• Geomechanics and Engineering
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• 제15권3호
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• pp.879-888
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• 2018

Probability-based design codes have been developed to sufficiently confirm the safety level of structures. One of the most acceptable probability-based approaches is Load Resistance Factor Design (LRFD), which measures the safety level of the structures in terms of the reliability index. The main contribution of this paper is to calibrate the load and resistance factors of the design code for tunnels. The load and resistance factors are calculated using the available statistical models and probability-based procedures. The major steps include selection of representative structures, consideration of the limit state functions, calculation of reliability for the selected structures, selection of the target reliability index and calculation of load factors and resistance factors. The load and resistance models are reviewed. Statistical models of resistance (load carrying capacity) are summarized for strength limit state in bending, shear and compression. The reliability indices are calculated for several segments of a selected circular tunnel designed according to the tunnel manual report (Tunnel Manual). The novelty of this paper is the selection of the target reliability. In doing so, the uniform spectrum of reliability indices is proposed based on the probability paper. The final recommendation is proposed based on the closeness to the target reliability index.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.214-220
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• 2003

Pipe jacking is a name for a method to excavate a tunnel by pushing pipe into the ground from an especial pit. Size of tunnels in this method is different from under 900mm (microtunneling) to more than 3,000mm. Method of excavation is also different from hand digging to use of any kind of tunnel boring machines such as slurry and earth pressure balance (EPB) machines. Slurry pipe jacking was firmly established as a special method for the nondisruptive construction of the underground tunnels in urban area. During the pipe jacking and microtunneling process, the jacking load is an important parameter, controlling the pipe wall thickness, need to and location of intermediate jacking station, selection of jacking frame and lubrication requirements. The main component of the jacking load is due to frictional resistance. In this paper the skin friction between pipe surface and surrounding condition also lubricant quality based on a few fundamental tests, were considered. During this study unconfined compressive strength test, dynamic friction measurement test and direct shear box test were raised for one of the largest diameter slurry pipe jacking project in Fujisawa city in Japan. It could be concluded that in slurry pipe jacking, prediction of frictional forces are mainly dependent on successful lubrication, its quality and lubricant strength parameters. Conclusions from this study can be used for the same experiences.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2008년도 국제학술회의
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• pp.43-51
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• 2008

Currently an increasing number of urban tunnels with small overburden are excavated according to the principle of the New Austrian Tunneling Method (NATM). For rational management of tunnels from planning to construction and maintenance stages, prediction, control and monitoring of displacements of and around the tunnel have to be performed with high accuracy. Computational method tools, such as finite element method, have been and are indispensable tool for tunnel engineers for many years. It is, however, a commonly acknowledged fact that determination of input parameters, especially material properties exhibiting nonlinear stress-strain relationship, is not an easy task even for an experienced engineer. Use and application of the acquired tunnel information is important for prediction accuracy and improvement of tunnel behavior on construction. Artificial Neural Network (ANN) model is a form of artificial intelligence that attempts to mimic behavior of human brain and nervous system. The main objective of this paper is to perform the deformation analysis in NATM tunnel by means of numerical simulation and artificial neural network (ANN) with field database. Developed ANN model can achieve a high level of prediction accuracy.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.404-412
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• 1997

The pipes and cables buried below ground, which may have helped to improve city landscape, is becoming direct and indirect causes for various kinds of disaster in Korea. Every advantage from the use of utility tunnel can not be converted in a dollar since there is associated huge contribution to safe urban environment. The Korean government has a certain role to play in helping promote utility tunnels for the past years. Most recently, many utility tunnels have been being checked to find out safety level, especially fire safety level, and main problems and shortcomings are checked out as a result of this survey. Because the fire safety level of existing tunnel is low, possible approaches and solutions are presented according to the analysis of fire safety level. In order for these approaches to be effective, existing tunnel should be supplemented appropriately and extra equipment must be installed according to the solutions. Hopefully, by performing both improvement of existing utility tunnel that provide a fire/disaster proof and introducing new types of tunnel which influence utility management and maintenance, the recent disaster rate in Korea can be diminished up to a desirable rate in a near future.

