흙댐(Earth Dam) 중심코어의 다짐에 관한 연구

姜乂默,趙成燮,姜信業,金成完 忠南大學校 1971 論文集 Vol.10 No.-

Soil compaction makes void of soils narrow, and it enlarges cohesion force and internal friction angle, also it lessen sensibility for water. Consequently, purpose of soil-compaction is to lessen permeability at the banks of rivers and earth dams, and it is able to maintain stability of soil structures, and it increases bearing capacity at roads and runway of airfield, also it can prevent settlement and frost heave because of lessening volume of soil structures. For the 28 samples of which grain size was different, this study researched the grain size distribution to be the maximum density and compaction effect in the case which used 10% salt water was compared with that in the case which used distilled water, and also compressive strength and permeability test were experimented. Results obtained in this study are as follows; 1. The maximum dry density showed at the case which the maximum grain size was 4.76㎜, percents passing of No. 200 sieve were 20%, and percents retained on No. 10 sieve were 5%. 2. Dry density in the case which used 10% salt water was larger than that in the case which used distilled water in general. 3. Compressive strength was the highest when percents passing of No. 200 sieve were 50%, also it was larger in the case that used 10% salt water. 4. Coefficient of permeability decreased according as percents passing of No. 200 sieve increased, and it became less than 0.1 gal./ft^2/day(4.7×10 exp (-6)㎝/sec.) proposed by Mr. Lee in the case which the maximum grain size was 4.76㎜ and percents passing of No. 200 sieve were more than 30%.

투수성(透水性) 기초지반(基礎地盤)의 침투량(浸透量)(III)

