• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.131-144
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• 2018

The urban center of a large city has a high concentration ratio of population, commerce, and traffic. Therefore, the expected effect is high from the introduction of the urban utility tunnel and it also has sufficient economic feasibility considering life cycle cost. Moreover, the construction cost can be greatly reduced if it is included in a large underground development such as a subway or a complex transfer center construction. However, it is not reflected in actual underground development plan. When planning a urban utility tunnel in Korea, it is expected to have difficulties such as the cost of relocation of the existing Life-Line, conflicts among the individual facility institutions, procurement of construction resources and sharing. Furthermore, it is possible to promote the project only if a consensus is drawn up by a collective council composed of all facilities and project developers. Therefore, an optimal alternative should be proposed using economic analysis and feasibility assessment system. In this study, the analytic hierarchy process (AHP) is performed considering the characteristics of urban areas and the importance of each indicator is quantified. As a result, we can support reasonable design capacity optimization using the feasibility assessment system.

• Journal of the Society of Disaster Information
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• v.16 no.3
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• pp.449-457
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• 2020

Purpose: The Seoul Metropolitan Government classifies the cavity risks into emergency, priority, general, and observation grades in consideration of the cavity size, asphalt pavement thickness, and pavement depth based on the cavity management grade criteria of Seoul. In this study, the depth of cracking was measured at 17 cracks identified by checking the pavement condition of the cavity at 265 cavities found in the 2019 cavity investigation service. Method: In the first phase, crack width and depth were measured using a vernier caliper, taper gauge, and depth gauge to check the cracks of the identified cavities. In the second phase, the location of the largest crack in the upper road surface was confirmed, and A.C. was drilled to further measure the crack depth. Results: As a result, the cavity management level was raised in nine of the 17 test cavity identified. Therefore, in case of emergency and priority recovery, the grade should be adjusted according to the depth of pavement crack and the thickness of residual A.C. pavement. Conclusion: In the case of cracks in the upper part of the cavity, the crack progression must be determined through the perforation and the remaining asphalt concrete thickness must be determined to determine the cavity grade.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.565-570
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• 2024

Recently, due to adjacent excavation work such as new buildings and common tunnel expansion concentrated around the urban railway, deformation of the underground box and tunnel structure of the urban railway built underground has occurred, and as a result, repair and reinforcement work is frequently carried. In addition, the subway is responsible for large-scale transportation, so ensuring the safety and drivability of underground structures is very important. Accordingly, an automated measurement system is being introduced to manage the safety of underground box structures. However, there is no analysis of structural damage vulnerabilities caused by subsidence or uplift of underground box structures. In this study, we aim to analyze damage vulnerabilities for safety monitoring of underground box structures. In addition, we intend to analyze major core monitoring locations by modeling underground box structures through numerical analysis. Therefore, we would like to suggest sensor installation locations and damage vulnerable areas for safety monitoring of underground box structures in the future.

• Journal of the Korean earth science society
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• v.32 no.6
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• pp.537-547
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• 2011

Electrical resistivity tomography surveys using boreholes were applied to reveal the cause of a catastrophic land subsidence accompanied by the excessive groundwater withdrawal in urban karst area and to map the connectivity of disseminated cavities over the study area. In order to understand the hydrogeological characteristics, resistivity using exsitu core samples, groundwater level for five boreholes, and hydraulic conductivity using slug test were measured. The hydraulic conductivity variation ranging from 0.8 to $9.3{\times}10^{-4}\;cm/s$ for five boreholes and a gentle slope of groundwater level indicated that there is no significant characteristics of hydraulic heterogeneity. Core samples of the lime-silicated rock were classified as three groups including cracked, weathered, and fresh and measured the resistivity values ranged from 103 to 161, 218 to 277, and 597 to 662 ohm-m, respectively. Drilling results that showed the cavity filled with clay materials and tomogram for this region indicated resistivity value lower than 50 ohm-m. From the inverted resistivity results for each section with five boreholes, cavity and fractured layer were distributed along the depth between 10 and 20 m overall area and cavities ranging from 4 to 6 m filled with clay materials.

• Journal of the Society of Disaster Information
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• v.15 no.3
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• pp.391-401
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• 2019

Purpose: In this study, the location and history information of the cavity identified in the cavity exploration, such as repacking of the pavement, is not known. Therefore, it is to review the field applicability of RFID(Radio Frequency Identification) systems that enable anyone to accurately identify information. Method: Basic experiments were conducted for field applicability for cavity recognition distance, recognition and recognition rate, tag performance and tag type, reader interference, communication, underground burial impact, and duplicate recognition by RFID system. Results: As a result of the depth of tag and reader recognition, the electronic tag chips and readers applied in the basic experiment are judged to be effectively applicable in the field environment where the road cavity is located. Conclusion: The RFID tags for field application of the pavement management system store various information such as location and size of cavity, identification date, cause of occurrence, and surrounding underground facilities to maximize cavity management effect with a system that can be computerized and mobile utilization.

