• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.538-538
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• 2012

최근 기후변화에 따른 이상홍수의 발생으로 인하여 댐의 수문학적 안정성 확보가 필요하다. 이에 따라 댐의 비상여수로를 건설하여 이상홍수에 대비한 대책을 마련하고 있다. 여수로의 운영상 고유속의 흐름이 방류되는데 이때 공동현상이 발생하며, 공동현상으로 인해 발생된 공동이 파괴되면서 구조물에 큰 피해를 주고 있다. 이러한 피해예방을 위해 현재까지 개발된 가장 경제적이고 효과적인 대책은 공기혼입장치이며, 국내에는 최근에 적용되고 있으나, 세부적인 설계기준과 설계기법, 절차등이 부족한 현실이다. 본 연구에서는 여수로 구조물을 대상으로 발생하는 공동현상에 대해서 이론적, 실험적인 분석을 실시하고자 한다. 공동현상에 대한 이론적인 배경과 최근의 연구동향을 분석하고, 국내 기존댐에 적용한 공기혼입장치 설치에 대해서 사례연구를 실시하여 적정성을 검토하였다. 또한 여수로의 대표단면인 개착식 여수로의 구형단면에 대해서는 주암조절지댐을 선정하고 터널식 여수로의 원형단면에 대해서는 임하댐 비상여수로를 대상구조물로 선정하여 각각 1차원 수치해석을 실시한 결과를 토대로 공기혼입장치의 위치 및 최적규모를 산정하고자 한다. 1차원 수치해석을 통해 분석된 공동현상 및 공기혼입장치에 대해서 3차원 수치해석을 실시하여 압력변화 및 공기혼입량등 공기혼입장치의 설치전과 설치후에 대한 효과를 검증하고 마지막으로 수리모형실험을 실시하여 1차원, 3차원 수치해석 결과에 대한 검증과 구조물의 안정성 증대를 확인하고, 추후 기타 여수로 구조물의 설계시 참고할 수 있는 기초자료가 될 수 있도록 하고자 한다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.3
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• pp.543-560
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• 2018

With the increased development in downtown underground space facilities that vertically cross under a railway at a shallow depth, the demand for non-open cut method is increasing. However, most construction sites still adopt the pipe roof method, where medium and large diameter steel pipes are pressed in to form a roof, enabling excavation of the inside space. Among the many factors that influence the loosening region and loads that occur while pressing in steel pipes, the size of the pipe has the largest impact, and this factor may correspond to the magnitude of load applied to the underground structure inside the steel pipe roof. The super equilibrium method (SEM) has been developed to minimize ground disturbance and loosening load, and uses small diameter pipes of approximately 114 mm instead of conventional medium and large diameter pipes. This small diameter steel pipe is called an SEM pile. After SEM piles are pressed in and the grouting reinforcement is constructed, a crossing structure is pressed in by using a hydraulic jack without ground subsidence or heaving. The SEM pile, which plays the role of timbering, is a fore-poling pile of approximately 5 m length that prevents ground collapse and supports surface load during excavation of toe part. The loosening region should be adequately calculated to estimate the spacing and construction length of the piles and stiffness of members. In this paper, we conducted a comparative analysis of calculations of loosening load that occurs during the press-in of SEM pile to obtain an optimal design of SEM. We analyzed the influence of factors in main theoretical and empirical formulas applied for calculating loosening regions, and carried out FEM analysis to see an appropriate loosening load to the SEM pile. In order to estimate the soil loosening caused by actual SEM-pile indentation and excavation, a steel pipe indentation reduction model test was conducted. Soil subsidence and soil loosening were investigated quantitatively according to soil/steel pipe (H/D).

• Journal of the Korean Geotechnical Society
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• v.34 no.11
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• pp.71-80
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• 2018

In this study, the seismic response of cut-and-cover box tunnels is evaluated from pseudo-static analyses and the fragility curves are derived. A series of site profiles were used to evaluate the effect of soil conditions. A total of 20 ground motions were used. The fragility curves were developed as functions of peak ground acceleration for three damage states, which are minor, moderate, and extensive states. The damage indices, defined as the ratio of the elastic moment to the yield moment, correlated to three damage states, were used. The curves are shown to greatly depend on the site profile. The curves are further compared to those derived in previous studies. The widely used empirically derived curves are shown not to account for the site effects, and therefore underestimate the response for soft sites.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.119-130
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• 2018

The VE/LCC study on the existing multi-utility tunnel examined the economical feasibility of the collective area through the cost-benefit analysis of the ten major routes of Seoul for the benefit (7 items) and the cost (5 items) through quantitative methods. In this paper, we analyzed the economic efficiency of 61 sectors by adding 3 items (reduced traffic accident, reduced vehicle noise, social-economic loss). The reduced traffic accident item is an improvement of the traffic accident cost that can be saved by the implementation of the project, and the reduced vehicle noise item is an indicator of the amount of noise change caused by the implement of the business. Finally, the social-economic loss items represent the impact on the local economy due to the construction of the multi-utility tunnel. The amounts of the additional items were compared and items added in the open type and tunnel type multi-utility tunnel were analyzed for each analysis. Result on the analysis, it analyzed the items applied to the basic and detail models in the economic evaluation of the multi-utility tunnel design, and makes it possible to evaluate the economic efficiency more efficiently. The economic evaluation of the basic and detailed models including the items presented in this study will be often used in the design of the multi-utility tunnel design.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1316-1323
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• 2005