강예묵 한국농공학회 1986 韓國農工學會誌 : 전원과 자원 Vol.28 No.4

흙의 粒度分布가 다짐 效果와 壓縮强度 및 透水係數에 주는 影響에 關한 硏究

姜乂默 충남대학교 대학원 1972 論文集 Vol.1 No.-

本硏究에서는 粒度配合이 다른 여러 가지 試料에 對하여 다짐試驗을 하여 最大密度를 나타내는 粒度配合을 求하고 粒度組成係數와의 相關性을 分析하여 最適含水比와 最大乾燥密度를 推定하는 關係式을 求했으며 또한 흙다짐이 一軸壓縮强度와 透水係에 주는 影響에 對하여 硏究하였다. 試料는 最大經 4.76㎜로서 組粒土는 大田川 下流에서 採取하고 細粒土는 大田市 三丁洞에서 陶磁器用으로 使用하는 Kaolin系統의 粘土를 여러 가지 比率로 配合하여 Iowa State Compaction Apparatus로 다짐 試驗을 하고 一軸壓縮强度와 透水係數를 測定하여 다음과 같은 結果를 얻었다. 最大俓 4.76㎜의 흙에서 2.00㎜以上이 40%, 2.00-0.074㎜가 35%, 0.074㎜ 以下가 25%로 配合된 흙에서 最大乾燥密度는 가장 큰 값을 나타냈고 2.00㎜ 以上의 粒子가 40%를 超過하면 最大 乾燥密度는 低減하였다. 또 均等係數와 Classification Area가 增加하면 最大乾燥密度도 增加하였다. 最大乾燥密度도(γdmax)와 最適含水比(Wopt)는 曲線關係가 成立되며 回歸分析에 依하여 다음과 같은 關係式을 얻었다. γdmax=1/(0.3625+0.0128Wopt) 위의 關係式으로서 最大乾燥密度의 推定値와 實測値의 誤差는 ±5% 以內에 屬했다. 粒度組成에 關係되는 Classification Area(C_(a))와 均等關係(C_(u))로서 最適含水比의 推定式을 結果 다음과 같다. Wopt=20.1-2.6C_(a)-1.71log_(10)C_(u) 위의 關係式으로서 最適含水比의 推定値와 實測値의 誤差의 範圍는 ±20% 以內이고 이 限界는 大部分이 最大乾燥密度의 95%의 乾燥密度에 對應하는 兩測含水比의 範圍內에 屬하고 있으므로 實驗室에서 求한 最大乾燥密度의 95%, 혹은 90% 以上으로 다지는 工事에서는 다짐 試驗을 하지 않고 위의 式으로 推定하여 使用할 수 있다. 다짐 에너-지의 量이 增加하던 最大乾燥密度와 一軸壓縮强度는 增加하고 最適含水比는 減少했다. 一軸壓縮强度는 흙의 構造 및 配列과 含水量에 支配되며 最適含水比보다 乾燥側에서 最大値를 나타냈다. 또 一軸壓縮强度는 均等係數, 液性限界 그리고 塑性指數가 增加함에 따라 增加하나 Classification Area가 增加하면 오히려 減少했다. 透水係數는 細粒土含量이 增加함에 따라서 減少하여 200番체 通過率이 40% 以上이면 Lee^((43))가 提案한 훨댐의 코어 材料에 透水係數限界가 10^(-6)㎝/sec 以下로 되었고 間隙比는 透水係數가 10^(-5)㎝/sec일때 最小로 되고 이보다 增減함에 따라 增加했다. It makes the void of soil narrow and heightens soil density to compact soil. On the occasion that the void of soil becomes narrow, not only the compaction reduces permeability, but also heightens the dynamical stability of soil-the internal friction and the cohesion force increase because the soil interlocking becomes good. Soil copmaction has been studied systematically for engineering development since Proctor proposed his thesis in 1933. These are soil characteristics, the sort and the size of compaction energy, and the moisture content in the essential factors for soil compaction. The Iowa State Compaction Mold was used in this study to do the compaction test of the various gradation, to research the grain size distribution showing the maximum density, and to analyse the correlation between the maximum dry density and the grain size distribution. This is a study for the effects of soil compaction upon the compression strength and the coefficient of permeability. Results obtained in this study are as follows: The coarser the grain size of the soil, the smaller the optimum moisture content becomes, and the bigger the maximum dry density grows. The dry density-moisture content curve of coarse soil has a sharp peak. On the other hand, the finer the grain size of soil, the bigger the optimum moisture content becomes, and the less the maximum dry density grows. The dry density moisture content curve of fine soil has a dull peak. In the condition that the maximum grain size is 4.76㎜, the maximum density of the soil shows up when proportion is as follows: 40% of the soil has a grain size from 4.76㎜ to 2.00㎜, 35% from 2.00㎜ to 0.074㎜, and 25% has less than 0.074㎜. The maximum dry density becomes small when particles larger than 2.00㎜ exceed 40% of the soil. Also it increases in proportion to the uniformity coefficient and the classification area. This test shows the curve relation that when the maximum dry density becomes bigger, the optimum moisture content becomes smaller. There is a high positive correlation which is r=0.9082 between 1/rdry and optimum moisture content by the regression analysis. And the following formula is obtained by the same analysis. γdmax=1/(0.3625+0.0128Wopt) In the formula mentioned above the range of deviations between the predicted maximum dry density and test values is within ±5%. The optimum moisture content shows the tendency to increase in proportion to the content of fine soils. But the optimum moisture content shows the smallest value in the soil that has the best compaction efficiency, because voids of soils become narrowest. A formula for estimating the optimum moisture content by the regression analysis with the classification area and the uniformity coefficient correlated with soil texure is as follows; Wopt=20.1-2.6Ca-1.7log_(10)Cu In the formula mentioned above, the range of deviations between the estimated optimum moisture content and test values is within ±20 percents, which belongs to the range of both sides of the moisture content correspondent with the dry density of 95 percent. In accordance with the increase of compaction energy, the maximum dry density increases, the optimum moisture content decreases, and the unconfined compressive strength increases. Unconfined compressive strength is correlated with structure, orientation, and water content, and shows the maximum test value at the dry side of the optimum moisture content. In accordance with the increase of the percent passing of No.200 sieve, unconfined compressive strength inereases, also the percent of deformation and the modulus of deformation increases. The maximum density shows at the time when the grain size distribution becomes good according to the increase of uniformity coefficient, consequently, unconfined compressive strength increases. Also, unconfined compressive strength increases in accordance with the increase of the liquid limit and the plasticity index, but it rather decreases when the classification area increases. The coefficient of permeability decreases according to the increase of the percent passing of No.200 sieve, and it becomes less than 10^(-6)㎝/sec-the limit of coefficient of permeability for core material of the earth dam proposed by Mr. Lee when the percent passing of No.200 sieve exceed more than 40%. Also, coefficient of permeability decreases in accordance with the decrease of the uniformity coefficient and the index of Talbot formula n. Coefficient of permeability seems to depend on the size and the shape of the flow path which is a series of void correlated with the structure and the gradation of soils, even though void ratios are the same. Consequently, it can not be calculated by the void ratio alone. It is supposed to be illustrated by the law of Poisseuille that the void ratio is smallest when coefficient of permeability is 10^(-5)㎝/sec, and that the void ratio increases when the coefficient of permeability becomes larger or smaller than 10^(-5)㎝/sec.

