• Journal of the Korean Geosynthetics Society
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• v.18 no.3
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• pp.33-44
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• 2019

Clinker layer is a stratum structure distributed in volcanic area such as Jeju Island. The clinker layers were formed in between the repetitive action of eruption and solidification of lava flows. Since the clinker layer contains a large amount of voids accompanied by the lava gas ejection process, there is a possibility of inducing overall stability of the ground due to the low stiffness and strength of the clinker layer. Therefore, in this study, site investigation was carried out at both ends of the 00 bridge where the clinker layers exist. And, based on the ground survey results, the behavior of shallow foundations was analyzed numerically. In addition, the improved shallow foundation behavior in grouting substitution using the chemical injection method of the clinker layer was compared with the shallow foundation behavior in the ground, and the grouting substitution efficiency of each layer was analyzed. As a result, the bearing capacity, the replacement efficiency and elastic settlement were different according to the presence or absence of the sediment layer. This is because the sediment layer has a lower stiffness and density than the clinker layer.

• Journal of the Korean Geotechnical Society
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• v.34 no.1
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• pp.25-35
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• 2018

Geocentrifuge tests are performed to investigate the structure-soil-structure interaction of shallow foundations that have various sizes. The soil specimen is prepared by using the air-pluviation, and the dynamic responses of the foundation are monitored with separation distances between the two foundations and the embedment. During the centrifugal test, the measured ground acceleration shows a tendency to increase with the increase of the input seismic amplitude, and maximum acceleration is measured at the surface due to the ground amplification. As the separation distance between the two foundations decreases, the ratio of the response spectral acceleration (RRS) increases and the period at the peak RRS decreases due to the structure-soil-structure interaction (SSSI). The RRS of the two foundations tends to decrease when the foundations are buried in the ground at the same separation distance.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.87-91
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• 2001

얕은 기초의 침하는 기초에 가해지는 상재 하중의 지반에 전달될 때 분포되는 응력의 특성과 크기에 관련되어 일어난다. 일반적으로 지반의 보강재로 사용되는 지오그리드로 두께가 작은 토체를 보강하면 지중에 전달되는 응력을 재분포시켜 감소시킨다. 이 논문에서는 현장시험을 통하여 여러 층의 지오그리드로 토체를 보강시 토체 상부에 가해지는 원형 등분포 하중하에서 토체의 응력 분포를 측정하였다. 인천국제 공항 건설 현장의 준설 매립 구간에서 행하여진 이 시험을 통하여, 지오그리드로 보강된 토체의 하중 분포는 기초에 가해지는 하중 강도와, 보강재 포설층수, 토체의 두께의 함수로 나타낼 수 있다.

• Journal of the Korean Geotechnical Society
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• v.28 no.7
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• pp.67-75
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• 2012

This paper addresses the size effect of shallow foundation settlement in very dense weathered granite soil commonly encountered in bridge foundation. Load-settlement curves measured from the plate load tests of 5 different plate sizes in 2 sites were analyzed. The test results showed that the ground beneath the plate was considered not to reach the failure state and the settlement continuously increased proportionately as load increased. The result implies that settlement would govern the stability or serviceability of foundation on very dense weathered soil. The size effect is expressed as a relationship of subgrade reaction modulus to the size of plate. Compared with the previous relationships, the size effect in this result was more prominent and indicated that settlement prediction using the previous method could possibly underestimate the settlement of foundation in dense weathered granite soil.

• Journal of the Korean GEO-environmental Society
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• v.11 no.4
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• pp.51-59
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• 2010

This article is a case study for the example of the foundation design, in the project area of the silty sand layer that is spread shallowly with loose status, to make the site for a structure and build it up. The site is located on the dredged and reclaimed land in Gun-San and In-Cheon that is formed the silty sand layer with loose status range around 10 meters underground level, the solid ground for the lower pile is shown around 20 meters underground level. Therefore, this area has to be done by ground improvement when applying for the shallow method of foundation. Dynamic compaction method considering the conditions of the design loads in each zone has to be decided through comparative review on the method of foundations and pilot field test was conducted, and drilling investigation and plate bearing test were achieved as well. The analysis results of the tests prove that stability against bearing capacity was acquired by ground improvement effect.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.3
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• pp.55-65
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• 2000

