• Title/Summary/Keyword: 암반절리

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Numerical Analysis of the Visco-plastic Behavior of Rock Mass Considering Continuum Joints and Rock Bolt Elements (연속체 절리와 록볼트 요소를 고려한 암반의 점소성 거동에 관한 수치해석)

  • 노승환;이정인;이연규
    • Tunnel and Underground Space
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    • v.14 no.3
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    • pp.215-228
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    • 2004
  • Rock mass contains discontinuities such as faults and joints, and their mechanical properties and spatial distribution dominate the stability of rock mass. Because the deformation of rock mass occurs discontinuities in many cases. However in the case of poor quality rock mass under high stresses, the deformation along intact rock can also influence the structure's stability. In this study, two dimensional finite element program was developed with a rheological model to analyze the stability of the structure excavated in jointed rock mass. The “equivalent material” approach was used assuming intact rock, joints and rock bolts as visco-plastic materials. The program was verified by analysing an intact rock model, a jointed rock mass model and a reinforced jointed rock mass model. The displacement was examined in each model with changing the intact rock behaviour as elastic and visco-plastic. In the case of poor quality rock mass under high stresses, e assumption of visco-plastic behaviour of intact rock resulted in larger displacement than when assuming elastic behaviour for intact rock. Therefore it is recommended to add intact rock's visco-plastic behaviour to the existing model, which only assumes visco-plastic behaviour of joints and rock bolts.

A Study on the Reinforcement of Rock Faults by Grouting (암석 절리면의 그라우팅에 의한 보강에 관한 연구)

  • Chun, Byung-Sik;Choi, Joong-Keun
    • Journal of the Korean GEO-environmental Society
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    • v.4 no.4
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    • pp.45-51
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    • 2003
  • Grouting materials in rock is grouted as vein type along the fault surface by the other way for soil and allow a change of characteristics in rock faults as a result of that. Therefore the deformation characteristics of rock faults after grouting differ as a direction and characteristic of grouted fault and stress condition of field rock. Thereby it must be analyzed the effect for deformation of rock according to characteristics of rock faults and characteristics of grouting materials to accurately evaluate the reinforced effect by grouting. But grouting method used in field until present depends on experience of workers, and inspection for those effects are evaluated by measurement of elastic wave velocity, permeability tests and etc. in field. In this study, it was investigated that the effects for shear characteristics of maximum shear strength, residual shear strength and etc. by comparison and analysis of test results which were worked by direct shear tests of rock faults with changing a type of grouting materials and the grouting depth(t) for average width(a) of fault surface roughness when OPC(Ordinary Portland Cement) and Micro cement was grouted in fault surface of field rock to evaluate characteristicsof the shear deformation for rock fault surface of dam by grouting.

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Suggestion of New Rock Classification Method Using the Existing Classification Method (기존의 암반분류법의 조합에 의한 새로운 암반평가법의 제안)

  • SunWoo Choon;Jung Yong-Bok
    • Explosives and Blasting
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    • v.24 no.1
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    • pp.21-28
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    • 2006
  • Rock mass classification systems such as RMR and Q system have been widely served as a simple empirical approach for the design of various rock mass structures in the stage of site survey as well as under the construction. For the RQD determination, the boring is partially carried out and what is more, the survey boring is not normally carried out under construction. Therefore RQD is frequently determined by empirical method or indirect method. Since it is difficult to determine the discontinuity characteristics such as RQD, spacing, persistence, filling and so on, it is essential to develop suitable and simple systems without drilled core and a cert 없 n number of representative parameters. One of the primary objectives of the classification systems for a practicing engineer has been to make it simple to use as a preliminary design tool for the structures in rock mass. In the present study, the modifications for both the RMR and GSI system are suggested by authors to introduce new classification system as well as to improve the scope of some of the existing classification systems for a practicing engineer.

Stability Analysis of a Jointed Rock Slope with the Barton-Bandis Joint Constitute Model Using UDEC (Barton-Bandis joint model을 이용한 절리 암반 사면의 안정성 해석)

  • 최성웅;정소걸
    • Tunnel and Underground Space
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    • v.9 no.2
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    • pp.141-148
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    • 1999
  • Distinct element simulation in jointed rock masses is largely dependent upon the joint constitutive equation used. This paper describes the differences between the Barton-Bandits (BB) and the Mohr-Coulomb (MC) joint constitutive models for the stability analysis of the jointed rock slopes. The BB model, which allows the modelling of the dilation accompanying shear, predicts results very similar to the present condition of slopes. Consequently the 10 cm thick shotcrete was proposed for the reinforcement of those slopes. The MC model, however, in which the dilation angle is constant, is relatively insensitive to the behaviors of joints.

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Analysis of electrical resistivity characteristics according to the mixing ratio of coarse fillings in artificial rock joint (인공 암반절리의 조립토 충진물 혼합비에 따른 전기비저항 특성 분석)

  • Haeju Do;Tae-Min Oh;Hangbok Lee
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.25 no.2
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    • pp.141-155
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    • 2023
  • Monitoring technology based on electrical resistivity is widely used for non-destructive data collection and health analysis of underground structures and tunnels. Vulnerable sections such as fault zone generates many problems during construction of the tunnel. These problems cause displacement and stress changes of the ground. Therefore, it is necessary to predict the state of the fault zone section to ensure the mechanical stability of the underground structure. Monitoring the size of joints and the porosity of the fillings is essential for rocks. Previous studies have not considered the variety of fillings in rock joints. In this study, electrical resistivity tests were conducted according to the particle mixing state of the sandy fillings. When the size of fillings is decreased at the constant porosity, the electrical resistivity tends to increase. The results of this study are expected to be useful as basic electrical resistivity data for predicting the ground conditions and evaluation of the ground behavior that is containing sandy fillings in the rock joint for tunnels.

