• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.05a
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• pp.48-53
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• 2003

최근 기존 암거구조물에 하수관로 등 추가적인 관로의 설치에 의해 암거 구조물이 손상을 입는 경우가 종종 발생되고 있으나, 현장여건상 이에 대한 구조적 안전성의 검토가 미비한 채 시공이 이루어지는 경우가 많다. 이에 본 연구에서는 기존 암거의 상단부에 흄관이 관통하였을 경우 block-out된 암거구조물의 구조적 거동을 검토하기 위하여, 암거구조물의 손상 인접부위의 종방향 및 횡방향 휨모멘트를 구조해석에 의해 산출하고, 이들 구조해석 결과에 의해 block-out된 암거의 손상 인접부위에 대한 구조안전성 검토를 수행하였다.(중략)

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.20-27
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• 2006

중국 Three Gorges Project의 대수로사면 안정성은 설계와 시공측면에 있어 주요 관심사가 되었다. 사면 굴착으로 인한 제하과정에서 암반은 역학적으로 불안정한 상태에 놓인다. 본 논문은 FEM(2D-3D)를 이용하여 단층 암반 굴착으로 인한 암반사면의 안정성을 평가하였다. 해석결과 굴착 후 수로사면의 양측 수직벽과 분리울타리의 중간 상부에서 인장응력과 전단손상영역이 주로 발생하였다. 해석결과를 토대로 대규모 사면활동에 대한 안정성을 확인하였으나 시공단계에서 국부적 사면활동을 방지하기 위한 록볼트와 록앵커 등의 보강이 필요한 것으로 검토되었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.203-204
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• 2017

In case of developing a guide-rail type window cleaning robot, only the first prototype has been developed. In this study, it was considered that the size and the load of the window cleaning robot was not optimized, and through the structural analysis of the self-weight of the window cleaning robot, the stress concentration area was derived and the concentrated stress was quantified. Analysis showed that the upper rail shaft had a bending stress of 9.964Mpa and the bolt had a shear stress of 19.544Mpa. The results of this study will be used as basic data for designing future prototypes.

• Journal of the Korean Geotechnical Society
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• v.28 no.12
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• pp.5-15
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• 2012

In this study, a series of CFD (Computational Fluid Dynamics) numerical analyses were performed in order to evaluate the thermal performance of six full-scale closed-loop vertical ground heat exchangers constructed in a test bed located in Wonju. The circulation HDPE pipe, borehole and surrounding ground formation were modeled using FLUENT, a finite-volume method (FVM) program, for analyzing the heat transfer process of the system. Two user-defined functions (UDFs) accounting for the difference in the temperatures of the circulating inflow and outflow fluid and the variation of the surrounding ground temperature with depth were adopted in the FLUENT model. The relevant thermal properties of materials measured in laboratory were used in the numerical analyses to compare the thermal efficiency of various types of the heat exchangers installed in the test bed. The simulation results provide a verification for the in-situ thermal response test (TRT) data. The CFD numerical back-analysis with the ground thermal conductivity of 4 W/mK yielded better agreement with the in-situ thermal response tests than with the ground thermal conductivity of 3 W/mK.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3C
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• pp.167-174
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• 2010

In this study, numerical analysis has been performed to compare the ground movements in a single ground layer and multiple ground layers due to nearby tunnel excavation. The numerical analysis has been conducted in the different ground layer conditions considering different construction conditions (volume loss at excavation face), and the results of the maximum surface settlement and horizontal displacement have been compared considering the ground layer and construction conditions. In addition, the maximum surface settlement from the numerical analysis has been compared with the maximum settlement at tunnel crown considering the ground layer and construction conditions, and the maximum surface settlement has been also compared with the maximum horizontal displacement with the ground layer conditions. Besides, the volume loss($V_L$) at tunnel excavation face has been compared with the total surface settlement volume($V_s$) with the variation of ground layer condition. The results from the numerical analysis have been compared with field measurements and by this comparison it is believed that the numerical results in this study can be utilized practically in analyzing the nearby ground behavior in different ground layer and construction conditions due to tunnel excavation.

