• Geomechanics and Engineering
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• v.27 no.6
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• pp.595-604
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• 2021

With the advantages of high permeability and strength, pervious concrete piles can be suitable for ground improvement with high water content and low bearing capacity. By comparing the strength and permeability of pervious concrete with different aggregate sizes (3-5 mm and 4-6 mm) and porosities (20%, 25%, 30% and 35%), the recommended aggregate size (3-5 mm) and porosity (30%) can be achieved. The model tests of the pervious concrete piles in soft soil (silt and clay) foundations were conducted to evaluate the bearing characteristics, results show that, for the higher consolidation efficiency of the silty foundation, the bearing capacity of the silty foundation is 16% higher, and the pile-soil stress ratio is smaller. But when it is the ultimate load for the piles, they will penetrate into the underlying layer, which reduces the pile-soil stress ratios. With higher skin friction of the pile in the silty foundation, the pile penetration is smaller, so the decrease of the pile axial force can be less. For the difference in consolidation efficiency, the skin friction of pile in silt is more affected by the effective stress of soil, while the skin friction of pile in clay is more affected by the lateral stress. When the load reaches 4400 N, the skin friction of the pile in the silty foundation is about 35% higher than that of the clay foundation.

• Geomechanics and Engineering
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• v.38 no.1
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• pp.79-91
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• 2024

The settlement, bearing capacity, axial force, and skin friction responses of pervious and impervious concrete piles in silty and sandy underlying layer foundations and of pervious concrete piles in model tests were determined. The results showed that pervious concrete piles can exhibit high strengths, provide drainage paths and thus reduce foundation consolidation time. Increasing the soil layer thickness and pile length could eliminate the bearing capacity difference of pervious piles in a foundation with a silty underlying layer. The pervious concrete piles in the sandy underlying layer were more efficacious than those in the silty underlying layer because the sandy underlying layer can provide more bearing capacity than the silty underlying layer. The results indicated that the performances of the pervious concrete piles in the sand and silt foundations differed. The pervious concrete piles functioned as floating piles in the underlying layer with a lower bearing capacity and as end-bearing piles in the underlying layer with a higher bearing capacity.

• Journal of the Korean GEO-environmental Society
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• v.6 no.1
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• pp.23-31
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• 2005

The "Silt Pond" is 180 hectares in size and contained ultra soft slurry-like soil varying between 3 to 20 meters in thickness. Reclamation works in the Silt Pond commenced in the mid of 1990s. A considerable amount of subsurface investigation inclusive of sampling, field vane and density logging tests were carried out prior to the reclamation of the Silt Pond. Since material in the Silt Pond is extremely soft, filling was done by spreading sand with high water content in thin and equal thickness lifts, allowing the stability of the slurry-like foundation. Despite the extreme care taken, failures occurred during the sand spreading phase. A large piece of high strength geotextile measuring $900m{\times}700m$ was placed to strengthen the slurry like soil foundation at locations where the ultra-soft soil was found to be exposed. Following the remedial works, the Silt Pond was again reclaimed by sand spreading up to +4.0m CD. The success of the reclamation was confirmed by marine CPT profiling.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.574-579
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• 2004

In this study, finite difference method used in order to analyze influence on settlement of shallow foundation as a result of vegetation and environmental changes, On boundary conditions to analyze, divided the foundation to clayey silt, changed the amount of evaportanspiration to consider the influence of vegetation, and assumed that the duration of enviromental changes are 180 days to consider the influence of environmental changes. It is expected that this study will do to predicting settlement of shallow foundation as well as to preventing damage of shallow foundation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.1 no.1
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• pp.87-92
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• 1989

In this study, the nonlinear dynamic model of the systems which include the offshore structure, the surrounding sea water in terms of the added mass, the foundation in terms of frequency independent springs, dashpots, and the floating ice feature with its hydrodynamic added mass, are proposed for the problem of the large ice floes impact. Dynamic Analysis is performed on two site conditions, sand site and silt site, and on two seasons, winter and summer, for various ice floe velocities. As a result of study, Ice floes from energy balenced method is lower than that from dynamic modeling on sand site, and higher than the on silt site.

