• Title, Summary, Keyword: 전단강도의 이방성

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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.

A Study of Estimation Method Considering Anisotropy of Shear Strength for Compacted Materials (다짐재료의 이방성을 고려한 전단강도 추정방법에 관한 연구)

  • Ham, Tae-Gew
    • Journal of The Korean Society of Civil Engineers
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    • v.28 no.5C
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    • pp.255-262
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    • 2008
  • In order to investigate the strength anisotropy of compacted materials, a series of unsaturated and saturated-drained triaxial compression tests was performed. Three different orientation angles of the axial direction of samples with respect to the horizontal plane were investigated: ${\delta}=0$, 45 and 90 degrees. As the results showed, the suction rate on the strength of the unsaturated specimen was not influenced by ${\delta}$. And the effect of the angle ${\delta}$ on the strength was more pronounced on unsaturated specimen as compared to saturated specimen. Moreover, a new procedure was proposed to take into account the effect of the angle ${\delta}$ on the shear strength of unsaturated soils.

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Anisotropy of shear strength according to roughness in joint surface (절리면 거칠기에 의한 전단강도 이방성)

  • 이창훈;정교철
    • The Journal of Engineering Geology
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    • v.12 no.4
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    • pp.421-437
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    • 2002
  • In order to quantify the anisotropic properties of rock included joints and shear behavior in joint surface, the mold is Produced for rock joint surface using gypsum Plaster and Peformed for replicated joint models made of cement mortar. Rock sample is measured using mechanical profilometer before testing and their result is expressed quantitatively. The statistical parameters and the fractal dimension by fractal theory for roughness is investigated its coordinate value for numerical process. The shear strength to the shear displacement in low level normal stress ismaintained or increased in most joint models. Their results present that this relationship is depended several roughness properties in joint model for natural rock joint. The relationship between the shear strength and the Properties for profiles estimated by some statistical parameter in roughness has the low correlation and is not constant. The result between the data for direct shear test and using Barton's equation, Barton's equation has not the effectiveness for the effect of anisotropy and has not suitable to recognizing the properties for joint surface. It means that JRC has not the properties of anisotropic rock surface. The fractal dimension is well correlated with the data of direct shear test than those of JRC. New experimental formulae using fractal dimension is comported with the anisotropic properties for direct shear test.

Elastic Buckling Strength of Orthotropic Plate under Combined In-Plane Shear and Bending Forces (면내 전단력과 휨을 동시에 받는 직교이방성판의 탄성좌굴강도)

  • 윤순종;박봉현;정상균
    • Composites Research
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    • v.12 no.2
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    • pp.46-52
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    • 1999
  • In this paper result of an analytical investigation pertaining to the elastic buckling behavior of orthotropic plate under combined in-plane shear and bending forces is presented. The existing analytical solution developed for the isotropic plates is extended so that the orthotropic material properties can be taken into account in the buckling analysis of web plate. For the solution of the problems Rayleigh-Ritz method is employed. Graphical form of results for finding the elastic buckling strength of orthotropic plate under combined in-plane shear and bending forces is presented. Brief discussion on the design criteria for the shear and bending interaction is also presented.

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Prediction of Undrained Shear Strength of Normally Consolidated Clay with Varying Consolidation Pressure Ratios Using Artificial Neural Networks (인공신경회로망을 이용한 압밀응력비에 따른 정규압밀점토의 비배수전단강도 예측)

  • 이윤규;윤여원;강병희
    • Journal of the Korean Geotechnical Society
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    • v.16 no.1
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    • pp.75-81
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    • 2000
  • The anisotropy of soils has an important effect on stress-strain behavior. In this study, an attempt has been made to implement artificial neural network model for modeling the stress-strain relationship and predicting the undrained shear strength of normally consolidated clay with varying consolidation pressure ratios. The multi-layer neural network model, adopted in this study, utilizes the error back-propagation loaming algorithm. The artificial neural networks use the results of undrained triaxial test with various consolidation pressure ratios and different effective vertical consolidation pressure fur learning and testing data. After learning from a set of actual laboratory testing data, the neural network model predictions of the undrained shear strength of the normally consolidated clay are found to agree well with actual measurements. The predicted values by the artificial neural network model have a determination coefficient$(r^2)$ above 0.973 compared with the measured data. Therefore, this results show a positive potential for the applications of well-trained neural network model in predicting the undrained shear strength of cohesive soils.

