• Title, Summary, Keyword: Ground subsidence

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A STUDY ON THE CORRELATION BETWEEN GROUND SUBSIDENCE AREA NEAR ABANDONED UNDERGROUND COAL MINE AND GEOPHYSICAL PROSPECTING DATA USING GIS

  • Kim Ki-Dong;Choi Jong-Kuk;Won Joong-Sun
    • Proceedings of the KSRS Conference
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    • pp.325-328
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    • 2005
  • To estimate presumptive local ground subsidence area near Abandoned Under ground Coal Mine(AUCM) at Samcheok city in Korea, the geological properties of existing ground subsidence area and the geophysical prospecting data were analyzed using GIS. The electrical resistivity survey and seismic reflection survey database were constructed from investigation reports and factors which are related with ground subsidence such as geological map, topological map, land use map, lineament map, groundwater level, RMR (Rock Mass Rating), mining tunnel map and slope database were constructed also to make a comparative study of each parameters. As a result of the spatial analysis of existing ground subsidence area, 9 major factors causing ground subsidence were extracted and a connection between the structure of underground and the ground subsidence was determined from the analysis of geophysical prospecting data. The estimation of presumptive ground subsidence area was performed using the correlation between the result from neural network analysis of 9 factors and the scrutiny of geophysical prospecting data.

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PRODUCTION OF GROUND SUBSIDENCE SUSCEPTIBILITY MAP AT ABANDONED UNDERGROUND COAL MINE USING FUZZY LOGIC

  • Choi, Jong-Kuk;Kim, Ki-Dong
    • Proceedings of the KSRS Conference
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    • v.2
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    • pp.717-720
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    • 2006
  • In this study, we predicted locations vulnerable to ground subsidence hazard using fuzzy logic and geographic information system (GIS). Test was carried out at an abandoned underground coal mine in Samcheok City, Korea. Estimation of relative ratings of eight major factors influencing subsidence and determination of effective fuzzy operators are presented. Eight major factors causing ground subsidence were extracted and constructed as a spatial database using the spatial analysis and the probability analysis functions. The eight factors include geology, slope, landuse, depth of mined tunnel, distance from mined tunnel, RMR, permeability, and depth of ground water. A frequency ratio model was applied to calculate relative rating of each factor, and the ratings were integrated using fuzzy membership function and five different fuzzy operators to produce a ground subsidence susceptibility map. The ground subsidence susceptibility map was verified by comparing it with the existing ground subsidences. The obtained susceptibility map well agreed with the actual ground subsidence areas. Especially, ${\gamma}-operator$ and algebraic product operator were the most effective among the tested fuzzy operators.

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Ground Subsidence Risk Ratings for Practitioners to predict Ground Collapse during Excavation (GSRp)

  • Ihm, Myeong Hyeok
    • International Journal of Advanced Culture Technology
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    • v.6 no.4
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    • pp.255-261
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    • 2018
  • In the field of excavation, it is important to recognize and analyze the factors that cause the ground collapse in order to predict and cope with the ground subsidence. However, it is difficult for field engineers to predict ground collapse due to insufficient knowledge of ground subsidence influence factors. Although there are many cases and studies related to the ground subsidence, there is no manual to help practitioners. In this study, we present the criteria for describing and quantifying the influential factors to help the practitioners understand the existing ground collapse cases and classification of the ground subsidence factors revealed through the research. This study aims to improve the understanding of the factors affecting the ground collapse and to provide a GSRp for the ground subsidence risk assessment which can be applied quickly in the field.

Study of Influence Factors for Prediction of Ground Subsidence Risk

  • Park, Jin Young;Jang, Eugene;Ihm, Myeong Hyeok
    • Journal of Korean Society of Disaster and Security
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    • v.10 no.1
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    • pp.29-34
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    • 2017
  • This Analyzed case study of measuring displacement, implemented laboratory investigation, and in-situ testing in order to interpret ground subsidence risk rating by excavation work. Since geological features of each country are different, it is necessary to objectify or classify quantitatively ground subsidence risk evaluation in accordance with Korean ground character. Induced main factor that could be evaluated and used to predicted ground subsidence risk through literature investigation and analysis study on research trend related to the ground subsidence. Major factors of ground subsidence might be classified by geological features as overburden, boundary surface of ground, soil, rock and water. These factors affect each other differently in accordance with type of ground that's classified soil, rock, or complex. Then rock could be classified including limestone element or not, also in case of the latter it might be classified whether brittle shear zone or not.

Field and laboratory assessment of ground subsidence induced by underground cavity under the sewer pipe

  • Kong, Suk-Min;Kim, Dong-Min;Lee, Dae-Young;Jung, Hyuk-Sang;Lee, Yong-Joo
    • Geomechanics and Engineering
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    • v.16 no.3
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    • pp.285-293
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    • 2018
  • In densely populated urban areas with a large amount of infrastructure, ground subsidence events can result in massive casualties and economic losses. In South Korea, the incidence of ground subsidence in urban areas has increased in recent years and the number of underground cavities suspected of causing such events has significantly increased. Therefore, it is essential to develop techniques to prevent the occurrence of underground and ground subsidence. In this study, a field test, laboratory test, and numerical analysis were conducted to determine the optimal compaction degree of the upper support layer of any underground cavity below the level of sewer pipes in order to prevent such cavities from collapsing and leading to ground subsidence accidents. During the field test, an underground cavity was simulated using ice, and the generation of the cavity was confirmed using ground penetrating radar. The ground investigation was performed using a cone penetration test, and the compaction of the ground where ground subsidence occurred was evaluated with a laboratory test. The behaviour of the ground under various conditions was predicted using a numerical analysis based on the data obtained from the field test and previous studies. Based on these results, the optimal compaction degree of the ground required to prevent the underground cavity from causing ground subsidence was predicted and presented.

