• Tunnel and Underground Space
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• v.20 no.5
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• pp.360-368
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• 2010

The paper presents a case study from a surface mine where the controlled augmentation of throw and drop of the blasted muck piles was warranted to spread the muck piles on the lower berm of the bench. While the augmentation of throw increased the lateral spread and the looseness of the broken muck, the augmentation of drop significantly lowered the muck pile height for easy excavation by the excavators. In this light, the present paper highlights and discusses some pertinent changes in the blast design parameters for such specialized application of cast blasting in a surface mine, where a sandstone bench, with average height of 22-24 m was to be made amenable for excavation by 10 m3 rope shovels, which possessed maximum digging capability of up to 14 m. The results of tailoring the blast design parameters for augmentation of throw and drop are compared with the baseline blasts which were earlier practiced on the same bench by dividing the full height of the bench in 2-slices; upper slice (10-14 m high) and lower slice (12-15 m high). Results of fragment size, its distribution and total cycle time of excavator (shovel) are presented, and discussed.

• Tunnel and Underground Space
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• v.26 no.2
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• pp.131-142
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• 2016

Investigation for rock joints, inspection for rock core, and laboratory tests for rock specimens, in this study, have been performed for identification of the extent and properties of Excavation Damaged Zone in a underground limestone mine, which plans to enlarge the size of openings to improve the production rate. Properties of EDZ and surrounding rock masses have been used numerically for discontinuum analysis, and it is concluded that the effect of EDZ can be increased with increasing the opening size and a blasting pattern of high precision can be suggested for the counterplan.

• Geomechanics and Engineering
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• v.34 no.5
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• pp.547-559
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• 2023

We evaluated the applicability of machine learning techniques and the Kuz-Ram model for predicting the mean fragmentation size in open-pit mines. The characteristics of the in-situ rock considered here were uniaxial compressive strength, tensile strength, rock factor, and mean in-situ block size. Seventy field datasets that included these characteristics were collected to predict the mean fragmentation size. Deep neural network, support vector machine, and extreme gradient boosting (XGBoost) models were trained using the data. The performance was evaluated using the root mean squared error (RMSE) and the coefficient of determination (r²). The XGBoost model had the smallest RMSE and the highest r² value compared with the other models. Additionally, when analyzing the error rate between the measured and predicted values, XGBoost had the lowest error rate. When the Kuz-Ram model was applied, low accuracy was observed owing to the differences in the characteristics of data used for model development. Consequently, the proposed XGBoost model predicted the mean fragmentation size more accurately than other models. If its performance is improved by securing sufficient data in the future, it will be useful for improving the blasting efficiency at the target site.

• Explosives and Blasting
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• v.33 no.4
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• pp.1-6
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• 2015

Abstract This study is to efficiently calculate and evaluate the elements of advance, overbreak and underbreak on the mine under the production using the 3D laser scanner. For this purpose, a 3D laser scanner was sued to acquire the point-cloud which records the space coordinates and modelling of the underground tunnel using the 3D modeling program. When each element was observed through the study result, the advance on the center cut was 2.6m in average while the total advance was 2.4m. If the drilling length of 3.8m is based, the advance rate was evaluated to be 67% in average in the center cut section with the total average of 64%. In addition, when the volume of overbreak was measured based on the design cross section, the average overbreak volume was found to be $4.5m^3$ on left wall, $4.5m^3$ on right wall, and $5m^3$ on roof with the total volume of $14m^3$. When the overbreak volume is measured based on the look-out cross section, it was $3m^3$ on roof with the total volume of $8.4m^3$. The rate of overbreak volume against the average excavation volume was 8% based on the design cross section and 5% based on the look-out cross section.

• KSBB Journal
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• v.25 no.5
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• pp.490-496
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• 2010

As sequencing technologies are steadily improving, massive sequence data have been accumulated in public databases. Thereby, programs based on various algorithms are developed to mine useful information, such as genes, operons and regulatory factors,from these sequences. However, despite its usefulness in a wide range of applications, comprehensive analyses of metagenome using these programs have some drawbacks, thereby yielding inaccurate or complex results. We here provide a possibility of signature sequences (cis-acting transcriptional and translational factors of metagenome) as a hallmark of ORFs finding from metagenome.

• Tunnel and Underground Space
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• v.21 no.4
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• pp.320-327
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• 2011

In this study, for stemming effect in blast of the mortar block body, the crushed granite sand as fine aggregate, which is waste rock obtained at the ○○ limestone mine, was investigated to compare with stemming materials such as sea sand, river sand, clayed soil and water can be acquired easily at the field. The mortar block body was manufactured with the dimensions of 50 cm width, 50 cm length and 70 cm height. The direct shear and sieve separator test were performed, and the properties of friction resistance were analyzed by the extrusion test for five stemming materials. Axial strain of steel bar and ejection velocity of stemming materials due to the explosive shock pressure in blasthole with the stemming length of 10 cm and 20 cm in the mortar blast test were measured by the dynamic data acquisition system. Among stemming materials, axial strain showed the largest value at the crushed granite sand as fine aggregate, and the ejection velocity was the smallest value at the stemming of water. The results has shown correlate with harden unit weight in blasthole, particle size distribution, shear resistance, and extrusion strength of stemming materials. The ejection velocity of stemming material at the mouth of blasthole and the axial strain of steel bar in the inside of blasthole tend to be inversely proportional to each other, represent exponentially.