동재하시험을 이용한 항타기의 성능과 항타말뚝의 지지력 평가

정두회 釜慶大學校 2000 釜慶大學校 論文集 Vol.5 No.-

A series of dynamic pile load tests have been performed on test piles driven into the unbound sedimental rock to estimate soil set-up effects on pile capacity and the efficiency of driving system. Test results were analyzed by using the CASE method and the CAPWAP method. An increase in pile capacity due to the soil set-up effect can be observed. Capacities of test piles increased by an amount of 32% ∼ 63% depending on soil conditions and pile lengths. The driving system efficiency was evaluated based on the transfer efficiency. The transfer efficiencies of the driving system employed in this study were rated as lower compared to the normal hydraulic hammer. This may be attributed to the weakness of the embedded layer which resulted in greater penetrations of test piles.

해안 매립지반에 설치된 지반앵커의 거동

정두회 釜慶大學校 1999 釜慶大學校 論文集 Vol.4 No.1

Several field tests have been performed to characterize the behaviors of friction type anchors and soil improved anchors subjected to uplifting loads. Six friction type anchors and two soil imporved anchors were installed ti the reclaimed marine soil layers. Design test loads were determined based on empirical data. Loading and unloading cycles were repeated until they reached the design test loads. Uplift resistances, displacements, and strains at fixed anchor bodies were measured. Test results were analyzed to apply them for the effective and economical construction controls. In sand and clay layers, some of friction type anchors were pulled out under extremely lower loads than design testing loads. In case of clay layers, this may be due to the much lower frictional resistance of surrounding clayey soils than expected. In sand layers, the formation of anchor body was imperfect because grout materials were dissipated into surrounding soil layers due to the high permeability of sand layers. Therefore, frictional resistances were not fully developed in sand layers. Test results were analyzed to apply them for the effective and economical construction controls. Frictional resistances were developed through the entir length of fixed anchor body in friction type anchors, whereas frictional resistances were developed around the top end of anchor body in soil improved anchors. Bearing resistances play an important role in large-diameter anchors. Frictional resistances around the anchor body tend to decrease as the length of anchor body increases. This may be due to the progressive behavior of anchor body.

고성토의 암성토에 대한 흙의 함유율이 다짐에 미치는 효과에 관한 실험적 연구

이종출,이영대,정진호,류재학,정두회 釜慶大學校 1999 釜慶大學校 論文集 Vol.4 No.1

We have carried out the field compaction tests in the site in which the high rock fill embankments are going to be constructed about 25m in height, to examine the effect of the soil fraction to the total embankment materials which are the mixture of rock fills and soils on the degree of field compaction. We have made four sets of in-situ concrete boxes of the size of 1.5m×1.5m×0.6m to obtain the maximum dry density of total embankment materials after compacting by using a 10-ton vibrating tamping roller. We have found, as a result, that the optimum passing number of the roller to yield the 90% of relative compaction economically attainable has appeared to be 8 passes, and that the percent of the soil fraction to the total embankment materials to yield the 90% of relative compation in the field has appeared to be 41.78% by weight.

지방 중소건설사의 건설중대재해 처벌법 대처를 위한 제도 개선 방안

정두회(Du Hwoe Jung ) 대한토목학회 2022 대한토목학회지 Vol.70 No.7

지방대학 토목공학 교육의 위기

정두회(Du Hwoe Jung) 대한토목학회 2021 대한토목학회지 Vol.69 No.4

합성섬유로 보강된 시멘트-점토-모래 혼합토의 휨성능 평가에 관한 연구

정두회(Du-Hwoe Jung),조백순(Baik-Soon Cho),이용운(Yong-Yun Lee) 한국지반신소재학회 2017 한국지반신소재학회 논문집 Vol.16 No.1

