• Title/Summary/Keyword: 암반절리

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Effect of Joint on the Earth Pressure Against an Excavation Wall in Rockmass (암반지층 굴착벽체에 작용하는 토압에 대한 절리의 영향)

  • Son, Moorak;Adedokun, Solomon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.2
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    • pp.505-513
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    • 2014
  • This paper investigated the effect of joint on the earth pressure against an excavation wall in rockmass with the consideration of various rock and joint conditions. For this purpose, this study briefly reviewed of the previous earth pressure studies, and then numerical parametric studies were conducted based on the Discrete Element Method (DEM) to overcome the limitations of the previous studies. The numerical tests were carried out with the controlled parameters including rock types and joint conditions (joint shear strength, joint inclination angle, and joint set), and the magnitude and distribution characteristics of the induced earth pressure were investigated considering the interactions between the ground and the excavation wall. In addition, the earth pressures induced in rock stratum were compared with Peck's earth pressure for soil ground. The results showed that the earth pressure against an excavation wall in jointed rockmass were highly affected by different rock and joint conditions and thus different from Peck's empirical earth pressure for soil ground.

Disturbed State Modeling for joints of Rock(Theory and Implementation) (암반절리에 대한 교란상태 모델링 (이론과 응용))

  • 박인준;전석원
    • Tunnel and Underground Space
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    • v.8 no.3
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    • pp.200-208
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    • 1998
  • This research is intended to investigate the behavior of the jointed rock under various loading conditions: static or dynamic load. The distributed state concept (DSC) is based on the idea that the response of the joint can be related to and expressed as the response of the reference states : relative intact (RI) and fully adjusted (FA) states. In the DSC, an initially RI joint modifies continuously through a process of natural self-adjustment, and a part of it approaches the FA state at randomly disturbed locations in the joint areas. In this study, based on the DSC concept, RI state, FA state, and disturbance function (D) are defined for characterizing the behavior of rock joint. From the results of this research, it can be stated that DSC model is capable of capturing the physical behavior of jointed rock such as softening and hardening and considering the size of joint and roughness of joint surface.

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절리암반 중에 굴착된 터널의 거동평가를 위한 수치 해석적 연구

  • Kang, Yong;Yoo, Gwang-Ho;Park, Yeon-Jun
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • 2001.03a
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    • pp.97-108
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    • 2001
  • 절리가 발달한 암반의 거동평가를 위한 해석적 방법은 연속체 모델과 불연속체 모델을 사용하는 방법으로 대별할 수 있으며, 연속체 모델을 사용할 경우에는 유한요소법이나 유한차분법을 이용하는 방법이 주종을 이루고 있다. 불연속체 모델은 개별 블록들의 움직임을 일일이 계산하므로 매우 매력적인 방법이지만 현재의 지반조사 기술수준으로는 지반내의 절리발달사항을 정확히 파악하기가 매우 어려우며, 컴퓨터의 계산용량이 너무 과다해지는 단점이 있다. 따라서, 불연속면을 포함한 암반을 연속체로 가정한 편재절리 모델(ubiquitous joint model)을 이용한 연구가 요구된다. 한편, 터널의 경우는 사면의 경우와는 달리 파괴면의 형상을 사전에 가정하기 어렵기 때문에 한계평형법에 기초한 해석법 등을 적용하여 안전율을 구하기가 곤란하다. 이러한 이유에서 터널을 대상으로 한 수치해석은 안전율을 구하기보다는 안정성을 평가하는 데만 제한적으로 사용되어 왔다. 본 논문에서는 편재절리모델을 이용한 절리암반터널의 거동 평가기법과 수치해석에 의해 터널의 안전율을 구하는 방법을 제시하는 데에 그 목적이 있다. 이를 위해 터널의 안전율 구하는 방법을 강도감소기법에 근거하여 제시하였다.

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Analysis of Joint Characteristics and Rock Mass Classification using Deep Borehole and Geophysical Logging (심부 시추공 회수코어와 물리검층 자료를 활용한 절리 및 암반등급 평가)

  • Dae-Sung Cheon;Seungbeom Choi;Won-Kyong Song;Seong Kon Lee
    • Tunnel and Underground Space
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    • v.34 no.4
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    • pp.330-354
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    • 2024
  • In site characterization of high-level radioactive waste, discontinuity(joint) distribution and rock mass classification, which are key evaluation parameters in the rock engineering field, were evaluated using deep boreholes in the Wonju granite and Chuncheon granite, which belong to Mesozoic Jurassic era. To evaluate joint distribution characteristics, fracture zones and joint surfaces extracted from ATV data were used, and major joint sets were evaluated along with joint frequency according to depth, dip direction, and dip. Both the Wonju and Chuncheon granites that were studied showed a tendency for the frequency of joints to increase linearly with depth, and joints with high angles were relatively widely distributed. In addition, relatively large amounts of weathering tended to occur even in deep depth due to groundwater inflow through high-angle joints. RQD values remained consistently low even at considerable depth. Meanwhile, joint groups with low angles showed different joint characteristics from joint sets with high angles. Rock mass classification was performed based on RMR system, and along with rock mass classification for 50 m intervals where uniaxial compressive strength was performed, continuous rock mass classification according to depth was performed using velocity log data and geostatistical techniques. The Wonju granite exhibited a superior rock mass class compared to the Chuncheon granite. In the 50 m interval and continuous rock mass classification, the shallow part of the Wonju granite showed a higher class than the deep part, and the deep part of the Chuncheon granite showed a higher class than the shallow part.

