• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.87-99
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• 2023

Ground excavation inevitably causes ground displacement of adjacent ground, and structures and facilities exposed to ground displacement may suffer various damages. Therefore, in order to minimize the damage and damage to adjacent structures and facilities caused by excavation, ground displacement (settlement and horizontal displacement) in the adjacent ground caused by excavation must first be predicted. There is many ground displacement information induced by general braced cut excavation, but the information is not enough for circular shaft excavation. This study aims to provide information on the estimation of ground settlement caused by circular shaft excavation through the case analysis of circular shafts and comparison with braced cut excavation. From this study, it was found that the use of the settlement criterion of braced cut excavation as the settlement management criterion for circular shaft excavation is a conservative approach in terms of safety. But when considering the economic aspect, it may result in overdesign of the wall and therefore, a more reasonable settlement criterion can be needed for circular shaft excavation.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1143-1148
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• 2011

In this study, seismic structural reinforcement are carried out, based on the estimated seismic performance of underground box structures in urban railway, and displacement based design method was developed to enhance seismic performance of structures. New seismic reinforcement design method is proposed and compared with existing design methods. And presented an overview of the developed design methodology through a design example to verify the validity of that methods.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.307-308
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• 2010

The present research carried out displacement measurement and section & capacity measurement of a archcrown of a tunnel by using a laser scanner in underground tunnel excavation work that a bridge construction is being executed.

• Journal of the Korean earth science society
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• v.34 no.3
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• pp.195-208
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• 2013

We employed electrical resistivity and optical borehole imaging methods to identify underground cavities and determine ground subsidence rate at the study area affected by land subsidence due to abandoned underground mines. At the study site 1, the anomalous zones of low resistivity ranging between 100 ohm-meter and 150 ohm-meter were observed and confirmed as an abandoned underground mine by subsequent borehole drilling and optical borehole imaging. Although the electrical resistivity survey was unavailable due to the paved surface of the study site 2, we were able to locate another abandoned underground mine with the collapsed mine shaft based on the distribution of the ore veins and confirmed it with borehole drilling. In addition, we measured vertical displacements of underground features indicating underground subsidence by conducting optical borehole imaging 6 times over a period of 43 days at the study site 2. The displacement magnitude at the deep segment caused by subsidence appeared to be 3 times larger than those at the shallow segment. Similarly, the displacement duration at the deep segment was 4 times longer than those at the shallow segment. Therefore, the combination of electrical resistivity and optical borehole imaging methods can be effectively applicable to detect and monitor ground subsidence caused by underground cavities.

• Journal of the Korean GEO-environmental Society
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• v.13 no.5
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• pp.25-33
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• 2012

In this study, gathered measuring data at fields constructed by IPS(Innovative Prestressed Support) system controls the ground displacement and improves the constructability of earth work and structure work greatly, and compared with horizontal displacement calculated by Elasto-plastic analysis program(EXCAV/W). As the result, displacement of calculated by pre-loading data is reduced 13.2% average of general method, and measuring displacement is also reduced 26.7% average of general method. Therefore that IPS system is more safe than conventional strut method in contrast to displacement of underground wall. In addition, horizontal displacement is reduced through the pre-loading effect used by IPS system.

• Tunnel and Underground Space
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• v.20 no.6
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• pp.408-420
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• 2010

It is important to forecast the final deformation of a tunnel during construction for evaluating its mechanical stability. In this study, the final deformation of a tunnel is forecasted by fitting tunnel deformations measured while excavating to a displacement function and exterpolating it. The tunnel for the study was built in two stages divided into an upper and a lower part. During the lower part construction of the tunnel, the displacement function forecasts the final incremental displacement well compared to the increment measured after completion of the tunnel. It is because the critical initial displacement occurred on passing the measurement pins can be adequately measured during excavating the lower part, which can not be measured during the upper part excavation of the tunnel.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.119-133
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• 2020

Underground utility tunnel, the most representative cut and cover structure, is subjected to seismic force by displacement of the surrounding soil. In 2020, Korea Infrastructure Safety Corporation has published "Seismic Performance Evaluation Guideline for Existing Utility Tunnel." This paper introduces two seismic evaluation methods, RDM (Response Displacement Method) and RHA (Response History Analysis) adopted in the guide and compares the methods for an example of an existing utility tunnel. The test tunnel had been constructed in 1988 and seismic design was not considered. RDM is performed by single and double cosine methods based on the velocity response spectrum at the base rock. RHA is performed by finite difference analysis that is able to consider nonlinear behavior of soil and structure together in two-dimensional plane strain condition. The utility tunnel shows elastic behavior for RDM, but shows plastic hinge for RHA under the collapse prevention level earthquake.

• Tunnel and Underground Space
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• v.2 no.2
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• pp.237-250
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• 1992

The cavities formed by the excavation of coal seam cause unstable within rock body, leading to large displacement around adjacent roadway. This displacement brings the closure of roadway and deformation of support. Therefore, it is necessary to understand and predict the deformation characteristics of roadway while coal seam is under excavation. In this study, the observed displacements are compared with the calculated ones through the analysis using Linear Boundary Element Mothod under the elastostatic conditions, in order to determine the virgin stress state and deformation modulus which affect the deformation characteristices.

• Tunnel and Underground Space
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• v.6 no.4
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• pp.287-297
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• 1996

Input data play an important role in numerical analyses. However, it is difficult to obtain appropriate data for many reasons. In order to overcome those difficulties, an automatic MPBX(Multi-Position Borehole Extensometer) monitoring system is developed. This system can be applied to the analyses of measured data which include evaluation of the stabiliyt, efficiency of construction and the validity of numerical analyses. At first, the MPBX among field measurement tools is considered in this study. Also, 3-dimension finite element analyses are carried out to verify the influence of geological conditions and excavation sequence on the MPBX displacement. The effect of geological conditons on the displacement can be estimated qualitatively qualitavely from the measured data by plotting displacement vs. depth.

• 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.