Most tunnel lining material which has been used in the domestic is a concrete. But many problems as the construction period, the cost, and the crack occurrence for the design, construction, and management were happened in the concrete lining. For this reason, many research institutes like the Korea Highway Corporation recognize the necessity of an alternate material development and grow on the interest for that. So in this study, the behaviour characteristics for the application of the Corrugated Steel Plate Lining in cut-and-cover tunnel are evaluated as several conditions for the backfill height, the cutting slope, and the relative density of backfill soil are changed. In addition, through using that conditions, CHBDC(2000, Canadian Highway Bridge Design Code) is evaluated if it could be applied to the design by comparing with the numerical analysis results. As the behaviour characteristics of the Corrugated Steel Plate Lining by CHBDC and the static numerical analysis are analyzed, both the methods show the same linear increases of the compressive stress according to the increase of the backfill height. The CHBDC of the dead load condition has very similar tendency by comparing with the result of the static numerical analysis.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.271-283
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• 2002

P-wave velocity of concrete is a crucial parameter in determining the thickness of concrete lining, the location of cracks or other defects in Impact-Echo(IE) method. This study introduces an IE-SASW method that may determine the P-wave velocity on a surface of each testing area using the Spectral Analysis of Surface Wave (SASW) method. In numerical studies(Part I), it was verified that P-wave velocities could be obtained from SASW. In this paper(Part II), experimental studies were made in slab type concrete model specimens in which voids and waterproof sheet were included at the known locations. Accordingly, the feasibility of the proposed method was evaluated. The IE-SASW method was also performed in the precast model tunnel on ground and open-cut tunnel in ground. SASW tests were performed to determine the P-wave velocity of the concrete and then IE tests were carried at regularly spaced points along the testing lines to determine the thickness of structures. The nondestructive testing method which combined SASW and IE tests showed the great potential in the field applications.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.167-174
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• 2002

Earth retaining structure is constructed structure in order to construct a multistoried building, the subway, a subterranean downtown for effective use and obtainments of the limited ground. Recently, many kinds of research have been actively developed for a standardization and a database on designing and constructing of bridge, tunnel, road. With the works of database construction of that, many kinds of data with respect to statistics is cumulated. However, Database work of designed and constructed earth retaining structure in the construction field is wholly lacking and lagged behind in the works of database construction. This paper suggested classification system on indication data in connection with designing and constructing earth retaining structures a hundred fields. On the basis of that, code work with classification system was practised and DB program of indication data in connection with designing and constructing earth retaining structures was developed.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.891-894
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• 2008

This study was performed to investigate how to design, where to construct, why to degrade, what plan to use systematically the underground structures such as underpass, underground passageways. About 50% of the underground structures are located on Seoul, Kyungi-Do. In design of the underground structures such as underpass, underground passageways, the required conditions are defined. And also in construction stage, the conditions of soil, required structure depth, site characteristics, reasonable construction method, are investigated. In the selection of details for underground structure, the items mainly considered, are the wall and column type, the sidewalk type, anchoring-system type, the water-proofing method, entranc shape. The reason and the adequate measures for the degradation of concrete structure are also investigated. The initial cracking properties due to the thermal characteristic are considered. The state of the art report on the new technologies are reviewed. The recent project for the systematically application to the underground structures is reviewed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.1
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• pp.11-27
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• 2017

The road network system of major domestic urban areas such as city of Seoul was rapidly developed and regionally expanded. In addition, many kinds of life-lines such as electrical cables, telephone cables, water&sewerage lines, heat&cold conduits and gas lines were needed in order for urban residents to live comfortably. Therefore, most of the life-lines were individually buried in underground and individually managed. The utility tunnel is defined as the urban planning facilities for commonly installing life-lines in the National Land Planning Act. Expectation effectiveness of urban utility tunnels is reducing repeated excavation of roads, improvement of urban landscape; road pavement durability; driving performance and traffic flow. It can also be expected that ensuring disaster safety for earthquakes and sinkholes, smart-grind and electric vehicle supply, rapid response to changes in future living environment and etc. Therefore, necessity of urban utility tunnels has recently increased. However, all of the constructed utility tunnels are cut-and-cover tunnels domestically, which is included in development of new-town areas. Since urban areas can not accommodate all buried life-lines, it is necessary to study the feasibility assessment system for utility tunnel by urban patterns and capacity optimization for urban utility tunnels. In this study, we break away from the new-town utility tunnels and suggest a quantitative assessment model based on the evaluation index for urban areas. In addition, we also develop a program that can implement a quantitative evaluation system by subdividing the feasibility assessment system of urban patterns. Ultimately, this study can contribute to be activated the urban utility tunnel.

• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.23-33
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• 2015

The earth pressure acting on underground structure was measured by application of the instrumentation system in the subway construction site constructed by the method of cut-and-cover tunnel. The measured earth pressure was compared with the earth pressure obtained from the existed theoretical equation, and the actual earth pressure diagram acting on the underground structure was investigated. As a result of investigation, the vertical earth pressure is mainly affected by the embankment height, and the lateral earth pressure is significantly affected by whether the existence of earth retaining structures or not. The measured vertical earth pressure is very similar to the theoretical earth pressure proposed by Bierbaumer. The measured lateral earth pressure is closed to the active earth pressure proposed by Rankine rather than the earth pressure at rest. The coefficient of earth pressure in soil deposit layer is about 0.35, and the coefficient in soft rock deposit layer is about 0.21. For design and construction the underground structures, therefore, it is reasonable estimation that the lateral earth pressure acting on structures installed in soil deposit layers is an average value between active earth pressure and earth pressure at rest. In rock deposit layers, the lateral earth pressure acting on structure is an active earth pressure only.