• Title, Summary, Keyword: 최대 접선응력 이론

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An experimental study on behavior of tunnel in jointed rock mass (절리암반내 터널라이닝 거동에 관한 실험적 연구)

  • Oh, Young-Seok;Park, Yong-Won;Yoon, Hyo-Seok
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.6 no.4
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    • pp.315-326
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    • 2004
  • This study performed model tunnel tests in order to investigate the influence of discontinuity condition of rock mass to the stress and deformation of tunnel lining. Tests were carried out changing the direction of main joint and lateral earth pressure condition of rock mass. Test results revealed that the axial force in tunnel lining showed a tendency of decrease with the presence of joints. It decreased much with the increase of lateral earth pressure coefficient. And, it also showed that the location or maximum displacement and maximum stress in lining were changed by the direction of main joint of rock mass. The tangential stress and normal stress showed the difference above the maximum twenty times as lateral earth pressure coefficient due to effect of joints increased. Also, these tendencies of concentration of tensile stress in tunnel lining were confirmed by elastic theory.

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A Study on the Interfacial Crack Propagation Criterion for Two Dissimilar Isotropic Bimaterial by the Static Photoelastic Experimental Hybrid Method (정적 광탄성 실험 하이브리드 법에 의한 두 상이한 등방성 이종재료의 계면균열전파 기준에 관한 연구)

  • Tche, Konstantin;Hawong, Jai-Sug;Shin, Dong-Chul;Nam, Sung-Su;Nam, Jeong-Hwan
    • Proceedings of the KSME Conference
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    • pp.1216-1221
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    • 2003
  • The specimen materials used in this research is bimaterial. The static photoelastic experiment was applied to them. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic hybrid method was introduced and it's validity had been assured. The static photoelastic hybrid method was applied to the Minimum Strain Energy Density Criterion, the Maximum Tangential Stress Criterion and Mode Mixity. Crack propagation criterion by the static photoelastic hybrid method was introduced and it was applied to the above various failure theories. Comparing the experimental initial angle of crack propagation with the theoretical initial angle of crack propagation from the various failure criterions. And then the optimal crack propagation criterion was suggested and it's validity was assured.

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Application of the Static Photoelastic Experimental Hybrid Method to the Crack Propagation Criterion for Isotropic Materials (등방성체의 균열전파 기준에 정적 광탄성 실험 하이브리드 법 적용)

  • Shin Dong-Chul;Hawong Jai-Sug;Nam Sung-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.8
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    • pp.1229-1236
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    • 2004
  • The specimen materials used in this research are isotropic epoxy resins. The static photoelastic experiment was applied to them. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic experimental hybrid method was introduced and its validity had been assured. Crack propagation criterion used the stress components, which are considered the higher order terms, obtained from the static photoelastic experimental hybrid method was introduced and it was applied to the minimum strain energy density criterion, the maximum tangential stress criterion and mode mixity. Comparing the actual initial angle of crack propagation with the theoretical initial angle of crack propagation obtained from the above failure criterions, the validities of the above two criterions are assured and the optimal distance (r) from the crack-tip is 0.01mm in order to get the initial angle of crack propagation of isotropic epoxy resin.

A Study on the Crack Propagation Criterion of Orthotropic Material by the Static Photoelastic Experimental Hybrid Method (정적 광탄성 실험 하이브리드법에 의한 직교이방성체의 균열전파 기준에 관한 연구)

  • Shin, Dong-Chul;Hawong, Jai-Sug;Nam, Sung-Su;Kwon, O-Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.11
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    • pp.1799-1806
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    • 2004
  • The static photoelastic experiment was applied to orthotropic materials. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic experimental hybrid method for orthotropic material was introduced and its validity had been assured. Crack propagation criterion used the stress components, which are considered the higher order terms, obtained from the static photoelastic experimental hybrid method was introduced and it was applied to the minimum strain energy density criterion, the maximum tangential stress criterion and mode mixity. Comparing the actual initial angle of crack propagation with the theoretical initial angle of crack propagation obtained from the above failure criterions, the validities of the above two criterions are assured and the optimal distance (${\gamma}$) from the crack-tip is 0.01mm in order to get the initial angle of crack propagation of orthotropic material(C.F.E.C.).

An Analytical Review on the Inelastic Region of Column Strength Curve Associated with Residual Stress of Steel Member under Axial Force (강 압축 부재의 잔류응력에 따른 기둥강도곡선의 비탄성영역에 대한 해석적 고찰)

  • See, Sang-Kwang
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.2
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    • pp.161-168
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    • 2018
  • This study is the analytical review on the inelastic region of CRC column strength curve. The inelastic region of CRC column strength curve is based on the Bleich theory and the maximum residual stress of $0.5{\sigma}_y$. This is somewhat conservative by considering the fact that the maximum residual stress of $0.3{\sigma}_y$ is well known. This study proposes column strength curve for nonlinear behavior of hot rolled structural steel members under axial force and tangent modulus Et, with the maximum residual stress of $0.3{\sigma}_y$ and compares them with those of CRC. The stress of the inelastic column under axial compression exceeds proportional limits and reaches yielding point before applied load render the column bent. The column strength curve that depends on gradually yielding state of section needs to be reviewed. In this study, it is derived that the critical load formular according to material yielding with the maximum residual stress of $0.5{\sigma}_y$ and compared with CRC column design curve.

Modeling of Multi-Stage Hydraulic Fracture Propagation (다단계 수압파쇄균열 전파 모델링 연구)

  • Jang, Youngho;Sung, Wonmo
    • Journal of the Korean Institute of Gas
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    • v.19 no.5
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    • pp.13-19
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    • 2015
  • This paper presents a hydraulic fracture propagation model to describe propagation more realistically. In propagating the hydraulic fractures, we have used two criteria: maximum tangential stress to determine the fracture initiation angle and whether a hydraulic fracture intersects a natural fracture. The model was validated for the parameters relevant to fracture propagation, such as initiation angle and crossing ability through natural fracture. In order to check whether a hydraulic fracture crosses a natural fracture, the model results on crossing state excellently matched with the experimental data. In the sensitivity analysis for direction of maximum horizontal stress, frictional coefficient of fracture interface, and natural fracture orientation, the results show that hydraulic fracture intersects natural fracture, and then, propagated suitably with theoretical results according to fracture interaction criterion. In comparison of this model against vertical fracture approach, it was ascertained that there are discrepancies in fracture connectivity and stimulated reservoir volume.