• 한국해양공학회지
• /
• 제18권4호
• /
• pp.46-51
• /
• 2004

The surface layer in dredged and reclaimed marine clay is improved by mixing of shallow soils and hardening agents, which is made of cement, containing some other special admixtures. Tests in both laboratory and field settings are performed to investigate the improvement effect and strength properties of cement-stabilized soils. The test results show that the hardening agent sufficiently improves the soil properties of the surface layer, while increasing the load-carrying capacity. The strength of cement-stabilized soils depends, primarily, on water-to-cement ratio and curing temperature. That is, the higher curing temperature and the longer curing time, the higher the strength in cement-stabilized soils. The high ratio of water-ta-cement results in a lower strength.

• 실내환경 및 냄새 학회지
• /
• 제16권2호
• /
• pp.139-149
• /
• 2017

In order to reduce odor and methane emission from the landfill, open biocovers and a closed biofilter were applied to the landfill site. Three biocovers and the biofilter are suitable for relatively small-sized landfills with facilities that cannot resource methane into recovery due to small volumes of methane emission. Biocover-1 consists only of the soil of the landfill site while biocover-2 is mixed with the earthworm casts and artificial soil (perlite). The biofilter formed a bio-layer by adding mixed food waste compost as packing material of biocover-2. The removal efficiency decreased over time on biocover-1. However, biocover-2 and the biofilter showed stable odor removal efficiency. The rates of methane removal efficiency were in order of biofilter (94.9%)>, biocover-1(42.3%)>, and biocover-2 (37.0%). The methane removal efficiency over time in biocover-1 was gradually decreased. However, drastic efficiency decline was observed in biocover-2 due to the hardening process. As a result of overturning the surface soil where the hardening process was observed, methane removal efficiency increased again. The biofilter showed stable methane removal efficiency without degradation. The estimate methane oxidation rate in biocover-1 was an average of 10.4%. Biocover-2 showed an efficiency of 46.3% after 25 days of forming biocover. However, due to hardening process efficiency dropped to 4.6%. After overturn of the surface soil, the rate subsequently increased to 17.9%, with an evaluated average of 12.5%.

• Journal of Ecology and Environment
• /
• 제46권3호
• /
• pp.218-242
• /
• 2022

Background: Promising specific growth regulators are employed in the tissue cultures of various bamboo species. Specific natural hardening mixtures support the acclimatization and adaptation of bamboo under protected cultivation. Results: The growth regulators like 2, 4-Dichlorophenoxyacetic acid (2, 4-D), Naphthaleneacetic Acid (NAA), Thidiazuron (TDZ), 6-Benzylaminopurine (BAP), Kinetin, Gelrite, Benzyl Adenine (BA), Indole Butyric Acid (IBA), Coumarin, Putrescine, Gibberellic acid (GA₃), Indole Acetic Acid (IAA) has been widely used for callus induction, root regeneration and imposing plant regeneration in various species of bamboo such as Bambusa spp. and Dendrocalamus spp. Different combinations of growth regulators and phytohormones have been used for regenerating some of the major bamboo species. Natural hardening materials such as cocopeat, vermicompost, perlite, cow dung, farmyard manure, compost, soil, garden soil, and humus soil have been recommended for the acclimatization and adaptation of bamboo species. Standard combinations of growth regulators and hardening mixtures have imposed tissue culture, acclimatization, and adaptation in major bamboo species. Conclusions: Bamboo contributes to soil fertility improvement and stabilization of the environment. Bamboo species are also involved in managing the biogeochemical cycle and have immense potential for carbon sequestration and human use. This paper aims to review the various growth regulators, natural mixtures, and defined media involved in regenerating major bamboo species through in vitro propagation. In addition, the ecological benefits of safeguarding the environment are also briefly discussed.

• 한국산업융합학회 논문집
• /
• 제15권1호
• /
• pp.21-27
• /
• 2012

Decomposed granite soils are in a wide range of conditions depending on the degrees of weathering. This paper is intended to examine laboratory tests such as consolidation tests and conventional triaxial compression tests conducted in order to find out the mechanical properties of Cheongju granite soil. Along with the foregoing, the results of basic physical tests conducted in order to grasp the physical properties of Cheongju granite soil were described and based on the results, methods to calculate the mechanical parameters of numerical approaches using Lade's double surface work-hardening constitutive model were examined. Finally, it is intended to explain the stress properties of Cheongju granite soil used as a geotechnical material based on its shear behavior and critical state concept using the results of isotropic consolidation tests and triaxial compression tests. As a conclusion, it can be seen that in the relationship between confining stress and maximum deviator stress, the slope is maintained at a constant value of 2.95. In the drained CTC test, maximum deviator stress generally existed in a range of axial strain of 6~8% and larger dilatancy phenomena appeared when confining stress was smaller. Finally, based on the results of the CTC tests on Cheongju granite soil, although axial strain, deviator stress and pore water pressure showed mechanical properties similar to those of overconsolidated soil, Cheongju granite soil showed behavior similar to that of normally consolidated soil in terms of volumetric strain.

