Abstract
This study describes a precise numerical analysis process by adopting the real image of mine openings obtained by light detection and ranging (LiDAR), which can produce a point cloud data by measuring the target surface numerically. The analysis target was a section of an underground limestone mine, to which a hybrid room-and-pillar mining method that was developed to improve ore recovery was applied. It is important that the center axis and the volume of the vertical safety pillar in the lower parts match those in the upper parts. The 3D survey of the target section verified that the center axis of the vertical safety pillar in the lower parts had deviated in a north-westerly direction. In particular, the area of the lower part of the vertical safety pillar was approximately 34 m2 lower than the designed cross-sectional area, which was 100 m2. In order to analyze the stability of the vertical safety pillar, a discontinuum numerical analysis and safety factor analysis were conducted using 3D surveying results. The analysis verified that instability was caused by the joints distributed around the vertical safety pillar. In conclusion, investigation of the 3D survey and 3D numerical analysis techniques performed in this study are expected to provide higher reliability than the current techniques used for establishing whether mining plans require new mining methods or safety measures.
Highlights
The sustainable development of mineral resources globally has become an important focus area of contemporary research
The results of the analysis verified that over-break and under-break areas were present locally in the vertical safety pillar formed in the stope
The stress concentration phenomenon was investigated in each direction, and the results showed that the tensile stress at a level of 1.0 MPa seemed concentrated locally in the northerly, southerly, and easterly directions of the pillar
Summary
The sustainable development of mineral resources globally has become an important focus area of contemporary research. Stability evaluation methods that may be utilized include safety management of mines, rock mass classification, safety factor analysis using empirical methods, surveying methods utilizing sensors, and numerical analysis. With the recent advancement in optical technologies, three-dimensional (3D) surveying techniques, such as 3D laser scanning and stereo photogrammetry methods, have been introduced to the mining industry and utilized actively in studies on stability evaluation. In the rock engineering field, LiDAR has been employed for studies on the evaluation of joint roughness [1,2,3,4], trace sSausmtaipnalbiniligty o20f1j9o, 1in1,txsF[O5R–7P]E,EaRnRaElVyIsEiWs of joint orientation [8], analysis of slope stability [9,102],oafn2a0lysis of rockfall and toppling [11,12], analysis of blasting over-break [13,14], and geometry research of underegnrgoiunenedrimngi,nceosn[s1tr5u]c.
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