Methodology to quantify rock behavior around shallow tunnels by Analytic Hierarchy Process and Fuzzy Delphi Method

유영일,송재준 한국자원공학회 2008 Geosystem engineering Vol.11 No.2

For the quantitative identification of rock behavior in shallow tunnels, we recommend using the rock behavior index (RBI) by combining the analytic hierarchy process (AHP) and the fuzzy Delphi method (FDM). AHP can aid engineers in effectively determining complex and un-structured rock behavior utilizing a structured pair-wise comparison matrix. FDM can assist them to overcome the uncertainty in the expert judgment. Rock behavior types are categorized as rock fall, cave-in, and plastic deformation. Seven parameters influencing rock behavior are determined: uniaxial compressive strength (UCS), rock quality designation (RQD), joint surface condition, stress, ground water, earthquake, and tunnel span. They are classified into rock mass intrinsic, rock mass extrinsic, and design parameters. An advantage of this procedure is its ability to obtain each parameter’s weighting. We applied the proposed method to the basic design of Seoul Metro Line 9 and quantified the rock behavior into RBI on rock fall, cave-in, and plastic deformation. The study results demonstrate that AHP can give engineers quantitative information on rock behavior. For the quantitative identification of rock behavior in shallow tunnels, we recommend using the rock behavior index (RBI) by combining the analytic hierarchy process (AHP) and the fuzzy Delphi method (FDM). AHP can aid engineers in effectively determining complex and un-structured rock behavior utilizing a structured pair-wise comparison matrix. FDM can assist them to overcome the uncertainty in the expert judgment. Rock behavior types are categorized as rock fall, cave-in, and plastic deformation. Seven parameters influencing rock behavior are determined: uniaxial compressive strength (UCS), rock quality designation (RQD), joint surface condition, stress, ground water, earthquake, and tunnel span. They are classified into rock mass intrinsic, rock mass extrinsic, and design parameters. An advantage of this procedure is its ability to obtain each parameter’s weighting. We applied the proposed method to the basic design of Seoul Metro Line 9 and quantified the rock behavior into RBI on rock fall, cave-in, and plastic deformation. The study results demonstrate that AHP can give engineers quantitative information on rock behavior.

Methodology to quantify rock behavior around shallow tunnels by Rock Engineering Systems

김만광,유영일,송재준 한국자원공학회 2008 Geosystem engineering Vol.11 No.2

For quantitative identification of rock behavior in shallow tunnels, we recommend using the rock behavior index (RBI) within the Rock Engineering Systems (RES) approach. RES can aid engineers in effectively determining complex and un-structured rock behavior utilizing interaction matrices. Rock behavior types can be classified into three groups: cave-in, rock fall and plastic deformation. Seven parameters influence rock behavior: rock mass compressive strength, rock quality designation (RQD), joint surface condition, stress, ground water, earthquake, and tunnel span. An advantage of RES is its ability to obtain each parameter’s weighting. We quantified the rock behavior into RBI on fall, cave-in, and plastic deformation. The study results demonstrate that RES can give engineers quantitative information on rock behavior. The proposed model is illustrated via a case study on Seoul Metro Line 9. For quantitative identification of rock behavior in shallow tunnels, we recommend using the rock behavior index (RBI) within the Rock Engineering Systems (RES) approach. RES can aid engineers in effectively determining complex and un-structured rock behavior utilizing interaction matrices. Rock behavior types can be classified into three groups: cave-in, rock fall and plastic deformation. Seven parameters influence rock behavior: rock mass compressive strength, rock quality designation (RQD), joint surface condition, stress, ground water, earthquake, and tunnel span. An advantage of RES is its ability to obtain each parameter’s weighting. We quantified the rock behavior into RBI on fall, cave-in, and plastic deformation. The study results demonstrate that RES can give engineers quantitative information on rock behavior. The proposed model is illustrated via a case study on Seoul Metro Line 9.

