• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1999년도 연약지반처리위원회 학술세미나
• /
• pp.78-83
• /
• 1999

The ultimate settlement of soft clay consists of three parts: $\circled1$ immediate settlement, S$\sub$d/; $\circled2$ Primary consolidation settlement, S$\sub$c/; $\circled3$ Secondary consolidation settlement, S$\sub$s/. In general, S$\sub$c/ can be accurately calculated by one-dimensional consolidation and S$\sub$s/ or S$\sub$d/ may be ignored. This paper focuses on a calculation method to estimate the immediate settlement induced by lateral deformation of subgrade, to which shear stress is applied by embankment on soft ground. Immediate settlement and consolidation settlement are discussed by comparing the field measurement of the Yangsan test embankment on treated soft foundation by vertical paper drains.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2002년도 기초기술위원회 워크샵
• /
• pp.53-80
• /
• 2002

Settlement in the Shallow Foundation are presented. Various practical methods to calculate immediate settlement, consolidation settlement, and secondary compression of the compressive soils under the shallow foundation are summerized. Especially the critical depth for settlement calculation, the contact pressure, the allowable settlement of the shallow foundation are recommended.

• Geomechanics and Engineering
• /
• 제15권3호
• /
• pp.823-831
• /
• 2018

The most important issue during shield TBM tunneling in soft ground formations is to appropriately control ground surface settlement. Among various operational conditions in shield TBM tunneling, the face pressure and backfill pressure should be the most important and immediate measure to restrain surface settlement during excavation. In this paper, a 3-D hydro-mechanical coupled FE model is developed to numerically simulate the entire process of shield TBM tunneling, which is verified by comparing with real field measurements of ground surface settlement. The effect of permeability and stiffness of ground formations on tunneling-induced surface settlement was discussed in the parametric study. An increase in the face pressure and backfill pressure does not always lead to a decrease in surface settlement, but there are the critical face pressure and backfill pressure. In addition, considering the relatively low permeability of ground formations, the surface settlement consists of two parts, i.e., immediate settlement and consolidation settlement, which shows a distinct settlement behavior to each other.

• 한국농공학회지
• /
• 제40권4호
• /
• pp.94-102
• /
• 1998

This paper aims at developing the prediction technique of the deformation for the embankment such as sea dike and shore protection relevant to reclamation project along the southern coast of the Korean Peninsula. Generally total deformation of a sea dike over clayey foundation are composed of immediate settlement, plastic deformation and consolidation settlement. Plastic deformation occurs when the ultimate bearing capacity is less than overburden pressure containing the stress increment due to the construction of an embankment. The reliable prediction of total settlement is very important since deformed final geometry of sea dike is directly connected for analysing the safety of the long-term slope failure and piping. During this study, plastic deformation, major part of deformation was analysed using the program developed by authors, whereas immediate settlement and consolidation settlement were predicted by Mochinaka and Sena's method and Terzaghi's 1-dimensional theory of consolidation respectively. In order to validate the prediction technique for the deformation, a case study of Koheung Bay reclamation works was carried out. A good agreement was obtained between observation and prediction, which means the applicability of the technique.

• 통상정보연구
• /
• 제8권4호
• /
• pp.71-88
• /
• 2006

This article want to discuss on comparative research between CHIPS and Fedwire as the cross-border payment systems which America have and use at present. CHIPS is a New York-based automated private-sector clearing facility for large-dollar transfers. It is a central switch communication and settlement system whose 53 participating banks exchange same-day payment messages over dedicated communication lines linking each one to the CHIPS central computer. On January 22, 2001, CHIPS introduced immediate finality for payment released from the CHIPS queue. Unlike the Fedwire system, The CHIPS system is not a real-time gross settlement system. Instead, CHIPS is hybrid system that uses a computer program to select payment order in a queue for release to the receiving bank. CHIPS are governed by CHIPS Rules and Administrative Procedures. Fedwire system is a nationwide electronic fund-transfer system facilitating same-day transfers throughout the United States. It is a gross settlement system providing immediate credit to the receiving bank's master account. Communicating between a Federal Reserve Bank and Fedwire users can be either on-line or off-line. Fedwire transfers are governed by Subpart B of Regulation J, issued by the Federal Reserve Board, which incorporates U.C.C. Article 4A but preempts or supersedes any of its inconsistent provisions.

• 한국지반환경공학회 논문집
• /
• 제20권1호
• /
• pp.13-17
• /
• 2019

This paper presents case history of railway embankment excess settlement on soft clay during service in southern region of Korea. A lot of field observations show that the measured settlements are a lot larger than settlements actually calculated in this area. Back analysis is carried out to verify the soil parameters which are intended to investigate in the subsurface exploration phase and later in a laboratory test program. Recommendations and causes for the engineering practice are suggested to review the determination of excess settlements and, consequently, to improve the settlement prediction. This enormous discrepancy is due to the passing over secondary consolidation, and the design filling did not meet to real construction filling. Immediate settlement could be subsidiary factor of excess settlement.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2001년도 가을 학술발표회 논문집
• /
• pp.147-158
• /
• 2001

