• 한국해양공학회지
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• 제25권3호
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• pp.34-39
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• 2011

This study investigated the shear and CBR characteristics of dredge soil-bottom ash-waste tire powder-mixed lightweight soil, which was developed to recycle dredged soil, bottom ash, and waste tire powder. Test specimens were prepared with various contents of waste tire powder ranging from 0 to 100% at 50% intervals by the weight of the dry dredged soil. Several series of triaxial compression tests and CBR tests were conducted. The shear strength characteristics of the lightweight soil were compared using two different shear tests (triaxial compression test and direct shear test). The experimental results indicated that the internal friction angle of the lightweight soil obtained by the direct shear tests was greater than that by the triaxial shear tests. However, the cohesion value obtained by the triaxial shear tests was greater than that by the direct shear tests. The CBR value of the lightweight soil decreased from 35% to 15% as waste tire powder content increased.

• Geomechanics and Engineering
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• 제15권1호
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• pp.687-694
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• 2018

To investigate the crushing behaviour of coarse granular materials, a specifically designed, large-scale simple shear apparatus with eight-staged shearing rings was developed. A series of monotonic simple shear tests were conducted on two kinds of coarse granular materials under different vertical stresses and large shear strains. The evolution of the particle breakage during the compression and simple shearing processes was investigated. The results show that the amount of particle breakage is related to the particle hardness and the state of the stresses. The amount of particle breakage is greater for softer granular materials and increases with increasing vertical stresses. Particle breakage may tend towards a critical value during both the compression and the shearing processes. Particle breakage mainly occurs during the processes of confined compression and contraction.

• 한국지반신소재학회논문집
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• 제15권4호
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• pp.63-69
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• 2016

본 논문은 삼축압축시험(CD)과 개선된 직접전단시험 결과 얻어진 불포화토의 전단특성을 비교분석하여 새로이 개선된 직접전단시험장비의 실용성을 검증하였다. 2010년 경기도 양평군 토석류 발생사면에서 채취한 시료를 대상으로 불포화토 상태의 전단강도실험을 수행하였다. 다른 두 종류의 실험방법에서 낮은 모관흡수력이 작용하는 경우는 전단강도와 선형적인 관계를 나타내며, 모관흡수력의 증가함에 따라 불포화토의 겉보기 점착력 역시 선형적으로 증가하였다. 다른 두 실험장비에 의한 결과를 비교한 결과, 산정된 불포화토의 강도정수($c^{\prime}$, ${\phi}^b$)는 전단 상자의 구속효과가 있는 개선된 직접전단시험에서 다소 크게 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1377-1383
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• 2005

Mechanical properties of Municipal Solid Wastes(MSW) and their influencing parameters were studied by using a series of triaxial compression tests and resonant column tests. The shear strength of MSW can be modeled by a bilinear failure criterion. As the unit weight increasing, cohesion and internal friction were increased linearly on semi-log scale. As the proportion of waste to soil increases, maximum shear moduli tend to decrease whereas minimum damping ratios increase. Shear moduli and damping of degradable waste are higher than those of non-degradable MSW.

• Geomechanics and Engineering
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• 제5권6호
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• pp.499-517
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• 2013

In order to investigate shear behavior of granular materials due to excavation and associated unloading actions, load-controlled plane strain compression tests under decreasing confining pressure were performed under drained conditions and the results were compared with the conventional plane strain compression tests. Four types of granular material consisting of two quartz sands and two glass beads were used to investigate particle shape effects. It is clarified that macro stress-strain behavior is more easily influenced by stress level and stress path in sands than in glass beads. Development of localized deformation was analyzed using photogrammetry method. It was found that shear bands are generated before peak strength and shear band patterns vary during the whole shearing process. Under the same test condition, shear band thickness in the two sands was smaller than that in one type of glass beads even if the materials have almost the same mean particle size. Shear band thickness also decreased with increase of confining pressure regardless of particle shape or size. Local maximum shear strain inside shear band grew approximately linearly with global axial strain from onset of shear band to the end of softening. The growth rate is found related to shear band thickness. The wider shear band, the relatively lower the growth rate. Finally, observed shear band inclination angles were compared with classical Coulomb and Roscoe solutions and different results were found for sands and glass beads.

