• 한국지반신소재학회논문집
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• 제14권3호
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• pp.21-29
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• 2015

인공어초는 해양환경을 개선하고 어류와 해양생물들에게 주거지를 제공하는 인공 수중 구조물이다. 특히 인공어초가 느슨한 모래, 연약한 점성토와 같은 연약지반에 설치될 경우 인공어초의 자중에 의해 인공어초의 침하가 발생하게 된다. 본 연구에서는 관입실험을 통해 토목섬유 보강 넓이에 따른 인공어초의 지지력 보강효과를 확인하였고, 실내 대형 토조 실험을 통해 침하 저감효과를 확인하였다. 관입실험과 실내 대형 토조 실험을 통해 지오그리드와 같은 토목섬유를 인공어초 하부에 포설하게 되면 지지력이 증가하며, 침하가 감소하는 경향을 나타내었다.

• 한국농공학회지
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• 제42권5호
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• pp.133-143
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• 2000

A large scale field test of prefabricated vertical drains was performed to anayze the effect of parameters of the very soft clay at a test site. compression index and the coefficient of horizontal consolidation obtained by back-analysis of settlement data were compared with those obtained by means of laboratory tests. Hyperbolic method, Asaoka meoth and curve fitting method were used to compute final settlement of coefficient of consolidation. The relationships of settlement measurement(Sm) versus design settlement(St) and the measurement consolidation ratio(Um) versus design consolidation (Ut) were shown as Sm=(1.0~1.1) St , Um=(1.13~1.17) Ut at 1.0m spacing of drain and Sm=(0.7~0.8)St, Um= (0.92~0.99) Ut at 1.5 m spacing of drain, respectively . The relationships of the field compression index(CcField) and virgin compression index(vcc lab) were shown as Ccfield =(1.0~1.2)vcc lab . But it was nearly within the same range when considering the error factor with the determination method of virgin compression index and the prediction back-analysis of the settlement data was larger than the coefficient of vertical consolidation, and the ratio of consolidation coefficient (Ch/Cv) was Ch =(2.4~2.9) Cv , Ch=(3.4~4.2) Cv at 1.0m and 1.5m spacing of drain, respectively.

• Geomechanics and Engineering
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• 제20권5호
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• pp.385-397
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• 2020

This paper presents an application of artificial neural networks (ANNs) in settlement prediction of a foundation on sandy soil. In order to train the ANN model, a wide experimental database about settlement of foundations acquired from available literatures was collected. The data used in the ANNs model were arranged using the following five-input parameters that covered both geometrical foundation and sandy soil properties: breadth of foundation B, length to width L/B, embedment ratio D_f/B, foundation net applied pressure q_net, and average SPT blow count N. The backpropagation algorithm was implemented to develop an explicit predicting formulation. The settlement results are compared with the results of previous studies. The accuracy of the proposed formula proves that the ANNs method has a huge potential for predicting the settlement of foundations on sandy soils.

• 한국철도학회논문집
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• 제2권4호
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• pp.20-31
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• 1999

When a foundation on the ground with tunnel is constructed, the ultimate bearing capacity of a footing is reduced by tunnel. In practice, structure may bate a considerable damage because of large settlement. This study shows that the settlement which is caused by variety of the ultimated bearing capacity leads fatal damages to the footing above tunnel. Therefore, it is necessary to study on the reduction both of the ultimate bearing capacity which leads a failure and of tolerable settlement which satisfies the safety of the building. For this reason, the variety of ultimated bearing capacity was analyzed using tub-dimensional elasto-plastic finite difference method in this paper. As a result, bearing capacity of the foundation above tunnel should be determined after establishing limit of allowable settlement and considering reduction-ratio of bearing capacity.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.350-357
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• 2002

The scale effect should be considered to determine the bearing capacity and settlement of footings from Plate-Load Test, because of the size difference between a footing and a loading plate. To analyze characteristics of bearing capacity and settlement according to the difference of loading plate sizes, model tests were peformed with four different sizes of square plate, which is B=10, 15, 20 and 25cm respectively, on five different kinds of subsoil, which is pure sand(100:0), sand-clay mixed soil(75:25, 50:50, 25:75), and pure clay(0:100). Based on the analyzed results, this paper also proposed a method of bearing capacity and settlement determination, where scale effect is considered depending on the mixing ratio of sand and clay. Applying the formular proposed in this research to field problems, it is expected that evaluation of bearing capacity and settlement of footings can be more reliable and more economic construction can be achieved.

• 산업기술연구
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• 제28권A호
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• pp.11-17
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• 2008

Applicability of hyperbolic settlement prediction method to consolidation settlement in the dredged and reclaimed ground was assessed by analyzing results of centrifuge tests modelling self-weight consolidation of soft marine clay. From literature review about self-weight consolidation of soft marine clays located in southern coast in Korea, constitutive relationships of void ratio - effective stress - permeability and typical self-weight consolidation curves with time were obtained by analyzing centrifuge model experiments. For the condition of surcharge loading, exact solution of consolidation settlement curve obtained by using Terzaghi's consolidation theory was compared with results predicted by the hyperbolic method. It was found to have its own inherent error to predict final consolidation settlement. From results of analyzing thc self-weight consolidation with time by using this method, it predicted relatively well in error range of 0.04~18% for the case of showing the linearity in the relationship between T vs T/S in the stage of consolidation degree of 60~90 %. However, it overestimated the final settlement with large errors if those relation curves were nonlinear.

