• 한국구조물진단유지관리공학회 논문집
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• 제11권6호
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• pp.213-219
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• 2007

본 연구는 소형FWD를 사용하여 노상토의 다짐도를 추정하였으며 본 연구의 결과는 다음과 같다. 다짐 회수에 따른 동적변형계수의 변화를 보면, 다짐 회수가 4(15MPa)에서 8(18.3MPa)로 증가할 때 동적변형계수는 27% 증가하였으며, 다짐 회수가 12(27.9MPa)였을 때의 동적변형계수는 다짐 회수 4일 때의 두 배의 값을 나타내었다. 다짐 회수의 증가에 따른 건조단위중량과 동적변형계수와의 관계에서 95% 다짐도에 해당하는 롤러의 다짐 회수는 약 13회이며, 이때의 동적변형계수 분포는 27MPa~29MPa이었다

• 한국농공학회논문집
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• 제52권4호
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• pp.73-81
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• 2010

The cemented sand and gravel (CSG) method is a construction technique that adds cement and water to rock-like materials, such as rivered gravel or excavation muck which can be obtained easily at areas adjacent to dam sites. This study was performed to evaluate the compaction and compressive strength properties of stress-strain, elastic modulus and fracture mode CSG materials reinforced polypropylene fiber. Polypropylene fiber widely used for concrete reinforcement is randomly distributed into cemented sand. The two types of polypropylene fiber (monofillament and fibrillated fiber) were used and fiber fraction ratio was 0, 0.2 %, 0.4 %, 0.6 % and 0.8 % by the weight of total dry soil. The effect of fiber fraction ratio and fiber shape on compaction and compressive strength were investigated. The optimum moisture contents (OMC) of CSG material increased as fiber fraction increased and the dry density of CSG material decreased as fiber fraction. Also, the maximum increase in compressive strength was obtained at 0.4 % content of monofillament and fibrillated fiber. CSG material behaviour was controlled not only by fiber fraction but also fiber distribution, fiber shape and fiber type.

• Geomechanics and Engineering
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• 제18권5호
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• pp.471-480
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• 2019

The constructions of engineering structures such as airports, highways and railway on clayey soils may create many problems. The economic losses and damages caused by these soils have led researchers to do many studies using different chemical additives for the stabilization of them. Lime is a popular additive used to stabilize the clayey soils. When the base course is stabilized by mixing with an additive, inevitable delays may occur during compaction due to reasons like insufficient workers, breakdown of compaction equipment, etc. The main purpose of this study is to research the effect of compaction delay time (7 days) on the strength, compaction, and dynamic properties of a clay soil stabilized with lime content of 0, 3, 6, 9, 12 and 15% by dry weight of soil. Compaction characteristics of these mixes were determined immediately after mixing, and after 7 days from the end of mixing process. Within this context, unconfined compressive strength (UCS) under the various curing periods (uncured, 7 and 28 days) and dynamic triaxial tests were performed on the compacted specimens. The results of UCS and dynamic triaxial tests showed that delayed compaction on the strength of the lime-stabilized clay soil were significantly effective. Especially with the lime content of 9%, the increase in the shear modulus (G) and UCS of 28 days curing were more prominent after 7 days mellowing period. Because of the complex forms of hysteresis loops caused by the lime additive, the damping ratio (D) values differed from the trends presented in the literature and showed a scattered relationship.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1175-1180
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• 2008

This study explored the compacition characteristics of organic weathered soils. Weathered soils were collected around the Gwangju University in Jinwol-dong, Gwangju city, and coal was used as organic material. Weathered soils were mixed with coal so that the ratio of organic elements against mixed soil can be 0%, 25%, 50%, and 75% respectively. Compaction tests were carried out on these organic mixture soils in different ratios of organic materials. And soap water instead of water in compaction tests was used. Through this study, We knew that the bigger the organic material ratio was, the more the optimum moisture content increased and the less the maximum dry unit weight reduced. In case of using small compaction energy, using soap water instead of water improved the compaction efficiency a little.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.127-132
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• 2002

While the pavement design is based on mechanical property such dynamic elastic modulus, the quality of highway subgrade during construction is controled by the optimum moisture content(OMC) and maximum dry density(${\gamma}$$\_$dmax/). However, since the quality control based on the OMC and maximum dry density does not consider the mechanical characteristics, there is a conceptional gap between design and PMS(pavement management system). Therefore, it is necessary to develope a new qualify control system using mechanical property for highway construction in more rational way. To achieve this goal, it is planned to perform various laboratory tests to collect mechanical properties of subgrade soil samples from several highway construction sites and to propose the relationship between dry unit weight (or OMC) and mechanical parameters. In this paper, the experimental data so far obtained are presented and analyzed. In addition, further research plan is presented and discussed.

