• 한국소음진동공학회논문집
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• 제20권3호
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• pp.257-262
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• 2010

Lower tunnels and concrete based tracks are introduced to newly constructed metro lines to reduce the construction and track maintenance fees. But such a lower tunnel together with concrete based track causes higher interior noise of metro trains. It is required that the trains should not only be a transportation media but also be comfortable. So, to lower the metro train's interior noise level, design was made to increase the transmission loss per sectional part. Through such a design, it is expected that about 7 dB(A) of noise level will be reduced compared to that of the conventional train.

• 터널과지하공간
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• 제2권1호
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• pp.28-49
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• 1992

• 한국지반공학회지:지반
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• 제39권2호
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• pp.9-34
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• 2023

• 한국지반공학회지:지반
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• 제39권6호
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• pp.25-54
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• 2023

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.125-131
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• 2008

This research tries to analyze and investigate the effects of the noise reduction test for the sound-absorbing materials installed tentatively on Metro Line 5. Though the noise reduction effects of each sound-absorbing material showed that there was about $2{\sim}5\;dB$ compared with before and after of the tentative installation, it shows that the noise reduction effects are reducing because of the section change condition such as dust absorption and the rail abrasion as time passes after the tentative installation. Also, many difficulties are occurring in the maintenance of the orbit facilities because of the installation of sound-absorbing materials. Though various abroad products for noise reduction are imported like this, the researches for the noise reduction effect increase for this and the improvement direction are being required because of the poor circumstance of the efficiency aspect compared to the economic investment effect because those are not suited to the character of domestic Metro.

• 한국재난정보학회 논문집
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• 제14권3호
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• pp.262-270
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• 2018

연구목적: 본 연구는 국내와 국외의 도시 및 고속철도터널 유지관리 계측센서의 손망실 현황을 조사하고 분석을 실시하였다. 연구방법: 도시철도터널 유지관리 계측센서 설치 후 5년에서 6년의 손망실율은 서울 지하철5,6,7,9호선은 14.2%에서 14.8%, 영국의 Channel tunnel은 13.9%로 거의 유사하게 나타나 5년 경과연수에서는 15%로 설정하는 것이 타당한 것으로 판단된다. 연구결과: 고속철도터널 유지관리 계측센서 설치 후 3년에서 5년의 손망실율은 호남고속 철도1단계 에서 60.9%로 서울지하철5,6,7,9호선의 4배 이상 크게 나타났다. 결론: 8년에서 10년의 경부고속철도2단계에서는 66.8%로 나타나 5년에서 10년 사이에 급격하게 증가하므로 향후 10년 이상 장기간의 경과연수에 따른 계측항목별 손망실율 연구가 필요할 것으로 판단된다.

• Geomechanics and Engineering
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• 제30권3호
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• pp.273-280
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• 2022

A certain amount of random vibration excitation to subway track is caused by subway operation. This excitation is transmitted through track foundation, tunnel, soil medium, and ground building to the ground and ground structure, causing vibration. The vibration affects ground building. In this study, the results of ANSYS numerical simulation was used to establish back-propagation (BP) neural network model. Moreover, a back-propagation neural network model consisting of five input neurons, one hidden layer, 11 hidden-layer neurons, and three output neurons was used to analyze and calculate the vertical Z-vibration level of New Capital's ground buildings of Qingdao Metro phase I Project (Line M3). The Z-vibration level under different working conditions was calculated from monolithic roadbed, steel-spring floating slab roadbed, and rubber-pad floating slab roadbed under the working condition of center point of 0-100 m. The steel-spring floating slab roadbed was used in the New Capital area to monitor the subway operation vibration in this area. Comparing the monitoring and prediction results, it was found that the prediction results have a good linear relationship with lower error. The research results have good reference and guiding significance for predicting vibration caused by subway operation.

