• 한국지반공학회논문집
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• 제23권5호
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• pp.63-75
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• 2007

Piled raft 기초는 연약지반상에서 과도한 침하와 raft 및 말뚝의 지지력 산정 문제 등으로 적합한 기초는 아닌 것으로 알려져 왔으나 최근 국내외에서 연약지반내 구조물 시공이 증대되면서 연약지반상 piled raft 기초에 대한 관심이 커지고 있다. 이에 본 연구에서는 연약지반에 시공된 piled raft기초의 거동을 분석하였으며 이를 위해 ABAQUS를 이용한 3차원 유한요소 해석을 실시하였다. 해석 시 하중은 등분포하중과 집중하중을 각각 적용하였으며 동일한 조건의 군말뚝과 piled raft 기초 및 다양한 말뚝 배치를 갖는 piled raft 기초를 대상으로 수행하였다. 본 연구결과, 하중형태, 다양한 말뚝 배치 및 근입 깊이에 대한 각각의 침하 및 하중분담특성을 비교, 분석하였으며 이를 통해 연약지반상의 piled raft 기초의 특성을 파악하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.964-968
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• 2010

Ground anchor, commonly referred to as tiebacks or tie-down, is essentially steel elements secured in the ground by cement grout. They are used to provide either lateral or vertical support for various engineered structures, and are effective in all types of soil and rock. However, ground anchor can not be used in soft clay because anchor resistance would not be guaranteed. In this paper, conceptual introduction of the Smart Anchor is presented. The Smart Anchor is a kind of friction type anchor, the load is diffused and applied to the various parts of the distributed bond length, having less impact on the grout strength, and being able to secure necessary anchoring force in relatively soft grounds. This study shows a numerical study of predicting the load transfer of The Smart Anchor in soft clay. A beam-column analysis was performed by a elastic-plastic P-y curves in soft clay.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.960-963
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• 2010

In recent days, the development project for industry or housing complex at west coast of Korea is on an increasing trend. the design of soft ground is necessarily required. So, the evaluation of consolidation characteristics for soft ground is very important in design and construction. Especially, the correct evaluation of preconsolidation pressure or OCR for given soft ground is essential at the west coast that has a large tidal range, since it affects the settlement of soft ground. In this study, various methods determining preconsolidation pressure were carried out to investigate the application of each method. The preconsolidation pressure that evaluated from the results of conventional consolidation tests on the songsan clay were compared.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1998년도 봄 학술발표회 논문집
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• pp.241-246
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• 1998

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.505-512
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• 1999

Soft marine clay deposits pose several foundation problems. Generally, lime stabilization is used worldwide for solidifying of soft marine clay deposits. In this paper, a series of laboratory tests were conducted to verify clay-lime reaction. A clay was collected from Pusan, which was mixed with various quantities of quick lime and slaked lime. Various compounds produced by clay-lime reaction were identified by X-ray diffraction analysis. The physico-chemical properties of the clay were also investigated. Compounds such as calcium silicate hydrate (CSH), calcium aluminate hydrate (CAH), calcium aluminate (CA), hillebrandite, and gehlenite were identified. It is likely that such compounds were mainly produced by pozzolanic reaction. Based on the change of physico-chemical properties obtained by the reaction, the water content was considerably decreased when lime was added to the clay. In addition, unconfined strength was increased. In the other hand, quick lime was more effective than slaked lime in decreasing and increasing of the water content and unconfined strength, respectively. Fewer cracks were produced when the clay was mixed with quick lime. It is suggested that these beneficial changes produced by the mixing of the clay and lime depend on the properties of compounds obtained by chemical reaction.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 연약지반처리위원회 학술세미나
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• pp.70-77
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• 1999

Consolidation settlements on soft clay are often large and potentially damaging to structures. Currently, large-scale projects are in progress in Korea. These structures will be constructed on both thick and soft clay layers, and so the accurate evaluation of magnitude of settlement is required at every step in design and construction. Especially, secondary compression play an important role in consolidation settlements on soft clay. Generally, the magnitudes of secondary compression are evaluated by laboratory and in-situ consolidation tests or by empirical $C_{a/}$ $C_{c}$ relationships. The empirical $C_{a/}$ $C_{c}$ may not be only economical, but a fast and powerful tool in estimating secondary consolidation settlement. However, databases of the $C_{a/}$ $C_{c}$ relationship for sites in Korea are currently insufficient. The purpose of this study is to investigate the relationship of $C_{a/}$ $C_{c}$, on marine clay near the southern sea in Korea. In this study a series of incremental loading consolidation tests (measuring base pore water pressure) are performed. It was found that the $C_{a/}$ $C_{c}$ on undisturbed marine clay equaled 0.0397. This value is similar to the value proposed by Mesri and Castro(1987) for inorganic clay and silt. and silt. and silt.

• Geomechanics and Engineering
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• 제8권5호
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• pp.707-726
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• 2015

This paper investigates the time dependent behaviour of Haarajoki test embankment on soft structured clay deposit. Half of the embankment is constructed on an area improved with prefabricated vertical drains, while the other half is constructed on the natural deposit without any ground improvement. To analyse the PVD-improved subsoil, axisymmetric vertical drains were converted into equivalent plane strain conditions using three different approaches. The construction and consolidation of the embankment are analysed with the finite element method using a recently developed anisotropic model for time-dependent behaviour of soft clays. The constitutive model, namely ACM-S accounts for combined effects of plastic anisotropy, interparticle bonding and degradation of bonds and creep. For comparison, the problem is also analysed with isotropic Soft Soil Creep and Modified Cam Clay models. The results of the numerical analyses are compared with the field measurements. The results show that neglecting effects of anisotropy, destructuration and creep may lead to inaccurate predictions of soft clay response. Additionally, the numerical results show that the matching methods accurately predict the consolidation behaviour of the embankment on PVD improved soft clays and provide a useful tool for engineering practice.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.507-511
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• 2009

This paper describes the performance design requirements of the slope and soft clay structures to confirm several contents of foundations systems to change existing design code to new one in the construction market. The concepts of performance design explain systematical needs for specific performance guidelines.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.725-730
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• 2002

The areas around the Nam-Hae are mostly covered in thick soft clay deposits(50∼60.0m). In order to improve the ground in these areas verticals trains have been partially penetrated up to the depth of about 25.0m. However, since the predicted values of settlement have often been changed at some predicted time. Finite element analysis was performed to investigate the consolidation behaviour for it. The results from FEM was compared with various observational methods.

• Geomechanics and Engineering
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• 제13권2호
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• pp.255-267
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• 2017

Soft clay strata can suffer significant settlement or stability problems under building loads. Among the methods proposed to strengthen weak soils is the application of a stone masonry trench (SMT) beneath RC strip foundations (as a masonry pad-stone). Although, SMTs are frequently employed in engineering practice; however, the effectiveness of SMTs on the ultimate bearing capacity improvement of a strip footing rested on a weak clay stratum has not been investigated quantitatively, yet. Therefore, the expected increase of bearing capacity of strip footings reinforced with SMTs is of interest and needs to be evaluated. This study presents a two-dimensional numerical model using the discrete element method (DEM) to capture the ultimate load-bearing capacity of a strip footing on a soft clay reinforced with a SMT. The developed DEM model was then used to perform a parametric study to investigate the effects of SMT geometry and properties on the footing bearing capacity with and without the presence of surcharge. The dimensions of the SMTs were varied to determine the optimum trench relative depth. The study showed that inclusion of a SMT of optimum dimension in a soft clay can improve the bearing capacity of a strip footing up to a factor of 3.5.