육상(陸上) 및 항만지역토(港灣地域土)의 압밀특성치(壓密特性値)의 상관성(相關性)

도덕현 ( Duk Hyun Doh ),이성태 ( Seong Tae Lee ),강우묵 ( Yea Mook Kang ) 한국농공학회 1983 韓國農工學會誌 : 전원과 자원 Vol.25 No.4

305 samples of alluvial deposit in inland and harbour districts were selected and consolidation charateristics of the alluvium were put in order statiscally. The correlations between them were as follows. 1. The relationships between LL(liguid limit) and C_c (compression index) were explained as C_c=0. 03(LL-21.7) in case of inland district soil and as C_c=0.019(LL-19) in case of harbour district soil. As compared with formular proposed by Skernpton, the gradient of this linear line was slight steep. 2. The relationships between PI(plastic index) and C_c were explained as C_c=0.063 PI-0.52 in case of inland district soil and C_c=0.043 PI-0.31 in case of harbour district soil. 3. As void ratio and natural moisture content were increased, C_c was increased, and as wet density was increased, C_c was decreased with a gentle curve. 4. As LL and P1 increased, m_v(coefficient of volume compressibility) was increased but if LL and P1 was increased beyond a certain extend, m_v has a tendency of constant value, that is, mv show a tendency to take constant value in the very soft clay. and m_v in P=2.5kg/cm² was about 10^-1cm²/kg in case of land district soil and 6x 10^-1cm²/kg in case of harbour district soil lower than that in P=0.25kg/crn². 5. C_v(coefficient of consolidation) was a tendency to decrease with a gentle curve as LL was increased, and C_v in P=0. 25kg/cm² was about 3x10^-1cm²/min larger than that in P=2.5kg/cm². 6. Relationships between P_y(pre-consolidation pressure) which is included over conso-lidation soil and ∑r1h(effective over-burden pressure) were explained as P_y=1.12 ∑r'h in case of land district soil and as P_y=1.15∑r'h in case of harbour district soil. 7. Some of the properties show good correlations between them, practical and effective applications of these correlations are expected in the planning and excution of soil investigation and also in the evaluation of the results.

반복하중(反復荷重)으로 인한 지반(地盤)의 변형(變形) 예측(豫測)

도덕현 ( Doh Duk Hyun ) 한국농공학회 1988 韓國農工學會誌 : 전원과 자원 Vol.30 No.3

The Repeated Load Triaxial and Oedometer Tests to the weathered granite & silty clay soil have been fulfilled to investigate their dynarnic characteristics. The results obtained are summarized as follows ; 1. In the relation between the repeated triaxial compression and the oedometer test, the recoverable strain of weathered granite soil showed a tendency to decrease by the increase of the repeated loads number(N), and that of silty clay showed approximately constant values while the total strain increased continuously. 2. The changes of plastic strain was dependent to the level of deviator stress which is the most important element in the calculation of soil deformation under repeated load condition. And there was a significance of 10% between the level of stress and plastic strain. 3. When the soil was aimost dried or saturated to 100%, the deformation by the repeated loads was small. However the deformation showed peak around the saturation of 50%. 4. When the deformation was predicted by the repeated triaxial load tests of a laboratory, it is desirable to introduce the threshold stress concept in the calculation of deformation of subgrade of the pavement. 5. The improved design equation (Eq. 16) introducing the modulus of conversion(Fo), which is based on the Boussineq' s theory, is considered to be rational in the design of flexible pavement. From the above results, the deformation to the repeated traffic loads could be predicted by the repeated triaxial tests on the pavement materials or undisturbed soil layers, therefore it is think that the durable and econornic pavement could be constructed by reflecting that to the design.

입장체식료의 (粒狀體試料) 공극비의 (空隙比) 빈도분포

도덕현(Duk Hyun Doh),고재만(Jae Man Koh),오규태(Kyu Tae Oh) 한국지반공학회 1988 대한토질공학회지 Vol.4 No.3

풍화 화강토와 loess의 붕괴특성 비교

도덕현(Duk Hyun Doh) 한국지반공학회 1986 지반 : 한국지반공학회지 Vol.2 No.1

방조제(防潮堤) 축조(築造) 예정지반(預定地盤)의 지진(地震)에 의한 액상화(液狀化) 거동(擧動) 평가(評價)

도덕현 ( Doh Duk Hyun ),장병욱 ( Chang Pyoung Wuck ),고재만 ( Koh Jae Man ) 한국농공학회 1993 韓國農工學會誌 : 전원과 자원 Vol.35 No.2

