• Title/Summary/Keyword: 암반특성 예측

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Prediction of ground-condition ahead of tunnel face using electromagnetic wave - analytical study (전자기파를 이용한 터널전방 예측 -해석기법 중심으로)

  • Choi, Jun-Su;Cho, Gye-Chun;Lee, Geun-Ha;Yoon, Ji-Nam
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.6 no.4
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    • pp.327-343
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    • 2004
  • During tunnel construction, ground failures often occur due to existence of weak zones, such as faults, joints, and cavities, ahead of tunnel face. It is hard to detect effectively weak zones, which can lead underground structure to fail after excavation and before supporting, by using conventional characterization methods. In this study, an enhanced analytical method of predicting weak zones ahead of tunnel face is developed to overcome some problems in the conventional geophysical exploration methods. The analytical method is based on Coulomb's and Gauss' laws with considering the characteristics of electric fields subjected to rock mass. Using the developed method, closed form solutions are obtained to detect a spherical shaped zone and an oriented fault ahead of tunnel face respectively. The analytical results suggest that the presence of weak zones and their sizes, location, and states can be accurately predicted by combining a proper inversion process with resistance measured from several electrodes on the tunnel face. It appears that the skin depth or resistivity in rock mass is affected by the diameter of tunnel face, natural electric potential and noises induced by experimental measurement and spatial distribution of uncertain properties. The developed analytical solution is verified through experimental tests. About 1800 concrete blocks of 5cm by 5cm by 5cm in size are prepared and used to model a joint rock mass around tunnel face. Weak zones are simulated ahead of tunnel face with a material which has relatively higher conductivity than concrete blocks. Experimental results on the model test show a good agreement with analytical results.

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Prediction of Geological Condition Ahead of Tunnel Face Using Hydraulic Drilling Data (유압 천공데이터를 이용한 터널 굴진면 전방 지질상태 예측)

  • Kim, Kwang-Yeom;Kim, Chang-Yong;Kim, Kwang-Sik;Yim, Sung-Bin;Seo, Kyoung-Won
    • The Journal of Engineering Geology
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    • v.19 no.4
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    • pp.483-492
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    • 2009
  • During construction of a tunnel and underground structure, it is very important to acquire accurate information of the rock mass will be excavated. In this study, the drill monitoring method was applied for rapid prediction of geological condition ahead of the tunnel face. Mechanical data(speed, torque and feed pressure) from drilling process using a hydraulic drilling machine were analyzed to assess rock mass characteristics. Rock mass information acquired during excavation from drilling monitoring were compared with results from horizontal boring and tunnel seismic profiling(TSP). As the result, the drilling monitoring method is useful to assess rock mass condition such as geological structures and physical properties ahead of the tunnel face.

Characteristics of Natural and Experimental Fracture Propagation in Rocks (암석 내의 자연균열과 인공균열의 진행특성)

  • 백환조
    • The Journal of Engineering Geology
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    • v.7 no.1
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    • pp.53-62
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    • 1997
  • Fracture mechanics properties of rock materials can he applied to predict the distribution of natural fractures in rock masses, and also to assess the safety of rock slopes and underground structures. In this study, rock fracture toughness and other fracture rrechanics properties of sorne lithologies showing apparently rock-property-controlled distribution of natural fractures were measured. Propagation behaviors of natural and experirnental fractures were also characterized both qualitatively and quantitatively, in terns of the propagation types and sorne statistical parameters. It was concluded that the application of fracture mechanics theories to the ge6logic materials should be based on the geological background and evidences.

