• Title/Summary/Keyword: Rock Support

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3D Tunnel Face Modelling for Discontinuities Characterization: A Comparison of Lidar and Photogrammetry Methods (불연속성 특성화를 위한 3차원 터널 막장 모델링: 라이더 및 사진 측량 접근 방식의 비교 분석 중심으로)

  • Chuyen, Pham;Hyu-Soung, Shin
    • Tunnel and Underground Space
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    • v.32 no.6
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    • pp.549-557
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    • 2022
  • Tunnel face mapping involves the determination of rock discontinuities or weak rock conditions where extra support might be required. In this study, we investigated the application of Lidar scanning and photogrammetry to quantitatively characterize discontinuities of the rock mass on the tunnel face during excavation. The 3D models of tunnel faces generated by using these methods enable accurate and automatic discontinuity measurement to overcome the limitations of manual mapping. The results of this study show that both photogrammetry and Lidar can be used to reconstruct the 3D model of the tunnel face, although the photogrammetric 3D model is less detailed than its counterpart produced by Lidar. Given acceptable accuracy and cost-effectiveness, photogrammetry can be a fast, reliable, and low-cost alternative to Lidar for acquiring 3D models and determining rock discontinuities on tunnel faces.

A study on rock mass classification in the design of tunnel using multivariate discriminant analysis (다변량 판별분석을 통한 터널 설계시의 암반분류 연구)

  • Lee, Song;Ahn, Tae Hun;You, Oh Shick
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.6 no.3
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    • pp.237-245
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    • 2004
  • In designing a tunnel, RMR has been widely used to classify rock mass and to decide the support pattern according to the class of rock mass. However, this RMS system can't help relying on the empirical judgment of engineers who use variables which can be obtained only through consideration of the site conditions. In actuality, it is impossible to consider all the rating factors of RMS when using RMR system at the stage of designing. Therefore, in order to confirm possibility of RMR by use of only the quantitative factors for designing, this paper has done discriminant analysis. Rock strength or RQD has high coefficient of correlation with RMR value, and in consideration of the existing standards for rock mass classification, rock intensity and RQD are important factors for classification of rock mass. Through rock mass classification by the existing RMR system and rock mass classification by the discriminant analysis which has considered two variables only, the discriminant analysis using the rock intensity as an independent variable has shown 74.8% accuracy while the discriminant analysis using RQD as an independent variable has shown 74.3% accuracy. In case of the discriminant analysis which has considered both rock intensity and RQD, it has shown 82.5% accuracy. The existing cases have shown 40.3% accuracy at the stage of designing in which all the RMR factors are considered. It means that at the stage of designing, RMR system can work only with the rock intensity and RQD.

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A risk analysis for the determination of a tunnel support pattern (터널 지보패턴 결정을 위한 위험도 분석)

  • You, Kwang-Ho;Park, Yeon-Jun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.5 no.3
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    • pp.241-250
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    • 2003
  • Rock mass is very inhomogeneous in nature and data obtained by site investigations and tests are very limited. For this reason, many uncertainties are to be included in the process of constructing structures in rock mass. In the design of a tunnel, support pattern, advance rate, and excavation method, which are important design parameters, must be determined to be optimal. However, it is not easy to determine those parameters. Moreover if those parameters are determined incorrectly, unexpected risk occurs such as decrease in the stability of a tunnel or economic loss due to the excessive supports etc. In this study, how to determine an optimal support pattern and advance rate, which are the important tunnel design parameters, is introduced based on a risk analysis. It can be confirmed quantitatively that the more supported a tunnel is, the larger reliability index becomes and the more stable the tunnel becomes. Also an optimal support pattern and advance rate can be determined quantitatively by performing a risk analysis considering construction cost and the cost of loss which can be occurred due to the collapse of a tunnel.

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The Improving Reliable Transport and The Efficient Multicast Support in Mobile environment (이동 환경에서 효율적이고 신뢰적인 멀티캐스트 지원 방안)

  • 성수련;권순홍;신용태
    • Proceedings of the Korean Information Science Society Conference
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    • 2001.10c
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    • pp.307-309
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    • 2001
  • In this paper, we present a scheme for the improving reliable transport and the efficient multicast support in mobile environment. The proposed scheme solves a problem of TCP layer resulted from mobility by using a Representative FA. RFA has a mechanism like a snoop module which has a cache and can provide retransmission of a multicast packet lost and solve the rock implosion problem. Also, we present an additional IGMP message. By using it, We can remove a delay for IGMP query cycle and serve a multicast service more promptly.

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Assessment of rock slope stability by slope mass rating (SMR): A case study for the gas flare site in Assalouyeh, South of Iran

  • Azarafza, Mohammad;Akgun, Haluk;Asghari-Kaljahi, Ebrahim
    • Geomechanics and Engineering
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    • v.13 no.4
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    • pp.571-584
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    • 2017
  • Slope mass rating (SMR) is commonly used for the geomechanical classification of rock masses in an attempt to evaluate the stability of slopes. SMR is calculated from the $RMR_{89-basic}$ (basic rock mass rating) and from the characteristic features of discontinuities, and may be applied to slope stability analysis as well as to slope support recommendations. This study attempts to utilize the SMR classification system for slope stability analysis and to investigate the engineering geological conditions of the slopes and the slope stability analysis of the Gas Flare site in phases 6, 7 and 8 of the South Pars Gas Complex in Assalouyeh, south of Iran. After studying a total of twelve slopes, the results of the SMR classification system indicated that three slope failure modes, namely, wedge, plane and mass failure were possible along the slopes. In addition, the stability analyses conducted by a number of computer programs indicated that three of the slopes were stable, three of the slopes were unstable and the remaining six slopes were categorized as 'needs attention'classes.

