• Tunnel and Underground Space
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• v.25 no.5
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• pp.408-416
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• 2015

The collapse of the underground cavities and voids, which were made for developing mineral resources, can cause the subsidence of the ground surface in the residential areas. During the Japanese colonial era and the 1960's mining boom period, lots of mines had been developed indiscriminately in Korea. Due to complicated geological conditions and mining methods, many of dangerous underground mine cavities with steep slopes had been generated at the shallow surface. Due to such conditions, it is difficult to directly apply valid foreign reclamation practice for the cavities in Korea environments. It is necessary to develop the efficient ground stabilization technologies for the Korea underground mine conditions to solve abandoned mine reclamation properly. Therefore, MIRECO and Korea government have been carrying out practical researches and technical developments together with other academic researchers and reclamation business partners, and various practical solutions such as surveying and exploration methods, proper cavity filling materials and reinforcement methods have been developed with application in the mine field. In this article, up to date technologies and R&D trends in the field of mine subsidence prevention technology are broadly reviewed to establish the future direction of a research and development.

• Tunnel and Underground Space
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• v.28 no.5
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• pp.387-399
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• 2018

Mine reclamation project is closely related to human's past mining activities and the current human's living environment. It is a reason for the national management. In order to efficiently carry out mine reclamation projects, a precise investigation and analysis of the underground space of the abandoned mine is required. Korea MINE RECLAMATION Corp. is developing a practical technology that is effective in investigating and actually measuring underground cavities. MIRECO EYE system is an exploration equipment for 3D digitization and figuration of underground cavities. As combining a laser, sonar and image acquisition technology, it enables access to information about inaccessible underground cavities and effective management of subsidence risk of mined area. and currently it is also utilized for various purposes in related areas such as investigating urban sinkholes. This article is precise numerical and geometric information analysis obtained through MIRECO EYE system.

• Tunnel and Underground Space
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• v.27 no.4
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• pp.205-216
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• 2017

Fluctuations in groundwater level are the major cause of ground subsidence in the abandoned limestone mine. In this study, evaluation of groundwater flow under three different cases of natural condition, aggregate-filling, temporary drainage in groundwater-saturated limestone mine cavities was executed by 3-dimensional analysis. In the case of aggregate-filling, although the water level both in the upper ground of mine cavities and an agricultural watershed was elevated, it was lower than the water level fluctuation of an agricultural water use and rainfall and the flow rate was similar to the flow rate of natural condition. In the case of temporary drainage, as the water level in the upper ground of mine cavities and an agricultural watershed decrease rapidly and the flow rate has increased by 25times, so the risk of ground subsidence increased.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.497-514
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• 2020

This study investigated the causes of large-scale ground subsidence in the upper part of mining cavities of the Samdo limestone mine, Samcheok city, Gangwondo, Korea. Geological and electrical resistivity surveys were undertaken on the collapsed slope of the mountain and in the mine tunnel where subsidence occurred, with geotechnical evaluations and numerical analysis. It is concluded that wide mining cavities, with irregular pillars in unstable rock masses hosting discontinuities, weathered over time, resulting in subsidence occurring along a fault plane due to increasing ground stress.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.147-154
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• 2000

The influence of the mined-out caves on the stability of the high speed railway tunnel was investigated with a series of geological logging and in-situ tests on the one hand, and with the rock mass classification using the multiple regression analysis on the other hand. The rock mass in this area can be classified as 'fair', and the condition of the discontinuities plays the most important role in the classification of the rock mass. The results of the analysis obtained by the FLAC showed that the western part of the tunnel locating at 50m above the mine cavities could be affected by subsidence associated with a considerable deformation, the magnitude of which might depend on the properties of the rock mass. Key word : multi regression analysis, subsidence, mine cavities

• Tunnel and Underground Space
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• v.11 no.2
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• pp.174-181
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• 2001

