, Chan-Ki
    • Journal of the Korea Concrete Institute
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    • v.15 no.2
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    • pp.197-208
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    • 2003
  • This paper is to determine the possibility of re-using waste concrete from Incheon city area. The strength test was conducted with five aggregate compounds which was replaced a natural aggregate with recycled aggregate. After checking the physical characteristics of recycled aggregate compounds, the mix design of recycled concrete was conducted. For the relatively comparison between natural and recycled compounds, while the unit aggregate weight was changed, other conditions were fixed. The freezing and thawing test which included fly-ash and super-plastezer were performed to check the durability and workability when recycling waste concrete. In the physical characteristics of recycled aggregate, it was found that the specific gravity of recycled coarse aggregate and recycled fine aggregate satisfied the first grade of recycle specification(KS), and all compounds of recycled aggregate also satisfied the second grade of absorption specification, Especially up to the 50% substitution of recycled aggregate is equal to or a bit lower than that of convention aggregate. In comparison with conventional concrete, the recycled concrete is lower than maximum by 7% in compressive strength decreasing rate after freezing-thawing test. From now, although most of recycled concrete was used to the building lot, subgrade, asphalt admixture, through the result. It was proved that possibility of re-using recycled aggregate as the substructure of bridge, retaining wall, tunnel lining and concrete structure which is not attacked the drying shrinkage severely.

An Experimental Study on Stabilization/Solidification of Plated Sludge using Cement (시멘트를 이용한 도금 슬러지 고형화에 대한 실험적 연구)

  • 김남중;김광서
    • Journal of the Korea Institute of Building Construction
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    • v.1 no.2
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    • pp.146-153
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    • 2001
  • Radical development has been made in the every field of our society for the past scores of year. Radical development of industry and lining environment has mass-produced various toxic wastes . Which comes to the fore as a serious environmental problem. The purpose of this is to suggest the optima mix design by studying the utility of a toxic waste, plated sludge as a building material and deciding the standards of quality and use of cement and evaluating the properties of mortar and concrete in which plated sludge mixed. From an experiment, compressive strength required high early strength cement or special cement. Watertightness proved to be excellent. Heavy metals, such as Cd, Pb, Cu came out below an environmental standard. Cr+6 exceeded an environmental standard under a steam curing, but came out below an environmental under a standard curing. The higher replacement rate was, the lower frost, fusion and resistance were. Thus, got better results above the goal by condition. It was possible that plated sludge was replaced and solidified to aggregate. Therefore, it is necessary to define the standards of quality on strength, replacement rate of wastes, water permeability, endurance in other to solidify plated sludge to concrete products.

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Sensitivity Analysis of Design Parameters of Air Tightness in Underground Lined Rock Cavern (LRC) for Compressed Air Energy Storage (CAES) (복공식 지하 압축공기에너지 저장공동 기밀시스템 설계변수의 민감도 해석)

  • Kim, Hyung-Mok;Rutqvist, Jonny;Ryu, Dong-Woo;Sun-Woo, Choon;Song, Won-Kyong
    • Tunnel and Underground Space
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    • v.21 no.4
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    • pp.287-296
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    • 2011
  • We performed a numerical modeling study of thermodynamic and multiphase fluid flow processes associated with underground compressed air energy storage (CAES) in a lined rock cavern (LRC). We investigated air tightness performance by calculating air leakage rate of the underground storage cavern with concrete linings at a comparatively shallow depth of 100 m. Our air-mass balance analysis showed that the key parameter to assure the long-term air tightness of such a system was the permeability of both concrete linings and surrounding rock mass. It was noted that concrete linings with a permeability of less than $1.0{\times}10^{-18}\;m^2$ would result in an acceptable air leakage rate of less than 1% with the operational pressure range between 5 and 8 MPa. We also found that air leakage could be effectively prevented and the air tightness performance of underground lined rock cavern is enhanced if the concrete lining is kept at a higher moisture content.

A study on the fire resistance method using FR-ECC in long tunnel (고인성내화모르터(FR-ECC)를 사용한 장대터널 내화안전대책에 관한 연구)

  • Kim, Se-Jong;Kim, Dong-Jun;Kwon, Young-Jin
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.13 no.1
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    • pp.9-18
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    • 2011
  • The spalling phenomenon occurs in high-strength concrete when several factors such as sharp temperature increase, high water content, low water/cement ratio and local stress concentration in material combine in the concrete material. On the basis of the factors, the preventing methods from the spalling are known as reduction of temperature increase, preventing of concrete fragmentation and fast drying of internal moisture. In this study, the reduction of temperature increase was proposed as the most effective spalling-preventing method among the spalling-preventing methods. Engineered cementitious composite for fireproof and repair materials was developed in order to protect the new and existing RC structures form exterior deterioration factors such as fire, cloride ion, etc. This study was carried out to estimate the fire-resisting performance of high strength concrete slab or tunnel lining by repaired engineered cementitious composite (ECC) or fiber reinforcement cemetitious composite (FRCC) under fire temperature curve. and them we will descrike the result of HIDA tunnel in Japan.