The Effect of Joint Condition on Rock Fragmentation in Bench Blasting (절리간격과 방향이 벤치발파시 암석파쇄도에 미치는 영향에 대한 실험 연구)

  • Choi Yong-Kun;Lee Chung-In
    • Explosives and Blasting
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    • v.23 no.2
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    • pp.37-44
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    • 2005
  • Recent studies reported that natural block size of rock and joint orientation highly affect on rock fragmentation. In this study, blasting test using high strength cement mortar was carried out to verify this fact. The result of this test indicated that fragmentation is influenced by the joint interval, and at same joint interval condition, fragmentation depends on joint orientation. These results are significantly coincident with field investigations.

Development of 3D Roughness Measurement System of Rock Joint Using Laser Type Displacement Meter (레이저 변위계를 이용한 암석 절리면의 3차원 거칠기 측정기 개발)

  • 이정인;배기윤;김태혁
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • 1999.03a
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    • pp.17-23
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    • 1999
  • 본 논문에서는 절리면 거칠기를 정밀하게 수치화 하기 위해 레이저 변위계를 이용한 3차원 거칠기 측정기를 구동시키는 프로그램 제작 및 여러 가지 상태의 절리면에 대해 수치화를 실시하여 각종 거칠기 파라미터를 결정한 후 오차분석을 실시하여 이 기계를 이용한 측정의 타당성을 검증하였다. 동일한 절리면에 대해 물리적인 접촉에 의한 3차원 거칠기 측정기로부터 얻어진 거칠기 파라미터와 레이저 변위계를 이용한 측정기로부터 얻어진 것들 사이의 관계를 살펴보았고, 레이저 측정기에 의해 수치화된 절리면 거칠기 파라미터 사이의 상관관계를 조사하였다. 연구에 사용한 시료는 황등화강암, 여산대리석의 2종류이며, 절리형상 측정을 위한 절리는 인장균열 발생장치를 이용하여 인공적으로 제작하였다. (중략)

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Comparison of Modelling Characteristics of Distinct Element Analysis Based on Implicit and Explicit Algorithm (Implicit 및 explicit 알고리즘에 기초한 개별요소 수치해석 방법의 모델링 특성 비교 연구)

  • 류창하
    • Tunnel and Underground Space
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    • v.10 no.3
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    • pp.410-417
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    • 2000
  • The distinct element method has been effectively applied to the analysis of stability and behavior of jointed rock masses. In this paper the modelling characteristics of different types of distinct element model were investigated. Arch tunnel examples were chosen to compare the calculation results of two computer codes, NURBM and CBLOCK, where the former is based on implicit algorithm, and the other on explicit one. CBLOCK calculations show that joint properties are very important parameters in the stability analysis and that the joint stiffness ratio associated with joint configuration could be used as an indicator, whereas NURBM differ from that. Some other disagreements were also identified.

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Effect of Step-Wise Excavation Depth on the Earth Pressure against an Excavation Wall in Rock Mass (암반지층 굴착벽체 발생토압에 대한 단계별 굴착깊이의 영향)

  • Son, Moorak;Adedokun, Solomon
    • Journal of the Korean Geotechnical Society
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    • v.30 no.2
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    • pp.43-52
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    • 2014
  • This paper examined the effect of step-wise excavation depth on the earth pressure against an excavation wall in rock mass. Numerical parametric studies were conducted based on the Discrete Element Method (DEM) to carry out the problems in rock mass. Controlled parameters included step-wise excavation depth, rock types, and joint conditions (joint shear strength and joint inclination angle). The magnitude and distribution characteristics of the induced earth pressure in a jointed rock mass were investigated and compared with Peck's earth pressure for soil ground. The results showed that the earth pressure against an excavation wall in rock mass were highly affected by different rock and joint conditions, and the effect of step-wise excavation depth increased as a rock type is deteriorated more. In addition, it was found that the earth pressure against an excavation wall in rock mass might be considerably different from Peck's empirical earth pressure for soil ground.

Barton-Bandis 절리 모델에 의한 지하대공동 암주의 변형 특성 연구

  • 강추원;임한욱;김치환
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • 2001.03a
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    • pp.118-131
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    • 2001
  • 우리 나라의 양수발전소는 지금까지 단일공동을 굴착하였다. 그러나 양양 양수발전소는 두 개의 대공동 즉, 발전소와 주 변전소로 구성된다. 이 경우 공동 구조물의 안정성, 특히 두 공동사이에 형성되는 암주를 영구적으로 안전하게 유지 할 수 있도록 보장되어야 한다. 본 연구에서는 개별요소법을 이용하여 두 공동과 암주의 구조적 안정성을 평가하였으며, 구성모델로 Barton-Bandis의 절리모델을 이용하였다. 현지 암반의 초기응력, 자연절리면의 거칠기계수 불연속면의 공간적 분포 특성과 같은 중요한 요인들은 현지 조사를 통하여 구하였다. 이외에 두 가지 경우 즉, 무보강과 보강의 경우 지보시스템의 최적화를 분석하였으며, 또한 보강효과를 검토하였다. 연구결과 보강의 경우 수평변위와 절리의 전단변위가 감소되었으며 암주내 이완영역 역시 감소됨을 확인하였다. 두 공동사이에 있는 약 36m 두께의 암주에 적절한 보강조치를 취하여 안정성을 확보할 수 있었다.

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