계층 분석적 의사결정과 암반 공학 시스템에 의한 저심도 암반터널에서의 암반거동 유형 정량화 방법론

유영일(Yoo Young-Il),김만광(Kim Man-Kwang),송재준(Song Jae-Joon) 한국암반공학회 2008 터널과지하공간 Vol.18 No.6

저심도 터널 굴착시 예상되는 암반 거동을 정량적으로 파악하기 위해 계층 분석적 의사결정 방법과 암반 공학 시스템 방법을 적용하여 암반 거동 지수를 산정하였다. 복잡하고 조직화되지 않은 암반 거동을 효과적으로 결정하기 위해 쌍대 비교 매트릭스를 이용하는 계층 분석적 의사결정 방법과 상호 영향 매트릭스를 이용하는 암반 공학 시스템 방법을 적용하였고, 전문가 의견의 불확실성을 극복하고자 퍼지 델파이 방법을 적용하였다. 저심도 암반 터널 굴착 시 예상되는 암반 거동 유형으로 소성 변형, 낙반과 낙석을 제시하였다. 각각의 암반거동 유형을 결정하기 위해 일축압축강도, 암질 지수와 절리 조건을 포함하는 암반 내생적 매개변수, 응력, 지하수와 지진 조건을 포함하는 암반 외생적 매개변수와 굴착 매개변수를 고려하였다. 이를 서울 지하철 ○호선 ○공구 설계에 적용하여 예상되는 암반 거동 유형을 정량적인 암반 거동 지수로 제시하였다. For the quantitative identification of rock behavior in shallow tunnels, we recommend using the rock behavior index (RBI) by the analytic hierarchy process (AHP) and the Rock Engineering Systems (RES). AHP and RES can aid engineers in effectively determining complex and un-structured rock behavior utilizing a structured pair-wise comparison matrix and an interaction matrix, respectively. Rock behavior types are categorized as rock fall, cave-in, and plastic deformation. Seven parameters influencing rock behavior for shallow depth rock tunnel are determined: uniaxial compressive strength, rock quality designation (RQD), joint surface condition, stress, ground water, earthquake, and tunnel span. They are classified into rock mass intrinsic, rock mass extrinsic, and design parameters. An advantage of this procedure is its ability to obtain each parameter’s weight. We applied the proposed method to the basic design of Seoul Metro Line ○ and quantified the rock behavior into RBI on rock fall, cave-in, and plastic deformation. The study results demonstrate that AHP and RES can give engineers quantitative information on rock behavior.

Methodology to quantify rock behavior around shallow tunnels by Analytic Hierarchy Process and Fuzzy Delphi Method

Yoo, Young-Il,Song, Jae-Joon 한국암반공학회 2008 Geosystem engineering Vol.11 No.2

For the quantitative identification of rock behavior in shallow tunnels, we recommend using the rock behavior index (RBI) by combining the analytic hierarchy process (AHP) and the fuzzy Delphi method (FDM). AHP can aid engineers in effectively determining complex and un-structured rock behavior utilizing a structured pair-wise comparison matrix. FDM can assist them to overcome the uncertainty in the expert judgment. Rock behavior types are categorized as rock fall, cave-in, and plastic deformation. Seven parameters influencing rock behavior are determined: uniaxial compressive strength (UCS), rock quality designation (RQD), joint surface condition, stress, ground water, earthquake, and tunnel span. They are classified into rock mass intrinsic, rock mass extrinsic, and design parameters. An advantage of this procedure is its ability to obtain each parameter s weighting. We applied the proposed method to the basic design of Seoul Metro Line 9 and quantified the rock behavior into RBI on rock fall, cave-in, and plastic deformation. The study results demonstrate that AHP can give engineers quantitative information on rock behavior.

Methodology to quantify rock behavior around shallow tunnels by Rock Engineering Systems

Kim, Man-Kwang,Yoo, Young-Il,Song, Jae-Joon 한국암반공학회 2008 Geosystem engineering Vol.11 No.2

For quantitative identification of rock behavior in shallow tunnels, we recommend using the rock behavior index (RBI) within the Rock Engineering Systems (RES) approach. RES can aid engineers in effectively determining complex and un-structured rock behavior utilizing interaction matrices. Rock behavior types can be classified into three groups: cave-in, rock fall and plastic deformation. Seven parameters influence rock behavior: rock mass compressive strength, rock quality designation (RQD), joint surface condition, stress, ground water, earthquake, and tunnel span. An advantage of RES is its ability to obtain each parameter's weighting. We quantified the rock behavior into RBI on fall, cave-in, and plastic deformation. The study results demonstrate that RES can give engineers quantitative information on rock behavior. The proposed model is illustrated via a case study on Seoul Metro Line 9.