The laboratory tests are performed on how the liquefaction potential of the sea dike structu-res on the saturated sand seabed could be affected due to earthquake before and after construction results are given as follows ; 1. Earthquake damages to sea dike structures consist of lateral deformation, settlement, minor abnormality of the structures and differential settlement of embankments, etc, It is known that severe disasters due to this type of damages are not much documented. Because of its high relative cost of the preventive measures against this type of damages, the designing engineer has much freedom for the play of judgement and ingenuity in the selection of the construction methods, that is, by comparing the cost of the preventive design cost at a design stage to reconstruction cost after minor failure. 2. The factors controlling the liquefaction potential of the hydraulic fill structure are magni-tude of earthquake(max, surface velocity). N-value(relative density), gradation consistency(plastic limit), classification of soil(G&V_s), ground water level, compaction method, volument-ric shear stress and strain, effective confining stress, and primary consolidation. 3. The probability of liquefaction can be evaluated by the simple method based on SPT and CPT test results or the precise method based on laboratory test results. For sandy or silty sand seabed of the concerned area of this study, it is said that evaluation of liquefac-tion potential can be done by the one-dimensional analysis using some geotechnical parame-ters of soil such as I_p γ_t, gradation, N-value, OCR and Classification of solis. 4. Based on above mentioned analysis, safety factor of liquefaction potential on the sea bed at the given site is F_s=0.84 when M=5.23 or a_max=0.12g. With sea dike structures H=42.5m and 35.5m on the same site F_s=3.54~2.08 and F_s=1.74~1.31 are obtained, respect-tively. Local liquefaction can be expected at the toe of the sea dike constructed with hydraulic fill because of lack of constrained effective stress of the area.

우리나라 포화사질지반(胞和砂質地盤)의 액상화 포텐셜 평가 (구성관계 개발을 중심으로)

도덕현(Duk Hyun Doh),장병욱(Pyoung Wuck Chang) 한국지반공학회 1990 대한토질공학회지 Vol.6 No.3

토목섬유(土木纖維)를 이용(利用)한 보강토옹벽(補强土擁壁)의 개발(開發)

도덕현 ( Doh Duk Hyun ),유능환 ( Ryu Neung Hwan ) 한국농공학회 1986 韓國農工學會誌 : 전원과 자원 Vol.28 No.2

The model was developed by applying the principles of Bacot and Vidal to measure the behavior of deformation of the reinforced earth wall, and various tests were performed by using the plastic fabric filter and the galvanized steel plate as a strip. The results obtained are as follows; 1. When the reinforced earth wall is deformed by the load, the strip is completely reinforced by the backfill materials and changed to the rigid block state, under the state of failure which permits sliding only, the next theoretical equation is formed. (H/L) · tanθ[cosø-sinøtanø] =2sinø[tan(θ+ø) +tanø] 2. The degree of the mutual reinforcement of the backfill material and the strip depend on the physical characteristics of the each material especially the angle of shearing resistance of the backfill material is desirable over 20° and, if it is over 40°, its function could be a maximum. 3. The distribution of the maximum tensile strain of the reinforcement is changing with the height of reinforced earth wall, and when the height from bottom of the reinforced earth wall is 1.85 to 3. 35m, the maximum tensile strain appears at 2m from the skin element. The maximum tensile strain is increased by the depth of the reinforced earth wall from surface, and increased with the lapse of time after construction. 4. The failure surface of the reinforced earth wall by the concrete skin was about 60° and the failure behavior of the reinforced earth wall in which the fabric filter was buried was slow, and so the pore pressure could be decreased. 5. It is possible to construct the fabric retained earth wall by the plastic fabric filter only. And the reinforcing effect between the steel plate and the plastic fabric filter is not largely different, however, in the aspect of the economic durability, the plastic fabric filter is more advantageous. 6. The reinforcing action mainly depends on the width and the length of the reinforcing materials, if possible, the full width is advantageous to enlarge the contact area with backfill, but considering the economic aspect, it is neccessary to develop the method controlling the space of the strip.

