• Title, Summary, Keyword: 인공절리

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Evaluation of Blast Velocity by Artificial Joint Conditions using Numerical Analysis (수치해석을 이용한 인공절리 조건에 따른 발파속도 평가)

  • Suk, Chul-Gi;Noh, You-Song;Park, Hoon
    • Explosives and Blasting
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    • v.35 no.4
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    • pp.1-9
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    • 2017
  • This study undertakes an evaluation of blast effect through the analysis of the contribution rate and effect that different artificial joint number, artificial joint spacing and artificial joint angle have on blast velocity. Blast velocity according to the different state of the artificial joint was obtained using AUTODYN, a dynamic analysis program. The result of the numerical analysis was subjected to further normalization analysis. For the contribution rate of design factors was analyzed using the robust design method. The orthogonal array used in the analysis was $L_9(3^4)$ and each parameters were having 3 levels. The result of normalization analysis regarding the artificial joint angle was indicated a tendency in which blast velocity decreased. The result of analyzing blast velocity regarding artificial joint spacing and artificial joint angle was indicated a tendency in which blast velocity decreased as artificial joint spacing increased when the angle was perpendicular. In the case of blast velocity contribution rates they were ranked in the descending order of artificial joint angle, artificial joint number, artificial joint spacing.

Evaluation of Blast influence by Artificial Joint in Concrete Block (콘크리트 블록에서 인공절리에 따른 발파영향 평가)

  • Noh, You-Song;Min, Gyeong-Jo;Oh, Se-Wook;Park, Se-Woong;Suk, Chul-Gi;Cho, Sang-Ho;Park, Hoon
    • Explosives and Blasting
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    • v.36 no.3
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    • pp.1-9
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    • 2018
  • This study was conducted to evaluate the influences of the angle of artificial joints, the distance between the artificial joints and the blast hole, and the number of artificial joints on the pressure wave propagation, crack propagation, and blast wave velocity. The evaluation was conducted numerically by use of the Euler-Lagrange solver supported by the AUTODYN, which is a dynamic FEM program. As a result, it was found that the blast wave velocity was decreased most rapidly as either the distance between the artificial joint and the blast hole was decreased or the angle of the artificial joint was increased. In contrast to the case of no artificial joint, the amount of attenuation of the blast wave velocity was considerably large when an artificial joint was present. However, the effect of the number of artificial joint on the attenuation of the blast wave velocity was negligible under the given condition.

A Comparison of Ground Vibration in Center Cut Blasting using Artificial Joints (인공절리를 이용한 심발 발파에서의 지반진동 비교)

  • Park, Hoon;Suk, Chul-Gi;Noh, You-Song
    • Explosives and Blasting
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    • v.36 no.4
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    • pp.16-25
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    • 2018
  • In order to reduce ground vibration during tunnel excavation, a free surface blasting method has been applied in which a partial free surface is formed on the excavation surface and controlled blasting is performed. In this study, the ground vibration reduction due to artificial joints was evaluated by forming artificial joints on center cut using diamond wire saw and comparing the ground vibration caused by center cut blasting. As a result of comparison, ground vibration was reduced by artificial joints center cut blasting more than normal center cut blasting, and the ground vibration reduction effect of horizontal artificial joints center cut blasting was evaluated more than that of vertical artificial joint center cut blasting.

Evaluation of Rock Fragmentation due to Artificial Joint Effect (인공절리에 의한 암석의 파쇄도 평가)

  • Noh, You-Song;Suk, Chul-Gi;Park, Hoon
    • Explosives and Blasting
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    • v.36 no.4
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    • pp.9-15
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    • 2018
  • Since the rock fragmentation by blasting can affect the subsequent processes including loading, hauling and secondary crushing, its control is essential for the assessment of blasting efficiency as well as production cost. In this study, we were analyzed the rock fragmentation by the direction of artificial joint. The underground blasting experiments were performed after forming the vertical and horizontal artificial joints. The blast fragmentation was conducted by the split-desktop which is a 2D image processing program. As a result, it was found that the horizontal artificial joint was evaluated to have lower overall the size of muck pile than the vertical artificial joint and the distribution of the size of muck pile was varied. It is possible that the direction of artificial joint could suppress the occur of oversize muck pile and control to a certain size or less.

Anisotropic Shear Strength of Artificially Fractured Rock Joints Under Low Normal Stress (낮은 수직응력 하에서 인공 절리면의 전단 이방성에 관한 연구)

  • 곽정열;이상은;임한욱
    • Tunnel and Underground Space
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    • v.13 no.3
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    • pp.169-179
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    • 2003
  • Anisotropic shear strength of rock joints is studied based on the artificially fractured specimens using experimental and analytical methods. Series of direct shear tests are performed to obtain the strength, stiffness and friction angle of joints under various low normal stresses and shearing directions. The results of shear strength and stiffness show anisotropic value according to shearing direction under low normal stress specially less than 2.45 MPa. But, the effect of joint roughness on strength decreases with increasing normal stress. To estimate more effectively the peak shear strength under low normal stress, the modified Barton's equation is suggested.