• 한국지반신소재학회논문집
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• 제6권4호
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• pp.7-13
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• 2007

폐탄광 지역에 도로, 철도 등의 시설물이 건설되는 경우, 침하를 억지하기 위한 지반보강이 필요하다. 본 연구에서는 다양한 보강공법을 적용한 경우에 대한 수치해석을 실시하여 적용공법별 지반보강효과를 평가하였다. 해석결과 채굴적 상부지반만을 보강하는 경우에는 보강효과가 작았으며, 채굴적을 충전하는 공법이 지반침하를 억지하는 효과가 가장 큰 것으로 나타났다. 또한, 채굴적을 충전하여 지반을 보강하는 경우, 지반침하는 채굴적의 충전율에 따라 쌍곡선형태로 감소하는 것으로 나타났으며, 채굴적 충전율과 침하저감율 사이의 상관관계를 제시하였다.

• Geomechanics and Engineering
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• 제21권4호
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• pp.337-348
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• 2020

Tropical organic soils having more than 65% of organic matters are named "peat". This soil type is extremely soft, unconsolidated, and possesses low shear strength and stiffness. Different conventional and industrial binders (e.g., lime or Portland cement) are used widely for stabilisation of organic soils. However, due to many factors affecting the behaviour of these soils (e.g., high moisture content, fewer mineral particles, and acidic media), the efficiency of the conventional binders is low and/or cost-intensive. This research investigates the impact of different constituents of cement-sodium silicate grout system on the compressibility behaviour of organic soil, including settlement and void ratio. A microstructure analysis is also carried out on treated organic soil using Scanning Electron Micrographs (SEM), Energy Dispersive X-ray spectrometer (EDX), and X-ray Diffraction (XRD). The results indicate that the settlement and void ratio of treated organic soils decrease gradually with the increase of cement and kaolinite contents, as well as sodium silicate until an optimum value of 2.5% of the wet soil weight. The microstructure analysis also demonstrates that with the increase of cement, kaolinite and sodium silicate, the void ratio and porosity of treated soil particles decrease, leading to an increase in the soil density by the hydration, pozzolanic, and polymerisation processes. This research contributes an extra useful knowledge to the stabilisation of organic soils and upgrading such problematic soils closer to the non-problematic soils for geotechnical applications such as deep mixing.

• 한국지반공학회논문집
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• 제23권6호
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• pp.85-95
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• 2007

본 연구에서는 버티칼 드레인으로 개량된 점성토 지반의 잔류침하 예측법을 제안하기 위하여 모델지반에 대해 탄-점성 압밀이론을 이용한 일련의 수치해석을 행하였다. 그리고 수치해석을 통하여 정규압밀영역에 대해 유효반경비, 압밀압력의 영향과 버티칼 드레인에 의한 3차원압밀에 있어서의 잔류침하를 감소시키기 위한 과압밀영역에서의 과압밀비의 영향을 조사하였다. 또한, 모델지반의 수치해석결과에 기초하여 버티칼 드레인 타설지반의 잔류침하 예측법과 잔류침하를 허용치 이내로 제어하기 위해 필요한 과압밀비의 결정법을 제안하였다.

• Geomechanics and Engineering
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• 제34권4호
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• pp.397-408
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• 2023

Pipe pile walls are commonly used as retaining structures for excavation projects, particularly in densely populated coastal cities such as Hong Kong. Pipe pile walls are preferred in reclaimed land due to their cost-effectiveness and convenience for installation. However, the pre-bored piling techniques used to install pipe piles can cause significant ground disturbance, posing risks to nearby sensitive structures. This study reports a well-documented case history in a reclamation site, and it was found that pipe piling could induce ground settlement of up to 100 mm. Statutory design submissions in Hong Kong typically specify a ground settlement alarm level of 10 mm, which is significantly lower than the actual settlement observed in this study. In addition, lateral soil movement of approximately 70 mm was detected in the marine deposit. The lateral soil displacement in the marine deposit was found to be up to 3.4 and 3.1 times that of sand fill and CDG, respectively, mainly due to the relatively low stiffness of the marine deposit. Based on the monitoring data and site-investigation data, a 3D numerical analysis was established to back-analyze soil movements due to the installation of the pipe pile wall. The comparison between measured and computed results indicates that the equivalent ground loss ratio is 20%, 40%, and 20% for the fill, marine deposit and CDG, respectively. The maximum ground settlement increases with an increase in the ground loss ratio of the marine deposit, whereas the associated influence radius remains stationary at 1.2 times the pipe pile wall depth (H). The maximum ground settlement increases rapidly when the thickness of marine deposit is less than 0.32H, particularly for the ground loss ratio of larger than 40%. This study provides new insights into the pipe piling construction in reclamation sites.