• Proceedings of the Korean Geotechical Society Conference
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• 1994.09a
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• pp.231-234
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• 1994

Concentrated stresses due to the tunnel excavation easily cause failure around opening in the soft rock mass layer. Thus, while excavatng tunnel in the soft rock mass layerm it is very important to predict the possibility of failure or yielding zones around tunnel boundary. There are two typical methods to predict these; 1) the analysis of field monioring data and 2) numerical analysis. In this study, it was attempted to describe the time-dependent or progressive rock mass manner due to the continuous failure and fracturing caused by surrounding underground openings using the second method. In order to apply the effects of progressive failure underground, an iterative technique was used with the Hoek and Brown rock mass failure theory. By developing and simulating, three different shapes of twin tunnels, this research simulated and estimated the proper size of critical pillar width between tunnels, distributed stresses on the tunnel sides, and convergences of tunnel crowns. Moreover, results out progressive failure technique based on the Hoek and Brown theory were compared with the results out of Mohr-Coulomb theory.

• Tunnel and Underground Space
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• v.3 no.2
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• pp.132-141
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• 1993

Laboratory and field tests were performed to find out the effectiveness of ground improvement by grouting for an urban subway tunnel that was excavated in weak rock by the NATM. Field measurements were carried out to monitor the behavior of rock mass around the tunnel and to ensure the validity of the current design of the distance form the measuring points to the tunnel face. The final converged displacement and the peroid were predicted using the gamma function. It was found that the ground improvement in terms of reduced permeability and increased stength in the self-supportability of the excavation face enabled the NATM applied in poor gorund. As the result of applying the gamma function to the predicting of displacement, the final displacement including the preceding one and the converged period could be approximately predicted at the early excavation stage.

• Tunnel and Underground Space
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• v.10 no.2
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• pp.249-256
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• 2000

According to the industrial restructuring in the late 1980's, most domestic mines have been shutdown or suspended in operation. The closed underground excavation caverns remain in their abandoned conditions, and they will potentially cause environmental hazards. To evaluate the feasibility of the utilization of the abandoned caverns, the foreign crises were studied. As a result, we proposed several possible examples including underground storage cavern fur food products, underground compressed air energy system(CAES), and underground repository (or incineration plant) of industrial wastes. Among them, the underground waste repositories are most probable to be seen in Korea in the near future. For this, the study in rock engineering aspects should be conducted, which will include the establishment of support system and safety measure of the abandoned underground excavation caverns.

• Explosives and Blasting
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• v.24 no.1
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• pp.1-8
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• 2006

Recently, most of limestone quarries have been not mined by open-pit mining but by underground excavation to reduce environmental pollution. As a result, the size of underground galleries became bigger to maintain mass-production close to open-pit mining. However, the scale of pillars and galleries as well as the excavation methods may induce a few adverse problems for the stability of a mined gallery. In this study, the nomogram analysis and the prediction of rock damage zone induced by blasting were carried out. The testing conditions include concurrent blasting of two adjacent galleries, concurrent blasting of a transport drift and a inclined shaft, sequential blasting of two galleries, and separate blasting for each gallery. For each testing condition, blast vibration velocity was measured and analyzed. From the prediction formulas for blast vibration velocity derived in this study, the maximum depth of rock damage zone induced by blasting were also predicted.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.222-229
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• 2022

Although stochastic programming and feedback control approaches could efficiently mitigate the overdue risks caused by inherent uncertainties in ground conditions, the lack of formal representations of planners' rationales for resource allocation still prevents planners from applying these approaches due to the inability to consider comprehensive resource allocation policies for hard rock tunnel projects. To overcome the limitations, the authors developed an ontology that represents the project duration estimation rationales, considering the impacts of ground conditions, excavation methods, project states, resources (i.e., given equipment fleet), and resource allocation policies (RAPs). This ontology consists of 5 main classes with 22 subclasses. It enables planners to explicitly and comprehensively represent the necessary information to rapidly and consistently estimate the excavation durations during construction. 10 rule sets (i.e., policies) are considered and categorized into two types: non-progress-related and progress-related policies. In order to provide simplified information about the remaining durations of phases for progress-related policies, the ontology also represents encoding principles. The estimation of excavation schedules is carried out based on a hypothetical example considering two types of policies. The estimation results reveal the feasibility, potential for flexibility, and comprehensiveness of the developed ontology. Further research to improve the duration estimation methodology is warranted.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1500-1505
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• 2010