• Geomechanics and Engineering
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• 제29권3호
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• pp.229-236
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• 2022

In this study, a model experiment and field experiment was conducted to introduce the optimal tensile force when constructing a non-open cut tunnel according to the ground conditions of sandy soil. CMR (Concrete Modular Roof) method is economical because of the high precision and excellent durability, and corrosion resistance, and the inserted parts can be used as the main structure of a tunnel. In addition the CMR method has a stable advantage in interconnection because the concrete beam is press-fitted compared to the NTR (New Tubular Roof) method, and the need for quality control can be minimized. The ground conditions were corrected by adjusting the relative density of sandy soil during the construction of non-open cut tunnels, and after introducing various tensile forces, the surface settlement according to excavation was measured, and the optimal tensile force was derived. As a result of the experiment, the amount of settlement according to the relative density was found to be minor. Furthermore, analysis of each tensile force based on loose ground conditions resulted in an average decrease of approximately 22% in maximum settlement when the force was increased by 0.8 kN per segment. Considering these results, it is indicated that more than 2.0 kN tensile force per segment is recommended for settlement of the upper ground.

• Earthquakes and Structures
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• 제24권1호
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• pp.65-79
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• 2023

A simplified analytical solution for seismic response of tunnel cross section in horizontally layered ground subjected to oblique incidence of SH wave is deduced in this paper. The proposed analytical solution consists of two main steps: free-field response in layered field and tunnel response. The free field responses of the layered ground are obtained by one-dimensional finite element method in time domain. The tunnel lining is treated as a thick-wall cylinder to calculate the tunnel response, which subject to free field stress. The analytical solutions are verified by comparing with the dynamic numerical results of two-dimensional ground-lining interaction analysis under earthquake in some common situations, which have a good agreement. Then, the appropriate range of the proposed analytical solution is analyzed, considering the height of the layered ground, the wavelength and incident angle of SH wave. Finally, by using the analytical solutions, the effects of the ground material, burial depth of the tunnel, and lining thickness and the slippage effect at the ground-lining interface on the seismic response of tunnels are investigated. The proposed solution could serve as a useful tool for seismic analysis and design of tunnels in layered ground.

• Geomechanics and Engineering
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• 제34권1호
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• pp.69-86
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• 2023

To overcome the dilemma of the [BQ] method's inability to predict mountain tunnel support loads, this study is based on the Hoek-Brown criterion and previous results to obtain the connection equations from GSI scores to each parameter of the Hoek-Brown criterion and the link between the [BQ] scores and the GSI system. The equations were embedded in the Hoek-Brown criterion of FLAC6.0 software to obtain tunnel construction forecasts without destroying the in-situ stratigraphy. The feasibility of the secondary development of the Hoek-Brown criterion was verified through comparative analysis with field engineering measurements. If GSI > 45 with a confining pressure of less than 10 MPa, GSI has little effect on the critical softening factor while we should pay attention to the parameter of confining pressure when GSI < 45. The design values for each parameter are closer to the FLAC3D simulation results and the secondary development of the Hoek-Brown criterion meets the design objectives. If the Class V surrounding rock is thinned with shotcrete or the secondary lining is installed earlier, the secondary lining may act as the main load-bearing structure. The study may provide ideas for rapid prediction of mountainous tunnels in China.