A Finite Eelement Analysis of Joint Behavior of Rock Masses (암반절리의 거동에 대한 유한요소해석)

  • ;;Kim, Moon Kyum;Hwang, Dae Jin
    • Computational Structural Engineering
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    • v.2 no.4
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    • pp.59-67
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    • 1989
  • Effect of joints which pre-exist in the rock mass on the behavior of underground structures is studied. A finite element program is developed using a constitutive mode for rock masses exhibiting nonlinear anisotropic behavior. The initial loading scheme combined with reduced region of analysis is employed to minimize the problem size. A circular tunnel within rock mass is analyzed and the results are compared with those of elasto-plastic analysis to verify that the program is reasonable. The effect of joint direction is also analyzed in regard to stress relaxation, displacement, and deformation shape. It is concluded that the joint direction has significant influence on the nonlinear behavior of rock masses such that the vicinity of tunnel perpendicular to the direction of the joints is stressed to slide. It is also observed that the circular shape deforms to an elliptical shape with a major axis in the joint direction.

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Rock Joint Survey System by image Processing and Stereophotogrammetry (화상처리 및 입체사진측량학을 이용한 암반 절리 조사 시스템)

  • 류동우;이유리;장윤섭;이희근;박형동
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • 2000.09a
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    • pp.77-91
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    • 2000
  • Rock joint survey consists of measurement of orientation and face mapping for trace informations. We have developed a new alternative approach called rock joint survey system by stereophotogrammetry and image processing to replace the conventional manual method. For the measurement of orientations and face mapping, we applied a stereophotogrammetry and developed two hybrid approaches using image processing techniques, respectively. These methods have advantages in making it possible to measure the orientations of joints and perform face mapping rapidly and objectively in unaccessible and dangerous areas.

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Effect of Joint Sets on the Earth Pressure against the Support System in a Jointed Rock Mass (절리형성 암반지층 굴착벽체에 작용하는 토압에 대한 절리군의 영향)

  • Son, Moorak;Adedokun, Solomon
    • Journal of the Korean Geotechnical Society
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    • v.31 no.12
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    • pp.59-69
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    • 2015
  • This study examined the magnitude and distribution of earth pressure on the support system in a jointed rock mass due to the different joint sets as well as varying the rock type and joint condition (joint shear strength and joint inclination angle). Based on a physical model test and its numerical simulation, a series of numerical parametric analyses were conducted using a discrete element method. The results showed that the induced earth pressure was affected significantly by a joint set depending on the inclusion of the joint inclination angle, which induces a joint sliding condition, but the number of joint sets alone was not important, even though the earth pressure could be increased slightly as the number of joint sets is increased. In addition, the study results were compared with Peck's earth pressure for soil ground, which indicated that the earth pressure in a jointed rock mass could be considerably different from that in soil ground. The study suggests that the effects of joint sets as well as rock type and joint condition are important factors affecting the earth pressure in a jointed rock mass and they should be considered when designing a support system in a jointed rock mass.

Calculation of Joint Center Volume (JCV) for Estimation of Joint Size Distribution in Non-Planar Window Survey (비평면 조사창에서의 암반절리 크기분포 추정을 위한 Joint Center Volume (JCV) 산정 기법 제안)

  • Lee, Yong-Ki;Song, Jae-Joon
    • Tunnel and Underground Space
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    • v.29 no.2
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    • pp.89-107
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    • 2019
  • Rock joints have an extremely important role in analyzing the mechanical stability and hydraulic characteristics of rock mass structures. Most rock joint parameters are generally indicated as a distribution by statistical techniques. In this research, calculation technique of Joint Center Volume (JCV) is analyzed, which is required for estimating the size distribution having the largest uncertainty among the joint parameters, then a new technique is proposed which is applicable regardless of the shape of survey window. The existing theoretical JCV calculation technique can be applied only to the plane window, and the complete enumeration techniques show the limitations in joint trace type and analysis time. This research aims to overcome the limitations in survey window shape and joint trace type through calculating JCV by using Monte Carlo simulation. The applicability of proposed technique is validated through the estimation results at non-planar survey windows such as curved surface and tunnel surface.

Constitutive modeling for rock joints of tunnel (터널 암반절리에 대한 구성방정식 모델링)

  • Park, Inn-Joon
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.4 no.2
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    • pp.101-111
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    • 2002
  • The purpose of this research is to develop improved model for joints of tunnel based on Disturbed State Concept (DSC) model. DSC model is verified with respect to comprehensive laboratory tests performed by Schneider and back prediction results. Based on results of this research, it can be stated that DSC model is capable of characterizing the strain softening and dilative behavior of rough granite joints under four different constant normal stresses.

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A Study on the Deformation Modulus for Tunnel Displacement Assessment in Multi-Jointed Rock Mass (다중절리 암반지층에서의 터널변위 산정을 위한 변형계수에 관한 연구)

  • Son, Moorak;Lee, Wonki
    • Journal of the Korean GEO-environmental Society
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    • v.18 no.5
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    • pp.17-26
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    • 2017
  • Tunnel excavation in jointed rock mass induces a displacement along tunnel excavation line and its assessment is very important to ensure the stability of tunnel and a demanded space. Tunnel displacement is directly related to the deformation modulus of ground and therefore it is essential to know the value of the parameter. However, most rock masses where tunnels are constructed are generally jointed and it is difficult to find out the deformation modulus of jointed rock mass simply based on an homogeneous isotropic elastic medium because the deformation modulus is highly affected by joint condition as well as rock type. Accordingly, this study carried out extensive numerical parametric studies to examine the variation of deformation modulus in different joint conditions and rock types under the condition of tunnel excavation. The study results were compared with existing empirical relationships and also shown in the chart of deformation modulus variation in different jointed rock mass conditions.