• 한국해양공학회지
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• 제19권6호통권67호
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• pp.44-49
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• 2005

This paper investigates strength characteristics and stress-strain behaviors of unreinforced and reinforced lightweight soils. Lightweight soil, composed of dredged soil, cement, and air-foam, was reinforced by a waste fishing net, in order to increase its compressive strength. Test specimens were fabricated by various mixing conditions, such as cement content, initial water content, air content, and waste fishing net; then, unconfined compression tests were carried out on these specimens. From the test results, it was shown that reinforced lightweight soil had different behavior after failure, even though it had similar behavior as unreinforced lightweight soil before failure. The test results also showed that stress became constant after peak strength in reinforced lightweight soil, while the stress decreased continuously in unreinforced lightweight soil. It was observed that the strength was increased due to reinforcing effect by the waste fishing net for most cases, except high water content greater than $218\%$. In the case of high water content, a reinforcing effect is negligible, due to slip between waste fishing net and soil particles. In reinforced lightweight soil, secant modulus (E50) was increased, due to the inclusion of waste fishing net.

• 한국농공학회논문집
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• 제63권6호
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• pp.17-26
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• 2021

Greenhouses have been damaged due to the uplift pressure from strong wind, for which rebar piles are often installed near the greenhouse to resist the pressure. For the effective design of rebar piles, it is necessary to access the shear strength of soil on which the greenhouse is constructed. This study experimentally evaluates the shear strength of the soil beneath the greenhouse. Four soil samples were collected from four agricultural sites, and prepared for testing with 75, 80, 85, and 90% compaction rates. One-dimensional unconfined compression test (UC), consolidated-undrained triaxial test (CU), and resonant column test (RC) were performed for the evaluation of shear strength and shear modulus. Generally, the higher shear strength and modulus were observed with the higher compaction rates. In particular, the UC shear strength increases with the increase of #200 sieve passing rate. Resulting from the CU test, the sample with the most of coarse soil had the highest friction angle, but the variation is small among samples. Resulting from the CU and RC tests, the ratio of maximum shear modulus with the major principle stress at failure was the higher at the finer soil. The ratio was two to three times greater than the ratio from the standard sand. This indicates that the shear strength is lower for the fine soil than the coarse soil at the same shear modulus. The results of this study will be a useful resource for the estimation of the pull-out strength of the rebar pile against the uplift pressure.

• 한국지반공학회지:지반
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• 제3권4호
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• pp.31-40
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• 1987

얕은 지반의 현장탐사와 다짐도의 측정등에 적합한 나선탐사시험을 개발하여 그 시기결과를 표준 관입시험, 도추관입시험, 현장밀도시험 등 기존의 현장시험결과와 비교, 분석하였다. 나선탐사설험은 다른 현장시광에 비하여 경제적이며 1인이 쉽게 시험할 수 있는 장점이 있다. 흙의 물성치는 택 사기를 지반에 관입시키는데 필요한 토오크로 나타내며 본 연구결과, 표준관입시험 및 원유관입시 험의 결과와 잘 일치하고 표준관입시험과의 상관관계는 흙의 종류에 따른 유관성이 낮으나 도유관 입시험과의 경우, 유관성이 높다. 또한 나선탐사시험은 상대다짐또와 다짐지반의 현장밀도의 측정 에도 정도가 높다. 한펀 지반의 평균정립(D50)이 증가함에 따라 나선탐사시험의 역포전비는 감소하는 특성을 보인다.

• 한국지반신소재학회논문집
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• 제20권1호
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• pp.35-44
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• 2021

본 연구는 제지 플라이애시 지반안정재를 활용하여 개량토 토사 비탈면의 현장 적용을 통한 안정화 방법을 연구하였다. 개량토에 요구되는 목표강도는 500kPa이며 토사 비탈면을 개량후 식생이 발아하기 위한 압축강도는 1,000kPa 이하이다. 이 조건을 만족하기 위해 현장에서 반입된 시료를 가지고 표층개량의 주원료인 지반안정재와 혼합하여 배합설계를 거처 강도시험 및 투수시험 그리고 식생 발아시험 등 다양한 시험을 실시 하였다. 그리고 개량토로 시공된 비탈면에 대한 기존 압축시험 결과를 분석한 후 개량토의 지반정수를 제안하였다. 또한 개량토의 비탈면 현장 적용성을 평가하기 위하여 붕괴된 비탈면에 대하여 현장 시공을 실시하여 개량토의 표층부 보강평가를 실시하였다. 그 결과 보강 전에는 안정성을 확보하지 못했지만 개량토로 보강한 이후 안전율은 강우 지속시간 48시간까지 최소 안전율을 확보하는 것으로 나타났다. 그리고 현장 개량토의 압축강도는 설계치인 점착력 200kPa 이상을 확보하고 토양경도계 시험 결과도 규정 값인 18~23mm 이내로 확인되어 개량토 비탈면의 경우 강우에 저항성이 증대되고 표층부의 식물생육이 가능한 것으로 나타났다.