The objective of this study is controlling of the large diameter Shield TBM excavation for subway tunnels. In this paper, it will focus on the selection of Shield TBM and the problems of excavation due to unusual abrasion of the Disk Cutters and the distorted Cutter Mounts, in mixed layer of soil in below and hard rock in above, and in rock layer. And also, it will be discussed that the type of ground improvement to change and repair the Disk Cutters and the distorted Cutter Mounts, Advance Rate, Cutter Torque, etc. The results of this study will be using controlling of the excavation in various large diameter Shield TBM for subway tunnels.

• Tunnel and Underground Space
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• v.5 no.1
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• pp.48-56
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• 1995

Recently, most of the underground excavation works are adopting heavy duty mobile diesel equipments which have outstanding merits in view of efficiency. However, these equipments are causing hygienic problems to the workers due to the various hazardous exhaust contaminants. Considering that there are always dead end workings in underground excavation sites, it is very important how to supply enough airflow to the workings to dilute diesel exhaust contaminants. This paper introduced the theoritical mechanism and actual trends of exhaust contaminants of diesel equipments under operation at local mines and suggested the design method of intake air volume in underground excavation workings using diesel equipments.

• Journal of the Korean Society of Industry Convergence
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• v.8 no.3
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• pp.161-168
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• 2005

This study is analysis for adjacent structures and ground movement by deep excavation work. Underground Inclinometer has shown that deformation of increment is minor within to allowable limit. According to the measurements result of slope and crack for adjacent structures, a detached house showed bigger than hospital structure to deformation of increment. Variation of underground water level didn't effect so much to ground and adjacent structures movement because underground water flows in rock and didn't give the water press to propped walls. Measurement data of strut variation is within tolerance limit. Because excavation site's wall was strengthened suitably. This study will contribute in establishment of measurement standard and information-oriented construction during deep excavation in multi-layered ground including rock masses.

• Geomechanics and Engineering
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• v.15 no.2
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• pp.805-810
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• 2018

The abrasivity of rocks results in tool wear in rock excavation or drilling projects. It can affect significantly the cost and schedule of the projects performed in abrasive rock massess. For this reason, the understanding of the mechanism of rock abrasivity is very important for excavation projects. This study investigates the effect of strength on the LCPC abrasivity coefficient (LAC) for igneous rocks. The LCPT test, the uniaxial compressive strength (UCS) and the Brazilian tensile strength (BTS) tests were carried out on the igneous rock samples. The abrasive mineral content (AMC) was also determined for each rock type. First, the LAC was correlated to the AMC and a very good correlation was found between the two parameters. Then, the multiple regression analysis was carried out by including the AMC, UCS and BTS to the analysis in order to infer the effect of the strength on the LAC. It was seen that the correlation coefficients of multiple regression models were greater than that of the relation between the LAC and the AMC. It is concluded that the AMC is the dominant parameter determining the abrasivity of rock. On the other hand, the rock strength has also significant effect on rock abrasivity.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.3
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• pp.265-274
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• 2010

In many tunnels, falling or sliding of rock blocks often occur, which cannot be predicted because of the complexity of rock discontinuities and it has brought an exponential increase in costs and time to manage. It is difficult to estimate the properties of rock masses before the tunnel excavation. The observational design and construction method in tunnels has been becoming important recently. In this study, a new hybrid stochastic-deterministic rock block analysis method for the prediction of the unstable rock blocks before the tunnel excavation is proposed, and then applied to the tunnel construction based on actual rock discontinuity information observed in the field. The comparisons and investigations with the analytical results in the tunnel construction have confirmed the validity and applicability of this new hybrid stochastic-deterministic rock block analysis method in tunnels.