• Journal of the Korea Safety Management & Science
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• v.14 no.1
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• pp.101-108
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• 2012

In this study was conducted numerical analysis to evaluate the stability of BTR(Built-in Timber Roof Tunneling Method), which is one of construction methods of underground structures in the non-opening state. The discretion method was applied to individually model reinforcing members of BTR, and the homogeneity analysis technic by area ratio was used to verify the feasibility comparing this result with that from conventional analysis method. The parameter study was performed to evaluate the effect varying ground depth, distance length of reinforcing supports and to verify the field applicability of new analysis method. The results showed the very precise value with allowable error, so this method can be applied in the field, The more length of supporting members caused the more vertical displacement and the top displacement increment of support members is larger than that of ground surace. The effect of ground depth was more impressive than that of distance length of reinforcing supports.

• Tunnel and Underground Space
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• v.18 no.4
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• pp.272-279
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• 2008

This paper describes the development of a simple and quantitative subsidence hazard estimation method appropriate to Korean coal mines using gangway depth information only. In spite of simpleness of estimation method, this new method gives good results close to those obtained using influence function method when applying to a virtual rectangular excavation model and to a closed mine where actual subsidence occurred. Therefore, this method can be effectively applied to the identification of zones liable to subsidence over closed coal mine in Korea where the shape of extraction is very complex and usually unknown.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1325-1334
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• 2016

The video incident detection System is a probe for rapid detecting the walker, falling, stopped, backwards, smoke situation in tunnel. Recently, the importance is increases from the downtown double deck tunnel in great depth underground space[1], but the legal basis is weak and the vulnerable situation experimental data. So, In this paper, we introduce a long-term log data analysis information in the tunnenl video incident detection system installed and experimental results in order to verify the feasibility of apply to video incident detection system for the double deck tunnel. It is proposed a few things about derives the problem of existing video incident detection system, improvements and reflect attributes for double deck tunnel. The contents described in this paper will contribute to refine the prototype of video incident detection system will apply to future double deck multi-layer tunnels.

• Journal of Korean Society for Quality Management
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• v.47 no.4
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• pp.739-754
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• 2019

Purpose: The purpose of this paper is to develop a reliability estimation procedure for the underground gas pipeline in the presence of corrosion defects. Methods: Corrosion is one of the major causes of the gas pipeline failure. Several failure forms caused by corrosion have been studied. Among them, small leak and burst are considered in this paper. The composite failure of the two is defined by limit state function, and it is expressed with pipe parameters. Given a modified corrosion dataset, in order to obtain reliability estimations, the method of first order and second moment is adopted because of its simplicity. The computation processes are conducted with MATLAB coding. Results: According to numerical results, the probability of composite failure is affected by both small leak and burst. In particular, when corrosion depth stays at low level, it is consistent with the probability of burst failure. On the contrary, it is more influenced by the small leak failure as corrosion depth is increasing. In such case, the probability of composite failure is fast approaching to the safety limit. Conclusion: By considering the composite failure, more practical predictions of remaining life can be obtained. The proposed method is useful for maintenance planning of the underground gas pipeline.

• Tunnel and Underground Space
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• v.14 no.4
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• pp.295-303
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• 2004

For the deep underground excavation site with the geological complexity of soft seam and hard rock, the numerical analysis and in-situ measurement on the behaviors of roadway and surrounding rock according to stepwise excavation of the steep soft seam are carried out. The strata behavior is modeled using elasto-plastic FEM considering the empirical failure criteria of Hoek ＆ Brown and the strain-softening model. Hydraulic pressure capsule, MPBX and tape extensometer are installed around the roadway for the in-situ measurement of rock stress and deformation. Despite the complexity of geology and excavation procedure, the elasto-plastic analysis considering the empirical failure criteria of Hoek ＆ Brown and the strain-softening model shows good agreement with the in-situ measurement. Comparison of numerical modeling with in-situ measurement enables to predict the behaviors of the roadway and to obtain design parameters for the excavation and support at depth.