粘性土의 一軸壓縮强度 試驗方法에 對한 考察

姜乂默,李世鎭,李達遠 충남대학교 농업과학연구소 1990 농업과학연구 Vol.17 No.2

In order to investigate the influence of unconfined compression strength on undisturbed cohesive soil, the unconfined compression test were carried out on the basis of various size of specimen and compression rate. The result of these experiments were summarized as follows. 1. As the section area of specimen increased. the unconfined compression strength was decreased. 2. As the ratio of height and diameter of specimen increased, the unconfined compression strength was decreased. 3. The unconfined compression strength was increased by 3%, but values over the 3% was decreased. 4. As the compression rate increased. the modulus of deformation was increased.

사면(斜面)의 안정해석(安定解析)에 관(關)한 연구(硏究)

강예묵,조성섭,Kang, Yea Mook,Cho, Seung Seup 충남대학교 농업과학연구소 1981 Korean Journal of Agricultural Science Vol.8 No.2

흙댐 및 자연사면(自然斜面)의 안정해석(安定解析)에 가장 많이 사용(使用)되는 Fellenius방법(方法)과 Bishop방법(方法)을 비교검토(比較檢討)하여 다음과 같은 결과(結果)를 얻었다. 1. 정상침투상태(定常浸透狀態)에서 Bishop방법(方法)이 Fellenius 방법(方法)보다 안전율(安全率)이 11~29%정도(程度) 큰 값을 나타냈다. 2. Bishop방법(方法)이 Fellenius방법(方法)보다 안전율(安全率)이 증대(增大)되는 비율(比率)($F_B-F_F/F_F$)은 경사면(傾斜面)의 기울기가 느릴수록 감소(減少)하는 경향(傾向)을 나타냈다. 3. 침투(浸透)가 없을때와 있을때의 안전율(安全率)이 증대(增大)되는 비율(比率)($F_1-F_2/F_2$)은 경사면(傾斜面)의 기울기가 느릴수록 증가하는 경향(傾向)을 나타냈다. This paper has been prepared to compare the safety factor of Fellenius method and Bishop method which are most frequantly utilized for stability analysis of dam and natural slope. The results are as follows. 1. Safety factor obtained by Bishop method shows 11-29% higher in steady seepage state and 46-57% higher in no seepage flow than the one by Fellenius. 2. The ratio of safety factor between no seepage flow and seepage flow ($F_1-F_2/F_2$) increases as the slope becomes flatter. 3. The ratio of safety factor between Bishop method and Fellenius ($F_B-F_F/F_F$) decreases as the slope becomes flatter.