In general, two methods have been used to predict settlement of soft ground. One method is Terzaghi's one dimensional consolidation theory which gives time-settlement relationship using the standard consolidation test results. The other is forecasting method of ground settlement to be occured in the future using in-situ monitoring data. The above both methods have some defects in application manner or in itself especially in very deep and soft clayey ground. In view of the lessons and experiences of soft ground improvement projects, several techniques were proposed for more accurate theorectical calculation of consolidation settlement as follows ; ① Subdivision of soft ground, ② Consideration of secondary compression, ③ Using the modified compression index, etc. And also, revised hyperbolic fitting method was suggested to minimize the error of predicted future settlement. In addition, revised De-Beer equation of immediate settlement of loose sandy soil was proposed to overcome the tendency to show too small settlement calculation results by original De-Deer equation. And also, considering the various effects of settlement delay in the improved ground by vertical drains, time-settlement caculation equation(Onoue method) was revised to match the tendency of settlement delay by using the characteristics of discharge capacity decreases of vertical drain with time elapse by the pattern of hyperbolic equation.

• 대한환경공학회지
• /
• 제27권5호
• /
• pp.486-490
• /
• 2005

본 연구에서는 일반(천연)모래를 대체하여 폐콘크리트 재생잔골재(이하 재생모래)를 하수관거 모래기초용 재료로 활용하였을 경우 재생모래의 지반적 거동(침하)에 대한 다양한 적용성 평가를 실시하였다. 이를 위해 상대적 재료 특성 차이에 따른 침하량 전산모사(FLAC 사용)를 실시하였으며 실내 재하 실험을 통한 즉시침하 평가, 우수에 의해 예상되는 재료특성 변화를 살펴본 후 실규모급 현장 적용성 평가를 실시하였다. 그 결과 FLAC으로 예측된 재생모래기초의 침하량은 $5.0{\times}10^{-6}\;m$ 미만이었으며, 실내 침하실험에서는 침하가 발생되지 않았다. 또한 용출에 인한 재료특성(흡수율 등) 변화 역시 미미하였다. 마지막으로 실규모급 현장 시공의 침하 모니터링 결과, 원지반의 압밀침하로 예상되는 5 mm의 침하만이 발생하였다. 이를 통해서 재생모래의 하수관 모래기초 적용성은 충분한 타당성을 가지는 것으로 판단된다.

• 한국터널지하공간학회 논문집
• /
• 제20권2호
• /
• pp.433-452
• /
• 2018

쉴드 TBM 공법은 터널 굴착으로 인한 터널 굴진면과 굴착면의 변형을 억제하여 지반의 변형을 최소화할 수 있는 공법이다. 이를 위해 쉴드 TBM의 운전 조건들을 적절히 제어하는 것은 매우 중요하다. 쉴드 TBM 공법의 여러 가지 운전 조건 중 굴진면압과 뒤채움주입압은 지반에 직접 압력을 가하는 과정으로 굴착에 인한 지반변위의 억제 뿐만 아니라, 지반 내 유효응력 및 간극수압의 변화에 영향을 미치는 요인이다. 굴진면압과 뒤채움압의 작용에 대한 지반의 반응은 지반의 강성 및 투수성에 따라 상이하다. 특히, 포화된 연약 점성토의 경우 굴진면압과 뒤채움압에 의한 지반 내 응력 변화의 영향이 장시간동안 잔류하므로 이에 대한 반응은 투수성이 큰 지반과 구별되는 거동을 보인다. 따라서 본 논문에서는 유한 요소법을 이용한 응력-간극수압 연계 매개변수해석을 통해 포화 점성토 지반에서 쉴드 TBM 운전 조건과 지반의 강성과 투수성이 지표침하에 미치는 영향에 대한 연구를 수행하였다. 연구 결과, 점성토 지반의 지표침하는 즉시침하와 압밀침하로 구분할 수 있었으며, 특히 압밀침하 거동은 지반의 투수성과 강성의 영향을 크게 받는 것으로 나타났다. 또한, 굴진면압과 뒤채움압의 증가가 항상 지표침하 감소로 이어지지는 않고, 임의 크기의 압력(한계 압력) 이상으로 증가된 굴진면압과 뒤채움압은 역으로 지표침하를 증가시키는 요인으로 작용할 수 있음이 확인되었다.

• 한국지반공학회논문집
• /
• 제24권5호
• /
• pp.55-64
• /
• 2008

연약지반 위에 토공구조물을 축조할 경우, 기초지반이 지지할 수 없는 큰 하중의 성토를 실시하게 되면 지반파괴가 발생하면서 연약층 내로 성토재료가 함몰하게 된다. 이때, 축조재료가 어떤 깊이까지 연약지반에 침하하여 단면이 형성되는가를 예측할 필요가 있다. 기존의 이론식(Janbu, Peroff의 이론식)을 이용하여 즉시침하량을 계산하구 결과를 검토한 후 문제점을 분석하여 대나무 매트를 부설한 지반에 적합한 이론식을 제시하였고, 이를 현장에 적용하여 즉시 침하량을 계산하고 지반조사에 의한 침하량과 유한요소해석 결과를 고찰하였다. 그 결과, 침하는 제체 중앙부에서 최대 침하가 발생하였으며 이론식과 비슷한 수치와 경향을 나타내었다. 기존 이론식으로 현장의 즉시침하량을 계산한 결과, Janbu의 방법과 Peroloff의 방법의 침하량은 실제 침하의 40%정도의 침하량이 계산되었다.