• Tunnel and Underground Space
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• v.33 no.6
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• pp.472-482
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• 2023

The grid-type or room-and-pillar method is applied for the purpose of mining horizontally buried minerals. In this study, design and pilot test were performed to apply the room-and-pillar method which uses natural rock as a rock pillar to the construction of underground space. The area where the pilot test was conducted was in stone mine and had good rock conditions with an appropriate depth (about 30 m) to apply the pilot test. The pilot test site was selected by reviewing accessibility and ground conditions and then site construction was performed through detailed ground investigation and design. The pilot test was designed with a column shape of 8×8 m and a cross-section of 8×12 m. The blasting pattern was determined through test blasting at the site, and blasting of 3 m excavation with 89 holes was performed. Through field observations, the average width of 12.5 m and the average height of 8.3 m were measured. Therefore, it is possible to proceed similar to the cross-sectional shape considered in the design.

• Tunnel and Underground Space
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• v.19 no.6
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• pp.526-533
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• 2009

This study presents Mine Green Framework(M.G.F) which can protect the slope of rock and tailings. M.G.F method provides the fiber frame which helps the growth of the plant in the barren site like mined rock slope. M.G.F system consists of the polyester fiber mat, soil, seeds and anchors for the attachment. The optimum rate of filling materials was figured out by many germination tests in order to improve the effect of filling materials and the optimum rate of filling materials was applied in four test sites individually. High rooting rate over 70% was confirmed in all field tests. Especially the moisturizer was the most important component of filling materials and it could make the better condition for the plants.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.4
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• pp.165-173
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• 2014

Open-pit mining method, is safe relatively work as compared with underground mining. And high yield, low production cost, has the advantage that it can provide a lot of production. But deforestation, tailings and slag deposition, mineral debris, dust, water, noise, land subsidence, sediment runoff discharge, I have internalized environmental disaster predisposing factors, such as landslides. Thus, it may be noted, also by typical environmental regulations. We try to deal with the changes in open pit terrain and environment related issues. Then, use the recovery period and the open pit mine and ecology off the gun, environment-friendly development of accurate monitoring methods, systems of this development is required. The use of open platforms and open source GIS tools have been developed during this period, it needs to develop spatial information environment monitoring system open pit mine construction.

• Tunnel and Underground Space
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• v.26 no.4
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• pp.274-282
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• 2016

Natural ventilation is employed in limestone mines that have been currently operated in Korea, and there has been a growing issue of a significantly weak airflow caused by the large-scale excavation. Thus, the air quality in the working area is considerably poor. In order to improve this circumstance, it is mainly required to examine ventilation performance. In this study, the examination of ventilation efficiency was conducted by using tracer gas method. The result of this work indicated detailedly the ventilation problems in research mine, in that extremely low air velocity, recirculation, and air change rate were evaluated quantitatively using tracer gas. Therefore the ventilation performance evaluation using tracer gas can be opted as a precise method to improve the working area in mines.

• Economic and Environmental Geology
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• v.2 no.3
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• pp.58-67
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• 1969

Songgwang lead zinc mine is located in about 12km to the north-east of Jeonju City. Geology of the mine and its visinity is consisted of Jeonju series belonged to so-called Okcheon system, Seodaesan tuff formation, Silla series, and the quartz porphyry intruded into these formations. Jeonju series comprising 3 formations; that is, of Sadaeri, Sindong, and Girinbong. Jeonju series is generally distributed in southern part of the area, striking NNW, and diping NE $30^{\circ}$, or NW $30^{\circ}$. It is deformed to form synclinorium and anticlinorium plunging to the north with low angle. In the northern part of the area, Jeonju series was cut by Sinpeongri-fault of NEE direction near Sinpeongri. In the north side of the fault, it is overturned and shows NEE or NWW strikes and NW $60^{\circ}$ dips. At the west of Songgwangri, it is cut by 3 thrusts; the two are almost parallel each other, and the third oneis manifested by the fact that the lower black shale zone thrusted over the upper limestone. Songgwangri thrust, so named, is a post-mineral fault and its plane represents a premineral slip plane. Enrichment of are took place along the bedding plane or fissure parallel to it, as seen in adit No. 1 or No. 2 along the floor of the thrust, and along the sheared zone or the brecciated zone oblique to the plane near the thrust in crystalline limestone of Sindong formation as observed in the underground levels of inclined slope. Ore minerals are chiefly zincblende, galena, pyrrhotite, arsenopyrite, acompanied pyrite and chalcopyrite, and contain Au and Ag. In earlier stage of mineralization, the limestone was recrystalized, and sulphide minerals were enriched in the· permiable zone said above by pyrometasomatism, and in later stage the limestone was affected chloritization and sericitization. However hydrothermal replacement was weak, so that enrichment did not took place. It seems that minerallizing materials came up through the premineral slip plane and injected, and replaced the limestone in permiable zone said above with sulphide are minerals. Then Songgwangri thrust took place and, the lower black shale zone thrusted upon crystalline limestone.