Mechanical characteristics of high-performance concrete shield segment containing ground granulated blast furnace slag and their improvement by steam curing (고성능 쉴드 세그먼트용 고로슬래그 미분말을 혼입한 콘크리트의 역학적 특성 및 증기양생 효과 분석)

  • Kim, Byoung-Kwon;Lee, Jin-Seop;Lee, Gyu-Phil;Chang, Soo-Ho;Bae, Gyu-Jin
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.13 no.3
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    • pp.233-242
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    • 2011
  • This study aims to evaluate the applicability of high-strength concrete mixed with blast furnace slag to shield segment lining in order to improve its performance and economic efficiency. Especially, it was also intended to derive the optimum replacing ratio of ground granulated blast furnace slag to ordinary cement as well as the optimum steam curing condition for shield segment concrete with the design strength of 60 MPa. From a series of experiments, the condition of 50% replacement of ordinary cement by ground granulated blast furnace slag and unit water content of 125 kg/$m^3$ was proposed as the optimum mixing condition. Comparing with standard curing conditions, it was also possible to expect approximately 110~442% strength improvement of concrete by steam curing in the same mixing condition.

Estimation of Shape of Voids behind Concrete Tunnel Linings Using Radar of Three Dipole Antenna Type (3 다이폴 안테나 방식 레이더에 의한 콘크리트 터널 라이닝 배면 공동의 형상 추정)

  • Park Seok-Kyun
    • Journal of the Korea Concrete Institute
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    • v.17 no.2 s.86
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    • pp.221-227
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    • 2005
  • The presence of voids behind tunnel linings is very likely to result in settlement or structural collapse. One proposed method of detecting such voids by non-destructive method is radar. More than effectively judging the existence of voids behind tunnel linings, this study aims to develop the analysis algorithm of radar capable of estimation of the shape of specific voids. To acquire directional information and estimate the shape of three-dimensional voids, the radar of three-dipole antenna type is used. As a foundation to this ongoing research, an investigation of microwave polarization methods using three-dipole antenna carried out with various void orientations and void geometries. As a result, it is clarified that the response of four microwave polarization modes depends on void geometry and thus there is a possibility of identifying the geometry and orientation (the shape) of specific voids using radar of three-dipole antenna type.

A Case Study on the Reinforcement Method of Subway Tunnel (도심지 지하철 터널의 지반보강공법 시공사례 연구)

  • 천병식;여유현;최현석
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.10a
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    • pp.201-208
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    • 1999
  • The NATM(New Austrian Tunnelling Method) has been used for tunnelling since 1980's. But Collapses of tunnel under construction take place frequently, especially at urban areas because of adjacent buildings, underground conduits and traffic loads. This paper is a case study on the reinforcement method of subway tunnel at urban areas. In this study, ground inspection, geological investigation, laboratory test and numerical analysis by means of FDM program were carried out. The tunnel excavation was stopped because of over excessive brake of tunnel crown and shotcrete was installed to prevent deformation of adjacent ground as the temporary method. From the result of field survey and geological investigation, it is found that the soft weathered soil was distributed to the ground of tunnel invert unlike original investigation. The results of the analysis and the study show that the SGR(Space Grouting Rocket) method and Umbrella method can be applied for the stability of tunnel excavation and in addition the reinforcement of concrete lining is required for long-term stability of tunnel.

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Evaluation of an applicability of lattice girders for the tunnel support (터널지보재로서 격자지보(Lattice Girder)의 현장적용성 평가 연구)

  • 문홍득;이성원;배규진
    • Tunnel and Underground Space
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    • v.6 no.2
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    • pp.122-130
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    • 1996
  • Generally the NATM technique uses shotcrete, rock bolts, H-beam steel ribs, and concrete lining for the tunnel support in Korea. Among them, H-beam steel ribs are extremely heavy and difficult for workers to handle. Therefore, especially in Europe, lattice girders are being used instead of H-beam steel ribs for tunnel support. Lattice girders have basically the same function as H-beam steel ribs in tunnelling. The main advantages of using lattice girders compared to H-beam steel rib supports are as follows: 1) lattice girders have relatively a low weight enough to be easily lifted and installed by labors and 2) they create a more effective bond with the shotcrete. The purpose of this study is to evaluate the effectiveness and applicability of lattice girders compared to H-beam steel ribs used in construction tunnel sites and to show that lattice girders can be adequately applied in domestic tunnel construction sites as a new tunnel support system.

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