An Experimental Study for the Scale Effects on Shear Behavior of Rock Joint (절리면 전단거동의 크기효과에 관한 실험적 연구)

  • Lee, Sang-Eun
    • Journal of the Korean Geoenvironmental Society
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    • v.7 no.3
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    • pp.31-41
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    • 2006
  • The scale effect of specimens on the shear behavior of joints is studied by performing direct shear tests on six different sizes in Granite. The peak and residual shear stress, shear displacement, shear stiffness, and dilation angle are measured with the different normal stress(0.29~2.65MPa) and roughness parameters. It is also shown that both the joint roughness coefficient(JRC) and the joint compression strength(JCS) reduce with increasing joint length. A series of shear tests show about 56~67% reduction in peak shear stress, and about 18~44% in residual shear stress, respectively as the contact area of joint increases from 12.25 to $361cm^2$. Also the variation of dilation angle is $27^{\circ}$ at normal stress of 0.29 MPa and $6^{\circ}$ at normal stress of 2.65 MPa, respectively. The envelopes considering scale effect for JRC are made for the peak shear strength of rock joint in comparison with the Barton's equation.

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A Study on Shearing Characteristics of Joint Model (인공 절리모델에 대한 전단특성 연구)

  • 장보안;조종수
    • The Journal of Engineering Geology
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    • v.9 no.1
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    • pp.69-82
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    • 1999
  • Direct shear tests are perfromed for artifical joint models made of cement with 25 types of different strength and roughness. The tests consist of the multi-stage test which is a common test method for a single joint plane and the test method suggested by ISRM. Then, not only the differences of friction angles between the two test methods are compared, but is the effectiveness of the multi-stage test investigated. The average of friction angles measured from the multi-stage test is $6.4^{\circ}$ lower than that from the ISRM test. Although the strength and roughness of samples vary, the differences of friction angles between the two test methods are constant. The relationship between the shear stress and the normal stress measured from the multi-stage test is well correlate with the Patton's equation. Whereas, the Barton's equation is best fitted with those measured from ISRM test.

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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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    • 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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A Study of Statistical Analysis of Rock Joint Directional Data (암반 절리 방향성 자료의 통계적 분석 기법에 관한 연구)

  • 류동우;김영민;이희근
    • Tunnel and Underground Space
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    • v.12 no.1
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    • pp.19-30
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    • 2002
  • Rock joint orientation is one of important geometric attributes that have an influence on the stability of rock structures such as rock slopes and tunnels. Especially, statistical models of the geometric attributes of rock joints can provide a probabilistic approach of rock engineering problems. The result from probabilistic modeling relies on the choice of statistical model. Therefore, it is critical to define a representative statistical model for joint orientation data as well as joint size and intensity and build up a series of modeling procedure including analytical validation. In this paper, we have examined a theoretical methodology for the statistical estimate and hypothesis analysis based upon Fisher distribution and bivariate normal distribution. In addition, we have proposed the algorithms of random number generator which is applied to the simulation of rock joint networks and risk analysis.

Development of Direct Shear Apparatus with Different Loading Conditions for Rock Joints and Its Application Tests (하중조건별 시험이 가능한 암석 절리편 전단시험의 개발 및 적용시험)

  • 천병식;김대영
    • Journal of the Korean Geotechnical Society
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    • v.16 no.6
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    • pp.161-172
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    • 2000
  • 자연암석절리 및 인공 절리에 대하여 일정수직응력제어, 일정 수직하중제어 그리고 무한 강성제어가 가능한 암석 절리면 전단기 시험기를 개발하였다. 이 시험기는 전단변위에 의한 첩촉면적의 변화량을 계산하여 하중변화량을 조절하여 일정수직응력상태를 유지한다. 수직하중에 따른 시험기 강성에 의한 변화향이 제어 프로그램 내에서 제어되어 순수한 시편의 변위량을 출력하도록 하였다. 전단하중에 따른 시험기 강성에 의한 변위량은 상, 하부 전단상자의 상대변위 측정으로 최소화하였다. 전단거동 중의 자유도는 전당방향에 대하여 수평이도, 연직이동, 피칭, 롤링이 가능하도록 하였다. 자연절리면을 모사한 석고시편에 대하여 일정 수직응력 제어, 일정수직하중제어 그리고 무한 강성제어 조건으로 시험하여 제어상태 검증 및 비교를 하였다. 또한 경사각이 16.7˚와 22.6˚인 톱니형 시편에 대하여 시험한 결과 경사각 16.7˚와 22.6˚는 JRC로 10과 15를 나타내었으며, 첨두팽창각이 첨두전단강도에서 발생되며, Barton의 모델과 잘 일치함을 보였다.

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