화강암질풍화토(花崗岩質風化土)의 Consistency 측정(測定)에 관한 연구(硏究)

강예묵,조성섭,홍순필,Kang, Yea Mook,Cho, Seung Seup,Hong, Soon Pil 충남대학교 농업과학연구소 1980 Korean Journal of Agricultural Science Vol.7 No.2

Slump시험(試驗)보다는 조작(操作)이 간편(簡便)한 유통(流動) Table을 사용(使用)하여 화강암질풍화토(花崗岩質風化土)의 유동한계(流動限界)를 측정(測定)하는 방법(方法)을 시험(試驗)하여 다음과 같은 결론(結論)을 얻었다. 1) 화강암질풍화토(花崗岩質風化土)의 유동한계(流動限界)는 입도분포(粒度分布), 퐁화도(風化度) 및 유색광물함량(有色鑛物含量)에 영향(影響)되므로 유동(流動) Table에 의한 유동한계시험법(流動限界試驗法)을 제정(制定)할 때는 최대입경(最大粒徑)이 규정(規定)되어야 할 것으로 생각된다. 2) 유동(流動) Table의 낙하회수(落下回數)를 10회(回)로 하여 유동고(流動高)와 유동폭(流動幅)이 1cm일 때의 함수비(含水比)의 평균치(平均値)를 유동한계(流動限界)로 택(擇)하면 Slump시험(試驗)에서 구(求)한 유동한계(流動限界)보다 약간 작은 값으로 되며 대략(大略) 10%오차한계선내(誤差限界線內)에 속(屬)했다. 3) 유동폭(流動幅)과 함수비(含水比) 및 유동고(流動高)와 함수비(含水比)의 관계곡선(關係曲線)은 유사(類似)한 변화(變化)를 나타내고 반대수용선(半對數用線)에 도시(圖示)하면 액성한계시험(液性限界試驗)에서와 같이 직선관계(直線關係)를 나타냈다. 4) Slump시험(試驗)에 비(比)하여 조작(操作)이 간편(簡便)하고 개인적(個人的)인 오차(誤差)가 작으며 유동폭(流動福)과 유동고(流動高)를 동시측정(同時測定)하여 시험오차(試驗誤差)가 작은 것으로 공학적(工學的) 성질(性質)을 판단(判斷)하는 자료(資料)로 사용(使用)될 수 있는 것으로 생각된다. This test was carried out to present criterion to measure the liquid limit of weathered granite soil by using the flow-table method whose operation is easier and more convenient than slump test. The results are as follows. 1. Since liquid limit of weathered granite soil depends upon the particle size distribution, weatheredness and content of colored minerals, maximum particle size should be prescribed when the testing rule of liquid limit by flow-table method is enacted. 2. If take the averaged water content as liquid limit where the height and width of flow are 1 cm respectively by 10 times dropping, this liquid limit is slightly less than the one by slump test. The differance of liquid limit between flow table method and slump test is about 10%. 3. Correlation curves of flow width-water content and flow hight-water content show similar shapes. Those are straight lines in semi-logarithm paper just as liquid limit test. 4. This flow-table method is more convenient and has less personal error of measurement than slump test does. So flow-table method would be favourably utilized for judging the engineering properties of soil.

石灰混合土의 壓縮强度에 關한 硏究 (第2報) : 후라이애쉬 添加가 强度에 미치는 影響 Effects of the Addition of Flyash on the Compressive Strength

