• 한국지반공학회논문집
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• 제21권7호
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• pp.31-42
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• 2005

본 연구에서는 락필댐 축조재에 대하여 대형 삼축압축시험 및 대형 오이도미터시험을 실시하고 재료의 전단강도 및 압축 특성에 관하여 조사하였다. 삼축압축시험시 재료의 다짐도 및 구속압을 변화시켜 이에 따른 재료의 전단거동 및 강도특성을 조사하였고 오이도미터 시험을 통하여 일정 단위중량의 입도분포 및 함수상태가 다른 재료의 파쇄 및 압축성을 관찰하였다. 삼축압축시험결과 다짐도 및 구속압에 따라 재료의 전단팽창성에 차이가 나타나고 이들 조건들이 전반적인 거동 및 전단강도에 영향을 미치는 것으로 나타났다. 오이도미터시험결과 재료의 평균입자크기의 증가와 함께 파쇄율이 증가하고 입도분포가 상대적으로 양호한 시료의 압축성이 적은 것으로 나타나 일반적인 조립재의 압축특성을 잘 반영하는 것으로 나타났다. 그리고 포화시료가 건조시료에 비하여 다소간 높은 압축성을 나타내었으며 접선구속계수 산정결과 포화시료의 계수값이 건조시료에 비하여 평균적으로 10$\~$20$\%$ 큰 것으로 나타났다.

• 콘크리트학회논문집
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• 제16권3호
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• pp.345-356
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• 2004

다양한 압축 응력 상태에서의 콘크리트의 거동 특성을 나타내기 위한 소성 모델을 개발하였다. 응력 성분은 압축 상태에서 각각의 거동특성을 갖는 세 개의 직교 성분으로 분리하였다. 각 성분의 거동 특성을 독립적으로 나타내기 위하여 각 성분에 대한 독립적인 다중 파괴기.준을 이용하는 소성모델을 적용하였다. 각 파괴면은 실험결과에 근거하여 각 파괴기준에 대한 등가 소성 변형률에 의하여 정의하였다. 또한, 압축손상에 의한 체적팽창을 나타내기 위한 간단한 비상관 소성흐름법칙을 제안하였다. 제안된 모델은 다양한 재료 특성 및 응력 상태를 갖는 기존의 실험 결과들과 비교를 통하여 검증되었다. 이 비교는 기존의 소성모델보다 제안된 모델의 적용성이 우수함을 입증하고 있다.

• 한국지반공학회논문집
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• 제19권2호
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• pp.7-14
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• 2003

본 연구는 광양만 지역과 목포 남악지역의 점토를 이용하여 양생온도를 20$\times$, 50$\times$ , 80$\times$로 달리하고 각각의 온도에서 양생기간을 1일, 7일 14일, 40일로 하여 재성형.재압밀 시료를 제작하여 양생온도.양생기간이 연대효과 재현에 어떤 영향이 있는지를 밝히고, 불교란시료와 재압밀된 점토의 역학적 특성과 연대효과의 특성을 알아보기 위하여 1축압축시험, 3축압축시험 그리고 표준압밀시험을 실시하였다. 그 결과 압축지수비는 원지반점토의 연대효과를 나타내는데 유용한 지수임을 확인할 수 있었으며 또한 고온으로 양생한 점토가 연대효과를 잘 표현하고 연대효과의 재현에 필요한 최적의 양생온도는 80$\times$ 정도 부근이고 양생기간은 27일정도 임을 알 수 있었다.

• 한국지반신소재학회논문집
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• 제9권3호
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• pp.19-27
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• 2010

