반복하중(反復荷重),온도변화(溫度變化) 및 초기조건(初期條件)이 충적점토(沖績粘土)의 구조변화(構造變化)와 역학적(力學的) 특성(特性)에 미치는 영향(影響)

류능환 ( Ryu Neung Hwan ),류형선 ( Ryu Young Sun ),최중대 ( Choi Joong Dae ),김기성 ( Kim Ki Sung ) 한국농공학회 1992 韓國農工學會誌 : 전원과 자원 Vol.34 No.4

To estimate soil behavior and structural characteristics under the conditions of cyclic loa-ding freezing & thawing and initial state, several testing was performed and obtained follo-wing results. 1. After repeated freezing and thawing processes, original soil structure was destroyed and changed to globular structure from honeycomb or tube in its structure types. Also above processes resulted increasing the soil compression strain while decreasing the failure stress in stress-strain relationship and reached the soil structure into the mode of brittle fracture Under cyclic lading conditions, soil cluster which was originally dispersed structure colloided with each other, separated, and finally the soil failed due to the effect of overcompaction. 2. Through the stabilization processes separated by four steps, the structure of soil skeleton was changed to quite different globular type. The degree of compressibility of soil skeleton was changed to quite different globular type. The degree of compressibility of soil was decree-sed in the normally consolidated zone, while the strength against external load increased due to soil particle stabilization. 3. Soil stress-strain characteristics were largely influenced by repeated up and down proce-sses of temperature. The maximum deformation was obtained in the case of temperature between 0~10℃ by the reseon of particle cluster reformation. 4. Soil compressibility was largely influenced by the optimum moisture content. Under freezing process, swelling could be found and its magnitude was proportional to the density of soil. 5. Density of soil was decreased as increasing the number or repeated freezing and thawing processes and the largest decreasing rate was found at the first turning point from freezing to thawing cycle.

화강암 풍화토의 동상 발현 및 융해에 따른 변형 거동에 관한 연구

류능환 ( Ryu Neung Hwan ),최중대 ( Choi Jung Dae ),류영선 ( Ryu Young Sun ) 한국농공학회 1995 韓國農工學會誌 : 전원과 자원 Vol.37 No.3

Natural ground is a composite consisted of the three phases of water, air and soil paircles. Among the three components, water as a material is well understood but soil particles are not in foundation engineering. Especially, weathered granite soil generally shows a large volumetric expansion when they freeze. And, the stability and durability of the soil have shown decreased with repetitive freezing and thawing processes. These unique charcteristics may cause various construction and management problems if the soil is used as a construction material and foundation layers. This project was initiated to investigate the soil's physical and engineering characteristics resulting from freezing and freezing-thawing processes. Research results may be used as a basic data in solving various problems related to the soil's unique characteristics. The following conclusions were obtained: The degree of decomposition of weathered granite soil in Kangwon-do was very different between the West and East sides of the divide of the Dae-Kwan Ryung. Soil particles distributed wide from very coarse to fine particles. Consistency could be predicted with a function of P₂₀₀ as LL=0.8 P₂₀₀+20. Permeability ranged from 10^-2 to 10^-4cm/sec, moisture content from 15 to 20% and maximum dry density from 1.55 to 1.73g /cm³ By compaction, soil particles easily crushed, D₅₀ of soil particles decreased and specific surface significantly increased. Shear characteristics varied wide depending on the disturbance of soil. Strain characteristics influenced the soil's dynamic behviour. Elastic failure mode was observed if strain was less than 10^-4/s and plastic failure mode was observed if strain was more than 10^-2/s. The elastic wave velocity in the soil rapidly increased if dry density became larger than 1.5g /cm³ and these values were V_p=250, V_g=150, respectively. Frost heave ratio was the highest around 0℃ and the maximum frost heave pressure was observed when deformation ratio was less than 10% which was the stability state of soil freezing. The state had no relation with frost depth. Over freezing process was observed when drainage or suction freezing process was undergone. Drainage freezing process was observed if freezing velocity was high under confined pressure and suction frost process was occurred if the velocity was low under the same confined process.

