• Tunnel and Underground Space
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• v.27 no.6
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• pp.366-376
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• 2017

In this paper, we investigated the subsidence possibility and countermeasures according to the current mining method through investigation of the subsidence condition in operation mine. Most of the metal mine were broken, investigating to subsidence pattern of the Sink-hole. Coal mines are becoming more and more deep, investigating to Trough type subsidence patterns in existing mining areas. History of nonmetallic mines have not been developed for over 30 years, but large and small ground deformation problems have been investigated. Mining also has ground subsidence functionality due to time dependence by relying more heavily on empirical methods than technical methods. Therefore, it is necessary to carry out the various researches on systematic development method and prevention of subsidence of nonmetallic mines.

• Tunnel and Underground Space
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• v.17 no.4
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• pp.255-265
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• 2007

As the mechanism and effect range of subsidence are altered according to the various conditions (the ground condition, the earth pressure, the geometric condition of underground cavity and the structure load), the analysis and prediction of subsidence in abandoned mining area are very difficult. Also, as the geological characteristics and the mining methods are differed in each mines, the application of the pre-existing reinforcements without improvement has a lot of difficulties and limits. In this study, the various underground investigation such as long-depth core drilling, seismic tomography and BIPS (borehole image processing system) were performed, the distribution of underground cavity and coal seam and rock relaxation condition were analyzed. And we predicted the type of subsidence and estimated the subsidence by theories of mining subsidence. With these results, we analyzed the mechanism of subsidence occurrence in the research object area. Finally, we improved existing methods which were applied to the abandoned mining area and also we established the rational reinforcement for the ground and structure foundation against each subsidence cause.

• Geomechanics and Engineering
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• v.16 no.2
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• pp.177-185
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• 2018

The subsidence mechanism of ground surface is a complex phenomenon when multiple seam coal mining operations are carried out. Particularly, the coal mining beneath karstic formations causes a very special form of subsidence. The subsidence causes elasto-plastic deformation of the karstic layers and the collapse of cavities leads to dolinization and/or sinkhole formation. In this study, a sinkhole with a depth of 90 m and a width of 25 m formed in Gelik district within the coal-basin of Zonguldak (NW, Turkey) induced by multiple seam coal mining operations in the past has been presented as a case-history together with two-dimensional numerical simulations and InSAR monitoring. The computational results proved that the sinkhole was formed as a result of severe yielding in the close vicinity of the faults in contact with karstic formation due to multiple seam longwall mining at different levels.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.253-255
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• 2004

The mining-related damages such as ground subsidence, acid mine drainage(AMD), and deforestation in the abandoned underground coal mine areas become an object of public concern. Therefore, the system to manage the miningrelated damages is needed for the effective drive of rehabilitation activities. The management system for Abandoned Underground Coal Mine using GIS includes the database about mining record and information associated with the mining-related damages and application programs to support mine damage prevention business. Also, this system would support decision-making policy for rehabilitation and provide basic geological data for regional construction works in abandoned underground coal mine areas.

• 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.

• Geomechanics and Engineering
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• v.18 no.1
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• pp.97-109
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• 2019

Physical conditions play vital role on the mechanical properties of frozen soil, especially for the temperature and moisture content of frozen soil. Subsequently, they influence the subsidence and stress law of permafrost layer. Taking Jiangcang No. 1 Coal Mine as engineering background, combined with laboratory experiment, field measurements and empirical formula to obtain the mechanical parameters of frozen soil, the thick plate mechanical model of permafrost was established to evaluate the safety of permafrost roof. At the same time, $FLAC^{3D}$ was used to study the influence of temperature and moisture content on the deformation and stress law of frozen soil layer. The results show that the failure tensile stress of frozen soil is larger than the maximum tensile stress of permafrost roof occurring in the process of mining. It indicates that the permafrost roof cannot collapse under the conditions of moisture content in the range from 20% to 27% as well as temperature in the range from $-35^{\circ}C$ to $-15^{\circ}C$. Moreover, the maximum subsidence of the upper and lower boundary of the overlying permafrost layer decreases with the increase of moisture content in the range of 15% to 27% or the decrease of temperature in the range of $-35^{\circ}C$ to $-15^{\circ}C$ if the temperature or moisture content keeps consistent with $-25^{\circ}C$ or 20%, respectively.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2004.10a
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• pp.171-180
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• 2004

Underground mining causes surface subsidence long after the mining operation had been ceased. Surface subsidence can be in the form of saucer-shaped depression or collapsed chimneys or sinkholes. Sinkhole formations are predominant over shallow-depth room and pillar mines having weak overburden strata. In this study, occurrences of sinkholes due to mining activity are assessed based on local geological conditions and mining parameters using fuzzy reasoning techniques. All input and output parameters are represented with linguistic hedges. Numerous fuzzy rules are developed to relate sinkhole occurrences with input parameters using fuzzy relational matrix. Based on the combined fuzzy rules, possibility of sinkhole occurrences can be ascertained once the geological and mining parameters of any area are known.

• Geomechanics and Engineering
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• v.18 no.4
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• pp.417-426
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• 2019

Gangue filling in the goaf is an effective measure to control the surface subsidence. However, due to the obvious deformation of gangue compression, the filling effect deserves to be further studied. To this end, the deformation of coal gangue filling in the goaf is analyzed by theoretical analysis, large-scale crushed rock compression test, and field investigation. Through the compression test of crushed rock, the deformation behaviour characteristics and energy dissipation characteristics is obtained and analysed. The influencing factors of gangue filling and predicted amount of main deformation are summarized. Besides, the predicted equation and filling subsidence coefficients of gangue are obtained. The gangue filling effect was monitored by the movement observation of surface rock. Gangue filling can support the roof of the goaf, effectively control the surface subsidence with little influence on the ground villages. The premeter and equations of the main deformation in the gangue filling are verified, and the subsidence coefficient is further reduced by adding cemented material or fine sand. This paper provides a practical and theoretical reference for further development of gangue filling.

• Tunnel and Underground Space
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• v.4 no.2
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• pp.170-185
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• 1994

Surface subsidence is one of the problems caused by mined out caverns. Depending on the geologic conditions and mining methods, subsidence can occur in various forms. This report describes the ground stability assessment for the mining induced subsidence area where unfilled caverns still exist abandoned. Geologic features which could affect the stability of the ground were investigated and all the possible geophysical methods were employed to obtain data that could explain the state of the ground in question. Basic rock tests were conducted from the drill cores and rock mass classification was performed by core logging and borehole camera investigation. Numerical analyses were carried out to predict the ground stability using data obtained by various investigations. The result could have been more reliable if in-situ stress were measure and reflected in the numerical analysis.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.139-146
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• 2000

This study investigates the changes of subsidence and hydraulic conductivity by underground mining. Coupling between post-mining induced strains and strain-dependent hydraulic conductivities is obtained by idealizing a jointed rock mass as an equivalent porous medium in which the hydraulic conductivity of a single joint is defined through parallel plate description. Results indicate that post-mining hydraulic conductivities are directly related to the strain field occurred by subsidence induced deformation. Maximum subsidence and hydraulic conductivity values increase as a panel width does widen. Joint spacing has an effect on the intensity of the changes in hydraulic conductivity.