• The Journal of Engineering Geology
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• v.17 no.4
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• pp.555-566
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• 2007

In general, RMR classification system is used for the support design of a tunnel. Face mapping during excavation and RMR-based rock classifications are conducted in order to provide information for complementary changes to preliminary survey plans and for continuous geological estimations in direction of tunnel route. Although they are ever so important, there are not enough time for survey in general and sometimes even face mapping is not available. Linear regression analysis for the estimation of mediating RQD and condition of discontinuities, which require longer time and more detailed observation in RMR, was performed and optimum regression equations are suggest as the result. The geological data collected from tunnels were analyzed in accordance with three rock types as sedimentary rock, phyllite and granite to see geological effects, generally not been considered in previous researches. Parameters for the regression analysis were set another RMR factor.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.5
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• pp.505-522
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• 2013

Previously, a new concept of indexing methodology has been proposed for quantitative assessment of tunnel collapse hazard level at each tunnel face with respect to the given geological data, design condition and the corresponding construction activity (Shin et al, 2009a). In this paper, 'linear' model, in which weights of influence factors are invariable, and 'non-linear' model, in which weights of influence factors are variable, are taken into account with some examples. Then, the 'non-linear' model is validated by using 100 tunnel collapse cases. It appears that 'non-linear' model allows us to have adapted weight values of influence factors to characteristics of given tunnel site. In order to make a better understanding and help for an effective use of the system, a series of operating processes of the system are built up. Then, by following the processes, the system is applied to a real-life tunnel project in very weak and varying ground conditions. Through this approach, it would be quite apparent that the tunnel collapse hazard indices are determined by well interlinked consideration of face mapping data as well as design/construction data. The calculated indices seem to be in good agreement with available electric resistivity distribution and design/construction status. In addition, This approach could enhance effective usage of face mapping data and lead timely and well corresponding field reactions to situation of weak tunnel faces.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.4
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• pp.313-322
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• 2003

This research work presents 3-D behavior of adjacent structures due to tunnelling induced ground movements by means of field measuring data and nonlinear FEM tunnel analysis. The results of the analytical methods from Mohr-Coulomb model are compared with the site measurement data obtained during the twin tunnel construction. It was found that the location and stiffness of the structure influence greatly the shape and pattern of settlement trough. The settlement trough for Greenfield condition was different from the trough for existing adjacent structures. Therefore the load and stiffness of adjacent structures should be taken into account for the stability analysis of the structures.

• The Journal of Engineering Geology
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• v.15 no.4 s.42
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• pp.463-473
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• 2005

Because of using the same rating ranges for every rock types the RMR or the Q-system could not usually consider local geological characteristics They also could not present sufficiently the engineering anisotropy of rocks. The canonical correlation analysis was carried out with 3 kinds of face mapping data obtained from granite, sedimentary rock and phyllite in order to clarify a discrepancy between rock types. According to analysis results, as a type of rocks changes, RM factors have different influences on the total rating of RMR.

• Journal of the Korean Geotechnical Society
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• v.40 no.3
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• pp.101-108
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• 2024

A system with the ability to recognize potential key blocks during tunnel construction by analyzing the rock face was developed in this study. This system predicts the formation of key blocks in advance and evaluates their safety factors. A laser scanner was used to collect a three-dimensional point cloud of the rock face, which was then utilized to model the excavation surface and derive the joint surfaces. Because joint surfaces have specific strikes and dip angles, the key blocks formed by these surfaces are deduced through iterative calculations, and the safety factor of each key block can be calculated accordingly. The model experiments confirmed the accuracy of the system's output in terms of the joint surface characteristics. By inputting the joint surface information, the calculated safety factors were compared with those from the existing commercial software, demonstrating stable calculation results within a 1% error margin.

