• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.64-71
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• 2009

The stresses acting on shotcrete lining of tunnel have been measured virtually by monitoring instruments installed during construction. However, the malfunction of instrument and the lack of consistency of signal have always been controversial, but re-installation of instrument after construction of tunnel lining is practically impossible. Therefore, authors have carried out the study to develop a new technique for estimating the stress acting on shotcrete lining during and after construction. In the technique, stresses of shotcrete lining can be estimate by the measurement of deformation of free face. Therefore, the relationships between the stresses of shotcrete lining and deformation of free surface are indispensable factor. In this paper, the parametric study using 2D FEM analysis was carried out to estimate the relationships between the stress level acting on the tunnel shotcrete lining and the deformation near the free face (e.g. artificial crack in this study). The distribution of stresses of shotcrete lining is also investigated in this study as the preliminary investigation for the large-scale tunnel lining test and detailed 3D FEM analysis.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.1
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• pp.1-11
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• 2014

In order to determine the optimal number of monitoring points in single-track tunnel lining, this thesis compares and evaluates the results of two cases: when the tunnel lining is modeled into a simple beam form and then is applied to 1) the tunnel lining inverse analysis program, and to 2) the commercially-used program. The displacement and stress of specific tunnel lining cross-sections are determined by entering the load conditions into the commercially-used program for tunnel interpretations. In doing so, two cases were assumed: where a symmetrically-distributed load was acting upon the tunnel lining of a single-track tunnel and where an asymmetrically-distributed load was in action. By comparing the computed displacement with the stress and displacement determined by entering side numbers 3, 5, and 7 into the tunnel lining inverse analysis program, the optimal number of monitoring points is determined. From the results of the research, it can be inferred that the number of monitoring points needs to be at least 5 points, considering the efficiency of monitoring in practice and the loss-and-damage rate of tunnel monitoring.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.3
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• pp.103-110
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• 2002

Maintenance monitoring of the tunnel which offers continuous data during and after tunneling has been applying to tunnels in order to meet the maintenance of tunnel and to confirm continuous security of the tunnel after tunneling. But, the maintenance monitoring of tunnel results for long period is not easy to find, and moreover, the rational analysis method on tunnel monitoring has not been established yet. In this study, the relationships between displacement and stress of the tunnel concrete lining using various analysis methods are compared with maintenance monitoring. The tunnel behavior were measured in the subway tunnel passing comparative soft the weathering and analyzed both security and mechanical characteristics of the tunnel concrete lining. Also, analyzed relationship between residual water pressure applied on tunnel design and one obtained by monitoring.

• International Journal of Concrete Structures and Materials
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• v.2 no.2
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• pp.145-152
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• 2008

So far, there has been no study of the concrete to strengthen in the lining of the tunnels, except for the study of the stability of subgrade and the tunnel construction technologies. In the existing concrete work for tunnel lining, lots of problems happen due to the partial compaction and the material segregation after casting concrete. Accordingly, the aim of this study is to improve economic efficiency and secure durability through the improvement of the construction performance and quality of the concrete for the tunnel lining among the civil structures. Therefore, the compactability and strength properties of the High Flowing Self-Compacting Lining Concrete (HSLC) are evaluated to develop the mixing proportion for design construction technology of HSLC that can overcome the inner cavity due to the reduced flowability and unfilled packing, which has been reported as the problem in the existing lining concrete. The result of the evaluation shows that the ternary mix meets the regulations better than the binary mix. Consequently, it has been judged applicable to the cement for tunnel lining.

• The Journal of Engineering Geology
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• v.13 no.4
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• pp.445-456
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• 2003

Backfill grouting and consolidation grouting are major reinforcing methods that enhance the stability of tunnel by filling the gap between the tunnel lining and the ground and increasing the stiffness of the ground. However, the effect of the grouting on the tunnel lining is not well established. Field measurements such as pressuremeter test, Lugeon test, and lining instruments were peformed to analyze the grouting effect on the tunnel lining for a waterway tunnel. The elastic modulus was increased up to 5 times than that of original rock mass due to consolidation grouting. This study shows that only 10% of grout pressure was acting on the back face of the tunnel lining. The final results are expected to be used for the design of the concrete lining.