• Geomechanics and Engineering
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• 제35권4호
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• pp.411-424
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• 2023

Reasonable estimates of tunnel lining dislocations in the operation stage, especially under longitudinal differential settlement, are important for the design of waterproof gaskets. In this paper, a modified shell-joint model is proposed to calculate shield tunnel dislocations under longitudinal differential settlement, with the ability to consider the nonlinear shear stiffness of the joint. In the case of shell elements in the model, an elastoplastic damage constitutive model was adopted to describe the nonlinear stress-strain relationship of concrete. After verifying its applicability and correctness against a full-scale tunnel test and a joint shear test, the proposed model was used to analyze the dislocation behaviors of a shield tunnel in Shanghai Metro Line 2 under longitudinal differential settlement. Based on the results, when the tunnel structure is solely subjected to water-earth load, circumferential and longitudinal joint dislocations are all less than 0.1 mm. When the tunnel suffers longitudinal differential settlement and the curvature radius of the differential settlement is less than 300 m, although maximum longitudinal joint dislocation is still less than 0.1 mm, the maximum circumferential joint dislocation is approximately 10.3 mm, which leads to leakage and damage of the tunnel structure. However, with concavo-convex tenons applied to circumferential joints, the maximum dislocation value reduces to 4.5 mm.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.208-213
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• 2010

In this study CFD(Computational Fluid Dynamics) analysis of the steady fire-driven fuid flow for the performance test of ventilation at railway tunnel between Heuksok and Nodeul Station from Seoul Metro 9 is performed. There were fans with exhaust and intake modes and each was installed at the middle and both ends of the tunnel. For this test, the pool fire source of methyl alcohol with 1.5MW and smoke generators were installed between the middle of tunnel and Heuksok Station. In this test, the smoke behavior from natural convection was observed for 10 minutes from the ignition of pool fire and then fans with intake-modes at both sides of Heuksok effect of fan-on with intake mode located in the opposite side of the tunnel nearby Heuksok Station on fire-driven fluid flow is studied on when the boundary conditions of fan-on at the tunnel between Heuksok and Nodeul Station are the same as test. FLUENT, a commercial CFD code, is used for this analysis.

• Geomechanics and Engineering
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• 제31권3호
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• pp.237-248
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• 2022

Nowadays, more and more subway tunnels were planed and constructed underneath the ground of urban cities to relieve the congested traffic. Potential damage may occur in existing tunnel if the new tunnel is constructed too close. So far, previous studies mainly focused on the tunnel-tunnel interactions with circular shape. The difference between circular and horseshoe shaped tunnel in terms of deformation mechanism is not fully investigated. In this study, three-dimensional numerical parametric studies were carried out to explore the effect of different tunnel shapes on the complicated tunnel-tunnel interaction problem. Parameters considered include volume loss, tunnel stiffness and relative density. It is found that the value of volume loss play the most important role in the multi-tunnel interactions. For a typical condition in this study, the maximum invert settlement and gradient along longitudinal direction of horseshoe shaped tunnel was 50% and 96% larger than those in circular case, respectively. This is because of the larger vertical soil displacement underneath existing tunnel. Due to the discontinuous hoop axial stress in horseshoe shaped tunnel, significant shear stress was mobilized around the axillary angles. This resulted in substantial bending moment at the bottom plate and side walls of horseshoe shaped tunnel. Consequently, vertical elongation and horizontal compression in circular existing tunnel were 45% and 33% smaller than those in horseshoe case (at monitored section X/D = 0), which in latter case was mainly attributed to the bending induced deflection. The radial deformation stiffness of circular tunnel is more sensitive to the Young's modulus compared with horseshoe shaped tunnel. This is because of that circular tunnel resisted the radial deformation mainly by its hoop axial stress while horseshoe shaped tunnel do so mainly by its flexural rigidity. In addition, the reduction of soil stiffness beneath the circular tunnel was larger than that in horseshoe shaped tunnel at each level of relative density, indicating that large portion of tunneling effect were undertaken by the ground itself in circular tunnel case.