• Journal of the Korean Geotechnical Society
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• v.27 no.2
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• pp.5-15
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• 2011

This research performed the laboratory model tests for Top-Base Foundation developed in Japan and Floating Top-Base Foundation developed in Korea on the typical clayey soft soils, namely, clay, clayey silt and clayey sand. The performances of the two types of top-base foundation were compared with each other and evaluated by measuring load-settlement, heaving of foundation side, ground stress distribution in this model tests. The change of settlement caused by the increase of top base width was also analyzed. As a result of the model tests, Floating Top-Base Foundation showed better performance in bearing capacity improvement, settlement decrease, stress dispersion effect and lateral confinement force. And settlement caused by the increase of top base width converged to a regular value from $5{\times}5$ layout of the width.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.28-35
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• 2001

Liquefaction potential on the specific site of nuclear power plant is analyzed and reviewed. The layered site fur this study consists of silt and sand. Based on the limited available soil data, maximum shear strength at critical locations using Seed & Idriss method and computer program SHAKE is calculated, and liquefaction potential is reviewed. Seismic input motion used fur the assessment of liquefaction is the artificial time history compatible with the US NRC regulatory Guider .60. Assessment results of the liquefaction are validated by analyzing to the other typical soil fecundations which can show the effects of foundation depth and soil data.

• Earthquakes and Structures
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• v.22 no.6
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• pp.597-608
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• 2022

One of the most important parameters affecting nonlinearsoil-structure interaction, especially rocking foundation, is the vertical factor of safety (F.S_v). In this research, the effect of F.S_v on the behavior of rocking foundations was experimentally investigated. A set of slow, cyclic, horizontal loading tests was conducted on elastic SDOF structures with different shallow foundations. Vertical bearing capacity tests also were conducted to determine the F.S_v more precisely. Furthermore, 10% silt was mixed with the dry sand at a 5% moisture content to reach the minimum apparent cohesion. The results of the vertical bearing capacity tests showed that the bearing capacity coefficients (N_c and N_γ) were influenced by the scaling effect. The results of horizontal cyclic loading tests showed that the trend of increase in capacity was substantially related to the source of nonlinearity and it varied by changing F.S_v. Stiffness degradation was found to occur in the final cycles of loading. The results indicated that the moment capacity and damping ratio of the system in models with lower F.S_v values depended on soil specifications such cohesiveness or non-cohesiveness and were not just a function of F.S_v.

• Geomechanics and Engineering
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• v.28 no.3
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• pp.239-253
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• 2022

Suitable techniques to stabilize organic soil and improve its engineering behaviour are in demand. Despite various alternatives, nano-additives proved to be an effective stabilizer owing to their strength enhancing properties. The study focuses on using nano-silica as a potential stabilizer to improve organic silt. Soil was treated with four dosages of nano-silica namely 0.2%, 0.4%, 0.6% and 0.8% of dry weight of the soil. Nano-silica treated soil showed a strength increase of nearly 25% at a dosage of 0.4% after curing for two hours. Strength of the treated soil improved with age. Strength improved by nearly 62.9% after 28 days of curing and 221.4% after 180 days of curing due to formation of Calcium - Silicate - Hydrate (CSH) gel in the soil matrix. Dosage of 0.6% nano-silica is observed to be the optimum dosage. Coefficient of permeability and compression index showed an increase by 13.32 and 5.5 times respectively owing to aggregation of particles and creation of void spaces as visualized from the scanning electron micrographs. Further model foundation study and numerical parametric studies using PLAXIS 2D indicate that optimized and economic results can be obtained by varying the additive dosage with depth.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.386-393
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• 2023

The domestic marine healing industry is undergoing significant revitalization efforts, with a focus on understanding the efficacy and effectiveness of marine healing resources. This study establishes utilization and management standards through a detailed analysis of the active components within well-recognized marine healing mud materials. Samples of mud materials were collected from domestic tidal flats. These samples exhibited an average composition of 7.87% sand, 74.95% silt, and 17.17% clay, with a combined mud content (silt+clay)(silt+clay) consistently exceeding 90%. Notably, SiO₂ emerged as the most prevalent effective ingredient at 68.4%, followed by Al₂O₃ (13.3%)>Fe₂O₃ (4.0%)>K₂O (2.9%)>Na₂O (2.3%)>MgO (1.6%)>CaO (1.0%)>TiO₂ (0.7%), in terms of average content. Subsequently, through an analysis of effective ingredients, Si, Al, Fe, K, Na, Mg, and Ca were identified as elements demonstrating significant functionality. Among these, key indicator ingredients were selected for quality control, all of which were found to possess efficacious properties. Notably, K, Mg, and Ca exhibited particularly high concentrations. Based on these findings and referencing existing literature, it is recommended that domestic tidal flat mud resources earmarked for utilization as marine healing resources should possess a raw material mud content of no less than 70.0%. Moreover, the cumulative index components K₂O+MgO+CaO should meet or exceed a threshold of 5.0% for optimal effectiveness.