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Analysis on the tunnel behavior characteristic in the excessive fractured zone distribution of rock area (파쇄대가 과대분포한 암반지역에서 터널의 거동특성에 관한 연구)

  • Park, Jae-Weon;Lee, Seung-Ho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.4
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    • pp.341-354
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    • 2016
  • This article is to apply the tunnel support system selected after comparatively analyzing of RMR and tunnel instrumentation between the tunnel behavior characteristic predicted through geotechnical investigations and the numerical analysis at the design stage and the properties deformation occurred at the construction stage. This attempt results from the behavior characteristic of the tunnel excavation ground shown differently in accordance with the ground quality and reinforcement method. This, therefore, provide the data and results analysed the actual decision RMR-crown settlement & convergence and reduction of material property of ground as parameters. Also, it's shown that the tunnel designer is able to predict tunnel behavior characteristic when designing in bedrock areas excessively distributed faults and fractured zones.

공주지역 퇴적암의 풍화특성에 관한 연구

  • 신방웅;최기봉;이봉직;배우석
    • Proceedings of the Korean Institute of Industrial Safety Conference
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    • 1998.11a
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    • pp.303-308
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    • 1998
  • 암반을 대상으로 하는 건설공사는 많은 시간과 비용, 설계, 시공, 안전상에 많은 문제점을 일으키고 있다. 이러한 암반들은 흡수, 풍화 등에 기인하여 안정성이 약화되어 낙석, 산사태, 붕괴 등의 위험을 안고 있으며 이러한 현상은 우기, 해빙기에 두드러지게 나타나고 있다 비균질, 비등방성의 역학적 성질을 지닌 암석은 변형 거동을 완벽하게 예측하지는 못하고 있는 실정으로 이러한 거동은 암석의 종류와 구성 광물, 내부 불연속면의 상태, 응력 조건과 온도, 습도의 함수비등과 같은 다양한 요소에 의해 영향을 받으며, 이러한 경향은 퇴적암의 경우 두드러지게 나타나고 있다. (중략)

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Assessment of Hydraulic Drilling Data on Homogeneous Rock Mass (균질암반에서의 유압식 천공데이터 평가)

  • Kim, Kwang-Yeom;Kim, Chang-Yong;Kim, Kwang-Sik
    • Tunnel and Underground Space
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    • v.18 no.6
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    • pp.480-490
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    • 2008
  • The drilling monitoring is a technique to assess rock mass properties by analyzing the mechanical quantities measured by drilling process. Since drilling survey can be conducted on real-time-basis for excavating blast holes or rockbolt holes, it may enables fast and quantitative prediction and evaluation of rock mass. Though a number of studies have been conducted on the drilling data, the selection of drilling parameters and numerical quantification of mechanical quantities or rock mass have not been well established yet. In this study, drilling tests were conducted with homogeneous rock specimen to identify drilling parameters and the relation of the drilling data. As a result, it is verified that above all drilling parameters, the percussion was the most important factor on the excavatability of hydraulic drilling.

A Proposal of Systematic Hydro-Environmental Impact Assessment of Tunnel Construction in Fractured Rock Masses (균열 암반 내 터널 설계 시 체계적인 지하수 환경 영향 평가 시스템 제안)

  • Kim Hyoung-Soo;Yoon Woon-Sang
    • Tunnel and Underground Space
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    • v.16 no.3 s.62
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    • pp.195-202
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    • 2006
  • Hydro-environmental impact assessments (HEIA) in tunnel constructions have been performed through various methods including preliminary investigations, field tests, numerical simulations, and monitoring. Specially, it is very important to evaluate quantitatively groundwater inflows into tunnels as well as drawdowns caused by tunnelling. Obvious definitions between porous and fractured rock media in hvdrogeologic properties of study regions must be needed to execute HEIA for rational tunnel construction in fractured bedrocks. In this paper, we propose a HEIA on tunnel constructions in fractured rocks media resulted from various hydrogeologic field tests and numerical models on given regions and determination of systematic order, i.e. the technical road map (TRM) of HEIA. These systematic HEIAs are expected to be usefully applied to base data in tunnel construction in fractured rock media.