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A study on the Fracture Mechanism and the Test for Strength Properties of the Granite-Gneiss (화강편마암의 강도특성 실험 및 파괴메카니즘에 관한 연구)

  • 최안식;조만섭;김영석
    • Tunnel and Underground Space
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    • v.10 no.2
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    • pp.165-172
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    • 2000
  • When tunnels or underground structures are constructed in anisotropic rock mass, designers and constructors have to consider the anisotropic characteristics in rock mass because their physical and mechanical properties are depended on the anisotropic angles(${\beta}$). In this study, therefore, we have first investigated the mechanical behavior of the gneiss specimen from lab. tests, and then have analysed the behavior of specimens for to the transversely isotropic model in elastic medium using the FLAC program. The results of this study were summarized as follows; 1) In the result of the variation tests, in general, the properties of strength were depended on the angle of inclination in spite of the hard rock. And except for the shear strength test, the lowest and peak stress were appeared at 60$^{\circ}$ and 90$^{\circ}$respectively. 2) The results of specimen modeling analysis using FDM well indicated the mechanical behaviors of the specimen of transversely isotropic model.

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Engineering Characteristics and Problems in The Sedimentary rock (퇴적암의 공학적 특성 및 문제점)

  • 이영휘;김용준;정강복
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.31-50
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    • 2002
  • The sedimentary rocks deposited in Taegu and Kyongbuk region consist of various rocks such as the shale, mudstone, siltstone and sandstone. The characteristics of the sedimentary rocks are distinguished from those of igneous rocks and metamorphy rocks for the stratum caused by deposit environment. This study investigated engineering characteristics of the anisotropy, weathering rock and filled rock joints in the notable features of sedimentary rocks.

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Nonlinear FE Analysis of RC Shear Walls (철근콘크리트 전단벽의 비선형 유한요소해석)

  • 곽효경;김도연
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.12 no.3
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    • pp.293-308
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    • 1999
  • 이 논문에서는 패널, 깊은 보 그리고 전단벽과 같이 평면응력상태하에 있는 철근콘크리트 구조물의 비선형 유한요소해석에 있어서의 직교이방성 콘크리트 구성 모델의 적용성을 보여준다. 등가의 일축 변형을 개념을 토대로 콘크리트의 구성 관계가 주변형률 축과 일치하고 하중이력에 따라 회전하는 직교하는 축에 대해 제시된다. 제안된 모델은 이축 압축응력상태와 인장-압축 응력상태에서 각각 압축강도의 증가와 인장 저항력의 감소효과를 보여주는 이축 파괴영역의 정의를 포함한다. 인장균열이 발생한 후, 콘크리트의 압축강도의 감소효과가 제시되고, 인장강화효과로 알려진 철근에 의해 지지되는 콘크리트의 인장응력이 고려된다. 평균응력과 평균변형률 개념을 사용하여 힘의 평형, 적합조건 그리고 철근과 철근을 둘러싼 콘크리트 사이의 부착응력-슬림 관계를 토대로 인장강화효과를 모사하기 위한 모델이 제안된다. 유한요소 모델에 의한 예측은 유용한 실험자료와의 비교에 의해 입증된다. 이 논문에서는 해석결과와 이상화한 전단 패널실험으로부터 얻어진 실험값의 비교연구가 수행되고, 제안된 모델의 타당성을 보여주기 위해 서로 다른 응력상태하의 전단 패널 보와 벽체의 힘-변위 관계를 평가하였다.

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A Reliability Study on Estimating Shear Strength of Marine Soil using CPT (Cone 관입시험을 이용한 해양토질의 전단강도 산정에 대한 신뢰도 연구)

  • 이인모;이명재
    • Geotechnical Engineering
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    • v.3 no.2
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    • pp.17-28
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    • 1987
  • Reliability of the cone penetration test (CPT) for estimating shear strength of marine soils is investigated in this paper. For sands, the uncertainty about the angle of internal friction is analyzed. It includes the spatial variation of the soil and the model error in the equation used for interpretation. The most serious uncertainty encountered was the error in the interpretative models. Different methods of interpretation gave quite different values. Subjective opinion was introduced to combine all the interpretative models in a systematic manner. For clays, the undrained Shear Strength from the CPT results is usually =derived by empirical correlations between cone resistance and untrained shear strength from laboratory tests or field vane tests, expressed in terms of cone factor and function of overburden pressure. The uncertainty of the undrained shear strength is caused by data scatter of the cone factor in the correlation, model error of the cone factor, effect of anisotropy, and spatial variability of cone resistance. Among these uncertainties, the most serious one was the data scatter of the cone factor in the .correlation. Between the laboratory test and the field vane test used for correlation, the field vane test was more reliable.

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