• Journal of the Korean Geotechnical Society
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• v.37 no.10
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• pp.65-76
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• 2021

There is a possibility of cavities occurring inside and behind the lining of an aged tunnel structure. In most cases, it is not easy to check the cavity because it exists in a place where visual inspection is impossible. Recently, attempts have been made to evaluate the condition of the tunnel lining and the backfill materials using non-destructive tests such as Ground Penetrating Radar, and various related model tests and numerical analysis studies have been conducted. In this study, the GPR signal characteristics for tunnel lining model testing were analyzed using gprMax software, which was compared with model test results. The numerical model applied to the model test reasonably simulated the electromagnetic wave signal according to the change of the material such as tunnel lining and internal cavity. Using the verified GPR model, B-scan data for the development of the GPR signal analysis technique were obtained, which can evaluate the thickness of the tunnel lining, the presence of the cavity, the effect of the waterproof membrane, and the frequency band.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.6
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• pp.451-461
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• 2010

Utilization of the fiber reinforced polymer (FRP) material has been enlarged as a substitution material to the general construction materials having certain long-term problems such as corrosion, etc. However, it could be difficult to apply the FRP material, which has a linear shape generally, to an arch-shaped tunnel structure. Therefore, an attempt has been made in this study to develop a device to form a designed cross section of FRP material by pulling out with a curvature. A sample of the circled FRP product was successfully produced and then the sample has been tested to identify its physical characteristics. Then, intensive feasibility studies on the circled FRP panel to be used for a tunnel lining structure have been carried out by numerical analyses. As a result, it appears that the new circled FRP-concrete composite panel has a high capability to be used for a tunnel lining material without any structural problem.

• The Journal of the Korean dental association
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• v.25 no.1 s.212
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• pp.25-27
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• 1987

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.3
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• pp.195-205
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• 2002

Most tunnel damage such as cracks or leakage which exist in tunnel liner commonly, is caused by the cavities that exist behind the tunnel liner, through the tunnel safety inspections. These cavities were analysed to check if they affect the stability of tunnels. This study is on the development of the controlled low-strength and flowable filling material which an be applied to the cavity behind the tunnel lining. The backfilling material studied here is crushed sand and stone-dust which is in cake-state and is a by-product obtained in the producing process of aggregate. Varying the compound mixing ratio, laboratory tests of compression test and chemical analyses were carried out. In addition, the material was applied to an old tunnel for the performance assessment.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.6
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• pp.641-646
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• 2004

Statement of Problem. Temporary soft relining materials are used in a diverse clinical situations such as tissue conditioner, relining material, functional impression by varying its viscoelasticity. However, reproduction of consistent viscoelasticity has been not possible. Materials and methods. Considering setting mechanism of this material, this study has measured the effect of varying amount of void in dynamic viscoelasticity of soft relining material, with three different mixing methods. In each methods 10 specimens were made and subjected to dynamic viscoelastic test which were measured at specific times over period of 72 hours. Results. The analysis of the result shown that there was no statistically significant differences between different mixing methods. Conclusion. Different mixing methods had no effect over control of viscoelasticity of soft lining material. Further research is recommended for under similar oral environmental condition.

• Journal of the Korean GEO-environmental Society
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• v.9 no.5
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• pp.29-36
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• 2008

The shotcrete is a NATM technique as a major tunnel support for ground stability after tunnel excavation. Instead of a general concrete lining method, it is a trend for curtail of construction periods and reduction of construction expenses that required to use of the permanent shotcrete lining. This high-strength shotcrete is required to use as a permanent shotcrete lining. This brought out the solution of environmental pollution and harmfulness to human. Accordingly, in this study specimens for strength measurement were made to develop shotcrete possible to develop materials in early with cement mineral accelerator as NATM method construction. It was compared with existing shotcrete material, unconfined compression test, flexural strength test, antiwashout underwater test were experimented. The fish poison test was experimented to evaluate an influence of environment. As a results of the test, unconfined compressive strength and flexural strength were equivalent with 28-curing day strength of existing material. An antiwashout of research subject material was revealed excellently in antiwashout Underwater test. As a results of the fish poison, an evaluation research subject material was founded more environmentally friendly than existing shotcrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.1023-1030
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• 2002

From the early 1980s, the New Austrian Tunnelling Method (NATM) has been developed as a one of the standard tunneling method in Korea. Approximately 10 years ago, wet-mix shotcrete with sodium silicate accelerator (waterglass) was introduced and widely used to tunnel lining and underground support. However, this accelerator had some disadvantages due to the decrease of long-term strength compared to plain concrete (without accelerator) and low quality of the hardened shotcrete. In order to compensate for these disadvantages, recently developed alkali-free accelerator has been successfully demonstrated in numerous projects and applications as a new material to make tunnels more durable and safer. An experimental investigation was carried out in order to verify the strength behavior of wet-mix Steel Fiber Reinforced Shotcrete (SFRS) with alkali-free accelerator. Compressive strength, flexural strength and equivalent flexural strength were measured by testing specimens extracted from the shotcrete panels. From the results, wet-mix SFRS with alkali-free accelerator exhibited excellent strength improvement compared to the conventional shotcrete accelerator.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.17.1-24
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• 1995

In tennelling lattice girders have basically the same function as steel arch supports. They serve as elements of temporary lining and in some cases also as part of the permanent lining. Also lattice girders are closely connected with that of the shotcreting lining technique. This paper presents the results of modelling test for analysing shorcrete rebound, shotcreting time and finding void spaces using the aretificial tunnel wall which consist of wood to evaluate the site applicability of lattice girders for tunnel support. Test results indicate that in case of using lattice girders as a tunnel support material, shotcrete rebound, shotcreting time and occurrence of void spaces are relatively reduced comparing to H-beam steel rib. And we can get some informations ths lattice girder has various advantages when we use it as one of tunnel support materials.

• Journal of KSNVE
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• v.9 no.2
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• pp.302-309
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• 1999

In this paper, a circular lined-duct is modeled by using an axisymmetric foam finite element, which is based on elastic porous material theory of Biot. For various thicknesses of three kinds of lining materials, finite element predictions are compared with measurement results and Morse's analytical results. While the analytical model has larger error as the lining becomes thicker, results of the present model have a good agreement with experimental results for all the thicknesses considered here. It has also been found that constraining the axial motion on the circumferential surface of the lining enhances sound attenuation at low freqneucies.

• Structural Engineering and Mechanics
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• v.89 no.1
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• pp.47-59
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• 2024

In this study, a new sustainable material was proposed to prepare precast tunnel lining segments (TLS), which were produced using a fiber-reinforced slag-based geopolymer composite. Slag was used as the geopolymer binder. In addition, polypropylene and carbon fibers were added to reinforce TLSs. TLSs were examined in terms of flexural performance, load-deflection response, ductility, toughness, crack characteristics, and tunnel boring machine (TBM) thrust force. Simultaneously, numerical simulation was performed using finite element analysis. The mechanical characteristics of the geopolymer composite with a fiber content of 1% were used. The results demonstrated that the flexural performance and load-deflection response of the precast TLSs were satisfactory. Furthermore, the numerical results were capable of predicting and realistically capturing the structural behavior of precast TLSs. Therefore, fiber-reinforced slag-based geopolymer composites can be applied as precast TLSs.