High-temperature tensile deformation behavior of hot rolled CrMnFeCoNi high-entropy alloy

Jang, Min Ji,Praveen, S.,Sung, Hyun Je,Bae, Jae Wung,Moon, Jongun,Kim, Hyoung Seop Elsevier 2018 Journal of Alloys and Compounds Vol.730 No.-

<P><B>Abstract</B></P> <P>In the present study, high temperature (700–1100 °C) tensile deformation behavior of hot-rolled CrMnFeCoNi high-entropy alloy was investigated. A single face-centered cubic phase was retained in the hot deformed specimens under different deformation conditions. The flow behavior was significantly influenced by temperature and microstructure evolution. A strong temperature dependence of yield stress was observed with a drastic drop in yield strength from 413 MPa at 700 °C to 94 MPa at 900 °C. A profound increase in ductility was observed above 700 °C and a perceptive decrease in ductility was observed above 900 °C. Electron backscatter diffraction analysis indicates incomplete dynamic recrystallization at 700 °C leading to a significant difference in the flow behavior.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The high-temperature tensile deformation behavior of hot rolled HEA was studied. </LI> <LI> FCC single phase is retained during hot deformation. </LI> <LI> The yield stress strongly depends on the testing temperature. </LI> <LI> A profound increase in ductility was observed at 900 °C due to DRX. </LI> <LI> Steady-state flow stress was observed in the samples tested above 700 °C. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Micromechanical analysis of the tensile deformation behavior for 3D printed unidirectional continuous fiber reinforced thermos-plastic composites

Jiuru Lu,Luyao Xu,Jun Hu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.12

The aim of this study is to analysis the tensile deformation behavior of 3D printed unidirectional continuous fiber reinforced thermos-plastic composites (UD-CFRTP). Tensile experiments were performed to obtain the deformation curves and tensile properties of composites specimens. It is found that the reinforcement fiber bundles of specimens bearing the load non-synchronously. Meanwhile, with the fiber content change, the deformation form could be different. An improved micromechanical model was proposed to investigate the influence of non-synchronous phenomenon and fiber content on the deformation behavior. The fiber content is measured by the number of reinforcement fiber bundles instead of fiber volume fraction in this model. Based on this model, the deformation behavior and tensile properties of test specimens with different fiber bundles number were analyzed in detail. The analytical results about deformation behavior and tensile properties show a good agreement with experiment results.

분무주조 고속도공구강의 고온변형 거동에 관한 연구

하태권,정재영 한국소성∙가공학회 2018 소성가공 : 한국소성가공학회지 Vol.27 No.2

In the present study, the mechanical behavior of the spray-formed high speed steel was investigated employing the internal variable theory of inelastic deformation. Special attention was focused on the effect of the microstructure evolution during the hot working process, such as the distribution of carbides to provide a basic database for the production condition of high speed steels with excellent properties. The billets of high speed steel ASP30TM were fabricated by a spray forming, and the subsequently hot-rolled and heat-treated process to obtain uniformly distributed carbide structure. As noted the spray-formed high speed steel showed relatively coarser carbides than hot-rolled and heat-treated one with fine and uniformly distributed carbide structure. The step strain rate tests and high temperature tensile tests were carried out on both the spray-formed and the hot-rolled specimens, to elucidate their high temperature deformation behavior. The spray-formed high speed steel showed much higher flow stress and lower elongation than the hot-rolled and heat-treated steel. During the tensile test at 900oC, the interruption of the deformation for 100 seconds was conducted to reveal that the recovery was a main dynamic deformation mechanism of spray formed high speed steel. The internal variable theory of the inelastic deformation was used to analyze data from the step strain rate tests, revealing that the activation energies for hot deformation of as-spray-formed and hot-worked steels, which were 157.1 and 278.9 kJ/mol, and which were corresponding to the dislocation core and lattice diffusions of -Fe, respectively

Deformation behavior and tensile properties of an austenitic Fe-24Mn-4Cr-0.5C high-manganese steel: Effect of grain size