• Tunnel and Underground Space
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• v.9 no.4
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• pp.296-305
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• 1999

In ordinary back analysis it if hardly possible to obtain the mechanical properties of tunnel lining by using commonly measured displacements of tunnel lining, because only a few displacements could be measured at the site. Therefore, it is necessary to develop a new method which can evaluate the state of stresses of tunnel by using measured data. In this study, in order to assess tunnel lining stability by estimating its stresses with a few measured displacements, a formulation of back analysis method was proposed. The accuracy of results were investigated through the parametric study for several types of measurement model of two dimensional elastic lining. This new back analysis method to assess tunnel lining stresses and strains with a few numbers of measured displacements showed high accuracy and good applicability when compared to the results of numerical experiments by FEM. The method has been tested on subway tunnel and its applicability has been confirmed by comparing field and analytical data. It is verified that the stress on the tunnel lining can be obtained by only more than 3 point of input displacements without any condition of external loads.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.10a
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• pp.32-37
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• 1993

A method of tunnel analysis for a new type of tunnel construction method (ACLCM, Automatic Concrete Lining Construction Method) is presented here. ACLCM is an unique tunnel construction method which provides concrete lining at the end of shield machine by extruding concrete into the space between the excavated ground surface and the inner form (Automatic Concrete Lining Machine). Since behaviors of tunnel and the surrounding soils are greatly influenced by the construction method, existing tunnel design methods may not be applicable to the design of ACLCM tunnel. In this study, a method of ACLCM tunnel analysis is suggested to provide the prediction of behavior of ACLCM tunnel and surrounding soils as well as to check up the safety during the construction and after the completion of ACLCM tunnel

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1369-1376
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• 2005

In case of the drainage type tunnel, the residual water pressure is likely to act on the tunnel lining due to the decrease of water-passing capacity of the filter material. Therefore, this study discussions a method to predict the lining load with the consideration of water passing capacity of the filter material through the literature review and numerical analysis. It is expected from the results of case studies that the design load acting on the concrete lining in the drainage type tunnel could be assumed to be about 50% of the hydrostatic water pressure in steady-state ground-water condition.

• Structural Engineering and Mechanics
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• v.29 no.1
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• pp.1-16
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• 2008

Tunnels are generally constructed below the ground water table, which produces a long-term interaction between the tunnel lining and the surrounding geo-materials. Thus, in conjunction with tunnel design, the presence of water may require a number of considerations such as: leakage and water load. It has been reported that deterioration of a drainage system of tunnels is one of the main factors governing the long-term hydraulic and structural lining-ground interaction. Therefore, the design procedure of an underwater tunnel should address any detrimental effects associated with this interaction. In this paper an attempt to identify the coupled structural and hydraulic interaction between the lining and the ground was made using a numerical method. A main concern was given to local hindrance of flow into tunnels. Six cases of local deterioration of a drainage system were considered to investigate the effects of deterioration on tunnels. It is revealed that hindrance of flow increased pore-water pressure on the deteriorated areas, and caused detrimental effects on the lining structures. The analysis results were compared with those from fully permeable and impermeable linings.

• The Journal of Engineering Geology
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• v.7 no.3
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• pp.207-216
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• 1997

Estimation of loads on tunnel lining is one of the major issues to be addressed in the design of a tunnel. The existing analytical methods do not consider important details of construction and the variation of geology along the tunnel axis. The measured loads obtained from several sanitary and subway tunnels in Edmonton, Alberta, Canada, are compared with the lining loads calculated using the existing analytical methods. However, the existing methods are determined to be not fully satisfactory for the estimation of lining loads. To account for face and heading effects occurring prior to lining installation, the stress reduction factor determined using Eisenstein and Negro's method is used coupled with an analytical solution for calculation of lining loads.