• Advances in Computational Design
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• v.5 no.4
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• pp.417-443
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• 2020

Tunnels have been an integral part of human civilization. Due to complexity in its design and structure, the stability of underground structures under extreme loading conditions has utmost importance. Increased terrorism and geo-political conflicts have forced the engineers and researchers to study the response of underground structures, especially tunnels under blast loading. The present study has been carried out to seek the response of tunnel structures under blast load using the finite element technique. The tunnel has been considered in quartzite rock of northern India. The Mohr-Coulomb constitutive model has been adopted for the elastoplastic behaviour of rock. The rock model surrounding the tunnel has dimensions of 30 m x 30 m x 35 m. Both unlined and lined (concrete) tunnel has been studied. Concrete Damage Plasticity model has been considered for the concrete lining. Four different parameters (i.e., tunnel diameter, liners thickness, overburden depth and mass of explosive) have been varied to observe the behaviour under different condition. To carry out blast analysis, Coupled-Eulerian-Lagrangian (CEL) modelling has been adopted for modelling of TNT (Trinitrotoluene) and enclosed air. JWL (Jones-Wilkins-Lee) model has been considered for TNT explosive modelling. The paper concludes that deformations in lined tunnels follow a logarithmic pattern while in unlined tunnels an exponential pattern has been observed. The stability of the tunnel has increased with an increase in overburden depth in both lined and unlined tunnels. Furthermore, the tunnel lining thickness also has a significant effect on the stability of the tunnel, but in smaller diameter tunnel, the increase in tunnel lining thickness has not much significance. The deformations in the rock tunnel have been decreased with an increase in the diameter of the tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.5
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• pp.799-812
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• 2017

Backfill grouting and realistic convergence distribution were not properly considered in previous studies on 2D numerical analysis of a shield TBM tunnel. In this study, a modeling method was suggested to cope with this problem by considering a realistic convergence distribution and proper properties of backfill grouting. To this end, the influence of gap parameter and depth of rock cover on volume loss and composed of ground volume loss around tunnel excavation and surface volume loss were analyzed with a single layer of weathered soil. As a result, most of surface settlements were occurred immediately after excavation. Additional, as depth of rock cover and gap parameter increased, the influence range of surface settlement curves obtained from 2D numerical analyses became broader than a suggested theoretical equation. Therefore, it is inferred that gap parameter should be applied based on load distribution ratio and the property of backfill grouting properly considered for the estimation of the precise behavior of a shield TBM tunnel in 2D numerical analysis.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.301-317
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• 2017

In this study, as an initial study for development of stability analysis program of a double-deck tunnel during life cycle, a structural analysis solver based beam-spring model for the double-deck tunnel is constructed. Effect of parameters(slab supporting type, depth of the tunnel and ground elastic modulus) is analyzed with the beam-spring model. The model is also compared and verified by commercial structural analysis program. It is considered that the slab supporting type affects the integrated behavior with segment lining and influence of intermediate slab on the stability of the tunnel decreases as the tunnel depth increases. The relationship between the ground elastic modulus and the effect of the intermediate slab on the segment lining needs further investigation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.459-467
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• 2016

Recently, new open-cut modular construction method, which is built within a 5~7m depth below the road, was proposed for the near-surface transit system to ensure the economic feasibility of underground structures. In this paper, the precast modular construction method was developed for the low-cost and rapid construction of underground structures. For the experiment on the flexural performance of the modular slab connections, a total of eleven specimens were fabricated according to the test variables; section shape, joint type, lap length, and transverse reinforcement. The test results were compared with those of the specimens without loop joints. To verify the performance of the slab connections, the 4-point loading tests of precast RC members with loop joints were conducted. As a result of the test, the flexural performance of the half-depth specimens with a 200mm lap length of loop joints were confirmed to be similar to those of the specimens without joints.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.104-110
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• 2016

To get the empirical data of GPR detection and to develop the image prosessing program of GPR detection data, GPR detection were proceed by the underground pipes and cavities buried in the Chamber. In the case of non pavement and asphalt pavement, water filled cavity that was buried in 0.7m depth was able to detection. But in the case of 1.0 m and 1.3 m buring depth, water filled cavity was not able to detection. In the case of non-reinforced and reinforced concrete pavement, it was difficult to detect the cavity caused by signal interference. GPRiPP programs was developed for image processing of the GPR detection data. The major processing algorithm were background removal, stacking and gain function. With proper image processing of gain function and background removal in GPRiPP program, it was showed that similar results can be obtained with conventional image processing program.