• 한국농공학회지
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• 제18권3호
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• pp.4163-4170
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• 1976

This study was conducted to investigate the effect of starch as a retarder on the maximum dry density and the unconfined compressive strength of soil cement mixtures for varied starch contents (0-3%), cement contents (3-12%), and delay times (0-6hrs) in four soils. The experimental results obtained from maximum dry density and unconfined compressive strength tests are as follows: 1. Maximum dry density and unconfined compressive strength were increased greatly in soil cement mixtues rwhen starch was added as retarder but their value schanged according to soil varieties. 2. Maximum dry density showed at about 0.5 percent to 1.0 percent of starch in KY soil and about 2.0 percent to 2.5 percent in SS soil when delay time was changed in 2.4, and 6 hours in compaction test. 3. The larger content of cement was, the bigger effects of maximum dry density and compressive strength were in soil cement. mixtures. 4. As delay time changed 2.4, and 6 hours in compaction test, 7-day unconfined compressive strength showed the biggest value at about 0.5 percent of starch in KY soil and 2.0 percent in SS soil, and the maximum value of 28-day unconfined compressive strength showed at about 0.5 percent in KY soil and 1.5 percent in SS soil.

• 한국지반신소재학회논문집
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• 제6권2호
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• pp.9-15
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• 2007

콘크리트 표면 차수벽형 석괴댐(CRFD)에서의 표층부기초지반은 콘크리트 차수벽을 균등하게 지지할 수 있는 지지력과 사면안정을 위한 소요강도를 확보하여야 하며, 콘크리트 차수벽의 누수시 세립토의 유실을 억제할 수 있는 차수성을 유지하여야 한다. 본 연구에서는 사면부 표층기초지반에 대하여 시험시공을 실시하여 다짐회수에 대한 제체의 변위량과 현장다짐밀도의 변화, 살수량에 따른 함수비 변화 등을 측정하여 효율적인 다짐관리기준을 마련하고자 하였다. 일련의 현장다짐시험결과 CFRD에서의 표층부기초지반은 층별 포설두께 및 다짐회수에 따라 영향 받고 있음을 확인할 수 있었다.

• Geomechanics and Engineering
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• 제30권2호
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• pp.211-218
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• 2022

This study characterizes Proctor and geophysical properties in a broad range of grading and fines contents. The results show that soil index properties such as uniformity and fines plasticity control the optimum water content and peak dry unit trends, as well as elastic wave velocity. The capillary pressure at a degree of saturation less than S = 20% plays a critical role in determining the shear wave velocity for poorly graded sandy soils. The reduction in electrical resistivity with a higher water content becomes pronounced as the water phase is connected A parallel set of compaction and geophysical properties of sand-kaolinite mixtures reveal that the threshold boundaries computed from soil index properties adequately capture the transitions from sand-controlled to kaolinite-controlled behavior. In the transitional fines fraction zone between F_F ≈ 20 and 40%, either sand or kaolinite or both sand and kaolinite could dominate the geophysical properties and all other properties associated with soil compaction behavior. Overall, the compaction and geophysical data gathered in this study can be used to gain a first-order approximation of the degree of compaction in the field and produce degree of compaction maps as a function of water content and fines fraction.

• 한국지반공학회논문집
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• 제25권6호
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• pp.89-99
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• 2009

다짐재료의 물리적인 지표와 역학적정수와의 관계를 명확히 하고, 설계에 필요한 역학정수를 간극비 및 건조밀도 등의 물리적 지표를 통해 간단히 추정하는 방법을 제시하기 위하여, 화강풍화토를 이용한 다짐시험, 일차원압축시험, 불포화삼축압축시험을 실시하였다. 실험결과, 다짐으로 인해 공시체는 과압밀상태가 되며 다짐 에너지의 증가로 공시체의 강도정수가 증가되는 것이 정량적으로 확인되었고, 다짐재료의 과압밀상태를 평가하는 선행압축이론을 이용하여 다짐 후의 간극비로부터 강도정수를 추정하는 방법을 제시하여 그 공학적 적정성을 확인하였다.

• 한국재난정보학회 논문집
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• 제19권4호
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• pp.950-957
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• 2023

연구목적:강한 독성을 보유하고 있는 유류 오염물의 유출에 따른 확산을 미연에 방지할 수 있도록 사전 대응 기술이 필요하다. 따라서 본 연구에서는 개발된 반응재료의 공학적 특성을 예측하기 위한 실험적 연구를 수행하였다. 연구방법:반응재료에 대한 다짐시험 및 분광정보 획득 실험을 실시하였으며, 각각의 시험 및 실험 결과를 평가하였다. 그리고 반응재료의 공학적 특성 예측 가능성을 평가하기 위하여 분광정보와 최대건조단위중량의 상관관계를 분석하였다. 연구결과:다짐시험 결과, 최대건조단위중량은 약 9kN/m³ ~ 10kN/m³ 범위로 확인되었다. 그리고 분광정보 획득 실험 결과로부터 반응재료의 폴리노보넨 감소에 따른 최대분광반사율은 감소하였다. 결론: 반응재료의 구성성분 비율에 따라 비선형적 관계를 갖는 최대분광반사율과 최대건조단위중량 상관성으로부터 최대분광반사율을 통해 유류 오염물 흡수를 위한 반응재료의 최적량 예측이 가능함을 확인하였다.