• Tunnel and Underground Space
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• v.24 no.2
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• pp.155-165
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• 2014

Multiple thermal energy storage (TES) caverns can be used for storing thermal energy on a large scale and for a high-aspect-ratio heat storage design to provide good thermal performance. It may also be necessary to consider the use of multiple caverns with a reduced length when a single, long tunnel-shaped cavern is not suitable for connection to aboveground heat production and injection equipments. When using multiple TES caverns, the separation distance between the caverns is one of the significant factors that should be considered in the design of storage space, and the optimal separation distance should be determined based on a quantitative stability criterion. In this paper, we described a numerical approach for determining the optimal separation distance between multiple caverns for large-scale TES utilization. For reliable stability evaluation of multiple caverns, we employed a probabilistic method which can quantitatively take into account the uncertainty of input parameters by probability distributions, unlike conventional deterministic approaches. The present approach was applied to the design of a conceptual TES model to store hot water for district heating. The probabilistic stability results of this application demonstrated that the approach in our work can be effectively used as a decision-making tool to determine the optimal separation distance between multiple caverns. In addition, the probabilistic results were compared to those obtained through a deterministic analysis, and the comparison results suggested that care should taken in selecting the acceptable level of stability when using deterministic approaches.

• Tunnel and Underground Space
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• v.24 no.4
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• pp.255-274
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• 2014

The target of this study is large scale rock slope collapsed by around 7 pm on August, 2012, which is located at ${\bigcirc}{\bigcirc}$ limestone quarries of Gangneung city, Gangwondo. The slope prior to the collapse is formed as the height of about 200 m and the average inclination of $45^{\circ}$. The estimated amount of the collapse is about $1,500,000m^3$ with respect to the slope after the collapse. Geotechnical and field investigations such as boring, geophysical prospecting, surface geological survey, geological lineaments, borehole imaging, metric 3D imaging, experimental and field test, mining work by year, and daily rainfall were performed to find the cause of rock slope failure. Various analyzes using slope mass rating, stereonet projection, limit equilibrium method, continuum and non-continuum model were conducted to check of the stability of the slope. It is expected that the cause of slope failure from the results of various analysis and survey is due to the combined factors such as topography, rainfall, rock type and quality, discontinuities, geo-structural characteristics as the limestone cavity and fault zones, but the failure of slope in case of the analysis without the limestone cavity is not occurred. Safe factor of 0.66 was obtained from continuum analysis of the slope considering the limestone cavity, so the ultimate causes of slope failure is considered to be due to the influence of limestone cavity developed along fault zone.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.3
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• pp.437-447
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• 2017

In current, there has not been the evaluation model for the optimum design of the multi-utility tunnel by considering urban type and size, the function of surrounding road and feasibility analyses with respect to construction method, and arrangement of accommodation facilities inside multi-utility tunnel. Thus, in this study, we developed the evaluation model for the optimum design of the multi-utility tunnel before and after the decision of the multi-utility tunnel installation. In this paper, we have selected the Deming cycle which is used in various fields among several decision methods for optimizing the design. For the purpose of reflecting the various factors in the design of the multi-utility tunnel, 11 higher indicators were set up to lead to more detailed approaches. In addition, based on the "Plan-Do-Check-Action (PDCA)" circulation method, we can realize the installation of the multi-utility tunnel and design more efficiently through the first phase for conception and the second phase for optimization, and develop the program for the evaluation model accordingly.

• Journal of the Society of Disaster Information
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• v.15 no.4
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• pp.459-468
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• 2019

Purpose: The cavity exploration of the lower part of the road is carried out to prevent ground-sinking. However, the detected communities cannot be identified by the cavity location and history information, such as repackaging the pavement. Therefore, the field applicability of RFID systems was evaluated in this study to enable anyone to accurately identify information. Method: During temporary recovery, tag recognition distance and recognition rate were measured according to underground burial materials and telecommunication tubes using RFID systems with electronic tag chips attached to the bottom of the rubber cap. Result: The perceived distance and perceived rate of depth for each position of the electron tag did not significantly affect the depth up to 15cm, but it did have some effect if the depth was 20cm. In addition, water effects from nearby underground facilities and rainfall are relatively small, and the effects of wind will need to be considered during the weather conditions of the road. Conclusion: The RFID tags for field application of the pavement management system store various information such as location and size of cavity, identification date, cause of occurrence, and surrounding underground facilities to maximize cavity management effect with a system that can be computerized and mobile utilization.

• The Journal of Engineering Geology
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• v.5 no.2
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• pp.139-153
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• 1995

Engineering characteristics of granitic rock masses in Geoje island were estimated by investigating the mechanical and hydraulic properties of core samples drilled in - situ. Since the effect of in -situ stresses could not be considered, some of the engineering properties estimated through rock mass classification were quite different from the in - situ tested results. Based on the results of rock mass classification, borehole tests, and laboratory test the empirical parameters for the design of underground structure were assessed. Though some number of fractured zones were found, granitic rock mass in the southern part of Geoje island showed fairly good quality and the excavating conditions were expected to be suitable for the construction of large scale underground facilities.