• Journal of the Korean GEO-environmental Society
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• v.14 no.2
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• pp.31-41
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• 2013

The dredged soils of western sea of Korea have been used as the fill materials because it possess the characteristics that constitute silt, silty sand and sand mainly. However, a study on dredged soils as the fill materials is insufficient. Hence, in this present study, the application the dredged soils of western sea of Korea as the fill materials was confirmed. Primary, the composition characteristics of the ground was analyzed to confirm the application on dredged soils as the fill materials by the piezo-cone penetration test. In laboratory test, it was performed the self-weight consolidation test for mechanical characteristics of the dredged soils. The direct shear test using self-weight consolidation test sample for shear strength characteristics was performed after self-weight consolidation test. Additionally, the mechanical characteristics of the dredged soils on elapsed time using self-weight consolidation test sample, which is drained naturally, was evaluated. The dredged soils of western sea of Korea show that unit weight and shear strength is increased as natural drain time elapses.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.597-604
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• 2002

This paper reviews depositional environments of marine deposits along the Nakdong river and then analytical solution of self-weight consolidation considering artesian pressure is made to find consolidated state. It's known that this area is in the under-consolidated state by the artesian pressure(u$\_$a/=0.3kg/$\textrm{cm}^2$) and the distribution of the artesian pressure is not linear but parabola. In predicting consolidation settlement for soft grounds improved by vertical drain, it is emphasized that the self-consolidation by sudden dissipation of artesian pressure should be considered.

• Geomechanics and Engineering
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• v.34 no.2
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• pp.209-220
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• 2023

In this study, a series of three-dimensional numerical analyses were carried out to investigate the penetration performance of a dynamically installed Hall anchor. The advanced coupled Eulerian-Lagrangian (CEL) technique was adopted to accurately simulate the large soil deformation during the vertical penetration of a Hall anchor. In total, 52 numerical analyses were conducted to investigate the relationship between anchor penetration depth and the initial kinematic energy. Moreover, a sensitivity analysis was performed to investigate the effects of soil shear strength and soil type on the penetration mechanism of a drop anchor under self-weight. There is a monotonic increase in the penetration depth with an increasing anchor weight when the topsoil of the riverbed is not subjected to erosion. On the other hand, all the computed depths significantly increase when soil erosion is taken into consideration. This is mainly due to an enhanced initial kinematic energy from an increased dropping depth. Both depths increase exponentially with the initial kinematic energy. An enhanced shear strength can potentially increase the side resistance and end-bearing pressure around a drop anchor, thus significantly reducing the downward penetration of a hall anchor. Design charts are developed to directly estimate penetration depth and associated plastic zone due to dynamically installed anchor at arbitrary soil shear strength and anchor kinematic energy.

• Journal of the Korean Geotechnical Society
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• v.31 no.1
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• pp.25-35
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• 2015

Penetration resistance of bucket foundations with skirt wall in the silty sand of the western coast of Korea was analyzed by centrifuge modelling. The penetration resistance is induced when the bucket foundations are jacked into the soil without suction, and is directly related to the self-weight penetration depth. The procedure by Houlsby and Byrne (2005), which takes into account the effect of stress increase by frictional resistance of skirt wall, was utilized to generate the penetration resistance similar to the experimental results. This paper describes the methods by which major parameters such as lateral earth pressure coefficient and friction angle between the skirt wall and the soil are evaluated. The effect of changes in these parameters on the predictions is analyzed. Also, observed soil behaviour during jacking penetration is investigated.

• Journal of the Korean Geotechnical Society
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• v.34 no.11
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• pp.21-31
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• 2018

Bucket foundations are widely used in offshore areas due to their various benefits such as easy and fast installations. A bucket is installed using self-weight and the hydraulic pressure difference across the lid generated by pumping out water from inside the bucket. When buckets are installed in high permeable soil such as sands, upward seepage flow occurs around the bucket tip and interior, leading to a decrease in the effective stress in the soil inside the buckets. This process reduces the penetration resistance of buckets. However, the soil inside and outside the bucket can be disturbed due to the upward seepage flow and this can change the soil properties around the bucket. Moreover, upward seepage flow can create significant soil plug heave, thereby hindering the penetration of the bucket to the target depth. Despite of these problems, soil disturbance and soil plug heave created by suction installation are not well understood. This study aims to investigate the behavior of soil during suction installation. To comprehend the phenomena of soil plug heave during installation, a series of small-scale model tests were conducted with different testing conditions. From a series of tests, the effects of tip thickness of bucket, penetration rate, and self-weight were identified. Finally, soil properties inside the bucket after installation were approximated from the measured soil plug heave.

