• Journal of the Korea Academia-Industrial cooperation Society
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• 제22권1호
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• pp.777-785
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• 2021

Many utility lines are buried underground to provide various functions of the city. Because historical records are not managed systematically, damage has occurred during excavation. In addition, the demand for an underground facility management system is increasing as the aerial underground project is progressing. By attaching an electronic recognition sensor to an underground facility, such as pipelines, the management history and site conditions can be carefully managed. Therefore, in this study, electronic recognition sensors, such as BLE Beacon, UHF RFID, geomagnetic sensor, and commercial marker, were tested to analyze the strengths, weaknesses, and field applicability through a pilot project. According to the limited research results collected through two pilot projects, the installation depth is most important to demonstrate the performance of the electronic reader. In addition, because it should be used in urban areas, the influence of environmental interference should be minimized, and there should be no performance degradation over time. In the case of the geomagnetic recognizer, the effect of environmental interference was large, and performance degradation occurred over time using the BLE Beacon. In the field situation, where the installation depth can be controlled to less than 40cm, the utility of the battery-free UHF RFID was the best.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• 제40권1호
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• pp.1-14
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• 2022

In order to conduct rapid, accurate and safe surveying at the excavation site, In this study, the possibility of underground facility survey using drones and the expected effect of 3D visualization were obtained as follows. Phantom4Pro 20MP drones have a 30m flight altitude and a redundant 85% flight plan, securing a GSD (Ground Sampling Distance) value of 0.85mm and 4points of GCP (Groud Control Point)and 2points of check point were calculated, and 7.3mm of ground control point and 11mm of check point were obtained. The importance of GCP was confirmed when measured with low-cost drones. If there is no ground reference point, the error range of X value is derived from -81.2 cm to +90.0 cm, and the error range of Y value is +6.8 cm to 155.9 cm. This study classifies point cloud data using the Pix4D program. I'm sorting underground facility data and road pavement data, and visualized 3D data of road and underground facilities of actual model through overlapping process. Overlaid point cloud data can be used to check the location and depth of the place you want through the Open Source program CloudCompare. This study will become a new paradigm of underground facility surveying.

• Tunnel and Underground Space
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• 제2권1호
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• pp.95-101
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• 1992

Norwegian technology related to preinvestigations, planning, design and construction of large underground caverns is wellknown worldwide. However, so far this technology is only slightly verified through scientiffic reports and documentation. The "Rock cavern stadium" research program is an interdisciplinary program related to the ongoing building and future use of Gjovik Olympic Subsite which is the largest cavern in the world for public purposes with a span of 61 meters and a height of 25 meters. The estimated budget for this program is about USD 4 million which is made possible through grants from The Royal Norwegian Council for Scientific and Industrial Research as well as through contributions from Norwegian and Swedish companies that are participating. The program is carried out in collaboration with The Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology. The Norwegian Geotechnical Institute and The Eastern Norway Research Center. The research program will continue until the end of 1994 to ensure that input comes from a full period of use in this stadium with different activities like exhibitions, conferences, concerts etc being included as verification through full-scale measurements and observations. The research program has five subtasks. Three of these are related to subjects like Energy consumption. HVAC installations. Fire safety design, Engineering geology and Rock mechanics, Environmental aspects. The fourth subtask is concerned with the collection of basic data, results and experience from these three subtasks to provide a basis for national Norwegian guidelines related to this interdisciplinary subject area. The guidelines will first be presented as a manual for planning and engineering purposes. The realization of this research program is a unique opportunity to enhance the expertise that has been acquired from this cavern stadium. By involving research in this extraordinary project from the excavation and building phase to its subsequent use. this will give the participants know-how and expertise which is very much in demand internationally. The coordination of the international activities between the participants as well as preparation of participations and presentations in international conferences and symposium are included in the fifth task of this national research program.

• Journal of the Korean Geosynthetics Society
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• 제17권1호
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• pp.55-64
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• 2018

The purpose of this study is to evaluate the suitability of emergency underground cavity restoration method filling cavity with expansive material based on numerical analysis. For the numerical analysis, experiments were conducted to evaluate properties of expansive material. Based on the measured expansion pressure of the expansive material from the experiment, behavior of underground cavity restoration with various cavity dimensions (variation of height and width of rectangular-shape cavity) was numerically assessed. As a result of analysis, the vertical displacements of the top and bottom of cavity were significantly influenced by the cavity width and lateral displacements of cavity sides were highly dependent on cavity height. These vertical and lateral displacements were increased with increasing expansion pressure of expansive material. Also, when the expansion pressure was applied, the vertical displacement of the upper surface layer of the road was less dependent on cavity height, and was greatly influenced by cavity width.