농도(農道)의 기층(基層) 및 보조기층(補助基層) 공법연구(工法硏究) -노상(路床) 및 시멘트 안정처리층(安定處理層)의 Mr 특성(特性)을 중심(中心)으로-

도덕현 ( Duk Hyun Doh ) 한국농공학회 1989 韓國農工學會誌 : 전원과 자원 Vol.31 No.2

The characteristics of resilient modulus(Mr) which dominates the life of pavement and the design of pavement were investigated on the test specimens which were cement treated and non-treated of the three different soil types. The results are summarized as follows : 1. The resilient modulus was decreased by increasing the cyclic deviator stress (σ_d), especially the resilient modulus was gradually decreased or sometimes increased when the value of ad was greater than 0.75-1.0kg/㎠. 2. The resilient modulus was increased by increasing the homogeneous confined stress (σ_do) and such phenomena were distinct on the coarse soils. 3. The resilient modulus was increased by increasing the ratio of confined stress(Kc), and this phenomena were eminent on the coarse soils too, and the higher permanent strain was showed by increasing the value of Kc. 4. In the drained cyclic triaxial compression test, the value of ad, Kc, and (Oho) was introduced by the following interrelated equations which were similar to the Mr model of Cole. Mr/Kcⁿ =K₁(J₂/ τ_oct)^K2 ............. (coarse soli) Mr/Mcⁿ=K₃(σ_dp/ τ_f)^k4 ...............(fine soils) 5. The stress path was not much affected by the value of Mr, however, moisture content, dry desity, and contant of fines affected the value of Mr. 6. In the soil-cement specimens, the resilient compression strain(ε_d) was decreased by the increment of the σho, and Mr was decreased by increasing the σ_d. 7. In the flexible pavement. the cement treated layer should be designed not to fail by the fatigue before the designed traffic load, and actually the pavement could cover the traffic load to a certain extent under the post-crack phase, therefore farther studies on this phenomena' are required in the design analysis. 8. The finite element computer program (ANALYS) was used for displacement analysis of pavement containing the cement-treated layer, The result showed that the program used for this analysis was proved to be usable.

석고(石膏)플라스터 혼합토(混合土)의 공학적(工學的) 특성(特性)

도덕현 ( Doh Duk Hyun ),정성모 ( Jung Sung Mo ) 한국농공학회 1985 韓國農工學會誌 : 전원과 자원 Vol.27 No.4

The plaster mixed to loam and sandy soil from 4 to 12 percent by dry soil weight, and the compaction, permeability, CBR, unconfined compressive strength and freezing-thawing test were performed The results obtained are summarized as follows; 1. The coefficient of permeability reduced sharply at the plaster content of 4 percent, and in the CBR test, the swelling ratio reduced by the increment of plaster content. 2. The addition of plaster incre1sed the unconfined compressive strength by the cementing effect, and it was found that the optimum plaster content existed with the soil type, which showed the maximum strength 3. It was possible to enhance the unconfined compressive strength of the gypsum-lime-soil mixtures when the optimum content of plaster was mixed to the hydrated lime. 4. In case of s3ndy soil, the relative frost heave decreased with the mixture of plaster, however in loam soil, the relative frost heave began to incre1s~ at the plaster content of 12 percent than non-treated soil. Therefore the optimum, plaster content existed for protecting frost heave by the different soil type. 5. The above summarized results make it possible to expect the effects such as improvement of soil properties, decrement of permeability, increment of unconfined compressive strength, and protection of frost heave, etc, therefore, it is considered that it is possible to use plaster as sub-base materials of rq1d.

減水劑가 콘크리트에 미치는 影響

김종천,도덕현,Kim, Jong-Cheon,Doh, Duk-Hyun 한국농공학회 1982 한국농공학회논문집 Vol.24 No.2

A study on the effect of water reducing agent on the various characteristics of concrete has been conducted. The experimental results of the study are summarized as follows. 1. Slump test for the concrete added water reducing setretarding agent in proper quantity have been conducted. According to the test results, the decreasing rate of slump value become bigger than plain concrete with increase of the unit weight of cement and elapse of time 2. In case the proper quantity content of maximum compressive strength in Fig. 5 of water reducing set retarding agent is added, unit weight of water is decreased about 15% or so as compared with plain concrete. with the increase of water reducing set accelerating agent content unit weight of water is decreased much more, And other hand, amount of air entraining shows the increasing tendency with the increase of water reducing agent content. 3. The adding rate of water reducing agent which produce maximum strength shows that WR-CH and WR-SA which is water reducing set-starding agent is 0.2% and WR-CO is 0.5% and that WS-PO which is water reducing set accelerating agent is 0.5 4. compressive strength jof the concrete made of sulfate resistant cement shows less than the strength of normal portland cement at initial strength but the strength of both cement shows almost same at curing age of 28 days. 5. when proper quantity of water reducing set retarding agent is used, boned strength is increased about 15% at curing age of 28days. 6. According to the result of durability test, dynamic young's mudulus of elasticity at plain concrete is decreased about 50% as compared with initial step at 300 cycle of freezing and thawing after curing age of days. on the contarary the concrete used water reducing agent is decreased less than 7%.