• Journal of Forest and Environmental Science
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• 제30권1호
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• pp.113-119
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• 2014

To examine the soil reinforcement by the shrub with shallow root systems for slope stability, we developed insitu apparatus for direct shear test and conducted the insitu field tests for Lespedeza cyrtobotrya, a representative revegetation species for artificial hillslopes. The insitu field tests were conducted for two different soil conditions (the rooted soils and non-rooted soils) and we then compared the experimental values with those calculated from the Wu model. The results showed that the soil reinforcement derived from the insitu field tests ranged from 0.01525 to 0.1438 $kgf/cm^2$ while the one calculated from the Wu model ranged from 0.1952 to 0.2696 $kgf/cm^2$. Our finding suggests more field tests are needed to collect the related parameters in the model application thereby predicting the reliable soil reinforcement by the shrub root systems.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.442-451
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• 2008

The evaluation of field degree of consolidation on soft clays has been an important problem in geotechnical areas. Monitoring either settlements or pore water pressures has been widely applied in the filed, but occasionally they have some problems. This study addresses the suggestion and application of another method for evaluating the degree of consolidation using shear wave velocities. A research site where soft clay layers were consolidated by surcharging loads was chosen. Laboratory tests were performed to determine the relation between shear wave velocity and effective stress. Field seismic tests were conducted several times during the consolidation of the clay layers. The tests results show that the shear wave velocity increased significantly as clays consolidated. The shear wave velocities at each field stress states were derived from the laboratory results and the degree of consolidation was evaluated by comparing the shear wave velocities obtained by laboratory and field seismic methods. In most stress states, the degree of consolidation evaluated using the shear wave velocity matched well with that obtained from field settlement record, showing the potential of applying the method using shear waves in the evaluation of field degree of consolidation on soft clay deposits.

• 전기의세계
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• 제27권2호
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• pp.64-68
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• 1978

By applying the streamer breamer breakdown criterion and the surface roughness factor, the effet of field distortion due to conductor surface roughness on breakdown is investigated theoretically in a uniform-field of compressed SF$_{6}$. It has been shown that the streamer constant has a significant influence on the threshold of breakdown and different shapes of protrusions do not result in different thresholds of breakdowns. Moreover, uniform-field tests can give results which apply to e-ratio coaxial-electrode systems of practical dimensions, and may offer some advantages compared with coaxial-electrode tests.s.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.821-828
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• 2011

A significantly larger lateral load and moment are applied on a high speed railway bridge foundation than other bridge foundations. Therefore most of bridge foundations on Honam high speed railway project were designed by high strength steel pipe piles to resist lateral load and moment, which caused the increase of construction costs. In order to perform optimum design, it is important to estimate accurate lateral resistance when designing this type of structure. Lateral load tests were carried out based on the field design data with the purpose of examining the lateral behavioral characteristics of a railway bridge foundation. The standard load test method(ASTM D 3966) was used for field tests by applying twice of design load. Total four load tests were performed on high speed railway bridge foundations with strain gages installed by every 1m along piles to measure load-resistance characteristics under applied lateral loads. The back-calculated P-y curves from strain gages were compared with estimated P-y curves using theoretical methods based on geotechnical investment data. Back-calculated P-y curves from field tests for sand and clay ground conditions were presented in this paper, which are different from theoretical P-y curves. By using the research results of this study, more accurate estimations of pile design under lateral loads can be available for similar geotechnical conditions.

• 산업기술연구
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• 제28권B호
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• pp.81-89
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• 2008

This paper is results of investigating the dominant factors influencing to coefficient of consolidation in horizontal direction of Korean marine clays and their correlations through literature review. From the results of analyzing data obtained from field tests such as piezocone penetration and dilatometer tests as well as laboratory tests, coefficient of consolidation in the horizontal direction was found to increase with increase of stiffness index of soil while it decreases with the increase of dissipation time of pore pressure developed during field tests. In general, the coefficient of consolidation in the horizontal direction tends to increase with increase of undrained shear strength and preconsolidation pressure although correlation between them are relatively low. Friction ratio has a high correlation with coefficient of consolidation in the horizontal direction in case of friction ratio being greater than 1.0. For methods of estimating coefficient of consolidation in the horizontal direction with different testing device, values obtained from methods of P2-logt and DMT-A with dilatometer were quite similar to values from piezocone penetration test. Consistency of soil is quite proportional to coefficient of consolidation in the horizontal direction. Clear correlation between coefficients of consolidation in the horizontal and the vertical directions could not be found. coefficient of consolidation in the horizontal direction estimated from the results of field test tends to be 1.13~3.11 times greater than that obtained from laboratory tests.

