• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.149-156
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• 2002

Field measurements were carried out in this study to investigate the behavior of cut and cover tunnel such as the distribution and the magnitude of the earth pressure during back fill process of the ground material. Three kinds of measuring instruments, such as the earth pressure load cell, the concrete strain gauge and the reinforcing bar meter of embedded type in concrete structure were installed and measured. Earth pressure load cells, installed after construction of the tunnel lining, measure the outside forces acting on the tunnel lining with radial directions. Three load cells were installed at the crown, the right and the left shoulder of the tunnel, respectively. Three sets of reinforcing bar meter were installed in the double reinforcements of the tunnel lining and their locations were the same with the position of the earth pressure load cells. Concrete strain gauge was installed only one site of the upper compressive part at the tunnel crown. Based on the measuring results in the field, the deformation and the earth pressure acting on the tunnel lining were investigated with the back fill process of the ground material. Considerations on the validity of the measuring results were paid. For the analysis of measurements, after dividing back fill process into three steps, various factors which affect on the behavior of tunnel lining were investigated at each step.

• 한국유체기계학회 논문집
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• 제17권5호
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• pp.54-59
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• 2014

The new high speed combi train prototype project was developed which named HSB. It runs over the speed of 330km/h. As the speed of the train exceeds over 300km/h, due to pressure change in tunnel, aerodynamic problems such as sudden drag increase, severe acoustic noise, passenger discomfort and tunnel pressure sonic boom were occurred. This aerodynamic characteristics in tunnel should be reviewed in early design state to enhance the performance and driving quality of new high speed train. In this paper, the aerodynamic characteristics in tunnel for HSB such as pressure waves in tunnel, a rate of pressure change in cabin and micro pressure wave that cause sonic boom outside tunnel are analyzed by 2D axisymmetric CFD simulations. The results are also compared with the value for ordinary high speed train like the KTX-Sancheon. It is helpful how to design the configuration of HSB train. Finally it shows that the HSB train was well designed in tunnel condition because all values fulfill the criterions on UIC code and Korean national regulations.

• 대한기계학회논문집B
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• 제21권8호
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• pp.963-972
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• 1997

As a high-speed train enters a tunnel, a compression wave is generated ahead of it due to the piston action of train. The compression waves propagate along the tunnel and reflect at the exit of tunnel. A complex wave phenomenon appears in the tunnel, because of the successive reflections of the pressure waves at the exit and entrance of tunnel. The pressure waves give rise to large pressure transients which impose the fluctuating loads on the running train. It is highly needed that the pressure transients should be predicted to design the train body and to improve the comfortableness of the passengers in the train. In the present study, the pressure transients were calculated numerically for a wide range of train speed and compared with the previous tunnel tests. The calculation results agreed with ones of the tunnel tests, and the mechanism of pressure transients was made clear.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.158-164
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• 2011

When a train passes a conventiaonl tunnel at high speed, external pressure variation problem arises. It is known that this issue can be reduced by control the tunnel length. We studied the variances of external pressure variation within the tunnel, by altering length of the dummy tunnel duct. We also studies the variances of micro-pressure waves at the exit of tunnel, by altering surface area of dummy tunnel duct. For analyzing this train-tunnel relation problem, axisymmetric steady compressible flow solver was used.

• 한국철도학회논문집
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• 제15권5호
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• pp.436-441
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• 2012

열차가 터널에 고속으로 진입하면, 압력파가 발생한다. 열차 선두부의 진입에 의하여 발생한 압축파는 터널을 따라 진행되어 터널 출구에서 반사되어 팽창파로 되돌아오며, 후미부의 진입에 의하여 발생한 팽창파도 터널을 따라 전파되어 터널 출구에서 압축파로 반사되어 터널 입구로 되돌아 온다. 열차 선두부 및 후미부에 의하여 발생한 이러한 압력파는 터널 입구 및 출구에서 각각 반사되어 터널 내부를 왕복하며, 차량 객실에 탑승한 승객들에게는 이명감을 일으키고, 터널 출구에서는 환경소음의 일종인 미기압파를 발생시킨다. 터널에서의 큰 압력 변동은 터널의 최적 단면적 설계에도 주요 인자로 고려되고 있으며, 차체의 반복 피로 하중으로 작용하므로, 이에 대한 정량적 및 정성적 분석이 필요하다. 본 연구에서는 고정 격자계를 이용한 특성 해법을 개발하였으며, KTX를 이용한 실차 시험 결과와 비교하였으며, 해석 결과는 시험 결과와 잘 일치하였다.