Propagation Characteristics of Ground Vibration Caused by Blast Hole Explosion of High Explosives in Limestone (고위력 폭약의 석회암 내 장약공 폭발에 의한 지반진동 전파특성에 관한 연구)

  • Gyeong-Gyu Kim;Chan-Hwi Shin;Han-Lim Kim;Ju-Suk Yang;Sang-Ho Bae;Kyung-Jae Yun;Sang-Ho Cho
    • Explosives and Blasting
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    • v.41 no.4
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    • pp.17-28
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    • 2023
  • Recently, the utilization of underground space for research facilities and resource development has been on the rise, expanding development from shallow to deep underground. The establishment of deep underground spaces necessitates a thorough examination of rock stability under conditions of elevated stress and temperature. In instances of greater depth, the stability is influenced not only by the geological structure and discontinuity of rock but also by the propagation of ground vibrations resulting from earthquakes and rock blasting during excavation, causing stress changes in the underground cavity and impacting rock stability. In terms of blasting engineering, empirical regression models and numerical analysis methods are used to predict ground vibration through statistical regression analysis based on measured data. In this study, single-hole blasting was conducted, and the pressure of the blast hole and observation hole and ground vibration were measured. Based on the experimental results, the blast pressure blasting vibration at a distance, and the response characteristics of the tunnel floor, side walls, and ceiling were analyzed.

Effects of Hydrological Condition on the Coupled Thermal-Hydrological-Mechanical Behavior of Rock Mass Surrounding Cavern Thermal Energy Storage (암반 공동 열에너지저장소 주변 암반의 수리적 조건에 따른 열-수리-역학적 연계거동 분석)

  • Park, Jung-Wook;Rutqvist, Jonny;Lee, Hang Bok;Ryu, Dongwoo;Synn, Joong-Ho;Park, Eui-Seob
    • Tunnel and Underground Space
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    • v.25 no.2
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    • pp.168-185
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    • 2015
  • The thermal-hydrological-mechanical (T-H-M) behavior of rock mass surrounding a large-scale high-temperature cavern thermal energy storage (CTES) at a shallow depth has been investigated, and the effects of hydrological conditions such as water table and rock permeability on the behavior have been examined. The liquid saturation of ground water around a storage cavern may have a small impact on the overall heat transfer and mechanical behavior of surrounding rock mass for a relatively low rock permeability of $10^{-17}m^2$. In terms of the distributions of temperature, stress and displacement of the surrounding rock mass, the results expected from the simulation with the cavern below the water table were almost identical to that obtained from the simulation with the cavern in the unsaturated zone. The heat transfer in the rock mass with reasonable permeability ${\leq}10^{-15}m^2$ was dominated by the conduction. In the simulation with rock permeability of $10^{-12}m^2$, however, the convective heat transfer by ground-water was dominant, accompanying the upward heat flow to near-ground surface. The temperature and pressure around a storage cavern showed different distributions according to the rock permeability, as a result of the complex coupled processes such as the heat transfer by multi-phase flow and the evaporation of ground-water.

Investigations on the Failure Modes of Rock Slopes in Gyeongsangnam-do (경상남도에서 발생한 암반사면의 파괴유형 연구)

  • Park, Choon-Sik;Ha, Jung-Chul
    • Tunnel and Underground Space
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    • v.28 no.6
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    • pp.569-583
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    • 2018
  • The purpose of this study is to identify the collapse characteristics by analyzing various factors causing collapse based on field survey and existing data on rock slopes occurring in the construction of roads and industrial complexes in Gyeongsangnam - do area. In the case of the slope where the slope has been directly surveyed, the analysis of the collapse characteristics can be used for the prediction and prevention of slope failure through the continuous collection of the slope data, database construction, management and analysis. The evaluation items used in the collapse characteristics of slope were selected among the items that can be regarded as objective evaluation items among the overlapping factors by comparing the evaluation items frequently used for the evaluation of the existing slope stability among various factors. The type of destruction of the rock slope depends on the type of carcass of the bedrock, such as planar fracture, wedge fracture, onho fracture, and conduction fracture, which are different from each other. And the slope stability analysis should be performed accordingly.