The cavities created by underground mining, if remained unfilled, can cause ground settlement and surface subsidence as a result of relaxation and breakdown of the carven roof. Construction of structures above the underground mine cavity will have serious problems concerning both structural stability and safely even if the cavity is back-filled. This study was conducted to confirm the location and condition of the cavern as well as the state of the back-fill in A mine area using core logging and borehole camera. The bearing capacity and other mechanical properties of the ground were also measured by the standard penetration test(SPT). Obtained data were used to assess the stability of the ground and the structures to be built by numerical analysis using FLAC. The site investigation results showed that the mine cavities were filled with materials such as boulder and silty sand(SM by unified classification). Result of the numerical analyses indicated that constructing building structures on the over-lying ground above the filled cavities is secure against the potential problems such as surface subsidence and ground settlement.

• Tunnel and Underground Space
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• v.26 no.6
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• pp.455-465
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• 2016

The collapse of underground mine development void for mineral resources can cause the subsidence of ground surface. In order to prevent the subsidence of ground, data such as maps or pictures of past mining site is important information for current mine reclamation works. In particular, mine subsidence management was based on mining maps and pictures. The process of the mining area surveys, safety evaluation, and ground reinforcement are normally possible with information such as maps and pictures in past mining. During the Japanese colonial period and 1960's, a lot of mines were developed in Korea indiscriminately. However, mining information at that time is limited to use. In the future, mining information will become even more rare. MIRECO intends to establish a realistic alternative solution. In this study, the basic numerical information of developed mine tunnels in Korea is statistically reviewed, and advanced underground cavity measuring technology was studied. 4,473 mine tunnel opening data of 1,784 abandoned mines in korea were collected and sorted. As a result of the analysis, the average value of small mine tunnel openings in Korea was 1.982 m in height and 1.959 m in width. The mean value of shape factor was analyzed as 0.485. The summary of these numerical mine data will be helpful for understanding and researching Korean abandoned mines. Therefore, the development of measurement technology for abandoned mine cavities and tunnels is expected to facilitate more effective mine subsidence management works in Korea.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.2
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• pp.62-71
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• 2000

The abandoned mines causing settlement of the surface above and collapse of the cavities are the major influencing factor on the stability of the nearby underground structures. To prevent the harmful effect, the backfill methods are commonly applied to the cavities although the design criteria and the analysis method are not properly addressed in some cases. An approximate analytical method together with the numerical technique is considered in this study to simulate the gradual deterioration of the rock masses around the cavities and, therefore, the influential zone to the underground structures passing through the cavities. Also considered in this study is the backfill effect on the stability of the rock masses around the cavities. Specifically, the incomplete backfill effect is compared with that of the idealized backfill method by adopting elasto-plastic analysis involving a strain softening material law.

• Tunnel and Underground Space
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• v.19 no.2
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• pp.107-122
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• 2009

Insufficient reinforcement for maximizing payability and benefits in mining cavities causes subsidence problems and it threatens residents' lives and properties. So many reinforcement management methods are developed and now various methods are being applied in the field. Among them, a filling method which sends reinforcement materials in the cavities is used extensively. However, domestic geological condition and coal mining methods are so complicate that make many steep cavities. Because of those problems, it is difficult to apply foreign methods directly, which is valid for horizontal cavities. In this study, the injection volume of quick setting grouting material which is developed for filling cavities in domestic condition and the shape of consolidated bodies are investigated. And a programming method for estimating proper injection amounts of filling materials is proposed. The results are verified by numerical analysis using UDEC.

• Tunnel and Underground Space
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• v.10 no.3
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• pp.395-402
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• 2000

The influence of the mined-out caves on the stability of the high speed railway tunnel was investigated with a series of geological logging and in-situ tests on the one hand, and with the rock mass classification using the multiple regression analysis on the other hand. The rock mass in this area can be classified as 'fair', and the condition of the discontinuities plays the most important role in the classification of the rock mass. The results of the analysis obtained by the FLAC showed that the western part of the tunnel locating at 50m above the mine cavities could be affected by subsidence associated with a considerable deformation, the magnitude of which might depend on the properties of the rock mass.