姜乂默,趙成燮,金成完 忠南大學校 1974 論文集 Vol.13 No.1

To study the effects of adding fly ash in lime stabilized soil on the compressive strength, lime of Non San Lime Co. and Han Yeung fly ash were used. Type A (sand:15%, silt:60%, clay:25%), Type B (sand:17%, silt:54%, clay:29%)and Type C(sand:19%, silt:52%, clay:29%)soils were treated with admixtures which contained various ratios of lime and fly ash. Cylinderical specimens (54㎜ by 108㎜) were prepared with 4%, 6%, 8% and 10% of admixtures by dry weight of soil and all specimens were moist cured for specific periods at neary constant temperature(21±1.5℃). The following results were obtained by the unconfined compressive strength test of 14 and 28 days cured lime, flyash as soil mixtures. 1. The lime stabilized soil increases in strength over a long period of time. The optimum amount of lime in the lime stabilized soil is 8 percent based on 28 days strength. 2. The compressive strength shows a higher strength in Type A soil than Type B or Type C soils in both the lime-soil mixtures and the lime-fly ash-soil mixtures. 3. The best ratio of lime to fly ash and the optimum amount of lime and fly ash were found depending the kind of soil. This experiment shows that the optimum ratio of lime to fly ash is 9:1 for Type A soil, and 8:2 for Type B and Type C soils at 14 days moist cured specimens but this phenomenon doesn't reveal at 28 days moist cured specimens. 4. Though it may improve the properties of freezing and thawing or drying and wetting to add fly ash in lime stabilized soils, in the economic point, it cannot be an effective method to add fly ash to the lime stabilized soil in order to improve the compressive strength only.

흙의 지수적(指數的) 특성(特性)에 관한 연구(硏究)

강예묵,조성섭,김성완,Kang, Yea-mook,Cho, Seung-seup,Kim, Seung-wan 충남대학교 농업과학연구소 1977 Korean Journal of Agricultural Science Vol.4 No.2

한강하류(漢江下流), 아산만(牙山灣), 금강하류(錦江下流)및 낙동강하류(洛東江下流) 지역(地域)에 대(對)한 Atterberg한계치(限界値)와 교란(攪亂)된 흙과 교란(攪亂)되지 않은 흙에 대(對)한 역학적(力學的) 성질(性質)을 규정(規定)하는 여러가지 토질상수치(土質常數値)의 상관성(相關性)을 분석(分析)하여 다음과 같은 결과(結果)를 얻었다. 1. 자연상태(自然狀態)의 흙에 단위체적중량(單位體積重量)은 함수비(含水比)를 좌우(左右)하는 성분(成分)인 점토광물(粘土鑛物)의 함유량(含有量)에 의하여 변화(變化)하는 것으로 생각된다. 따라서 습윤단위중량(濕潤單位重量)은 점토광물(粘土鑛物)의 함유량(含有量)이 가장 많은 낙동강하류(洛東江下流)에서 가장 작은 값을 나타내고 한강하류(漢江下流), 금강하류(錦江下流), 아산만(牙山灣)의 순(順)으로 큰 값을 나타냈다. 2. 함수비(含水比)가 증가(增加)하면 건조밀도(乾燥密度)는 감소(減少)하는 곡선관계(曲線關係)가 성립(成立)하며 건조밀도(乾燥密度)의 값은 조립토(粗粒土)의 함유량(含有量)이 많은 아산만(牙山灣)에서 가장 컸고 금강하류(錦江下流), 한강하류(漢江下流) 및 낙동강하류(洛東江下流)의 순(順)으로 나타났다. 3. 각지역(各地域)의 액성한계(液性限界)와 소성지수(塑性指數)의 값은 액성한계(液性限界)의 값이 40% 이상(以上)에서는 소성도(塑性圖)의 A-선(線)보다 위에 있었다. 4. 건조밀도(乾燥密度)는 공극비(空隙比)의 증가(增加)에 따라 감소(減少)하는 곡선관계(曲線關係)가 성립(成立)하며 조립토(粗粒土)의 함유량(含有量)이 많은 흙에서 변화(變化)의 폭(幅)이 컸다. 따라서 공극비(空隙比)의 증가(增加)에 따라 건조밀도(乾燥密度)의 감소(減少)하는 경향(傾向)은 점토함유량(粘土含有量)이 가장 작은 아산만(牙山灣) 지역(地域)에서 가장 큰값을 나타내고 금강하류(錦江下流), 한강하류(漢江下流) 및 낙동강하류(洛東江下流)의 순(順)으로 나타났다. These experiments were carried out to analyse the correlation among various soil parameters which characterize the mechanical properties of the disturbed and undisturbed soil, and to analyse Atterberg Limits for the basin of downstream of Hanriver Keum river, Nakdong river, and Asan bay. 1. Wet density of soil was the lowest in the basin of Nakdong river which contains the highest amount of clay minerals among the soil samples, and was increased in the order of Han river, Keum river and Asan bay. It was appeared that the unit weight of natural soil was changed in accordance with the clay mineral content which determines the moisture content. 2. Curved relationship was recognized, showing that dry density of soil was decreased with increasing the moisture content. Soils from the basin of Asan bay were appeared to have the highest dry density and the next was those of Keum river, the second lowest Han river, and the lowest Nakdong river. 3. When the liquid limit of soils was over 40 percent, their plastic index was above the A-line of plastic chart. 4. Between dry density and void ratio of soils, a curved relationship was found, in which dry density was decreased as void ratio increased, and the differences between them became greater in soils containing higher amount of coarse grained soil. Decreasing tendency of dry density in accordance with increase of void ratio was the most significant at Asan bay which contained the lowest clay content, and other decreasing order of dry density was Keum river, Han river, and Nakdong river.