• 터널과지하공간
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• 제11권4호
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• pp.319-327
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• 2001

장대도로터널 환기시스템의 최적 설계 및 운영은 새로운 설계도구의 개발을 요구하며 최근 환기 관련 변수들의 동적인 관계를 정량적으로 분석할 수 있는 도구로써 널리 이용되고 있다. 본 연구는 도로터널 환기시뮬레이션 모델인 NETVEN의 현장 검증연구를 국내 도로터널을 대상으로 수행함을 목적으로 하였다. 환기방식 및 차량통행방식이 다른 4개 터널을 대상으로 시뮬레이션 및 현장 측정연구를 수행하였으며 시뮬레이션 모델의 적용 결과와 측정 결과의 차이는 다음 4가지 요인에 기인한 것으로 분석된다. (1)실제 터널내 기류는 정상류 유동을 가정하는 시뮬레이션 모델과는 달리 천이-지연계의 특성을 가지고 있다. (2) 시뮬레이션 모델은 정상상태를 가정하나 측정값은 순간값을 대상으로 하므로 분산이 상대적으로 크게 나타난다. 환기력 관련변수들은 거의 정상상태가 아니며 교통 및 기상관련 변수들은 특히 순간적인 변화가 심한 편이다. (3) CO 농도의 경우에 출구부근에서의 차이가 상대적으로 크게 나타나는 현상이 뚜렷하며 특히 농도가 상대적으로 클수록 차이가 크다. 이는 난류확산에 의한 농도 저하가 원인으로 보인다. 난류확산 가능성은 최대 농도지점이 출구점이 아닌 약간 안쪽 지점에서 나타나는 현상에서도 나타나고 있다. (4) 교통량이 많을 경우 환기속도 오차가 크게 나타나므로 차량의 배기특성뿐만 아니라 공기역학적 특성에 대한 지속적인 연구가 필요하다.

• 한국터널지하공간학회 논문집
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• 제26권3호
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• pp.223-242
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• 2024

2000년대 초 싱글쉘 터널이 한국에 소개된 이후, 광주우회도로를 시작으로 이 공법에 기반한 터널을 실제 프로젝트에 적용하려는 시도가 여러 번 있었으나 20여 년이 지난 지금까지도 도로나 철도와 같은 교통 터널의 본선에 채택된 적은 없다. 이는 터널 지보재가 영구지보재로서의 성능을 확보하지 못한다는 우려와 이와 관련된 기준이나 시방의 부재에 기인한 바가 크다. 이후 터널 전문가들의 많은 연구와 노력으로 고강도 및 최종 마감재로서의 숏크리트에 대한 기준과 내부식성 록볼트 등 영구지보재로서의 요구 조건이 설계 및 시공기준에 반영되었을 뿐만 아니라 장비, 시공기술, 작업자의 숙련도 등 시공 측면에서도 상당한 개선이 이루어져 왔다. 따라서, 이제는 기존 NATM 공법에 비해 환경 영향, 공기 및 공사비 측면에서 차별성이 있는 싱글쉘 터널공법의 국내 적용을 다시 고려해볼 때라고 생각된다. 다만, 싱글쉘 터널공법에 대한 부족한 설계 및 시공 경험, 불충분한 세부기준, 미흡한 시공상세 등에 대해서는 추가 연구 또는 시험시공 등을 통해서 보완이 필요하다. 본 논문에서는 싱글쉘 터널의 기본 개념부터 적용 및 연구현황, 기술발전 동향, 극복과 제 등에 대하여 고찰하였으며, 이를 통하여 싱글쉘 터널의 국내 적용성에 대하여 다시 한 번 적극적인 논의를 제안하고자 한다.

• 대한조선학회논문집
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• 제43권4호
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• pp.431-439
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• 2006

Due to the limitation of size of the test section, blockage effects could not be avoided in the model test of yacht sails for common wind tunnels. In this paper, a numerical analysis is performed to investigate the blockage effects on the lift and drag forces measured from wind tunnel experiments for a 30 feet sloop yacht sail. Complex airflows around the jib and main sails including three-dimensional flow separations are calculated for various close-hauled conditions. It is found that the blockage of a wind tunnel changes the flow separation and consequently the lift and drag forces of the sails, especially the main sail, reduce and increase, respectively, due to the blockage effects.