초기함수비, 비표면적, 풍건 및 동결·융해작용이 흙의 액성한계에 미치는 영향

류능환 ( Ryu Neung Hwan ) 한국농공학회 1996 韓國農工學會誌 : 전원과 자원 Vol.38 No.5

The purpose of The work described in this paper is to clear up the initial moisture content, specific surface, air drying and freezing-thawing process on liquid limit of clayey soils distributed widely at estuary of three main rivers in the west coast. To this end, a series of tests were conducted on clayey soils samples with natural state and treated state. From the test results, the liquid limit was decreased with decrement of initial moisture content, air drying process, and freezing-thawing cycles and increased with increment of specific surface. The specific surface which influenced on the liquid limit is over 25㎡/g, and their relationships are well formulated. Air drying process is expected to improve the engineering properties of the soils such the pro-water properties were changed to anti-water proper-ties through lowering of water holding as resulted to incline from A-7-5 to A-5 on the soil classificaction plastic chart. The freezing-thawing process decreased 20% of liquid limit, especially under the first cycle of the behavious, as a result of above mentioned reasons, phase change of soil-water system brought the decrement of specific surface and affected to the liquid limit.

압밀특성(壓密特性)에 관(關)한 연구(硏究) (I) (선행하중(先行荷重)이 압밀특성(壓密特性)에 주는 영향(影響))

류능환 ( Neung Hwan Ryu ),강예묵 ( Yea Mook Kang ) 한국농공학회 1976 韓國農工學會誌 : 전원과 자원 Vol.18 No.4

The determination of the pre-consolidation load known to have a great effect on the consolidation characteristics of the soil have been researched and discussed in detail by many other researchers. A study was undertaken to investigate and compare the effect of pre-consolidation loads on the coefficient of permeability and the consolidation characterisics of soil through the consolidation test on the three types of soil samples. The results of this study are follows; 1. Large compression index is dependent on initial void ratio of the sample being used and the pressure-void ratio curve shows a curved linear relationship in over-consolidated area but a linear relationship in normally consolidated area. 2. Settlement-time curve is S-shaped where the pressure is larger than pre-consolidation load and regardless of over-burden pressure, it is a similar straight line respectively in the secondary consolidation area. 3. Primary consolidation ratio of the sample increases almost linearly with the increase of over-burden pressure but the coefficient of volume compressibility decreases linearly with the increase of it. 4. Time factor of a certain degree of consolidation increases with over-burden pressure but the coefficient of consolidation decreases with it in over-consolidated area. There is a linear relationship between them in normally consolidated area. 5. The void ratio of completion point of primary consolidation decreases linearly with over-burden pressure. 6. The coefficient of permeability of sample decreases linearly with over-burden pressure in normally consolidated area, also it increases linearly with increment of the void ratio of the sample.

동결토의 압축강도에 관한 실험적 연구 (2)

류능환(Neung Hwan Ryu) 강원대학교 농업과학연구소 1995 강원 농업생명환경연구 Vol.6 No.-

도로포장 재료로서 폐콘크리트 재생골재의 활용성 연구

김광우,류능환,도영수,이상범,Kim, Kwang-Woo,Ryu, Neung-Hwan,Doh, Young-Soo,Li, Xiang-Fan 한국도로학회 2001 한국도로포장공학회 논문집 Vol.3 No.2

본 연구는 재생골재를 도로의 보조기층재료 및 포장용 콘크리트 골재로 사용하기 위하여 수행되었다. 우선 보조기층재료로서의 활용성 여부를 파악하기 위하여 실내다짐시험, CBR 시험, 평판재하시험을 수행하였으며, 콘크리트용 골재로의 활용성을 보기 위하여 재생골재 첨가비율을 0, 20, 40, 60, 80%로 하여 설계기준강도 $280kgf/cm^2$인 표층용 콘크리트를 제조하였다. 제조된 콘크리트로 굳지 않은 콘크리트 성질과 28일 양생 후 강도시험과 동결 융해에 따른 내구성 시험을 통해 폐콘크리트 재생골재의 활용성을 도로포장재료 측면에서 검토하였다. 실험결과 재생골재는 보조기층재료로서의 사용이 충분히 가능하며 표층용 콘크리트 골재로서 재생골재 첨가비율 40%까지 활용이 가능함을 알 수 있었다. This study was performed to evaluate applicability of recycled aggregates as subbase and surface concrete materials for cement concrete pavement. Laboratory compaction test, CBR test and plate load bearing test were conducted to evaluate applicability for pavement subbase materials. Recycled concrete for surface course was manufactured with a design strength of $280kgf/cm^2$. Normal coarse aggregate was substituted with recycled aggregates with five different ratios, 0%, 20%, 40%, 60% and 80% for recycled concrete mixes. Fresh concrete Properties, concrete strength properties for the five substitution percentages of recycled aggregates after 28-day curing and freezing-and-thawing resistance were evaluated experimentally. Based on the experimental results, it was concluded that the recycled aggregate was the material good enough to use for subbase material, and 40% or lower substitution ratio was an appropriate percentage of recycled aggregates replacement for surface concrete.