연약지반 굴착사면의 안정해석

강예묵,조재홍,김용성,김지훈 충남대학교 농업과학연구소 1996 농업과학연구 Vol.23 No.1

To investigate the stability problem of irrigation-drainage channel excavation slope on soft ground, analyzed the behavior of the soft ground with excavation slope by the limit equilibrium method and the finite element method, and compared with field tests. The results of this study were summarized as follows; 1. When rapid drawdown the water level, the carck was occurred by the effect of the excess pore water pressure, and the pore water pressure was decreased slowly. 2. As the width of excavation was larger, the crack width was larger. And, excavated depth was deeper, the progressive failure was appeared. 3. When the soft ground excavation was small-scale, the minimum safety factor was more effected by cohesion(1.0, 1.5, 2.0, 2.5, 3.0) than excavated slope inclination(1:1, 1:1.5, 1:2). 4. As excavation was progressed, the settlement occurred on the top-slope due to plastic domain, and heaving was occurred at the bottom of excavation. 5. The maximum shear stress was appeared greatly as the base part of slope went down. Because of the increase of the maximum shear stress, tension area occurred and local failure possibility was increased. 6. As the excavation depth was increased, the maximum shear strain was appeared greatly at the base of slope and distribution pattern was concentrated beneath the middle of slope.

FEM에 의한 필댐의 應力解析

姜乂默,趙成燮,梁海鎭 충남대학교 농업과학연구소 1992 농업과학연구 Vol.19 No.1

The embankment material of Andong Dam was the decomposed granite soil, and FEM analysis with settlement and stress characteristics were studied in this thesis. and also the results were as follows: 1. The vertical settlement of dam quite nearly coincides with the calculated one by FEM. A maximum value of the measured and the calculated is 40cm and 42cm, respectively, at the EL. 130m. 2. The measured settlement values of the central parts in elevation are nearly the same as those of the calculated, and the settlement values in order of magnitude are in core, filter, random and rock. 3. Horizontal deformation of max. 21cm in downstream is larger than that of max. 17cm in upstream, which is highly influenced by the water pressure of reservoir water level and the earth pressure of coffer dam in upstream. 4. Reverse arching effect of vertical stress in streamflow section are caused by the difference of stiffness, because stiffness is larger in core zone than in filter zone. 5. Load transfer ratio which is the ratio of principal stress of core zone and filter zone is 1.06, which clearly showes the reverse arching effect in vertical stress.