• The Journal of Engineering Geology
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• v.12 no.4
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• pp.367-378
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• 2002

Recently, the number of tunnels on national roads has been increased due to the trend that construction of the large-scaled cut slopes is limited because of the environmental issues. Therefore, the slope failures of tunnel portal have often occurred. The tunnel portal in use has limitations on selection of the countermeasure and construction against slope failure. In the cases of Suanbo hot springs 1 and 2 tunnel portals, seedding was chosen and constructed as the countermeasureof slope failure when the tunnel was first built but collapsed in April, 2002. In this study, the failure sites were examined accurately through the site investigation and an efficient countermeasure according to stability analysis is presented. It is shown that it is very efficient to use resloping for Suanbo hot springs 1 tunnel and concrete buttress, rock anchor to reinforcement countermeasure, and attached rockfall prevention net by dividing the site into 3 sections for Suanbo hot springs 2 tunnel.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.77-81
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• 2010

D&B(Drill & Blast) method in tunnel construction requires accurate and rapid measurement of the ground movement, which is essential for feedback analysis. Case study and adaptability of IT technique for tunnel survey are discussed in this paper. The application of laserscannig and existing light wave instrument method in the field of tunnel construction were reported in several advanced country including Austria and Japan. Survey for the shoulder movements by IT survey method was conducted at a subway construction site and the results were compared to the conventional method. Also, the economic aspects of laserscannig method were analyzed using measured data which were categorized by expenses, frequency, interval and period in the field of construction. Therefore IT survey solution may contribute to execute more economic and safe construction

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.3
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• pp.255-264
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• 2009

This paper concerns the behavior of 2-Arch tunnel constructed under various conditions. A 2-Arch tunnel section adopted in a subway tunnel construction site is considered in this study. A calibrated 3D finite element model was adopted to conduct parametric studies on a variety of construction scenarios including lagged distance between left and right tunnels, overburden, and geological condition. The results of analyses were examined in terms of crown settlement, shotcrete lining stress, and load on center column in relation to the lagged distance, cover depth, and the ground condition. The results indicate that the shotcrete lining stress and the center pillar load are more influenced by the second tunnel excavation than the tunnel deformation. Also shown is that a greater lagged distance is required to minimize the interaction between two tunnels when the ground condition becomes weaker. Fundamental mechanisms of 2-arch tunnel were also discussed based on the results.

• Journal of the Korean Geosynthetics Society
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• v.5 no.4
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• pp.35-42
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• 2006

This paper describes a field experience on geogrid-reinforced soil walls rising up to 29.5m in height. Since experiences of design and construction on very high-raised geogrid reinforced soil wall were limited, thorough design and construction management was performed for safe construction of the wall. Regarding design of the wall, both internal and external stabilities were examined based on the design guideline specified by FHWA and overall slope stability analyses were performed by using Bishop simplified method. Moreover, a series of instrumentations were performed. The results of instrumentation for two tiered reinforced soil wall showed that not only the deformations of both the wall face and the reinforcement but also the horizontal earth pressures acting on the wall facing were very small. These results indicate that the reinforced soil wall technology can be applied successfully for high-raised tiered wall more than 20m heights and FHWA design guideline is very conservative for that large wall.

• Tunnel and Underground Space
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• v.20 no.1
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• pp.28-38
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• 2010

In order to investigate the tendency of general displacements and behaviors with respect to each construction process as well as the applicability of numerical analysis schemes, this research has focused on not only analyzing a variety of field observations made in a NATM tunnel, such as displacement of top and side, stress of shotcrete and axial strength of rock bolt, but also carrying out a series of numerical analyses. It was established from the investigation that the 2-dimensional continuum numerical analysis was the one which could more accurately predict displacement of crown and side in the area of one step excavation (patten, P1-P3), while the 2-dimensional discontinuum analysis was the most suitable scheme to study that of two step excavation (patten, P4-P6). In addition, the 2-dimensional continuum analysis enabled to appropriately predict the axial strength of rock bolt and stress of shotcrete in all the area of the tunnel. Finally, it has been possible to conclude from the study that the 3-dimensional continuum analysis should be applied to inspect the behavior and tendency with respect to each stage of the construction as well as in the case of joints, such as large turnouts where relaxation loads in both of horizontal and vertical direction are piled up.