구조물 지진해석을 위한 구조물 -지반 상호작용 해석에서도 비선형 지반 특성을 고려한 비선형해석이 요구되고 있어 구조물 비선형 지진 해석을 위해 기초 지반에 대한 수평방향 비선형 해석을 수행하였다. 기초지반은 UBC 분류에서 규정한 보통지반인 Sn 지반과 연약지반인 SE 지반을 고려하였고, 지반의 비선형 특성은 Ramberg-Osgood 모델을 이용하였다. 비선형 지반이 기초지반 수평 및 회전 동적 강성 및 감쇠비에 미치는 영향을 조사하기 위하여 얕은 기초와 묻힌기초에 대해 기초 크기, 지반깊이 및 말뚝유무에 따른 동적 강성 및 감쇠비 변화를 조사하였는데, 지반의 비선형 특성이 기초지반의 선형 수평 및 회전 강성과 감쇠비를 크게 감소 또는 증가시키는 것으로 나타났으며, 기초크기, 지반깊이 및 말뚝유무의 영향도 큰 것으로 나타나 구조물 지진해석시 기초크기, 지반깊이 및 말뚝유무와 함께 지반의 비선형성도 고려하는 것이 필요한 것으로 판단되었다.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.11a
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• pp.53-80
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• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.933-939
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• 1994

This paper has primarily been directed to evaluate the beneficial effects of geogrid reinforcement in a medium sand on the ultimate bearing capacity (UBC) of a surface foundation. Also, this study was conducted to investigate the permanent settlement of a shallow square foundation in improving the cyclic load-settlement characteristics of reinforced sand deposits by conducting a series of laboratory model tests. Use of geogrids provides an economical and time efficient method for improving load-settlement and strength characteristics of weak soils. Especially the geogrid reinforced soil will be necessary in the case of foundation supporting machines, embankments for railroads, and foundations of structures in earthquake-prone areas. Finally, the test results indicate that the use of geogrid reinforcement in sand subgrades improves their performance under dynamic loads which shows promise for future work.

• Journal of the Korean Geotechnical Society
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• v.20 no.7
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• pp.107-117
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• 2004

A series of model tests were conducted to investigate how the number of reinforcement layers, stiffnesses, types of reinforcement material and buried depth of a flexible pipe can affect bearing capacity-settlement curve at a loose sand foundation. In the test results, whereas the type of failure in unreinforced sand was local shear, the type of failure, for model tests with more than 2 reinforcement layers in loose sand, was general shear: The number of the optimum reinforcement layers was found to be two: Stiffness and type of reinforcement were more important than the maximum tensile strength of reinforcement in improving bearing capacity. When the depth of buried pipe from the sand surface was less than the width of the footing, test results showed that both bearing capacity and ultimate bearing capacity of buried pipe in unreinforced sand significantly decreased, and the type of failure in the reinforced sand changed from general shear to local shear.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.229-240
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• 2002

This paper is an experimental and numerical work of Investigating the bearing capacity of shallow foundation of rubble mound under eccentric loads. Parametric centrifuge model tests at the 50g level environments with the model footings in the form of strip footing were performed by changing the loading location of model footing, relative density and materials for ground foundation. For the model ground, crushed rock sampled from a rocky mountain was prepared with a grain size distribution of having an identical coefficient of uniformity to the field condition. Model ground was also prepared with relative densities of 50 % and 80 %. For loading condition, model tests with and without eccentric load were carned out to investigate the effect of eccentric loads and a numerical analysis with the commertially available software of FLAC was performed. For numerical estimation with FLAC, the hyperbolic model of a nonlinear elastic constitutive relationship was used to simulate the stress-stram constitutive relationship of model ground and a series of triaxial compression test were carried out to find the parameters for this model Test results were analyzed and compared with Meyerhof method (1963), effective area method based on the limit equilibrium method, and a numerical analysis with FLAC.