• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.6
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• pp.667-681
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• 2012

In general, risk management consists of a series of processes or steps including risk identification, risk analysis, risk evaluation, risk mitigation measures, and risk re-evaluation. In this paper, potential risk factors that occur in shield TBM tunnels were investigated based on many previous case studies and questionaries to tunnel experts. The risk factors were classified as geological, design or construction management features. Fault Tree was set up by dividing all feasible risks into four groups that associated with: cutter; machine confinement; mucking (driving) and segments. From the Fault Tree Analysis (FTA), 12 risk items were identified and the probability of failure of each chosen risk item was obtained.

• Tunnel and Underground Space
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• v.29 no.5
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• pp.356-366
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• 2019

Various TBM performance prediction models have been developed and most of them were considered penetration rate only. Despite the fact that some models have suggested equations and charts for estimating the utilization factor, but there are a few studies to estimate the TBM utilization factor. Utilization factor is affected by the type of TBM machine, operation, maintenance of machine, geological conditions, contractor experience and other factors. In this study, more than 100 case studies are analyzed to determine the relationship between the utilization factor and RMR, geological conditions, TBM types, tunnel length, and TBM diameter. Simple and multiple linear regression analysis are performed to develop predictive models for the utilization factor. The predictive model with explanatory variables of geological conditions, TBM types, tunnel length, and TBM diameter does not give a good correlation. The predictive models with explanatory variable of RMR give higher values of the coefficient of determination.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.385-392
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• 2021

When ordering a slurry shield TBM to be used for power cable tunneling, the client organizes an evaluation committee composed of experts, suggest the criteria and evaluation method for technical specifications for supplier selection, and based on the manufacturer's technical proposal were attempted to evaluate and select. It is expected to be referred to as a guideline for future projects to using Shield TBM as one of the methods of verifying performance and quality in advance and securing economic feasibility in the shield TBM tunneling in the recent increasing trend.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.4
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• pp.611-634
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• 2017

In rapid urbanization, demand for utility tunnel increases more, and tunnel boring machine (TBM) has been used widely. Prediction of TBM penetration rate is important for proper estimation of construction period and cost. Although there are several methods, such as NTNU model and CSM model that require many input parameters, fundamental understanding on correlations between rock properties and TBM penetration rate is critical. In this study, we explored the brittleness indices of hard rocks according to various definitions, and the correlations between the brittleness indices and the TBM penentration rates.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.6
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• pp.403-421
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• 2023

As the number of underground structures has increased in recent decades, it has become crucial to predict geological hazards ahead of a tunnel face during tunnel construction. Consequently, this study developed a finite element (FE) numerical model to simulate electrical resistivity surveys in tunnel boring machine (TBM) operations for predicting mixed ground conditions in front of tunnel faces. The accuracy of the developed model was verified by comparing the numerical results not only with an analytical solution but also with experimental results. Using the developed model, a series of parametric studies were carried out to estimate the effect of geological conditions and sensor geometric configurations on electrical resistivity measurements. The results of these studies showed that both the interface slope and the difference in electrical resistivity between two different ground formations affect the patterns and variations in electrical resistivity observed during TBM excavation. Furthermore, it was revealed that selecting appropriate sensor spacing and optimizing the location of the electrode array were essential for enhancing the efficiency and accuracy of predictions related to mixed ground conditions. In conclusion, the developed model can serve as a powerful and reliable tool for predicting mixed ground conditions during TBM tunneling.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1023-1037
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• 2018

The interest in the use of shield TBM (Tunnel Boring Machine) on the tunnel excavation has been increased rapidly in Korea. The shield TBM tunnel is generally designed as non-drainage tunnel. Consequently, if water leakage through the segment joints happens, big problems on the usage and stability of tunnel can be occurred. In this study, the variation of waterproof capacity of hydrophilic rubber waterstop and gasket, respectively by the construction error and excessive displacement of segment was studied. The test results show that hydrophilic rubber waterstop has favorable on the offset, however unfavorable on the gap. On the other hand, gasket has unfavorable on the offset, however favorable on the gap.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1D
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• pp.71-77
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• 2010

This study presented the operation method through of productivity on eight analysis work items (TBM boring, cutter check and exchange, TBM maintenance, succeeding facilities, reinforcement in tunnel, operation alternation, a tram car) which have developed equipment at WRITH with TBM a waterway tunnel works. It was inquired lose time with analyzed result by work items and removed lose time. It was analyzed TBM boring length, TBM boring length percentage and TBM boring length time. This study analyzed TBM operation utility factor of a foreign work with TBM operation boring length percentage, a monthly average boring length, pure boring length percentage etc. and assumed a monthly average boring length and a monthly average boring length of rise forecast. Based on analyzed Data, TBM boring has been forecasted propriety pure boring length at compressive strength $675{\sim}1662kgf/cm^2$.

• Tunnel and Underground Space
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• v.27 no.5
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• pp.271-281
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• 2017

Generally, TBM specifications have been empirically designed by the know-hows of its manufacturers. Since they govern the excavation performance and the cost of TBMs, it is very crucial to reliably determine them in the design stage of TBMs. In this study, a database consisting of TBM data collected from a various kinds of TBM tunnel projects was built to propose the statistical correlations for estimating TBM main specifications. From the statistical analyses, TBM outer diameters are found to have a strong effect on the TBM specifications such as thrust, torque and cutterhead driving power, which are much more important than TBM types and ground conditions.

• Tunnel and Underground Space
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• v.10 no.4
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• pp.526-532
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• 2000

The uniaxial compressive strength of rock mass is known as the major factor in the assessment of drillability and the optimum excavation design in full-face tunnel excavation by TBM. Referring to worldwide cases, TBM has been applied mostly to the rock mass within the strength range of 80~250 MPa. Recently, a water way tunnel has been constructed as a part of Milyang dam project by TBM within the rock masses where the rock type is mainly granite with some granophyre, hornfels and andesite. Their uniaxial compressive strengths in extended area are estimated higher than 260 MPa. In this paper, the relation between the penetration rate and the rock mass properties is analyzed and TBM application to the very hard rocks is discussed. As a result that three suggestions to predict the TBM net penetration rate are analyzed, NTH method seems a better approach than other methods in the extremely hard rocks. NTH prediction matches with the results of actual values with the variations of 2~20%. Hardness measurement by Schmidt hammer and RMR estimation are carried out along the L = 5.3 km entire TBM tunnel alignment. The net penetration rate measured monthly is shown to be reciprocally proportional to Schmidt rebound hardness and RMR where coefficients of correlation, $R^2$are 0.705 and 0.777 respectively. As a result, they are good quantitative indices for the prediction of TBM net penetration rate in the extremely hard rocks. Magnitude of in-situ stress has a certain effect on TBM performance, and it is required to measure the in-situ stresses in TBM excavation design.

• Geotechnical Engineering
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• v.38 no.6
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• pp.30-55
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• 2022