• Advances in concrete construction
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• v.5 no.3
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• pp.271-288
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• 2017

This paper aims to investigate the effects of replacing cement with ground granulated blast furnace slag (GGBFS) in self compacting concrete in the fresh and hardened state. The performance of SCC in moderate climate is well investigated but few studies are available on the effect of hot environment. In this paper, the effect of initial water-curing period and curing conditions on the performance of SCC is reported. Cement was substituted by GGBFS by weight at two different levels of substitution (15% and 25%). Concrete specimens were stored either in a standard environment (T=$20^{\circ}C$, RH=100%) or in the open air in North Africa during the summer period (T=35 to $40^{\circ}C$; R.H=50 to 60%) after an initial humid curing period of 0, 3, 7 or 28 days. Compressive strength at 28 and 90 days, capillary absorption, sorptivity, water permeability, porosity and chloride ion penetration were investigated. The results show that the viscosity and yield stress are decreased with increasing dosage of GGBFS. The importance of humid curing in hot climates in particular when GGBFS is used is also proved. The substitution of cement by GGBFS improves SCC durability at long term. The best performances were observed in concrete specimens with 25% GGBFS and for 28 days water curing.

• Advances in concrete construction
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• v.6 no.2
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• pp.103-121
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• 2018

This paper reports the effects of coarse and fine recycled concrete aggregates (RCA) on fresh and hardened properties of self-compacting concrete (SCC) containing ground granulated blast-furnace slag (GGBFS) as cement replacement. For this purpose, three SCC mixes groups, were produced at a constant water to binder ratio of 0.38. Both fine and coarse recycled aggregates were used as natural aggregates (NA) replacement at different substitution levels of 0%, 25%, 50%, 75% and 100% by volume for each mix group. Each group, included 0, 15% or 30% GGBFS as Portland cement replacement by weight. The SCC properties investigated were self-compactability parameters (i.e., slump flow, T500 time, V-funnel flow time, L-box passing ability and sieve stability), compressive strength, capillary water absorption and water penetration depth. The results show that the combined use of RCA with GGBFS had a significant effect on fresh and hardened SCC mixes. The addition of both fine and coarse recycled aggregates as a substitution up to 50% of natural aggregates enhance the workability of SCC mixes, whereas the addition from 50 to 100% decreases the workability, whatever the slag content used as cement replacement. An enhancement of workability of SCC mixes with recycled aggregates was noticed as increasing GGBFS from 0 to 30%. RCA content of 25% to 50% as NA replacement and cement replacement of 15% GGBFS seems to be the optimum level to produce satisfactory SCC without any bleeding or segregation. Furthermore, the addition of slag to recycled concrete aggregates of SCC mixes reduces strength losses at the long term (56 and 90 days). However, a decrease in the capillary water absorption and water permeability depth was noticed, when using RCA mixes with slag.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1908-1914
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• 2012

As the turbine capacity and the water depth of wind farms are increasing, the construction cost of substructures and foundations for offshore wind turbines is expected to increase. Since the installation of suction bucket foundation is achieved by both self-weight and applied suction, the construction generally does not require heavy equipment for penetration. This study provides an economic analysis on the tripod which have the bucket foundations and compares that the jacket foundation at 50m water depth on sand layer or soft layer. As the strength of the soil and the number of the foundation is increasing, the construction cost of the tripod with the bucket foundations is more economically feasible than the jacket foundation.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.87-94
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• 2009

Volume of concrete slab changes by variations of temperature and moisture after its placement. Shrinkage due to evaporation causes tensile stress in the slab when contraction of the slab is restrained by its self weight, friction with subbase, and etc. Actual tensile stress caused by the shrinkage was less than theoretically predicted stress according to previous studies. It was the stress reduction due to visco-elastic property of the early-age concrete slab partially restrained. In this study, strains of restrained circumferential, unrestrained circumferential, and unrestrained square pillar concrete specimens were measured to investigate stress reduction of the specimens with age of concrete. Elastic modulus of the concrete was measured at the age of 1, 3, 7, 14, 28 days and penetration test was performed. The stress reduction was calculated by input the test results into theoretical equations suggested by previous researchers. The stress reduction of the restrained concrete specimens will be applied to design of concrete pavements based on results of the study.

• Journal of the Korean Geotechnical Society
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• v.29 no.4
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• pp.23-32
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• 2013

In order to evaluate the bearing capacity behaviour of a monopod suction bucket foundation for an offshore wind tower at the western sea of Korea, a centrifuge load test and numerical analyses were performed. The monopod bucket foundation was designed to be installed in a silty sand layer. The model soil was prepared to simulate a target site by using soil samples having similar properties and controlling relative density. In-flight miniature cone penetration test and bender element array were used to confirm that the model soil had represented the target site conditions. The load - rotation curve of the centrifuge load test was analysed. A series of numerical analyses were performed to validate the experimental conditions. Self-weight of the model, distance to the boundary and elastic modulus of the soil layer were varied to study their effects on the load - rotation curves.