본 연구에서는 제주도 현무암에 대한 삼축압축시험을 실시하고 Lade(1977)의 3차원 파괴규준을 적용하여 강도정수를 산정하였다. 그리고 3차원 파괴규준에 의해 산정된 강도정수와 파괴면의 특성을 살펴보고, Mohr-Coulomb의 파괴규준으로 산정한 전단강도정수와 비교검토하였다. 삼축압축시험결과를 토대로 Lade(1977)의 3차원 파괴규준을 이용하여 파괴시의 ($I_1^3/I_3-27$)과 ($P_a/I_1$) 관계로부터 매개변수인 ${\eta}_1$ 및 m을 구하였다. 3차원 파괴면을 나타내는 정팔면체 평면에서 조면암질 현무암의 파괴면이 가장 크고 스코리아가 가장 작으며, 단면형상은 조면암질 현무암이 가장 삼각형에 가깝고 스코리아가 가장 원형에 가까운 것으로 나타났다. 정팔면체 평면에서 삼축실험결과와 Lade의 파괴포락선 및 Mohr-Coulomb의 파괴포락선을 비교한 결과 높은 응력하에서는 Lade의 파괴규준이 실험치와 일치하며, 낮은 응력하에서는 Mohr-Coulomb의 파괴규준이 실험치와 일치하는 것으로 나타났다. 그리고 Lade의 3차원 파괴면은 Mohr-Coulomb의 3차원 파괴면보다 크며, 이는 Lade의 파괴규준으로 산정된 전단강도정수가 Mohr-Coulomb의 파괴규준으로 구한 것 보다 더 크게 산정됨을 의미한다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 토목섬유 학술발표회 논문집
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• pp.143-155
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• 1999

An experimental study has been carried out to investigate the reinforcing effect of marine dredging clay(MDC) mixed with the Micro-Fiber(MF). A series of laboratory tests was performed using specimens of MDC alone and MDC with MF by means of uniaxial and triaxial compression test. In the test programme, three stages of water content of MDC were chosen according to the elapsed time after dredging, and content and length of MF were considered as important factors for reinforcing effect. And the developed strength due to curing was measured both in MDC and composite. The enhancement of strength of composite was found to be increased with the increasing content and length of MF, and curing time, and with decreasing water content of MDC. An additional study has been made for in-situ trafficability on the soft reclaimed ground by MDC due to high water content. It was found that the waste lime was to be applicable for this purpose to get a reinforcing effect of MDC. A further study would lead to the better understanding of the reinforcing mechanism of the composite.

• 소성∙가공
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• 제11권1호
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• pp.69-74
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• 2002

In addition to lightweight and moldable characteristics, polymeric foams possess an excellent energy absorbing capability that can be utilize for a wide range of commercial applications, especially in the crashworthiness of the automobiles. The purpose of the present study is to develop experimental methodology to characterize the pressure dependent yield behavior of the energy absorbing polymeric foams. For the compression test in a triaxial stress sate, a specially designed device was placed in a hydraulic press to produce and control oil pressure. For the test material, the polyurethane foams of two different densities were used. The displacement of the specimen, the load subjected to the specimen, and oil pressure applied to the specimen were measured and controlled. Stress strain curves and yield stresses for the four different oil pressure were obtained. It was found from the present experiments that the polyurethane foams exhibited significant increases in yield stress with applied pressure or mean normal stress. Based on this observation, a yield criteria which included the effect of the stress invariant were established for the polymeric foams. The obtained experimental constants which constituted the pressure-dependent yield criterion were verified.

• Computers and Concrete
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• 제22권6호
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• pp.563-572
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• 2018

Uniaxial compressive strength test and uniaxial compression creep one were produced on four groups of twelve concrete specimens with different hole number by RLW-2000 rock triaxial rheology test system. The relationships between horizontal holes and instantaneous failure stress, the strain, and creep failure stress, the strain, and the relationships between stress level and instantaneous strain, creep strain were studied, and the relationship between horizontal holes and failure mode was determined. The results showed that: with horizontal hole number increasing, compressive strength of the specimens decreased whereas its peak strain increased, while both creep failure strength and its peak strain decreased. The relationships between horizontal holes and compressive strength of the specimens, the peak strain, were represented in quadratic polynomial, the relationships between horizontal holes and creep failure strength, the peak strain were represented in both linear and quadratic polynomial, respectively. Instantaneous strain decreased with stress level increasing, and the more holes in the blocks the less the damping of instantaneous strain were recorded. In the failure stress level, instantaneous strain reversally increased, creep strain showed three stages: decreasing, increasing, and sharp increasing; in same stress level, the less holes the less creep strain rate was recorded. The compressive-shear failure was produced along specimen diagonal line where the master surface of creep failure occurred, the more holes in a block, the higher chances of specimen failure and the more obvious master surface were.