Ground Subsidence Mechanism by Ground Water Level and Fine Contents (지하수위와 세립분 함유량에 따른 지반함몰 메커니즘)

  • Kim, JinYoung;Lee, SungYeol;Choi, ChangHo;Kang, JaeMo;Kang, KwonSoo;Jeong, HyoJin;Hong, JaeCheol;Lee, JaeSoo;Baek, WonJin
    • Journal of The Korean Society of Agricultural Engineers
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    • v.59 no.5
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    • pp.83-91
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    • 2017
  • Recently, ground subsidence frequently occurs in downtown area. The major causes of the subsidence on the subsurface were the damages of the water supply and sewer pipelines and excavation works in adjacent areas, etc. Because of these various factors, it is not easy to analyze the tendency of occurrence of ground subsidence. The purpose of this study is to clarify the effect of ground subsidence by the change of the fine particle content and ground water level and to establish the ground subsidence mechanism. In this study, a model soil-box was manufactured to simulate the failure of the old sewer pipe which is one of the causes on ground subsidence. And a model test was conducted to investigate the effects of fine contents and ground water level on the cavity occurrence. From the test results, firstly the higher the ground water level, the faster the primary cavity is formed as the seepage stress increases. As a result, the secondary cavity and the ground subsidence rapidly progress due to the relaxation of the surrounding ground. The total amount of discharged soil was decreased as the fine content increased.

Case Studies of Ground Subsidence Risk Ratings (GSRp) Applied to the Excavation Sites (지반함몰 위험등급 분류(GSRp)의 굴착현장 사례 연구)

  • Shin, Sang-Sik;Ihm, Myeong-Hyek;Kim, Hak Joon
    • 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.

A COMPARATIVE ANALYSIS BETWEEN GROUND SUBSIDENCE AT ABANDONED UNDERGROUND COAL MINE AND ELECTRICAL RESISTIVITY SURVEY RESULTS USING GIS

  • Ahn, Seung-Chan;Lee, Sa-Ro;Kim, Ki-Dong
    • Proceedings of the KSRS Conference
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    • v.2
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    • pp.728-731
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    • 2006
  • Ground subsidence near abandoned underground coal mines has become a serious social problem in Korea. The purpose of this study is to perform a comparative analysis between the ground subsidence area and the electrical resistivity measured by field survey at Samcheok City. A raster database composed of ground subsidence areas and electrical resistivity data was constructed for GIS. To analyze correlation between the two constructed raster datasets, we used a frequency ratio model. The results show that low and high electrical resistivity anomaly zones coincide with the existing subsidence areas. We infer that the high anomaly zone means saturated and low anomaly zone means vacant. It suggests that electrical resistivity might be a useful factor for analyzing ground subsidence hazard zone.

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The Risk Evaluation of Ground Subsidence based on GIS Analysis Method (GIS 분석기법을 활용한 지반침하 위험도 평가)

  • Choi, Byoung Il;Kim, Jong Hoon;Park, Won Joo;Choi, Chang Ho;Kim, Jin Young
    • Journal of the Korean Society of Safety
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    • v.32 no.6
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    • pp.104-109
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    • 2017
  • As the ground subsidence occurred at the center of Seoul area in 2014, the ground subsidence phenomenon was emerged as a social issue in Korea. Even so far, national and local governments and related experts have been making a lot of efforts to prevent ground subsidence phenomenon, but it is still happening all over the country. In this study, we chose 9 influence factors on which ground subsidence and derived weights using AHP(Analytic Hierarchy Process) method for ground subsidence risk analysis. And we analyze the risk of subsidence in ${\bigcirc}{\bigcirc}$city using GIS(Geographic Information System) analysis method and evaluate the potential risk.

Trend of Physical Modelling For Ground Subsidence And Study of Its Application (지반함몰 모형실험 연구동향 및 적용방안 고찰)

  • Jeong, Seong-Yun;Jeong, Yeong-Hoon;Kim, Dong Soo
    • Journal of Korean Society of Disaster and Security
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    • v.10 no.1
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    • pp.1-10
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    • 2017
  • Recently, increasing cases of ground subsidence in the urban area has become social issue, and related bill has been passed. Ground subsidence occurs through complex combination of various factors, and numerical analysis of this problem is limited thereby. This is why verification of ground subsidence mechanism has been conducted through physical modelling. Previous researches has been focused on modelling ground subsidence caused by utility pipe defects, and there has been insufficient physical modelling study on ground subsidence caused by various reasons such as groundwater flow and excavation activity. Also, most previous physical modelling studies were performed in 1g condition, which cannot take the in-situ stress condition into the evaluation of the ground subsidence mechanism. Therefore, in this study, physical modelling techniques to simulate various conditions is discussed by studying the previous researches on the ground subsidence mechanism through physical modelling. Also, centrifuge modelling test is suggested in this study as the technique to perform more reliable evaluation of ground subsidence mechanism. Lastly, this study suggests to apply the techniques used in the evaluation of ground subsidence mechanism into Ground Stability Assessment.