• 한국지반공학회지:지반
• /
• 제13권1호
• /
• pp.35-46
• /
• 1997

실제지반에 하중이 가하여 질 경우 발생되는 주응력회전시의 지반거동을 해석하기 위하여 등 방단일경화구성모델이 적용되었다. 이 모델에 의한 해석결과는 Ko압밀점토의 중공 원통형 공시체에 여러가지 응력경로를 대상으로 실시된 일련의 비틀림전단시험에 의한 시험치와 좋은 일치를 보이고 있다. 결국 주응력회전시의 지반거동은 등방압축 및 통상적인 압밀비배수 삼축압축시험으로 얻을 수 있는 간단한 정보만을 활용한 이 모델로 예측될 수 있음을 알았다. 비틀림전단시험결과와 해석결과 모두에서 등방탄소성 지반거동을 최초재하 (primary loading)단계 동안에 관찰할 수 있었다. 그러나, Ko압밀응력의 등방항복면내에서 감하나 수재하와 같은 응력 반전을 실시할 경우 최대주변형률증분 방향의 해석치는 시험치와 일치하지 않았다. 이는 응력반전시의 지반거동을 해석하기 위하여는 등방경화모델 (isotropic hardening model)보다 는 이동경화모델(kinematic hardening model)이 개발되어야함을 의미한다. 또한 본 연구에서는 일공간에서 변형률증분벡터의 시험치가 관련흐름법칙 및 비관련흐름법칙에 의한 해석법과 비교되었다.

• 한국지반공학회지:지반
• /
• 제8권2호
• /
• pp.81-96
• /
• 1992

본 문은 Lade의 단일항복면 구성모델(single work-hardening model)을 선정하여 사질토의 거동해석에 필요한 토질매개변수를 실내시험을 하여 구하는 과정에서 필연적으로 발생하는 실험오차가 해석결과에 미치는 영향을 분석하였다. 연구방법으로서는 백마강 모래에 대하여 등방압축-팽창시험과 구속압력을 달리한 일련의 배수삼축시험을 하고 이 시험자료를 이용하여 회귀분석을 근거로, 본 연구에서 개발된 토질 매개 변수 결정 프로그램에 의해 기찬매개변수를 결정하고 그 평균치에서 표준편차를 증감시켜 축방 향변형률에 대한 축차응력 및 체적변형률의 상계 및 하계 범위를 밝힘으로서 각 토질매개변수의 민감도를 규명하였다. 그 결과 토질매개변수결정 프로그램의 실용성이 크다는 것을 화인하고 Lade의 단일항복면 구성모델의 예측능력이 좋다는 것을 알았다.

• Geomechanics and Engineering
• /
• 제11권3호
• /
• pp.325-343
• /
• 2016

A total stress-based bounding surface model is developed to predict the undrained behaviour of saturated soft clays under cyclic loads based on the anisotropic hardening modulus field and bounding-surface theories. A new hardening rule is developed based on a new interpolation function of the hardening modulus that has simple mathematic expression and fewer model parameters. The evolution of hardening modulus field is described in the deviatoric stress space. It is assumed that the stress reverse points are the mapping centre points and the mapping centre moves with the variation of loading and unloading paths to describe the cyclic stress-strain hysteresis curve. In addition, by introducing a model parameter that reflects the accumulation rate and level of shear strain to the interpolation function, the cyclic shakedown and failure behaviour of soil elements with different combinations of initial and cyclic stresses can be captured. The methods to determine the model parameters using cyclic triaxial compression tests are also studied. Finally, the cyclic triaxial extension and torsional shear tests are performed. By comparing the predictions with the test results, the model can be used to describe undrained cyclic stress-strain responses of elements with different stress states for the tested clays.

• 한국지반환경공학회 논문집
• /
• 제2권2호
• /
• pp.59-64
• /
• 2001

고화재를 이용한 천층혼합처리공법을 적용할 경우, 주행성 확보, 공기의 단축, 치환토부족 문제 해결, 사토로 인한 환경문제해결 등의 장점으로 최근 그 활용가치가 점점 커지고 있다. 본 연구에서는 최적의 천층고화처리를 위하여 국내의 대표적인 3가지 고화재를 이용한 현장토의 실내개량강도 특성을 고화재별, 양생일수별, 함수비별로 분석하였다. 실내시험결과를 토대로 적정 배합비에 따른 현장강도를 추정하여 현장시공 후 개량보강효과를 확인하여, 현장개량강도는 소요설계강도 $5.0kgf/cm^2$이상 확보되었다.

• Geomechanics and Engineering
• /
• 제6권4호
• /
• pp.321-340
• /
• 2014

Uplift response of symmetrical circular anchor plates has been evaluated in physical model tests and numerical simulation using Plaxis. The behavior of circular anchor plates during uplift test was studied by experimental data and finite element analyses in loose sand. Validation of the analysis model was also carried out with 50 mm, 75 mm and 100 mm diameter of circular plates in loose sand. Agreement between the uplift responses from the physical model tests and finite element modeling using PLAXIS 2D, based on 100 mm computed maximum displacements was excellent for circular anchor plates. Numerical analysis using circular anchor plates was conducted based on hardening soil model (HSM). The research has showed that the finite element results gives higher than the experimental findings in the loose sand.

• Geomechanics and Engineering
• /
• 제6권6호
• /
• pp.593-612
• /
• 2014

The uplift response of symmetrical square anchor plates has been evaluated in physical model tests and numerical simulations using Plaxis. The behavior of square anchor plates during uplift test was studied by experimental data and finite element analyses in loose sand. Validation of the analysis model was also carried out with 50 mm, 75 mm and 100 mm Length square plates in loose sand. Agreement between the uplift responses from the physical model tests and finite element modeling using PLAXIS 2D, based on 100 mm computed maximum displacements was excellent for square anchor plates. Numerical analysis using square anchor plates was conducted based on the hardening soil model (HSM). The research has shown that the finite element results are higher than the experimental findings in loose sand.