압밀(壓密) 특성(特性)에 관(關)한 연구(硏究)(II) -하중(荷重) 증가율(增加率)이 압밀특성(壓密特性)에 미치는 영향(影響)-

강예묵,류능환,Kang, Yea-Mook,Ryu, Neung-Hwan 충남대학교 농업과학연구소 1977 Korean Journal of Agricultural Science Vol.4 No.1

흙의 압밀시험(壓密試驗)에서 하중증가율(荷重增加率)을 변화(變化)시켰을 때 압밀(壓密)의 제계수에 미치는 영향을 고찰하기 위하여 표준압밀시험(標準壓密試驗)에서 적용하는 전하량(戰荷重) 증가율(增加率)을 여러가지로 변경(變更)하여 압밀시험(壓密試驗)을 실시(實施)하여 다음과 같은 결과(結果)를 얻었다. 하중증가율(荷重增加率)이 클수록 침하량(沈荷量)은 크나 팽창량(膨脹量)은 하중증가율(荷重增加率)과 무관(無關)하다. 일침압밀(一沈壓密) 완자점(完子點)까지의 시간은 하중증가율(荷重增加率)이 작을수록 큰 값을 나타냈고, 또 과압밀 영역에서는 하중증가(荷重增加)에 따라 일침압밀완자점(一沈壓密完子點)의 시간(時間)은 큰 값을 나타내고 정규압밀(正規壓密)영역에서는 거의 일정(一定)한 값을 나타냈다. 압밀계수(壓密係數)는 재하량(載荷重)이 증가(增加)함에 따라 감소(減少)하며 하중증가율(荷重增加率)이 클수록 압밀계수(壓密係數)의 값도 크게 나타났다. 이침압밀비(二次壓密比)의 값은 곡연(曲緣)의 변곡점(變曲點)과 거의 일치(一致)되는 점(點)에서 최대(最大)로 되었다. The following is the result of experiment on consolidation test under various load increment ratios by alternation of standard load increment ratio. The more load increment ratio was, the more settlement was resulted. But expansions were not associated with load increment ratios. Primary consolidation took longer period to complete as load increment ratio was decreased. And under the condition of over-consolidated range, the completion of primary consolidation took longer period as the load was incremented. Under the condition of normal consolidated range, there was no change in time of completing primary consolidation. The coefficient of consolidation was decreased with increment of consolidation load, and the coefficient of consolidation had high values as the load increment ratio was increased. The values of ratio of secondary consolidation was highest near the transition point of consolidation curve.

태양열을 이용한 농산물건조에 관한 연구 (Ⅰ) - 벼의 건조에 대하여 -

이문남,금동혁,류능환 ( Moon Nam Lee,Dong Hyeuk Keum,Neung Hwan Ryu ) 한국농업기계학회 1978 바이오시스템공학 Vol.3 No.2

壓密 特性에 關한 研究(Ⅱ)

姜乂默(Yea-Mook Kang),柳能桓(Neung-Hwan Ryu) 충남대학교 농업과학연구소 1977 農業技術硏究報告 Vol.4 No.1

페콘크리트를 재활용한 소도로 포장에 관한 연구

김광우 ( Kim Kwang Woo ),류능환 ( Ryu Neung Hwan ),최영규 ( Choi Young Kyu ) 한국농공학회 1996 韓國農工學會誌 : 전원과 자원 Vol.38 No.4

This paper presents the results of field experience from an experimental pavement construction on a low volume road using recycled concrete. The recycled concrete was prepared by replacing a half of coarse aggregate with recycled aggregate. Virgin natural sand was used as fine aggregate together a plasticizer and a fly ash (0.8% and 5% by wt. of cement, respectively). The load bearing capacity of the subbase made of recycled aggregate was acceptable. The length, thickness and width of the pavement were l00m, 20cm and 3m, respectively. From construction experience, it was found that workability and finishability of the recycled concrete mixture were relatively poor, but strengths were satisfactory. Flexural strength, compressive strength and elastic modulus at 28 days were 54Kg/㎠, over 250Kg/㎠, and 220,000Kg/㎠, respectively. The construction could be performed by hand without much difficulty. The surface was finished smoothly by wet fabric and only minor cracks were found on the surface.