• Journal of the Korean GEO-environmental Society
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• v.23 no.8
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• pp.5-10
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• 2022

Ground Subsidence has been continuously occurring in densely populated downtown. The main cause of ground subsidence is the damaged underground facility like sewer. Currently, ground subsidence is being dealt with by discovering cavities in ground using GPR. However, this consumes large amount of manpower and cost, so it is necessary to predict hazardous area for efficient operation of GPR. In this study, ◯◯city is divided into 500 m×500 m grids. Then, data set was constructed using the characteristics of the underground facility and ground subsidence in grids. Data set used to machine learning model for ground subsidence risk grade prediction. The purposed model would be used to present a ground subsidence risk map of target area.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.289-302
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• 2019

As the occurrence of ground subsidence near the excavation site increases recently, studies are being conducted to predict the possibility of ground subsidence prior to excavation. In this study, the ground subsidence risk rating for pre-excavation (GSRp) developed by the previous study was applied to actual excavation sites to verify its applicability. The final results for the evaluation of the ground subsidence risk level for five excavation sites revealed that GSRp scores were calculated between 40 and 79 points and classified mainly into grades II (Good Ground)~III (Fair Ground). In order to verify the evaluation method, the obtained GSRp grades were compared with the measured horizontal displacements. The horizontal displacements measured in five excavation sites were between 25% and 47% of the allowable displacement, which were well agreed with the low subsidence risk level obtained from GSRp calculation. It is expected that the GSRp method can be used as an evaluation tool for predicting the risk of ground subsidence before excavation if GSRp is verified and supplemented through the additional research for the poor soil with the high risk of ground subsidence.

• The Journal of Engineering Geology
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• v.28 no.4
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• pp.553-563
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• 2018

The recent increase of ground subsidence in Korea requires the development of technology for predicting the possibility of ground subsidence. Eighteen parameters affecting the ground subsidence for pre-excavation are classified into 6 categories considering ground types, groundwater, and external factors. Eighteen parameters consists of a table which gives ground subsidence risk ratings for pre-excavation(GSRp). Certain scores are given to these parameters after they are divided into several classes considering the importance and the credibility of parameters and the engineering judgements of the authors. Because of the difference of ground subsidence factors depending on the ground and field conditions, weighting factors for the individual factor and for the each category are multiplied. Weighting factors are calculated from citation frequencies of influencing factors. Ground subsidence risk ratings for pre-excavation can be quantified by considering the individual score of each parameter and weighting factors for the individual factor and for the each category. The suggested GSRp tables obtained from this study are expected to be used by engineers for the estimation of ground subsidence risk ratings for pre-excavation sites.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.40-41
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• 2011

본 연구에서는 기존 기판에 배선 형성 방법과 비교하여 매우 간단한 방법으로 배선을 기판 안에 함몰시키는 방법을 개발하였다. Gravure Offset Printing 방법으로 제작한 4 ${\mu}m$ 높이의 Ag 배선을 함몰하여 100 nm 로 만듬으로써 95% 이상이 기판 내부로 함몰되었음을 확인할 수 있었고, 함몰 전후의 면저항 값이 변화되지 않음을 확인할 수 있었다. 본 제작한 배선 함몰형 유연 기판은 각종 회로에 적용할 수 있고, 그 뿐만이 아니라 투명전극에 대한 보조 전극으로 적용 가능성을 확인할 수 있었다.

• Tunnel and Underground Space
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• v.30 no.2
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• pp.149-163
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• 2020

This paper presents a logistic regression and GIS based urban ground sink susceptibility assessment using underground facility information considering soil particle loss. In the underground environment, the particle loss due to water flow or groundwater level change leads to the occurrence and expansion of cavities, which directly affect the ground sink. Four different contributory factors were selected according to the two underground facility domains (water pipeline area, sewer pipeline area) and subway line area. The logistic regression method was used to analyze the correlation and to derive the regression equation between the ground sink inventory and the contributory factors. Based on these results, three ground sink susceptibility maps were generated. The results obtained from this study are expected to provide basic data on the area susceptible to ground sink and needed to safety monitoring.