시멘트-점토-모래 혼합토의 휨성능 개선을 위하여 합성섬유를 이용해서 보강한 섬유보강토에 대한 휨성능 시험을 실시하였다. 시멘트, 모래, 그리고 섬유가 혼합토의 휨성능에 미치는 영향을 평가하기 위하여 시멘트량(15%, 20%, 25%), 모래함량(0%, 10%, 20%), 섬유의 종류(PP, PVA)와 길이(6mm, 12mm), 섬유혼입량(0.5%, 1.0%, 1.5%)을 조합하여 시험편을 제작하였다. 본 연구의 결과 시멘트 개량토를 섬유를 이용해서 보강하면 휨강도와 휨인성이 개선되는 효과를 확인할 수 있었다. 휨성능 시험 결과에 대한 다중선형회귀분석 결과 시멘트량과 모래함량은 휨강도에 영향을 미치는 주요 인자인 것으로 나타났고, 반면에 섬유혼입량은 균열발생 후의 거동에 영향을 미치는 주요 인자인 것으로 나타났다. The effects of synthetic fibers, cement content, and sand content on the flexural performance of cement-clay-sand mixtures has been evaluated through a flexural performance test with a third-point loading. Beam specimens for the flexural performance test were fabricated with a various amount of cement, sand, and synthetic fibers. Two types of fibers, PVA (Polyvinyl alcohol) and PP (Polypropylene) fibers, were employed in the test. The test results have exhibited that the factors considered in the test have significant effects on the flexural performance of the mixtures in several aspects. The flexural performance of the mixtures has been improved if the mixtures were reinforced with synthetic fibers. The flexural strength and the flexural toughness of the mixtures has been increased as the fiber content was increased. A multiple linear regression analysis has been performed to evaluate the effect of fiber content, cement dosage, and sand content on the flexural performance of the mixtures in terms of flexural strength and flexural toughness. Cement content and sand content were estimated as important factors to have an influence on the first-crack strength and the peak strength whereas the fiber content has the most significant influence on the post-crack behavior. The first-crack strength and the ultimate strength were increased as the cement content and the sand content were increased. As the fiber content was increased, the flexural toughness was increased.

개별진공압밀공법을 적용한 연약점토 지반의 압밀거동 분석을 위한 수치해석적 사례연구

정두회(Jung, Du Hwoe),이정빈(Lee, Jeong Bhin),이준석(Lee, Jun Seuk) 한국지반공학회 2021 한국지반공학회논문집 Vol.37 No.4

PVA섬유보강 시멘트 혼합토의 휨강도 특성에 관한 연구

정두회(Jung Du Hwoe),조백순(Cho Baik Soon),조일묵(Cho IL Muk),최성일(Choi Sung Il) 대한토목학회 2010 대한토목학회 학술대회 Vol.2010 No.10

성상복원을 위한 폐아스팔트의 화학적 분석 및 재생첨가제 연구

정두회,Jung, Du-Hwoe 한국도로학회 2001 한국도로포장공학회 논문집 Vol.3 No.1

본 연구는 노후된 폐아스콘으로부터 폐아스팔트를 추출하여 ASTM방법을 이용해서 폐아스팔트의 화학적 조성을 성분별로 분리하고, 이들을 신제아스팔트의 구성성분과 비교하여 노후시 변화하는 성분들을 파악하였다. 이러한 분석결과를 토대로 폐아스팔트의 성상복원을 위한 재생첨가제를 제조하여 재생첨가제를 10%, 20% 첨가했을 때 폐아스팔트의 복원정도를 침입도$(25^{\circ}C)$, 신도, 연화점, 점도의 네 가지 시험을 수행하여 폐아스팔트의 물성 변화 특성을 고찰하였다. 연구결과에 의하면 아스팔트의 노화시 아스팔텐의 함량이 하고, 방향족성분의 함량이 감소함을 알 수 있었고, 증가한 아스팔텐의 함량을 줄여주기 위해 아스팔트의 방향족 성분자 화학적으로 비슷한 아로마틱기유를 사용하여 재생첨가제를 제조했다. 그리고 제조된 재생첨가제를 노화가 진행된 폐아스팔트에 무게 비로 20% 첨가했을 때, 신제아스팔트 (AP-3)와 유사한 정도로 성상이 복원됨을 확인할 수 있었다. A recycling agent has been manufactured on the basis of the chemical composition of reclaimed asphalt binders and virgin asphalt binders. The chemical compositions of reclaimed asphalt binders extracted from reclaimed asphalt pavements have been analyzed according to the ASTM method and the results were compared to those of virgin asphalt binder AP-3. Reclaimed asphalt binders have shown that asphaltenes was increased whereas saturates, naphthene aromatics, and polar aromatics fractions were decreased. A recycling agent made of aromatic compounds, in which its chemical composition is similar to the aromatics fraction in asphalt binders, has been produced to reduce the amount of asphaltenes in reclaimed asphalt hinders. The evaluation of the recycling agent produced was performed by testing ductility, rolling and ball softening point, penetration at $25^{\circ}C$ and viscosity at $60^{\circ}C$. It was found that, by adding the recycling agent 20% by weight to the reclaimed asphalt binders, the physical properties of reclaimed asphalt binders was recovered to the level of virgin asphalt binder AP-3.

