• Journal of the Korean Professional Engineers Association
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• v.14 no.3
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• pp.9-21
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• 1981

The rationalization for Tunnel Drifting is based on the high productivity which is achievable due to Continuous work with a Jumbo Drill, resulting in a much higher efficiency them the Conventional method of blasting, mucking and supporting services. Large projects of over 4,000m Tunnel Drifting are condidated to justify the use of a Jumbo Drill with a combination of superior explosives, machinery and techniques. During a Tunnel Drifting test, Gulita, Nabit and slurry made by Nitro Nobel were employed with following results. 1, Conditions: a. Granite Rock with Two free face b. Burden (W), 2m c. Diameter of hole, 42mm d. Depth of hole 3.5m e. Hole pitch 0.6m f. Charged Explosive per hole Gelatin Dynamite 4 pieces (112.5${\times}$4ea)+Guuita 5 pieces(110g${\times}$5ea) g. Simal-taneous Detonation h. After the blasting resultant rock size was Less 40% of the 0.3m Lumps. 2. Calculation results W=q/Wn=100cm‥‥‥Burden in simultaneous blasting 0.865kg(7.7ea)/hole ‥‥‥Amount of charge but hole pitch is 1.5W-2W The estimated cost of using a Jumbo Drill for the Construction of a 3,000,000 bbL sub-surface oil storage would be as follows: This calculation is based on the Jumbo Drill advancing 3.6m per blasting cycle. Unit cost/bbL Excavation $3.13 The attached sheet shows ideal Drilling pattern with Burn Cut & Smooth blasting method. In conclusion, it is my opinion that this method will assure safety and save cost and improve our technical know-how.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.445-456
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• 2005

The research concentrates on improving the in-hole seismic probe, which has been developed in past five years, to be used in stiffness measurements of tunnel-face materials. The probe was down-sized to be fit in 45-mm diameter holes(or BX) drilled by a jumbo-drill, which is used to drill holes to install explosives for tunneling. Also trigger system was improved by using a down-speeding motor for operating convenience and air packing system was replaced with a set of plate-springs to eliminate supply of compressed air. These modifications are to adjust the probe for the unfavourable environment inside of tunnels and to test without any further drilling cost. The probe and testing procedure were successfully adopted with horizontal holes drilled by a jumbo-drill at a tunnel-face to evaluate the stiffness of rock mass. The measured shear wave velocities can be used to estimate deformation properties of rock mass for tunnel analyses.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.10a
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• pp.171-176
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• 1997

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.4
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• pp.17-24
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• 2001

Four road tunnels of which the construction conditions were similar were selected in the paper, and laboratory tests and rockmass classification for the tunnels were carried out. And the analysis was performed to find out the correlation between ratio of bit abrasion or drilling parameter and support pattern of tunnel using jumbo drill machine. It was analyzed that there was average abrasion of bit from 11.85% to 3.25% per support patterns of tunnel in four tunnels. Drilling parameter happens to fluctuate according to extent of fracture zone.

• Journal of the Korean Professional Engineers Association
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• v.16 no.3
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• pp.5-23
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• 1983

On the Seoul Metropolitan Subway Construction of No. 3, 4 Line, the total length is 57 Km and it is now undergoing almost 55％ progress. The working method is classified into Open Cut of 70% and the rest of 30% tunnelling method in the 48 job site. Above tunnelling method is execute by American Steel Support System and the rest of 10 job site carried out by New Austria Tunnelling Method. This paper describes Blasting Standardizations works on the above Tunnelling ' Open Cut Method under big slogan, first safety, second execution. As a superintendent, I strived standardization of works with Better powder, Better Drills ' Better Pattern. Geological structure of Seoul area is composed by Jurassic Granite and also the above rockgroup are over burden by Alluviums as a Unconformity. First of all, I carried out the standard amount of powder and burden through experimental standard blasting by each powder as following Blasting works in the subway construction is surrounding shop Building, under pass the city river and also under pass highest building basement floor. I made allowable Blasting Vibration Value by West-Germany Vornorm DIN 4150, Teil 3 and should measure each blasting works as fellows all of powder is used basically Low-Gravity and Low Velocity such as Slurry, Ammonium Nitrate ' Finex I, II. for Smooth Blasting Instead of Gelatin Dynamite. Electric Detonation Cap is used basically M/S Delay Cup instead of Electric delay ' Simultaneous cap. I applied following formula V=KW3/4 $D^{-2}$ V=Particle Velocity (Cm/sec) K=Ginh Huh's Value W=Delay Charge (Kg) D=Distance(m) In the Open Cut, within 1m distance from H-pile I made to use the Concrete breaker, as following V=7W/$^{0.5}$V/$^{-1.75}$ On the Concentrate Building area, I advise to use Light class drill ø36m Bit and advance 1.1m per round blasting the three boom jumbo drill over ø45mm used only suburb of city.e Light class drill ø36m Bit and advance 1.1m per round blasting the three boom jumbo drill over ø45mm used only suburb of city.