• Journal of the Korean GEO-environmental Society
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• v.22 no.11
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• pp.23-29
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• 2021

Recently, ground subsidence has been steadily occurring mainly in downtown areas, threatening the safety of citizens. Under the road, various underground facilities such as water supply pipe, sewage pipe, and communication pipe are buried. Due to the aging of these underground facilities and the reckless development of the underground, it is acting as a cause of ground subsidence. Although there is a result of analyzing the risk of ground subsidence according to the deterioration of the existing pipeline, there is no result of analyzing the risk of ground subsidence using the density of pipelines indicating ground disturbance. Therefore, in this study, the density of the underground space was analyzed using the data of six types of representative underground pipelines in Seoul, and a study was conducted on whether there is a correlation with the ground subsidence. As a result, it was found that the density of underground facilities is high in the area where the ground subsidence occurred, indicating that the density of pipelines have an effect on the ground subsidence.

• Journal of the Korean Geotechnical Society
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• v.37 no.12
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• pp.117-125
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• 2021

The occurrence of ground subsidence and sinkhole in downtown areas, which threatens the safety of citizens, has been frequently reported. Among the various mechanisms of a sinkhole, soil erosion through the damaged part of the sewer pipe was found to be the main cause in Seoul. In this study, a random forest model for predicting the occurrence of sinkholes caused by damaged sewer pipes based on sewage pipe information was trained using the information on the sewage pipe and the locations of the sinkhole occurrence case in Seoul. The random forest model showed excellent performance in the prediction of sinkhole occurrence after the optimization of its hyperparameters. In addition, it was confirmed that the sewage pipe length, elevation above sea level, slope, depth of landfill, and the risk of ground subsidence were affected in the order of sewage pipe information used as input variables. The results of this study are expected to be used as basic data for the preparation of a sinkhole susceptibility map and the establishment of an underground cavity exploration plan and a sewage pipe maintenance plan.

• Journal of the Society of Disaster Information
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• v.14 no.4
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• pp.399-408
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• 2018

Purpose: Recently, the ground subsidence has caused social problem, because it occurred life and economic damage. Method: Ground subsidence is different from a sink hole. Ground subsidence occurred cavities from loss of by groundwater flow, surface layer is collapsed due to relaxation and expansion. Results: According to the survey, the caused of ground subsidence are classified as ground cavities, surrounding ground relaxation and pipe joint failure. Conclution: Cavities of ground is mainly caused by cavities formed by rainfall induced infiltration of the heavy rainfall, loss of soil due to rise and fall of ground water level and repeated sewage runoff.

• Journal of the Korean GEO-environmental Society
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• v.19 no.7
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• pp.13-18
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• 2018

Recently, road subsidence has been increasing in urban areas, threatening the safety of citizens. In the lower part of the road, various road facilities such as water supply and drainage pipelines and telecommunication facilities are buried, and the deterioration of the facilities causes the road subsidence. In particular, in the case of old sewer pipes which are attracting attention as a main cause of road subsidence, the management of sewer pipe replacement, repair and reinforcement is being performed depending on the burial year. Therefore, in this study, we tried to suggest a reliable road subsidence risk assessment method considering various sewer specifications and surrounding environment information and CCTV exploration result and GPR exploration result.

• Journal of the Korean GEO-environmental Society
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• v.18 no.6
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• pp.31-37
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• 2017

In recent years, the increasing trend of ground subsidence in major cities has caused social problems. Aged sewer pipeline as a main attribute for the subsidence is simply replaced and maintained according to a survey result with related to its buried period. However, other attributes and risk analysis for the subsidence have not been well studied yet. In this point, this study proposed various environmental and structural attributes with related to sewer pipelines and, then, a method of ground subsidence risk evaluation with a certain level of reliability. In order to find effective attributes to ground subsidence near to sewer, the nearest sewerage data were extracted at the location of subsidence in the City of Seoul, and a level of correlation was analyzed between subsidence and individual attribute. The effective weight factors for the proposed attributes was estimated through AHP analysis and its applicability was verified by comparing the actual subsidence data to the risk evaluation in the pilot study district of Seoul.