Main challenges for deep subsea tunnels based on norwegian experience

  • Nilsen, Bjorn
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.5
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    • pp.563-573
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    • 2015
  • For hard rock subsea tunnels the most challenging rock mass conditions are in most cases represented by major faults/weakness zones. Poor stability weakness zones with large water inflow can be particularly problematic. At the pre-construction investigation stage, geological and engineering geological mapping, refraction seismic investigation and core drilling are the most important methods for identifying potentially adverse rock mass conditions. During excavation, continuous engineering geological mapping and probe drilling ahead of the face are carried out, and for the most recent Norwegian subsea tunnel projects, MWD (Measurement While Drilling) has also been used. During excavation, grouting ahead of the tunnel face is carried out whenever required according to the results from probe drilling. Sealing of water inflow by pre-grouting is particularly important before tunnelling into a section of poor rock mass quality. When excavating through weakness zones, a special methodology is normally applied, including spiling bolts, short blast round lengths and installation of reinforced sprayed concrete arches close to the face. The basic aspects of investigation, support and tunnelling for major weakness zones are discussed in this paper and illustrated by cases representing two very challenging projects which were recently completed (Atlantic Ocean tunnel and T-connection), one which is under construction (Ryfast) and one which is planned to be built in the near future (Rogfast).

A Study on Slope Reinforcement Method for Control of Rockfall and Small Scale Failure (낙석 및 소규모 붕괴 방지를 위한 사면보강방안에 관한 연구)

  • Lee, Seung-Ho;Hwang, Young-Cheol;Noh, Heung-Jae;Sim, Seok-Rae
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.796-805
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    • 2005
  • Most rockfall prevention net among the rockfall prevention equipment that is constructed in around the road is actuality lack of function by quantitative research insufficiency etc.. Most of rockfall prevention net are composed to setting needle, perpendicular and horizontal wire rope and wire net. Also, function of rockfall prevention net depend on setting needle and the wire net and perpendicular and horizontal wire rope are fixed by setting needle. when unreasonable load is offered setting needle, rockfall prevention net can lose the function and happen continuous falling off of rockfall prevention net. Because rockfall prevention net have a such structural defect, improvement had been required in reply. So in this paper, spot application of Rock Bolt & Net Connection method and falling rock support ability are estimated by numerical analysis. As a result, when Rock Bolt & Net Connection Method is applied to cutting slope, decreases of stress and displacement is examined than current rockfall prevention net.

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Rock Mass Classification by Surface-borehole Hybrid Array Seismic Refraction Tomography in the Region of Serious Electrical Noises (전기적 잡음이 심한 지역에서 지표-시추공 복합배열 탄성파탐사에 의한 암반등급 산정)

  • Kim Ye Ryun;Sha Sang Ho;Nam Soon Sung;Jo Cheol Hyun;Cha Young Ho;Park Jong Bum;Shin Kyung Jin
    • Proceedings of the KSR Conference
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    • 2005.05a
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    • pp.610-614
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    • 2005
  • Rock mass classification by using electrical resistivity tomography(ERT) method is widely performed for the determination of rock support type in tunnel design. In the region of high electrical noise level, however, the result of the ERT will have many erroneous features. In this study, the back ground electrical noise had been measured to find out the reason why the results of ERT in this area did not agree to the expected geology confirmed by boreholes. In order to overcome this limitation of ERT, a hybrid surface-borehole array seismic refraction tomography had been followed. Using this technique, we could get P-wave velocity section including the depth level of tunnel. The comparison of the P-wave velocity and RMR shows fairly good statistical relationship to make it possible to set up the rock mass classification for the entire tunnel line.

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New Surveying Methods for Rock Slopes (암반사면의 새로운 조사기법)

  • Hwang, Sang-Gi
    • Proceedings of the KSR Conference
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    • 2009.05a
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    • pp.1016-1019
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    • 2009
  • Detailed survey of the rock mass is essential for design, construction and maintenance of rock slope. However, geological survey of poor outcrops and various geophysical aids provides limited information for slope engineering. Remote measurement system for excavation surface (Surface Mapper) and projection s/w for borehole data (Fracjection) are developed for further support of slope surveying. The Surface Mapper measures orientation of joint, fault, foliation on excavated rock surface and database the measured data. The Fracjection projects measurements in boreholes, which are obtained by BIPS, Televideo and DOM operation, to any expected excavation space. These methods promise new approaches for surveying, designing, constructing and maintaining processes of slope.

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Deformation process and prediction of filling gangue: A case study in China

  • Wang, Changxiang;Lu, Yao;Li, Yangyang;Zhang, Buchu;Liang, Yanbo
    • Geomechanics and Engineering
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    • v.18 no.4
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    • pp.417-426
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    • 2019
  • Gangue filling in the goaf is an effective measure to control the surface subsidence. However, due to the obvious deformation of gangue compression, the filling effect deserves to be further studied. To this end, the deformation of coal gangue filling in the goaf is analyzed by theoretical analysis, large-scale crushed rock compression test, and field investigation. Through the compression test of crushed rock, the deformation behaviour characteristics and energy dissipation characteristics is obtained and analysed. The influencing factors of gangue filling and predicted amount of main deformation are summarized. Besides, the predicted equation and filling subsidence coefficients of gangue are obtained. The gangue filling effect was monitored by the movement observation of surface rock. Gangue filling can support the roof of the goaf, effectively control the surface subsidence with little influence on the ground villages. The premeter and equations of the main deformation in the gangue filling are verified, and the subsidence coefficient is further reduced by adding cemented material or fine sand. This paper provides a practical and theoretical reference for further development of gangue filling.