• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.559-575
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• 2021

Due to the increase in ground excavation work, the possibility of ground subsidence accidents is increasing. And it is very difficult to prevent these risk fundamentally through institutional reinforcement such as the special law for underground safety management. As for the various cases of urban ground excavation practice, the ground subsidence behavior characteristics which is predicted using various information before excavation showed a considerable difference that could not be ignored compared to the results real construction data. Changes in site conditions such as seasonal differences in design and construction period, changes in construction methods depending on the site conditions and long-term construction suspension due to various reasons could be considered as the main causes. As the countermeasures, the safety management system through various construction information is introduced, but there is still no suitable system which can predict the effect of excavation and risk assessment. In this study, a web-based system was developed in order to predict the degree of impact on the ground subsidence and surrounding structures in advance before ground excavation and evaluate the risk in the design and construction of urban ground excavation projects. A system was built using time series analysis technique that can predict the current and future behavior characteristics such as ground water level and settlement based on past field construction records with field monitoring data. It was presented as a geotechnical data visualization (GDV) technology for risk reduction and disaster management based on web-based system, Using this newly developed web-based assessment system, it is possible to predict ground excavation impact prediction and risk assessment.

• Journal of the Korean GEO-environmental Society
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• v.16 no.6
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• pp.23-30
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• 2015

This study analyzed degree of disturbance, using specimens by laboratory test with large block specimens and piston samplers collected from the Korea's two typical soft ground districts: South coast Gwangyang and Yangsan. To assess the characteristics of compression index of laboratory test incurred by disturbance, the compression index of laboratory test was compared with the back analysis compression index resulting from the analysis of the measured settlement. The analysis of specimen disturbance of the laboratory test results with the piston specimens of the two districts found that the qualities of most specimens were poor and the settlement predicted by the laboratory test compression index was underestimated. The analysis of test material taken from nearby areas proved that the disturbance degrees of large block specimens were lower than that of the piston specimens. The hyperbolic method, Hoshino method, Asaoka method, and ${\sqrt{S}}$ method, all of which are predictive methods using measured settlement, were employed to reach a conclusion that reliabilities of each predictive method except predictive material of a few points were the same. To compensate the disturbance effects on compression index of the piston specimens, we suggested a new modification formula that estimates compression index of piston specimens, using Schmertmann's corrected compression index, and back analysis compression index from the analysis of predictive settlement.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.334-343
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• 2023

Purpose: In this study, the cavity data found through ground cavity exploration was combined with underground facilities to derive a correlation, and the ground subsidence prediction map was verified based on the AI algorithm. Method: The study was conducted in three stages. The stage of data investigation and big data collection related to risk assessment. Data pre-processing steps for AI analysis. And it is the step of verifying the ground subsidence risk prediction map using the AI algorithm. Result: By analyzing the ground subsidence risk prediction map prepared, it was possible to confirm the distribution of risk grades in three stages of emergency, priority, and general for Busanjin-gu and Saha-gu. In addition, by arranging the predicted ground subsidence risk ratings for each section of the road route, it was confirmed that 3 out of 61 sections in Busanjin-gu and 7 out of 68 sections in Sahagu included roads with emergency ratings. Conclusion: Based on the verified ground subsidence risk prediction map, it is possible to provide citizens with a safe road environment by setting the exploration section according to the risk level and conducting investigation.

• Journal of the Korean Geotechnical Society
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• v.18 no.2
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• pp.107-121
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• 2002

In this study, GIS(Geographic Information System), a new approaching method, is proposed to effectively manage long-term settlements in the big reclamation sites. To verify an applicability of the proposed method, the prediction of long-term settlements which may occur in the overall soft deposits of the Incheon International Airport is carried out. During the process of the prediction of long-term settlements, measured settlement data obtained from an early stage of preloading are analyzed in detail. For purposes of the analysis, an estimation of the recompression index is also made based on the Nagaraj's research results. The coefficient of the secondary consolidation is further determined based on the relationship presented by the Mesri & Godlewski, which defines a ratio between the coefficient of the secondary consolidation and the recompression index.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.111-120
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• 2003

A new stress path test method, which is more suitable f3r evaluating settlements of clay deposits, was introduced. This new method is basically based on back pressure equalization concept and makes it possible to estimate deformations corresponding to all points on a specific stress path by only one test. As a result, deformation characteristics of a clay deposit can be predicted by a few tests and the more practical application of stress path method can be realized. In addition, anisotropic deformation behaviors following arbitrary stress paths also can be experimentally measured by this test method. Experimental applicability of the proposed method was confirmed by performing various stress path tests on remolded kaolinite samples and the actual process to evaluate overall deformation characteristics and settlements was also presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.725-730
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• 2002

The areas around the Nam-Hae are mostly covered in thick soft clay deposits(50∼60.0m). In order to improve the ground in these areas verticals trains have been partially penetrated up to the depth of about 25.0m. However, since the predicted values of settlement have often been changed at some predicted time. Finite element analysis was performed to investigate the consolidation behaviour for it. The results from FEM was compared with various observational methods.