• Tunnel and Underground Space
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• 제17권4호
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• pp.311-321
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• 2007

Failure of underground structures in hard rocks is a function of the in-situ stress, the intact rock strength and the distribution of fractures in the rock mass. At highly stressed regime, brittle failure is often observed due to excavation-induced stress. The characteristics of brittle failure are classified as failure grade, failure initiation stress, extent of failure and depth of failure. For safety construction of underground structures, these characteristics of brittle failure with stress conditions should be understood. In this study we evaluated the relationship between the extent and depth of failure with stress conditions for failure happened model specimens through true triaxial model experiments. The extent and depth of failure were determined using visual observation and computed tomography (CT). The results indicate that the depth of failure was affected by differential stress perpendicular to the axis of tunnel. However the extent of failure was irrelevant to the stress conditions.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제12권4호
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• pp.81-93
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• 1992

Numerical modeling of problems having infinite and semi-infinite boundaries is studied using a coupled method of distinct elements and boundary elements. The regions which are restricted on stress concentration area of loading points, excavation surface, and geometric discontinuity in the underground structures, are modeled using distinct elements, while the infinite and semi-infinite regions are modeled using linear boundary elements. Linear boundary elements for infinite and semi-infinite region are respectively composed using the Kelvin's and the Melan's solution, respectively. For the completeness, the boundary element method, the distinct element, and the coupled method of distinct elements and boundary elements are studied independently. The coupled method is verified and is applied to underground structures of infinite and semi-infinite regions. Through the comparison of the results, it is concluded that the coupled analysis may be used for discontinuous underground structures in the effective manner.

• Journal of Korean Tunnelling and Underground Space Association
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• 제9권3호
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• pp.263-273
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• 2007

When a tunnel or an underground structure is excavated in deep geological environments, the failure process is affected and eventually dominated by stress-induced fractures growing preferentially parallel to the excavation boundary. This fracturing is generally referred to as brittle failure by spatting and slabbing. Continuum models with traditional failure criteria such as Hoek-Brown or Mohr-Coulomb criteria have not been successful in prediction of the extent and depth of brittle failure. Instead cohesion weakening and frictional strengthening (CWFS) model is known to predict brittle failure well. In this study, CWFS model was applied to predict the brittle failure around a circular opening observed in physical model experiments. To obtain the input parameters for CWFS model, damage-controlled tests were carried out. The predicted depth and extent of brittle failure using CWFS model were compared to the results of the physical model experiment and numerical simulation using traditional model.

• Journal of Korean Tunnelling and Underground Space Association
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• 제16권1호
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• pp.75-89
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• 2014

In recent years, utilization of underground space has been increasing in various parts of the world. In particular, open-cut method is usually applied to the shallow depth excavation. However some problems such as extreme traffic congestion and unstability of adjacent structures etc. might occur. In order to cope with these problems, the M-CAM (Modified Cellular Arch Method) method was proposed to excavate soil tunnels at shallow depth with secured enough stability and minimized construction period. In this study, sensitivity analysis was performed to predict the influence of the size of CPW(Continuous Pile Wall) and ground conditions on the behavior of the tunnel. First of all, embedded depth and diameter (or thickness) of CPW, coefficient of lateral earth pressure, and ground conditions were selected as parameters that could affect tunnel stability. Meanwhile, FLAC 2D based on finite difference method was used for numerical analysis. As a result of this study, it was checked out that embedded depth among sizes of CPW had a greatest influence on the stability of a tunnel.

• Journal of the Korean Geotechnical Society
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• 제16권1호
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• pp.243-250
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• 2000

The mechanical behavior of the underground box culvert constructed by the open cut method depends mainly on the earth pressure acting on it. In this study, the earth pressure on the underground box culverts constructed by the open cut method during and after the construction sequence was numerically analysed by using FLAC. The results are compared with those of the Marston-Spangler's theory, silo theory, and the model tests. The results showed that the vertical earth pressure on the upper slab of the box structure was not uniform. It was as large as the overburden in the middle part of the slab but was smaller or larger than that at its end part depending on the slope of the excavation, the depth of the cover, and the width of the side refill. The horizontal earth pressure on the side wail was much smaller than the earth pressure at rest and grew nonlinearly with the depth.

• Proceedings of the KSR Conference
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1964-1969
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• 2010

Recently, as construction market scale is getting bigger and transportation industry is developing, the underground structure construction such as subway, tunnel (excavation box) or shield tunnel structure is becoming more diverse, and its demand is gradually increasing. However, for the concrete structures constructed underground, the water leakage is occurred due to the expansion joint and construction joint, or movement, uneven settlement, excessive load and vibration during application causing cracks. Many waterproofing method and materials are used in jobsites, but areas such as underground railroad and subway that has movement and vibration at all times, the ability of waterproofing layer is declined causing repetitive water leakage due to crack, erosion and separation, which is a vicious cycle. Therefore, this study evaluates the responsiveness to a movement for adhesive/flexible waterproofing material that can cope with the vibration and the movement of the structure. Also to recommend a waterproofing technology that can cope with structure movement through examples of actual jobsite applications such as subway and tunnel where there are constant movement and vibration.