• 한국농공학회지
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• 제31권2호
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• pp.66-81
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• 1989

The characteristics of resilient modulus(Mr) which dominates the life of pavement and the design of pavement were investigated on the test specimens which were cement treated and non-treated of the three different soil types. The results are summarized as follows : 1. The resilient modulus was decreased by increasing the cyclic deviator stress ($\sigma$d) , especially the resilient modulus was gradually decreased or sometimes increased when the value of ad was greater than 0.75- 1. 0kg/cm$^2$. 2. The resilient modulus was increased by increasing the homogeneous confined stress ($\sigma$do) and such phenomena were distinct on the coarse soils. 3. The resilient modulus was increased by increasing the ratio of confined stress(Kc), and this phenomena were eminent on the coarse soils too, and the higher permanent strain was showed by increasing the value of Kc. 4. In the drained cyclic triaxial compression test, the value of ad, Kc, and (Oho) was introduced by the following interrelated equations which were similar to the Mr model of Cole. Kcn/Mr=K1(J$_2$/ $\tau$oct)K2 ............. (coarse soli) Mcn/Mr=K3($\sigma$dp/ $\tau$f)k4 ...............(fine soils) 5. The stress path was not much affected by the value of Mr, however, moisture content, dry desity, and contant of fines affected the value of Mr. 6. In the soil-cement specimens, the resilient compression strain($\varepsilon$d) was decreased by the increment of the $\sigma$ho, and Mr was decreased by increasing the $\sigma$d 7. In the flexible pavement. the cement treated layer should be designed not to fail by the fatigue before the designed traffic load, and actually the pavement could cover the traffic load to a certain extent under the post-crack phase, therefore farther studies on this phenomena' are required in the design analysis. 8. The finite element computer program (ANALYS) was used for displacement analysis of pavement containing the cement-treated layer, The result showed that the program used for this analysis was proved to be usable.

• 한국농공학회지
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• 제39권1호
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• pp.102-111
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• 1997

Experiments both in laboratory and field were performed to compare and analyze the characteristics of alluvial clay. The alluvial clay was sampled in test site in which large-scaled tests for the part of the site are under process to suggest the rational method for alluvial clay and the criterion for ground settlement monitoring system. The followings were observed through the experiments : 1. Natural water content, plastic limit, and liquid limit of alluvial clay composed of highly fine grains were 40~80%, 10~20%, and 30~55%, respectively. The values of these properties were relatively small at the ground surface, while the values showed maximum at G.L.- l0m and gradually decreased below the level. 2. Shear strength of alluvial clay was proportionally increased to the depth. Unconfined and triaxial compressive strengths were 0.2~0.6kgf/$cm^2$ and 0.1~0.3kgf/$cm^2$, respectively. 3. Compression index and secondary compression index showed maximum values at G.L.-l0m and gradually decreased below the level. The value of consolidation coefficient was relatively large at the ground surface, constant with decreasing the depth, and incresed when G.L. was below -20m. 4. Piezocone test appeared that alluvial clay with N value of 2~4 was uniformly distributed with 20~ 30m thickness from the ground surface, sand seam was nonuniformly distributed, and penetration pore pressure was 0.8 ~ 1 times of the hydrostatic pressure. Undrained shear strength and consolidation coefficient were 0.04 ~ 0.76kgf / $cm^2$ and $2.88{\times} 10{^-4}~1.3{\times} 10{^-2} cm^2/s$ respectively.

• 한국지반신소재학회논문집
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• 제9권4호
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• pp.39-45
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• 2010

부직포에 의한 보강이 모래의 역학적 거동에 미치는 영향에 대해 검토하였다. 이 검토를 위해 보강모래와 무보강모래에 대한 일련의 삼축압축시험이 수행되었다. 표준사인 주문진사가 사용되었고, 부직포 보강재가 모래시료 속에 최대 3층 배치되었다. 분석결과 모래속의 부직포 배치는 모래의 전단강도를 크게 증가시켰고, 보강모래는 파괴시의 변형률도 증가하였다. 또한, 보강층수가 증가할수록 보강재에 의한 시료내 전단층의 확산 방지효과의 증가로 보다 연성화하고, 모래시료의 체적팽창 경향은 부직포 배치에 의해 억제됨이 밝혀졌다. 보강층수 증가에 의한 효과는 간극비 감소로 인한 효과와 같다.