• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.4
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• pp.25-32
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• 2010

High performance shotcrete has been recently researched partly as a result of high consensus on high strength and durability. However, they are very initial step compared from the advanced countries. For instance, they has been mainly on high strength or durability without any consideration on pumpability and shootability which are very crucial on workability. The purpose of this dissertation was to make a high performance wet-mix shotcrete (high workability) which would solve the general problems of wet-mix process in Korea. For this, the main experimental variables were selected to be silica fume(0.0, 4.5, 9%), air entrained agent(0.0, 0.005%). Rheology with IBB rheometer was measured for evaluating pumpability and shootability as well as pump pressure, rebound rate and build-up thickness. The conclusions from a series of experiments were as follow: The results of analyzing the effects of AE agent and silica fume on rheology indicated that AE agent reduced both of flow resistance(G) and torque viscosity(H) and silica fume increased flow resistance (G) and reduced torque viscosity(H). An increase in the value of torque viscosity(H) produces an increase in the requried pumping pressure. These result indicated that the reduction of torque would work better at improving pumpability. And an increase flow resistance(G) improved shootability(increase build-up thickness and reduce rebound).

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2007.03a
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• pp.29-40
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• 2007

• 한국도로학회:학술대회논문집
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• 2009.11a
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• pp.501-504
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• 2009

• Explosives and Blasting
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• v.9 no.2
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• pp.13-18
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• 1991

It was described Several Tuneling method for applying petrolum oil storage. The most Important factor of Tunneling is not only reinforcing works such as pre-grouting and after grouting but also rock bolting and shotcrete. The efficent works should be done by professional skillman, and also the classification of rock should be decided by professional engineers.

• Magazine of the Korea Concrete Institute
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• v.22 no.1
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• pp.36-39
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• 2010

• Magazine of the Korea Concrete Institute
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• v.27 no.5
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• pp.49-51
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• 2015

• Magazine of RCR
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• v.8 no.3
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• pp.36-40
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• 2013

• Magazine of RCR
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• v.17 no.3
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• pp.33-37
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• 2022

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.9
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• pp.841-849
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• 2013

Workers engaged in construction works have been exposed to high levels of noise during their work in tunnels. Noise is one of the major health hazards for employees working in construction sites. The aim of this study is to evaluate the noise levels generating from tunneling equipments such as jumbo drills, backhoes, payloaders, shotcrete machines and service cars. Explosion and turbo fan noises were also monitored. A high precision sound level meter was introduced for measuring LAeq, LAFmax, LAFmin and LCpeak noises in 5 tunneling work sites that were located in Seoul, Kyunggi-do and Kangwon-do areas with NATM and shield methods. The highest noise was recorded by explosion(151.9 dB LCpeak) followed by jumbo drills of higher than 110 dB(A) LAeq. Backhoe normally generated 90~110 dB(A) LAeq while breaking work of rock showed additional around 5~15 dB(A). Noise exposure levels for payloader and shotcrete machine scored more than 90 dB(A) which might be a source of noise-induced hearing loss. Additional research in revealing noise levels from construction equipments operating in tunneling works may enhance the protection of workers who exposed to noise primarily at the sites.

• Tunnel and Underground Space
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• v.14 no.2
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• pp.154-166
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• 2004

A numerical stability analysis was conducted on the large oil storage caverns excavated in a rock mass under high initial horizonal stress. The behaviors of the surrounding rock mass, rockbolts, and shotcrete were analyzedr and stability of the support members were assessed. For a proper support system design, the effect of the modelling technique, cavern shape and rockbolt length on the stability of the cavern was investigated. Results show that installation timing of supports and the change in cavern shape due to stepwise excavation affect the stress induced in support members. Also found was desperate need for a numerical technique which can properly reflect the behavior of the steel fiber reinforced shotcrete.