• Geophysics and Geophysical Exploration
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• v.1 no.1
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• pp.64-70
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• 1998

Diffraction tomography (DT) is a quantitative technique for high resolution subsurface imaging. In general DT algorithm is used for crosswell imaging. In this study high resolution GPR DT algorithm which is able to reconstruct high resolution image of subsurface structures in multi-monostatic geometry is developed. Developed algorithm is applied to finite difference data and its criteria of application and its limit are studied. Inversion parameters (number of imaging frequency, regularization factor, frequency range) are deduced from isolated weak scattering model. And the usuability of the algorithm is proved by applying to models which break the weak scattering approximation.

• Tunnel and Underground Space
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• v.10 no.4
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• pp.506-515
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• 2000

A lot of underground construction projects have been conducted by economical, social and military purposes in Korea for the last three decades. As a result, magnificent amount of data were obtained from geological site investigations, laboratory and field tests, design and field monitoring. But up to now, these valuable informations were neither systematically stored nor utilized efficiently resulting in a great loss of time and money. In this study, a database system named GeoINFO was developed using Microsoft Access 97 for management of informations which can be obtained from underground construction. The developed database system is especially designed to cover three major types of underground facilities-tunnels, underground storages and rock slopes and has multi-layered tree structures for data input. The system also has a unique indexing system for efficient data search using Visual Basic code.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.194-200
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• 2010

Recently, a longitudinal tunnel construction has increased because of subway construction extension, geomorphological effect and the development of construction Technologies etc. When the fire occurs in a tunnel and an underground structure, the many damage of human life and the economic losses are caused. In Korea, fire resistance character study of a tunnel and an underground structure is proceeding. However, when a concrete is exposed to high temperature, study of load carrying capacity reduction and stability evaluation for spalling of a concrete is not enough. Therefore in this study, fire resistance character of a concrete evaluated according to time heating temperature curve(RABT and RWS) and a result compared on virtual fire accident in order to apply fire scenario. Also this study performed thermo-mechanical coupled analysis of a FEM-based numerical technique and estimated fire-induced damage of a tunnel and an underground structure.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.73-81
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• 2018

The purpose of this study is to research the regulation of durability standard of underground structures monitoring sensors. The durability criteria for construction monitoring sensors of domestic construction companies, the standard years of contents such as buildings on the income tax implementation regulations, and the standards of the Public Procurement Service for construction monitoring and construction machinery were analyzed. The durability criterion on products such as the inclination meter and the strain gauge, which are purchased from the Public Procurement Service prior to installation on the underground structure, is 8 to 10 years. It is considered that the monitoring sensor installed in the paperboard and the concrete structure at the time of construction will have considerably shortened service life rather than the useful life of the product itself due to various adverse factors such as groundwater influence and compaction.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.5
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• pp.497-506
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• 2014

In this study, analysis results described in the companion paper was used to determine shapes of room-and-pillar underground structure. To select optimized shapes, structural stability, space applicability and vehicle applicability were considered. In the structural stability step, ratio between strength and stress of the pillar and the critical strain at the roof span were adopted. The space applicability was used to retain the sufficient space of underground structure as its purpose is for human activity. The vehicle applicability was used to consider a radius for rotation of construction equipments in the room-and-pillar underground structure. From the given procedure in this study, proper shapes of rock pillar and room can be selected to design supports at the pillar and roof.

• Tunnel and Underground Space
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• v.25 no.3
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• pp.275-283
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• 2015

Excavation of underground space in soft ground implicate to the structure, such as subsidence. As a result, it has been acting as a serious risk to the stability of the roads and facilities. Therefore, in order to stabilize the soil stabilization and reinforcement of the structure, we have been using a number of methods and injecting material. In this study, we compared and analyzed the amount of subsidence regarding the ground reinforcement during underground excavation in soft ground by performing model test. And three-dimensional numerical analysis was performed using FLAC 3D. The subsidence was simulated numerically according to the tunnel excavation. The subsidence results of the model tests and numerical analyzes were relatively consistent. Thus comparing the ground subsidence by varying the reinforcement area on the numerical analysis was analyzed. As a results, three-dimensional numerical simulation could be regarded to simulate better on the ground subsidence by various kinds of underground excavation and it can be used as a material of subsidence prevention methods.

• Journal of the Society of Disaster Information
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• v.7 no.2
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• pp.110-122
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• 2011

In this study, the disaster management and disaster medical improvement was described in underground space(specifically underground shopping center) in case of fire disaster occurred. Firstly, statue and system was discussed concerning building law, safety, fire services, refuge. The underground in Seoul management is classified as to space and form and management agent is different according to the type form. Because the difficulty of emergency rescue arises due to individual management system unified system needs to be established and improvement of facility management agent is necessary. For the patient to be transfer on the ground, corporation between command head quarter and emergency rescue team are essential. And disaster information and emergency medical information are also need to be considered. Therefore, effective countermeasures for emergency saving is urgent considering distribution of medical institution and medical treatment.

• Korean Journal of Construction Engineering and Management
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• v.6 no.1 s.23
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• pp.125-132
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• 2005

Domestic construction firms make every effort to save cost and, contrarily, enhance quality for competitive advantage in the market. Structural work of building construction takes chaise of the total cost and schedule, thus elaborate planning and management of the work help to lead the project into a successful way. Therefore, the idea to save time and cost and enhance constructability securing quality and safety of the work should be developed after analyzing the designed documents and site conditions comprehensively in the initial construction planning phase. Value Engineering (VE) technique is introduced in the substructural work in this paper to save cost creatively and systematically in the design and construction phase. A practical VE model that is applied to the underground building work systematically is proposed to save cost and it applies to the actual project to confirm the effectiveness of the model.

• Geotechnical Engineering
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• v.8 no.4
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• pp.81-98
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• 1992

Deep excavation increases utility of underground spaces for high buildings. subways etc. To excavate vertically the underground, safe earth retaining walls and supporting systems should be prepared. Recently anchors have been used to support the excavation wall. The anchored excavation has some advantages toprovide working space for underground construction. In this paper the prestressed anchor loads were measured by load cells which attacted to the anchors to support the excavation walls at eight construction fields. where under-ground deep excavation was performed on cohesionless soils. The lateral pressures on the retaining walls, which are estimated from the measured anchor forces, shows a trapezoidal distribution that the pressure increases linearly with depth from the ground surface to 30% of the excavation depth and then keeps constant value regardless of the stiffness of the walls. The maximum lateral pressure was same to 63% of the Ranking active earth pressure or 17% of the vertical overburden pressure at the final depth The investigation of the measured lateral pressure on the anchored excavation walls shows that empirical earth pressure diagram presented by Terzaghi-Peck and Tschebotarioff could be applied with some modifications to determine anchor loads for the anchored excavation in cohesionless soils.

• Explosives and Blasting
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• v.38 no.4
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• pp.1-15
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• 2020

With the increase of the utilization of underground space in Korea, explosion accidents at the underground facilities such as gas pipes have occurred frequently. In urban area with high population density, individual explosion accidents are likely to spread into large complex accidents. It is necessary to investigate the effect of explosion on the stability of underground structures in urban area. In this study, a sensitivity analysis was carried out to investigate the possible influence of nearby explosion on the stability of underground structure with 8 parameters including explosion conditions and rock properties. From the sensitivity analysis using AUTODYN, the main and interaction effects of each parameters could be determined. From the analysis, it was found that the distance between explosion point and tunnel, charge weight, and Young's modulus are the most important parameters on the stress components around a tunnel.