• Geomechanics and Engineering
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• 제37권4호
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• pp.323-339
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• 2024

If the pressure exerted on the face of a tunnel excavated by TBM exceeds a threshold, it leads to failure of the soil or rock masses ahead of the tunnel face, which results in heaving the ground surface. In the current research, the upper bound method of limit analysis was employed to calculate the blow-out pressure of tunnels excavated in rock masses obeying the Hoek-Brown nonlinear criterion. The results of the proposed method were compared with three-dimensional finite element models, as well as the available methods in the literature. The results show that when σ_ci, m_i, and GSI increase, the blow-out pressure increases as well. By doubling the tunnel diameter, the blow-out pressure reduces up to 54.6%. Also, by doubling the height of the tunnel cover and the surcharge pressure exerted on the ground surface above the tunnel, the blow-out pressure increased up to 74.9% and 5.4%, respectively. With 35% increase in the unit weight of the rock mass surrounding the tunnel, the blow-out pressure increases in the range of 14.8% to 19.6%. The results of the present study were provided in simple design graphs that can easily be used in practical applications in order to obtain the blow-out pressure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1655-1660
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• 2004

Theoretical study has been conducted to clarify pressure characteristics of KTX(Korea Train eXpress) in tunnel. The external and internal pressure of rolling stock have been measured by using the atmospheric pressure sensors and portable data acquisition system on Seoul-Busan high speed railroad line. These pressure change may give rise to the ear-discomfort for passenger and fatigue for car body. In this study, the tunnels from 200m to 4000m in length have been chosen for the investigation of tunnel length effects. From the results of experiment, the pattern of pressure change generally agrees to RTRI's experimental result for Shinkansen. We found that there are similar patterns of external pressure variation for each critical tunnel length. The critical tunnel lengths are governed by train speed, train length and sonic velocity.

• 대한기계학회논문집B
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• 제21권10호
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• pp.1294-1302
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• 1997

For the purpose of investigating the impulsive noise at the exit of high-speed railway tunnel and the pressure transients inside the tunnel, experiments were carried out using a shock tube with an open end. A great deal of experimental data were obtained and explored to analyze the peak pressures and maximum pressure gradients in the pressure waves. The effects of the distance and cross-sectional area ratio between two-continuous tunnels on the characteristics of the pressure waves were investigated. The peak pressure inside the second tunnel decreases for the distance and cross-sectional area ratio between two tunnels to increase. Also the peak pressure and maximum pressure gradient of the pressure wave inside the second tunnel increase as the maximum pressure gradient of initial compression wave increases.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2008년도 춘계학술발표회 논문집
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• pp.51-68
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• 2008

고속열차의 터널 진입시 발생하는 압력파는 압축파의 형태로 터널내부를 전파하여 터널출구에 도달할 때에는 펄스형태의 충격성 압출파로 방사된다. 터널에서 방사된 압축파는 특정한 방향으로 전파되는 것이 아니라 전방향으로 확산되며, 압축파의 크기가 크면 주변 환경에 대한 환경소음 및 진동문제를 야기하게 되는데, 이를 미기압파(Micro Pressure wave)라 한다. 이러한 미기압파는 열차의 주행속도, 터널연장, 터널 및 열차의 단면적 등에 의존하므로 고속철도 터널의 적정단면을 결정하기 위하여 반드시 고려해야 된다. 이에, 본 논문에서는 호남고속철도 단면결정사례를 통하여 단면규모별 수치해석결과에 의한 미기압 기준 만족여부 및 최적단면선정과정을 소개하였다. 호남고속철도의 단면결정사례에서는 경부고속철도 화신 5 터널에서 터널내 압력 및 터널 출구에서의 미기압을 실측하여, 수치시뮬레이션의 입력조건으로 사용된 각종 매개변수 등의 적정성을 비교 검증하였으며, 모형실험을 통하여 합리적인 미기압과 저감대책을 제시하였다.

• 한국철도학회논문집
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• 제16권6호
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• pp.454-459
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• 2013

열차가 터널에 고속으로 진입하면, 압력파가 발생한다. 열차 선두부의 진입에 의하여 발생한 압축파는 터널을 따라 진행되어 터널 출구에서 반사되어 팽창파로 되돌아오며, 후미부의 진입에 의하여 발생한 팽창파도 터널을 따라 전파되어 터널 출구에서 압축파로 반사되어 터널 입구로 되돌아 온다. 열차 선두부 및 후미부에 의하여 발생한 이러한 압력파는 터널 입구 및 출구에서 각각 반사되어 터널 내부를 왕복하며, 차량 객실에 탑승한 승객들에게는 이명감을 일으키고, 터널 출구에서는 환경소음의 일종인 미기압파를 발생시킨다. 터널에서의 큰 압력 변동은 터널의 최적 단면적 설계에도 주요 인자로 고려되고 있으며, 차체의 반복 피로 하중으로 작용하므로, 이에 대한 정량적 및 정성적 분석이 필요하다. 본 연구에서는 고정 격자계를 이용하여 개발한 특성 해법을 교행하는 열차에 대하여 적용하였으며, 교행시의 열차 선두부 및 후미부의 경계 조건식을 개발하여, X-t선도와 같이 해석하였다. 해석 결과, 교행 열차의 특정 터널진입 시간에 압력파 간의 상쇄가 일어남을 알 수 있었다.