Lee, Sang-In,Lee, Seung-Yong,Han, Jeongho,Hwang, Byoungchul Elsevier 2019 Materials science & engineering. properties, micro Vol.742 No.-

<P><B>Abstract</B></P> <P>Deformation behavior and tensile properties of an austenitic Fe-24Mn-4Cr-0.5C high-manganese steel with different grain sizes were discussed in this study. Effective grain size including annealing twins and stacking fault energy increased with increasing annealing temperature from 800 °C to 1200 °C. Room-temperature tensile test results indicated that the yield and tensile strengths increased, but the total elongation decreased with decreasing the effective grain size. According to electron back-scattered diffraction and transmission electron microscopy analyses, the deformed microstructure of all the specimens having stacking fault energy between 24.0 mJ/m<SUP>2</SUP> and 31.6 mJ/m<SUP>2</SUP> showed deformation twinning. However, the formation of the deformation twinning was suppressed with decreasing the grain size, resulting in different work hardening behaviors. Experimental and calculated twinning stress increased with decreasing the grain size because dislocation activity and the movement of partial dislocations required for form the deformation twinning were further inhibited by interaction of relatively high dislocation density in specimens with finer grain size.</P>

A Study on Torsional Characteristics of the Car Body Types at Cornering Motion

Joon-Seong Lee(이준성),Seong-Gyu Cho(조성규) 한국산학기술학회 2017 한국산학기술학회논문지 Vol.18 No.10

탄성변형과 피로손상은 카트의 주행성능에 영향을 미치는 것으로 카트 프레임에 영구변형을 유발할 수 있다. 카트프레임은 현가장치와 다른 장치를 포함하지 않으므로 두 가지 변형에 결정적인 영향을 미칠 수 있는 코너주행 시 동적 거동은 비틀림 변형이 원인이 된다. 선회주행 시 카트의 동적 거동을 분석하기 위해 카트의 GPS추적이 실시간으로 이루어지고 카트프레임에 작용하는 비틀림 응력값을 측정하였다. 레저카트와 레이싱카트의 재료물성치들은 인장실험을 통해 얻었다. 비틀림 응력집중과 프레임 변형은 얻어진 결과 값을 토대로 프레임의 응력해석을 통하여 파악하였다. 개발된 주행분석장치를 이용하여 레저카트와 레이싱카트를 각 조건별로 실차실험을 수행하였고 이를 통한 코너에서 카트의 주행거동을 살펴보았다. 카트가 곡선주행 시 원심력으로 인해 하중이동이 발생하였으며 카트프레임에 비틀림 응력이 발생하였다. 예를 들어 레저카드의 경우, 40 km/h의 속도로 운전할 때 최대 비틀림 피로한도를 측정한 최대 비틀림응력은 230 MPa이며 비틀림 피로한도계수는 0.65를 나타내었다. 뿐만 아니라 카트의 선회 시 운전요소들을 운전측정시스템을 인스톨한 실측장비에서 측정하였으며 카트의 운전거동은 수직변위에 의해 측정하였다. Elastic deformation and fatigue damage can cause the permanent deformation of a kart"s frame during turning, affecting the kart"s driving performance. A kart"s frame does not contain any suspension ordifferential devices and, therefore, the dynamic behavior caused by torsional deformation when driving along a curve can strongly affect these two kinds of deformations. To analyze the dynamic behavior of a kart along a curved section, the GPS trajectory of the kart is obtained and the torsional stress acting on the kart-frame is measured in real time. The mechanical properties of leisure and racing karts are investigated by analyzing their material properties and conducting a tensile test. The torsional stress concentration and frame distortion are investigated through a stress analysis of the frame on the basis of the obtained results. Leisure and racing karts are tested in each driving condition using driving analysis equipment. The behavior of a kart when being driven along a curved section is investigated through this test. Because load movement occurs owing to centrifugal force when driving along a curve, torsional stress acts on the kart"s steel frame. In the case of a leisure kart, the maximum torsional stress derived from the torsional fatigue limit wasfound to be 230 MPa, and the torsional fatigue limit coefficient was 0.65 when driving at a speed of 40 km/h. Furthermore, the driving elements during thecornering of a kart were measured based on an actual auto-test after installing a driving measurement system, and the driving behavior of the kart was analyzed by measuring its vertical displacement.