• Tunnel and Underground Space
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• v.11 no.4
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• pp.289-300
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• 2001

In the design of tunnel, it contains inaccuracy of data, fuzziness of evaluation, observer error and so on. The face observation during tunnel excavation, therefore, plays an important role to raise stability and to reduce supporting cost. This study is carried out to minimize the subjectiveness of observer and to exactly evaluate the natural properties of ground during the face observation. For these purpose, fuzzy set theory and neuro-fuzzy techniques in artificial intelligent techniques are applied to the inference of the RMR value from the observation data. The correlation between original RMR vague and inferred RM $R_{_FU}$ and RM $R_{_NF}$ values from fuzzy set theory and neuro-fuzzy techniques is investigated using 46 data. The results show that good correlation between original RMR value and infected RM $R_{_FU}$ and RM $R_{_NF}$ value is observed when the correlation coefficients are ｜R｜=0.96 and ｜R｜=0.95 respectively. From these results, applicability of fuzzy set theory and neuro-fuzzy techniques to rock mats classification is proved to be sufficiently high enough. enough.

• Tunnel and Underground Space
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• v.13 no.1
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• pp.6-19
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• 2003

This study has for its object to increase an objectivity of the observation result in the face mapping of tunnel and to suggest the reasonable support and reinforcement methods to be considered the rock properties. It was developed in this study to the tunnel stability evaluation system(Prototype NFEST) to be used fuzzy set theory and neuro-fuzzy techniques, and this system was verified according to the reliability evaluation between the 36 learning data and the inferred results. When it summarized the results; (1) 12 evaluation items and ranges were proposed to be modified basis on the RMR which are well known to the domestic workers. (2) It was shown that correlation coefficient(│R│) between $RMR_{inf}$ inferred by 12 items and $RMR_{org}$ due to arithmetic total, $RMR_{chk}$ due to subjective judgement of observer are relatively high relationship with each 0.83 and 0.79. (3) Inferred result of the total tunnel safety shows also a good relationship with $RMR_{inf}$ (│R│=0.7) and the rock weathering(│R│=0.84).

• Journal of the Korean GEO-environmental Society
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• v.11 no.2
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• pp.43-52
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• 2010

Shield method is the tunnel boring method that propels a steel cylinder in the ground and excavates tunnels at once. After Marc Isambard Brunel started using the method for the Thames Riverbed Tunnel excavation in London, many kinds of TBM (Tunnel Boring Machine) developed and applied for the construction of road, railway, electricity channel, pipeline, etc. In comparison with NATM concept that allows to observe ground condition and copes with difficulty. The machine selected before starting construction is not able to be changed during construction in shield TBM. Therefore the machine should be designed based on the ground survey result and experiment, so that the tunnel might be excavated effectively by controlling penetration speed, excavation depth and cutter head speed according to the ground condition change. This research was conducted to estimate penetration depth, excavate speed, wear of disc cutter on Boondang Railway of the Han Riverbed Tunnel ground condition by TBM performance prediction models such as NTNU, $Q_{TBM}$, Total Hardness, KICT-SNU and compare the estimated value with the field data. The estimation method is also used to analyze the reason of poor excavation efficiency at south bound tunnel.

• Tunnel and Underground Space
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• v.27 no.4
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• pp.185-194
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• 2017

This technical paper is a study on the unique displacements of Shotcrete Lining at the mined tunnel during excavation period through deep consideration with real time data from monitoring instrumentations correlation with the numerical analysis to identify the rock stresses and the rock spring points at the working face of the Conventional tunnelling by the Drill and Blast, based on the geological face mapping results of the project NS2, Transmission cable tunnel project in Singapore. The created geometry of numerical model was prepared to the real mined tunnel construction site including, vertical shaft, construction adit, tunnel junction area, and 2 enlargement caverns. The convergence measurements by the monitoring instrumentation were performed during the tunnel excavation and shaft sinking construction stages to guarantee the safety of complicated underground structures.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.369-375
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• 2020

The section of this study is the geological vulnerable zone where groundwater leakage occurred through the tunnel barrier during excavation of the shield tunnel boring machine(TBM) for the construction of the electric power unit. Therefore, a Three D imensions(3D) numerical analysis was performed to analyze the actual situation from before construction to the time when the change in groundwater level occurred, and to reflect the surrounding ground conditions based on the observed change in groundwater level during construction. As a result of the study, the correlation between groundwater level change and tunnel construction around the site was identified. Therefore, it was similar to the measurement result of groundwater level at the target ground. The amount of groundwater discharge to the entrance of the tunnel construction was also similar to the actual measured result, and the numerical analysis method and modeling in this study were analyzed to reflect the site conditions.