쉴드터널 라이닝 세그멘트의 해석과 거동 특성

정두회,이환우,김관수,Jung, Du-Hwoe,Lee, Hwan-Woo,Kim, Gwan-Soo 한국터널지하공간학회 2007 한국터널지하공간학회논문집 Vol.9 No.1

환경훼손 및 주거 과밀지역의 민원을 최소화할 목적으로 도심지 공사에서 쉴드터널공법의 적용이 날로 증대되고 있다. 쉴드터널의 주 구조체인 라이닝 세그멘트는 연속체가 아닌 이음부를 가지는 구조로 되어져 있다. 지금까지 설계실무에서는 라이닝 세그멘트의 구조해석 모델이나 설계하중 및 지반정수의 영향 등에 대한 별다른 검증 평가없이 과거의 국내 외 설계자료를 관행적으로 적용하고 있다. 본 연구에서는 국 내외에서 현재 사용하고 있는 쉴드터널의 세그멘트 해석 및 설계 모델들에 대해 이론해와 수치해의 비교를 통하여 적정성을 평가하였다. 그 결과, 사용의 편이성과 현장조건 의 적용성, 해석결과의 적용성 측면에서 전주면빔이음스프링 모델(1R-S0)을 제안하였다. 그리고, 제안된 모델을 이용하여 이음부 강성과 지반강성, 이음부 분할 분포 및 분할 개수 등에 대한 매개변수 해석을 수행하였다. 그 결과, 이음부를 갖는 라이닝 세그멘트에 발생하는 휨모멘트는 일정한 크기 이상의 지반강성에서 이음부가 없는 연속체의 라이닝 세그멘트에 발생하는 휨모멘트의 크기에 일정한 비율로 수렴함을 알 수 있었다. 또한, 이음부의 강성이 작을수록 측벽부에 비하여 천정부와 바닥부의 휨모멘트가, 수평변위에 비하여 수직변위가 이음부 분할 분포에 따라 큰 영향을 받는 것을 알 수 있었다. The shield tunneling method has been increasingly employed to minimize environmental damages and civil complaints in the populated and developed area. A lining segment, which is a main structure of the shield tunnel, consists of joints. Conventional foreign and domestic design data have been commonly used for design practices without a specific verification of structural analysis models, design load, and the effect of soil characteristics on the performance of lining segment. In this study, the suitability of existing analytic models used for the design of shield tunnel lining segment has been evaluated through a comparison between analytical and numerical solutions. Based on the evaluation of their suitability performed in the study, a full-circumferential beam jointed spring model (1R-S0) is proposed for design practices by considering user's convenience, the applicability of field conditions and the accuracy of analysis result. By using the proposed model, the parameter analysis was performed to investigate the effects of joint stiffness, ground rigidity, joint distribution and the number of joints on the behavior of lining segment. Parameters considered in the investigation have been appeared to affect the behavior of lining segment. Among those parameters, joint stiffness has been appeared to have the most significant effect on the bending moment and displacement of lining segment.