• 한국강구조학회 논문집
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• 제19권1호
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• pp.79-86
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• 2007

도장, 용사 및 도금 등의 강교용 방청법의 장기내구성 평가에는 대기노출실험법이 사용되고 있으나, 노화데이터를 얻기까지는 수년에서 수십 년이라는 장기간의 실험기간을 필요로 한다. 본 연구에서는 기존의 방청법을 포함하여 최근에 개발, 사용되고 있는 강교용 방청법의 장기내구성의 단기간 평가를 위한 기초단계로서 무도장 강재의 부식내구성 평가를 위한 부식환경 촉진실험법의 활용에 대해 검토하였다. 본 실험에는 일본공업규격(JIS)에 규정되어 있는 S6-cycle 부식환경 촉진실험조건을 이용하여, 30, 60, 90, 120, 150일간의 무도장 강재의 부식 중량감소량 및 두께감소량의 경시변화를 정량적으로 평가하였다. 그리고 기존의 대기노출실험과 본 실험으로부터 구한 중량감소량을 이용하여 촉진배율을 산출하고, 대기노출실험지의 지역환경구분, 해안선으로부터 거리, 아황산가스량 및 비래(飛來)염분량과의 관계를 검토하였다. 그 결과, 촉진배율을 비래염분량으로 정식화하였으며, S6-cycle 부식촉진실험결과의 대기노출환경에의 활용 가능성을 제시하였다.

• 한국지반환경공학회 논문집
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• 제14권1호
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• pp.61-68
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• 2013

본 연구에서는 지반보강재로서 폐타이어 사용에 따른 환경영향을 평가하기 위하여 실내실험 및 현장시험시공을 수행하였다. 실내실험을 통하여 폐타이어의 용출특성에 가장 큰 영향을 미치는 폐타이어의 입경과 배수조건을 변화시켜가며 유출수의 pH, 탁도, TOC, Zn 농도를 분석하였다. 또한, 현장시험시공을 통하여 폐타이어를 이용한 보강토 옹벽 시공 후 하부 집수정의 수질을 분석하였다. 입경에 따른 용출실험 결과 폐타이어 입경이 증가할수록 용출농도가 감소하는 것을 확인할 수 있었으며, 이는 비표면적의 차이 때문으로 판단된다. 배수조건에 따른 용출실험 결과 배수조건인 경우 시간이 경과할수록 용출농도가 감소하여 주변 환경에 큰 영향을 미치지 않을 것으로 판단되나, 비배수 조건인 경우 시간이 경과할수록 용출농도가 증가하는 현상을 발견할 수 있었다. 1년간의 현장모니터링 결과 폐타이어로 보강된 옹벽으로부터 발생되는 침출수는 전반적으로 용출농도가 높지 않은 것으로 나타났으며, 침출수 발생 초기에 농도가 증가하다가 이후 점점 감소하여 원수인 우수와 비슷해지는 경향을 나타내었다. 따라서 폐타이어를 지반보강재로 사용함에 따라 발생하는 환경적 영향은 무시할 수 있는 수준임을 알 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.323-330
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• 1999

The concepts of mounting a pressuremeter module behind a cone penetrometer was applied in the early 1980s. The pressuremeter module is of 40mm diameter with length / diameter ratio of 10 inflated by nitrogen gas. This cone pressuremeter(CPM) is used to obtain the ground characteristics consisted of mainly silty, clay and sand. Field tests such as SPT, PMT, Vane tests are also carried out to understand the ground condition. Undisturbed samples are obtained to carried out Lah tests. The results of these field and lab tests are presented, discussed in detail, and compared with each others.

• 산업기술연구
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• 제32권A호
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• pp.79-86
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• 2012

In this paper, centrifuge model tests and numerical analysis on the breakwater structure were performed to investigate the stability and behavior of breakwater in field. In centrifuge model tests, construction sequence of breakwater structure such as preparation of weathered rock and sand deposit, construction of D.C.M, rubble mound with crushed stones and installment of breakwater structure was reconstructed like field condition and the behavior of ground settlement and breakwater displacement during stage of construction was observed during tests. For the final stage of simulating the horizontal movement of breakwater due to wave force, horizontal load was applied by horizontal loading apparatus being specially designed so that horizontal displacement of structure could be observed. Numerical analysis were also carried out and its results were compared with test results to assess the property of centrifuge model tests with respect to the behavior of structure as well as ground.

• 한국농공학회지
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• 제36권4호
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• pp.103-116
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• 1994

The objective of this study was to determine the criteria for density and moisture content measurements made with a nuclear density meter on common materials in the construction field. The study also sought to test a full-type nuclear density meter in controlling the density of overlay layers( 2.5~5.0cm). In order to determine the accuracy and reliablility of nuclear guage measurements made on construction materials, laboratory and field tests were conducted. Wooden blocks( 65 x 45 ${\times}$ 50 cm) and a special steel compactor( 4.7kg) were constructed in order to carry out tests which were conducted on three different materials; coarse gramed soil, fine grained soil, and AC material. Throughout all laboratory and field tests, the nuclear density and moisture content were determined using Humboldt 5OOLP nuclear gauge. The tests on subgrade material entailed obtaining density measurements by means of both the sand replacement method and the nuclear density meter. The results of the sand replacement method were then compared to the readings recorded bu the meter. As in the subgrade material tests, density measurements made during AC pavement tests were also determined using the unclear meter in addition to a second means; through the core method. The meter readings and core densties were compared as was done in the tests on subgrade materials. The correlation between the results of the sand replacement test( also, the core method) and meter readings on subgrade material was then determined. Sirnilarly, the observed results were then analyzed through linear regression. The tests to determine thin-lift density by means of a full-type nuclear density meter also conducted on the overlay layers( about 4. 8cm thickness) above AC pavements at road construction sities in Korea.