• Economic and Environmental Geology
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• v.41 no.4
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• pp.453-464
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• 2008

This study is to examine a relation between coal mining subsidence occurrence at abandoned underground coal mines and underground goaf with respect to surface geology, subsurface structure, depth and thickness of coal beds and the distribution of drifts. A study is carried out at the site where susceptibility of coal mining subsidence was proven high in a previous study. In that previous study, the susceptibility of coal mining subsidence was spatially analyzed by GIS using digitized geological maps, investigation reports, digitized mining tunnel maps without consideration of subsurface structure and the multi-level arrangement of drifts. Here we analyze geological characteristics around the goaf and the distribution of coal seam based upon digitized geological maps and investigation reports on the study area. And digitized mining tunnel maps are also used to analyze the depth and multi-level arrangement of drifts. The results show that weakened surface rock strength, relatively shallow depth and large thickness of coal seam below the surface are closely related to the coal mining subsidence occurrence. Complicatedly inter-connected drifts, shallow depth of drifts and surface rock fractures are revealed as additional control factors affecting coal mining subsidence. These factors examined in this study as well as original factors should be taken into account for the quantitative estimation of coal mining subsidence occurrence at abandoned underground coal mine.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.1
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• pp.1-21
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• 2020

The domestic abandoned mines are generating subsidence and it is difficult to predict this subsidence and evaluate the risk. The study of the subsidence risk evaluation using the existing numerical analysis only applies the integrative property to the geological structure and ground condition, and analyzes the goaf peripheral plastic domain. Also, there is a realistic limit that only restricted materials can be apprehended in securing the input information, which leads to the low reliability of the numerical analysis result. In this study, 2-dimensional modeling was performed by applying the field geological structure and ground information targeting abandoned mine where the subsidence occurred. Also, the analysis model was revised by repeating the numerical analysis for the difference between the real subsidence ground information and the analysis result to be minimized by modifying the ground property. This revision was automated by applying the optimization technique and the gradational optimal design method dividing multiple ground properties was developed.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.91-99
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• 2008

Applicability of existing methods of predicting consolidation settlement was assessed by analyzing results of centrifuge tests modelling self-weight consolidation of soft marine clay. From extensive literature review about self-weight consolidation of soft marine clays located in southern coast in Korea, constitutive relationships of void ratio-effective stress-permeability and typical self-weight consolidation curves with time were obtained by centrifuge model experiments. For the condition of surcharge loading, exact solution of consolidation settlement curve was obtained by Terzaghi's consolidation theory and was compared with the results predicted by currently available methods such as Hyperbolic method, Asaoka's method, Hoshino's method and ${\sqrt{S}}$ method. All methods were found to have their own inherent error to predict final consolidation settlement. From results of analyzing the self-weight consolidation with time by using those methods, Asaoka's method predicted the best. Hyperbolic method predicted relatively well in error range of 2~24% for the case of showing the linearity in the relationship between T vs T/S in the stage of consolidation degree of 60~90 %. For the case of relation curve of T vs $T/S^2$ showing the lineality after the middle stage, error range from Hoshino method was close to those from Hyperbolic method. However, Hoshino method is not able to predict the final settlement in the case of relation curve of T vs $T/S^2$ being horizontal. For the given data about self-weight consolidation after the middle stage, relation curve of T vs T/S from ${\sqrt{S}}$ method shows the better linearity than that of T vs $T/{\sqrt{s}}$ from Hyperbolic method.

• Journal of the Korean GEO-environmental Society
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• v.2 no.4
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• pp.51-61
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• 2001

A series of model tests and analyses by load transfer function were performed to study load-settlement behaviour with relative compaction ratio of soil and embeded depth of pile. In the model tests, embeded depth ratio(L/D) of pile were installed 15, 20, 25 and relative compaction of soil(RC) is 85%, 95% and then cement were injected at around perimeter of pile. For analysis of embedded pile, the paper were compared results of model tests with analysis results by Vijayvergiya model and Castelli model, Gwizdala model of elastic plasticity-perfect plastic model and then the fitness load transfer mechanism was proposed to predict load-settlement behaviour of embeded pile. The analysis results of predicted bearing capacity by load transfer function, ultimate bearing capacity of embeded pile were approached to measured value and behaviour of initial load-settlement curve were estimated that load transfer function by Castelli were similar to measured value. The result of axial load analysis of bored pile shows that skin friction estimated by load transfer mechanism is investigated more a little than that of measured values.