• Explosives and Blasting
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• v.34 no.2
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• pp.10-17
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• 2016

Drilling operation for blasting is an important factor to determine blast effect. Drilling errors that arise from performing drilling for blasting purposes can reduce blasting effect causing residual holes, overbreak, and heterogeneous fragmentation, etc. Automatic drilling system was induced for precise drilling. As a result, drilling error caused by spaces between holes and burden was minor at 0~2.6% and accordingly, blasting effect was improved with over 90% drilling rate, the ratio of overbreak amount to total drilling amount at 4.3%, proportion of fragmentation rock under 50cm at 89~95% and so from this analyses, it was estimated to reduce the total cycle times related to blasting process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.739-744
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• 2013

The aim of this study is to evaluate the noise level from the machines used for tunnel construction and to analyze the noise exposure level of workers engaged in tunneling works. The sound level meter and noise dosimeters was used for the monitoring of noise in the tunneling work sites. The average noise from jumbo drill was 113.0 dE(A), the noise from pay loader was 92.4 dB(A), the noise from backhoe was 99.9 dB(A) and the noise from shotcrete machine was 94.3 dE(A). The tunneling workers were exposed to 66.9~94.9 dB(A) of noise and other workers exposed to less than 90 dB(A) of noise. Jumbo drill operators were exposed to to 82.5~84.2 dB(A) of noise, backhoe operators were exposed to 70.2~94.9 dB(A) of noise, shotcrete machine operators were exposed to 68.2~74.7 dB(A) of noise and pay loader operators were exposed to 59.2~81.3 dE(A) of noise.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.133-142
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• 2005

The research concentrates on improving the in-hole seismic probe, which has been developed in past five years, to be used in stiffness measurements of tunnel-face materials. The size of probe was reduced to be fit in 45-mm diameter holes (or BX) drilled by a jumbo-drill, which is used to drill holes to install explosives for tunneling. Also trigger system was improved by using a down-speeding motor for operating convenience and air packing system was replaced with a set of plate-springs to eliminate supply of compressed air. These modifications are to adjust the probe for the unfavourable environment inside of tunnels and to test without any further drilling cost. The probe and testing procedure were successfully adopted with horizontal holes drilled by a jumbo-drill at a tunnel-face to evaluate the stiffness of rock mass. The measured shear wave velocities can be used to estimate deformation properties of rock mass for tunnel analyses.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.6
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• pp.605-614
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• 2015

A room-and-pillar underground structure is characterized by its grid-type array of room and pillar. As a result, its construction and economical efficiency can be governed by excavation sequence. In this study, the construction period by the drill and blast method which can be treated as a main sequence for excavation was examined by considering the regulation for blasting and construction standard of estimation in Korea. To evaluate the construction period for the room-and-pillar underground structure constructed in 4 kinds of square-type area ($30{\times}30{\sim}57{\times}57m$), the concurrent excavation pattern which was suggested in the previous researches was used. From the suggested condition, the total construction period by drill-and-blast method can be estimated with the consideration of the construction area, number of jumbo drill and faces in operation.

• Journal of Industrial Technology
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• v.24 no.B
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• pp.3-17
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• 2004

Overbreak, underbreak and range of disturbed rock zone (DRZ) are the most important factors in evaluating the results of tunnel blasting. These factors, which depend on the discontinuities in rock mass, the blasting patterns and drilling conditions, have been studied. The range of DRZ can be estimated by relationships between vibration velocity and associated tensile stress. A new computerized rocket jumbo drill has been adopted to reduce overbreak based on the analysis of drilling accuracy. In-situ blasting tests were also performed by varying initiating systems. Overbreak can be reduce from 34.5cm to 20cm. The range of DRZ is 0.2m with stoping holes and 0.4m with wall holes respectively. In addition, some methods to reduce DRZ have been presented in this study.