• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.3
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• pp.187-195
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• 2005

When a tunnel is excavated below groundwater table, the groundwater flow occurs towards the tunnel resulting in the seepage pressure. In this paper, the effect of groundwater flows on the behavior of shotcrete lining installed between ground-liner interfaces was studied considering permeability ratio between the ground and the shotcrete into account. Three-dimensional coupled finite element analysis was performed for this assessment. Seepage forces will seriously affect the shotcrete behavior since arching phenomena do not occur in seepage forces. A parametric study was conducted on the various tunnelling situations including interfacial properties between ground and shotcrete lining, the shape of tunnel cross-section and the thickness of liner, etc. Moreover, the convergence-confinement method (CCM) of a NATM tunnel considering seepage forces was proposed. The result showed that the more water tight is the shotcrete, the smaller is the convergence and the larger is the internal pressure. Therefore, the watertight fiber-reinforced shotcrete is found to be even more advantageous when used in under water tunnel.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.3
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• pp.209-215
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• 2004

Together with the requirements of tunnels, its construction methods and technologies have been pretty much developed, but frequent accidents happened under the constructions are just one of important problems which should be improved. To detect the potential hazardous factors in or ahead of time, speedy and accurate observation are absolutely required, but currently surveying method using tapes, level and total station, has been generally taken in measuring of tunnel convergence and crown. The purpose of this study is, as using of industrial photogrammetry system which is supplying more accuracy and speedy in the measure of tunnel convergence and crown. From the result of this study, we have got up to 1/20,000 accuracy and totally 6 minutes, from picturing 5 sections by one person to data edition, has been taken except setting targets.

• Tunnel and Underground Space
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• v.15 no.1 s.54
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• pp.1-8
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• 2005

Measurement of convergence was/is carried out manually throughout the world for tunnels under construction. However, manual method has certain limitations in terms of applicability for the tunnels in operation. This paper describes state of the art of convergence monitoring systems which are available for measuring displacement of existing tunnels. These technologies are analyzed as follows: 1 The Sofo system using the fiber optic sensors has been applied to the stress measurement of the tunnel lining. It has not yet been used for the monitoring of tunnel convergence because of its cost and reliability 2. A TPMS(Tunnel Profile Monitoring System) using tilt sensors and displacement sensors is used for the convergence monitoring of highway tunnels, subway tunnels and underground ducts. 3. A BCS(Bassett Convergence System) using a pair of tilt sensors can be used for the convergence monitoring of tunnels, however the accuracy of the measurement has to be improved because it uses AC input voltage during data acquisition. The system has to be validated before it can be applied to the tunnels in operation. Convergence monitoring systems using TPMS and/or BCS are recommended to be evaluated and improved by a series or tests in tunnels under construction in order to be applied to the main measuring section and the tunnels in operation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.3
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• pp.235-245
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• 2002

The purpose of this study is to figure out the tendency of tunnel convergence during excavation and to present a methodology for the prediction of a fault zone ahead of a tunnel face by analyzing three dimensional displacements in various ways. 3-D numerical analysis was performed to investigate changes of tunnel convergence vectors near a fault zone and to propose a flow chart for predicting fault zones. Results of the site investigation and results of trend line analysis of in-situ data were compared to verify the usefulness of a trend line analysis. It is concluded that the orientation of faults can be predicted by using stereonets and the direction of initial stresses can be predicted from the arm length of a displacement vector as a tunnel approaches fault zones. The results of the trend line analysis coincided with those of the site investigation, and a methodology for the prediction of a fault zone was proposed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.4
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• pp.329-340
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• 2010

Mechanical behavior of underground cavity construction such as tunnel is very difficult to estimate due to complexity and uncertainty of ground. Prediction of behavior according to excavation of tunnel mainly uses method utilized of model test or numerical analysis. But scale model test is difficult to reappear field condition, numerical analysis is also very hard to seek choice of suitable constituent model and input data. To solve this problem, this paper forecasted the deformation of tunnel that applied to information of crown settlement and convergence, RMR in weathered granite by using the regression analysis. The result of the analysis shows that the crown settlement according to excavation occurs approximately 70~80% of total displacements within about 20 days. As a result of the prediction of crown settlement and convergence, an exponential function becomes more accurate at measurements than an algebraic function. Also this paper got a correlation in comparison of RMR and displacements of 6 sections.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.3
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• pp.185-193
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• 2002

In this paper, deformation behavior of shallow subway tunnel excavated in weathered soil and reinforcement effects of longitudinal support measures are investigated via three dimensional FDM analysis. Two excavation methods, half-face excavation and full-face excavation, are considered in simulation to study the influences of excavation methods on tunnel deformation behavior. In addition, the reinforcing effects of RPUM and fiberglass pipe are compared. Face extrusion, covergence, preconvergence, and sidewall displacement are investigated to analyze tunnel deformation behavior, and surface settlement is used to analyze the effects of excavation methods and longitudinal supports measures. The simulation results show that half-face excavation induces larger convergence, preconvergence, sidewall displacement, surface settlement than full-face excavation, while full-face excavation induces larger extrusion than half-face excavation. In addition, under same excavation method, all displacements are larger when RPUM is only used for longitudinal support than when RPUM is jointly used with fiberglass pipes.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.3
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• pp.59-69
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• 2000

Three-dimensional total station system which integrated the instrument with Target Pin and TEMS 3D software developed by SKEC R&D center was applied to a tunnel excavation for monitoring of convergence and crown settlement. The efficiency of the system was proved as the result in the aspects of exact monitoring and prediction of rock conditions ahead of the face. To monitor the behavior of tunnel lining at the maintenance stage, DOCS system was applied to the subway tunnel section. Such many effects as the vibration of sensors, verification of the system efficiency, the effect of test trains operation, the variation of temperature and the effect of high voltage was checked. Thus the management scheme for tunnel maintenance was laid out as a proposal.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.891-896
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• 2008

Behavior of the existing tunnel in the jointed rocks was affected by the adjacent slope excavation. In this study, large scale model tests were conducted. To investigate the tunnel distortion depending on the excavated slope angle and the joint dip of the ground performed model tests were numerically back analyzed. Consequently, as the joint dip and slope angle became larger, the tunnel distortion was tended to be larger. Ground displacement was also greatly dependent on the joint dip and the excavated slope angle, which indicated the possibility of the optimal slope reinforcement.

• Tunnel and Underground Space
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• v.11 no.2
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• pp.146-155
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• 2001

An inverse calculation method to obtain sectional forces, axial force and flexural moment of a tunnel concrete lining was developed by utilizing convergence measurements acquired at the maintenance stage. To monitor the behavior of the lining, DOCS system was applied to a subway tunnel section. The method was proved to be effective, yielding the same results as measured forces of buried instruments. Many effects such as vibration of sensors, vibration due to test train operation, the variation of temperature and high voltage were checked and a new management scheme for tunnel maintenance was proposed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2C
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• pp.81-90
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• 2009

In this study the behavior of a steel pipe structure used as an auxiliary method was evaluated by the convergence-confinement method and load-transfer approach, and the result was compared with that of numerical approach and in-situ measured data. As calculated partially increased displacement of the installed pipe to obtain the tunnel displacement. A numerical analysis simulate well the general behavior of measured displacement of tunnel crown. Through this study, it was found that the proposed procedure produces conservative result so that it can be applied in preliminary design of the auxiliary method of tunnel face.