• Tunnel and Underground Space
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• v.24 no.1
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• pp.1-10
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• 2014

This paper presents a case study that performed simulations on shovel-truck haulage systems in an open-pit mine by considering truck's breakdown and crusher's capacity. The SSangyoung limestone open-pit mine in Korea was selected as a study area and investigated to design the simulation algorithms. The GPSS/H simulation language is used to implement the simulation algorithms as a console application(simulator). The values of input parameters for simulator were measured by field investigation in the study area. The simulation results showed that 7 trucks can maximize the daily profit of haulage operations(i.e., 73,775 USD) when considers the frequency of trucks' breakdown as 1/40 $hour^{-1}$. In addition, the crusher capacity of 1300 tph is required to improve the efficiency of shovel-truck haulage systems in the study area.

• Tunnel and Underground Space
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• v.25 no.3
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• pp.231-243
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• 2015

In this study, both in-situ stress measurements and a lot of laboratory rock tests were conducted at a metal mine in Jeongseon, Korea. The stress ratio obtained from in-situ stress measurements showed a tendency to decrease according to depth below surface and its average value was 1.10. The mechanical properties such as unit weight, absorption ratio, porosity, elastic wave velocity, uniaxial compressive strength, Young's modulus, Poisson's ratio, tensile strength, shore hardness, friction angle and cohesion were investigated for the four different rocks mainly distributed at a studied mine, which were dolomite, felsite, granite and magnetite. The mechanical properties of the four different rocks were compared by means of statistical analyses, whereupon the felsite and the granite turned out to have more strength characteristics than the magnetite. The correlation of mechanical properties was also investigated, whereupon a few results against the general correlation were found out. The failure criteria of the four different rocks were finally discussed by means of both Mohr-Coulomb criterion and Hoek-Brown criterion.

• Tunnel and Underground Space
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• v.23 no.2
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• pp.99-109
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• 2013

The slopes of open-pit mine are typically designed without considering the reinforcement and support method due to the economical efficiency. However, the long-term stability of final pit slope is needed in some case, therefore the appropriate measures that can improve the stability are required. In this study, the field survey and laboratory test were carried out in S limestone mine. The stability assessment of final pit slope was performed through the stereographic projection method, SMR, and numerical analysis. And countermeasures for stabilization were proposed. The results of analysis show that full scale of slope failure is not expected but the failures of bench slope scale are likely to occur. In oder to increase the stability of bench slope, we suggested the remedial methods as follows: excavating the final pit slope by pre-splitting blasting, placing the wide berm in the intermediate bench slope and installing the horizontal drainage hole in the place of local ground water runoff.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.555-568
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• 2018

To perform efficient and safe haulage operations in mines, the condition of unsurfaced roads where dump trucks are moving should be regularly investigated, and systematic maintenance should be carried out according to the results. In this study, we developed a smartphone application that can be used to periodically investigate the unsurfaced road conditions in mines. Using the developed application, necessary data can be easily collected on site to evaluate the condition of unsurfaced roads according to the Unsurfaced Road Condition Index (URCI) evaluation system presented by the US Army Corps of Engineers. The smartphone application was tested at several sections of unsurfaced road in the Ilkwang mine, Busan, Korea. The results showed that the field investigation about 7 factors considered in the URCI evaluation system can be conducted through the user interface screen, and the URCI value can be calculated in the field to evaluate the condition of unsurfaced road. The smartphone application developed in this study can be useful for surveying and evaluating the unsurfaced road conditions at the mine site.

• Geomechanics and Engineering
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• v.17 no.4
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• pp.375-383
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• 2019

In underground retreating longwall coal mining, hard roof collapse is one of the most challenging safety problems for mined-out areas. Identifying precursors for hard roof collapse is of great importance for the development of warning systems related to collapse geohazards and ground control. In this case study, the Xinhe mine was chosen because it is a standard mine and the minable coal seam usually lies beneath hard strata. Real-time monitoring of hard roof collapse was performed in longwall face 5301 of the Xinhe mine using support resistance and microseismic (MS) monitoring; five hard roof collapse cases were identified. To reveal the characteristics of MS activity during hard roof collapse development and to identify its precursors, the change in MS parameters, such as MS event rate, energy release, bursting strain energy, b value and the relationships with hard roof collapse, were studied. This research indicates that some MS parameters showed irregularity before hard roof collapse. For the Xinhe coalmine, a substantial decrease in b value and a rapid increase in MS event rate were reliable hard roof collapse precursors. It is suggested that the b value has the highest predictive sensitivity, and the MS event rate has the second highest.