• Steel and Composite Structures
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• 제44권6호
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• pp.883-898
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• 2022

A hollow-core partially-encased composite beam, named HPEC beam, is investigated in this paper. HPEC beam comprises I-beam, longitudinal reinforcement, stirrup, foam formwork, and cementitious grout. The foam formwork is located on both sides of the web, and cementitious grout is cast within the steel flange. To investigate the shear performance of HPEC beams, static loading tests of six HPEC beams and three control beams were conducted. The shear span ratio and the number of studs on the shear behavior of the HPECspecimens were studied. The failure mechanism was studied by analyzing the curves of shear force versus both deflection and strain. Based on the shear span ratio (𝜆), two typical shear failure modes were observed: shear compression failure when 1.6 ≤ 𝜆 ≤ 2; and diagonal compression failure when 𝜆 ≤ 1.15. Shear studs welded on the flange can significantly increase the shear capacity and integrity of HPEC beams. Flange welded shear studs are suggested. Based on the deformation coordination theory and superposition method, combined with the simplified modified compression field model and the Truss-arch model, Modified Deformation Coordination Truss-arch (M.D.C.T.) model was proposed. Compared with the shear capacity from YB9038-2006 and JGJ138-2016, the calculation results from M.D.C.T. model could provide reasonable predictions.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1124-1131
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• 2008

Thanks to a new in-situ seismic probe, using bender elements and penetration scheme, a simple linear relationship between undrained shear strength(Cu) and shear wave velocity(Vs) was obtained. This priceless relationship is worthy to be illuminated further in ideal laboratory environment. To avoid sampling disturbance effect, special consolidation cylinders were used to make normally consolidated specimens from kaolinite suspension. The undrained shear strengths of the specimens were measured using unconsolidated undrained triaxial compression tests. Also shear wave velocity measurements were performedprior to shearing the same specimens, using the bender elements installed in the base pedestal and the top cap of the triaxial compression cell. The Cu-Vs relationship is fairly linear and supports the linear trend of clayey silt obtained using field testing. Also the classic density-shear modulus relationship for soft clay proposed by Hardin and Black(1969) was once more verified hereby.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1181-1192
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• 2008

A laboratory investigation was carried out into effects of strain rate on undrained shear behavior of Holocene clay underneath Kobe Airport with an objective to evaluate the factor of safety of the retaining structure built on it. It was examined in a series of triaxial compression and extension tests performed using different rate of axial straining. A comparative compression test in which the strain rate was changed in steps was also carried out. Similar tests were performed in constant-volume direct shear box (DSB) test. And, the deformation characteristics of the clay were also examined in order to evaluate the variation of stiffness during undrained shearing. It was found that the undrained strength increased with not only the shear rate but also the consolidation period. ISOTACH properties seemed a key to govern the undrained shear behavior.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.827-830
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• 2008

In this study, large triaxia mpression tests of sand-gravel soils were carry out to clarify the influence of fines on shear strength characteries. Two soil specimens with/without fines that is used for construction material of dam were prepared. One was reproduced with wide range of grain size and the other was removed fines below 2mm from the one. The compaction tests proposed by our center were performed to obtain relative density of the specimens, and then each specimen was adjusted two dry density. The large triaxial compression tests were carry out under CD condition. Based on the results, the sand-gravel soils with low fines content has no effect on shear strength characteries.

• 한국지반공학회논문집
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• 제18권1호
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• pp.29-39
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• 2002

본 연구에서는 미소변형률에서 파괴규준을 포함하는 대변형률에 이르는 전체 변형률 영 역의 거동을 획득하기 위하여, LVDT를 장착하여 국부변위를 측정한 삼축압축시험을 수행하였다. 이러한 결과 미소변형률(0.001% 수준)에서 대변형를까지(10%)의 거동을 합리적으로 구할 수 있었으며, 불교란 및 교란 풍화토 시료에서의 변형계수가 미소변형률 영역에서 유사하게 나타났다. 그리고 공진주(RC)시험과 비배수 삼축압축시험에서 구한 정규화 전단변형계수$(G/G_{max})$ 곡선이 일치한 반면 최대전단변형계수$(G/G_{max})$는 포화도에 따라 상이하게 나타났다. 또한 비등방경화 구성모델의 계수 연구를 통하여 전체 변형률 영역 거동을 합리적으로 예측할 수 있음을 확인하였다.