• 한국지반공학회논문집
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• 제21권5호
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• pp.59-64
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• 2005

불포화토를 연구하는데 있어 함수특성곡선과 투수계수방정식을 결정하는 것은 필수요소이나 이는 쉬운 일이 아니다. 본 연구에서는 함수특성곡선과 투수계수방정식을 얻기 위한 새로운 시험장치가 개발되었다. 개발된 시험장치를 사용하여 두 종류의 토사에 대해 포화투수계수시험과 함수특성곡선을 결정하기 위한 시험을 실시하였다. 시험진행순서는 먼저 포화투수계수시험을 실시한 후, 함수특성곡선의 건조과정에 대한 시험을 실시하고 다음으로 함수특성곡선의 습윤과정에 대한 시험순으로 진행하였다. 시험결과에 의하면 건조과정의 함수특성곡선과 습윤과정의 함수특성곡선 간에는 이력현상이 존재함을 알 수 있었다. 투수계수방정식의 결정은 시험으로부터 얻어진 포화투수계수와 함수특성곡선 이용하여 구하는 이론적인 방법을 사용하였다.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1396-1403
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• 2009

The Ministry of Construction and Transportation (MOCT) has been constructing a nationwide soil information DB since 2000, as basic data for the construction of 'underground geographical information,' a project under the 2nd National Geo-spatial Information System (NGIS) master plan. The inputted soil information includes not only underground conditions such as the layer depth, type, color, and groundwater level, but also engineering information that can be applied to construction work design, such as on the standard penetration test and the compression test. It is difficult to use this information in soil analysis and design, however, because only the test results are currently available. A web-based geo-spatial information system was developed in this study to facilitate the effective application of the soil information database (DB). First, the space information, layer information, and engineering test information were loaded from the soil information DB in real time, and the earth volume, bearing capacity, and settlement were calculated to develop a web client that will evaluate the ground softness and liquefaction. It seems that the soil information DB can be actively applied to the planning and design of construction works using this system.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.191-194
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• 2003

The purpose of this paper was to derive soil-water characteristic curve equation for unsaturated soil. To this end, a series of suction measured test was conducted on the selected 4 kinds of soil which is located in Korea, used the modified pressure plate apparatus. From the test results, it was proved that characteristic curve changes according to grain size distribution, size of void and fine grained soil contents. Residual degree of saturation(Sr) was decreased with void ratio and changed with fine grained soil contents, parameter ${\lambda}$ and hr was increased with void ratio. Soil-water characteristic curve equation based on the test result was suggested by void ratio or grain size distribution.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.183-186
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• 2003

This study was conducted to evaluate effects by adding oil to clay soil and influences of remained oil in soil as time elapsed. Unconfined compression test and direct shear test were performed to analyze strength properties of contaminants in clayey soil. As a results of $q_u$ test for kerosene and diesel contaminated clayey soil indicate that were decreased from near 5% oil content rapidly and the declination of strength were blunt as oil content over 10%. The cohesions(c) and internal friction angle(${\psi}$) of kerosene contaminated clayey soil were not varied as quantities of kerosene in clayey soil increased. In the case of diesel contaminated clayey soil, the cohesions(c) were decreased and the internal friction angle(${\psi}$) were increased.

• 한국지반공학회지:지반
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• 제2권1호
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• pp.7-14
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• 1986

The structure of the collapsible soils, such as decomposed granite soil and loess, were examined by the odeometer test, SEM & XES analysis and static & cyclic triaxial test, and hove this structure have influences upon the collapsible behaviour under static and cyclic load was investigated. The study results obtained are as follows; 1. The macropores space of decomposed granite soil (rd=1.50g/cm3) and loess (rd=1.43g/cm3) used in this test were well developed, and showed the behaviour of collapsible soil. 2. Collapsible soil has high resistance on the strain under natural moisture content, however, the resistance on the strain was sharply decreased by the absorption and increasing load since its special structure was destructed. 3. Under the static load, the strain of collapsible soil was high by the viscous flow of the cyclic bonds with time lapse, but Infer the cyclic load, the strain of collapsible soil was low since the tinge needed to destruct the bonding force of clay was not enough. 4. The understanding about the cyclic behaviour of collapsible soil may be helpful to predict the elastic & residual strain of the foundations by the earthquake together with the damage by the additional failure.

• 한국농공학회논문집
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• 제54권1호
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• pp.83-91
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• 2012

In this study, the compressive strength characteristics of lime-cement-soil mixtures, composed of lime, soil, and a small amount of cement, were investigated by performing the unconfined compression tests, the freezing and thawing tests, the wetting and drying tests and the permeability tests. The specimens were made by mixing soils with cement and lime. The cement contents were 0, 6, 8 and 10 %, and the lime contents were 2, 4, 5, 10, 15 and 20 % in weight. Each specimen was cured at constant temperature in a humidity room for 3, 7 and 28 days. The compressive strength characteristics of the lime-cement-soil mixtures were then investigated using the unconfined compression tests, freezing and thawing tests and the wetting and drying tests. Based on the test results, a discussion was made on the applicability of the lime-cement-soil mixtures as a construction material.