• Journal of Korean Society of Disaster and Security
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• v.10 no.1
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• pp.35-42
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• 2017

This is a comparative study on the characteristics of excavated soils, which is proceeded using soil strength parameter by literature, geotechnical investigation, standard penetration test by drilling, and downhole test by borehole at six sites in urban areas. The results of these site surveys are used as basic data for the evaluation and development of prediction of ground subsidence risk. Geotechnical properties are estimated with the result of standard penetration test-N value and literature. The dynamic geotechnical characteristics are also estimated with top-down seismic exploration at borehole.

• Geomechanics and Engineering
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• v.11 no.6
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• pp.771-785
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• 2016

The thermal conductivity of soils is an important property in energy-related geotechnical structures, such as underground heat pumps and underground electric power cable tunnels. This study explores the effects of geotechnical engineering properties on the thermal conductivity of soils. The thermal conductivities of quartz sands and Korean weathered silty sands were documented via a series of laboratory experiments, and its variations with effective stress, porosity, and water saturation were examined. While thermal conductivity was found to increase with an increase in the effective stress and water saturation and with a decrease in porosity, replacing air by water in pores the most predominantly enhanced the thermal conductivity by almost one order of magnitude. In addition, we have suggested an improved model for thermal conductivity prediction, based on water saturation, dry thermal conductivity, saturated thermal conductivity, and a fitting parameter that represents the curvature of the thermal conductivity-water saturation relation.

• International Journal of High-Rise Buildings
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• v.4 no.4
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• pp.227-239
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• 2015

This paper discusses the design parameters that are required for the design of high-rise building foundations, and suggests that the method of assessment for these parameters should be consistent with the level of complexity involved for various stages in the design process. Requirements for effective ground investigation are discussed, together with relevant in-situ and laboratory test techniques for deriving the necessary strength and stiffness parameters. Some empirical correlations are also presented to assist in the early stages of design, and to act as a check for parameters that are deduced from more detailed testing. Pile load testing is then discussed and a method of interpreting bi-directional tests to obtain pile design parameters is outlined. Examples of the application of the assessment process are described, including high-rise projects in Dubai and Saudi Arabia.

• Geotechnical Engineering
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• v.4 no.3
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• pp.27-34
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• 1988

Soils behave non-linearly at high strain. This study investigated the non-linear behavior of silty sands (Mixture of Ottawa Sand and Quartz Powder) by resonant column tests. The results were ·compared with Ramberg-Osgood's non-linear equation. From the tests, it was shown that the change of shear modulus and damping ratio was more sharp at low fine content, high void ratio and low confining pressure. It was also found that famberg-Osgood parameter, R was approximately 2.0, however the range of C varied from 200 to 3200.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1320-1325
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• 2006

When the train running on the high-speed track, there is a speed band which track distortion is unusually increased according to the condition of track and roadbed. This speed is called critical velocity and physical parameter values are increased greatly. These phenomenon happened as high-speed train were developed, studied regularly through TGV 100 running test in France. As research result until now, the main reason is soft roadbed's bearing capacity. Wave propagation and track support capacity is varied by the ground characteristics. This paper achieved theoretical examination about resonance band(speed and frequency) that occurred in roadbed on the base rock in point of geotechnical engineering. The examination of resonance divides with ground response analysis, critical band analysis by the shear wave velocity of roadbed and train critical speed through the ground stratum.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1484-1489
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• 2005

An inhomogeneous and anisotropic rock has different properties at different location. Thus, this refers to any of the properties which we may be measuring. There are two concepts of rock mass, namely, CHILE(Continuous, Homogeneous, Isotropic, Linear Elastic) material and DIANE(Discontinuous, Inhomogeneous, Anisotropic, Non-linear Elastic) rock. The former is essentially the properties of intact rock, the latter is essentially the properties governed by the structure of rock. In geotechnical aspect, the most important parameter is strength of rock or rock mass. In particular, characteristics of strength of rock mass depend upon the orientation of discontinuities And this orientation of discontinuities has different properties at different direction of excavation. Therefore, it needs for characterization of different properties of discontinuity orientation against different direction of excavation.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.188-194
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• 2009

Consolidation settlement, a crucial parameter in geotechnical design of soft ground, has not been computed in a unique way due to different computation methods in practice. To improve computational error in calculating consolidation settlement, a number of researches has been attempted. Conventional 1-dimensional consolidation theory assumes the center of the clay layer as the representative point to obtain effective stress in calculation, which could resort to erroneous results. To calculate exact solutions considering initial distribution of effective stress, diving a stratum into multi-layers could resort to wasting time and effort. In the study, a novel methodology for calculating consolidation settlement via Guassian quadrature is developed. The method generally is capable of computing settlements in any case of the stress conditions encountered in fields.

• Geotechnical Engineering
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• v.3 no.3
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• pp.63-74
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• 1987

A practical constitutive equation with sufficient generality is proposed for porous materials to deal with plastic pore compaction and pore related strain-hardening. With an application of this proposed model, finite element calculations are executed for the compaction of a porous material. Results show powerful potential of finite element method in a quantitative investigation of the process of the compaction. Special attention is given to the process of unloading during which the development of tensile principal stress may lead to phenomena such as lamination and end-capping.

• Geotechnical Engineering
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• v.9 no.2
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• pp.65-69
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• 1993

강우에 의해 발생되는 토양(soil)에서의 Recharge를 구하기 위해 두가지 모델 즉, ((i) Simple Mass Balance Model (ii) Numerical Model : UNSAT 1)을 사용했는데, 이 두 모델들은 불포화상태의 흙(unsaturated zone : above groundwater table)에서 그의 가정과 개념에 약간 차이가 있다. Unsaturated Zone에서의이 두 모델의 적용에 있어서 몇가지 중요한 사항이 지적되고 있는데, 균질의 불포화 영역(unsaturated zone)의 토양에서 Mass Balance Model을 사용함으로써 얻은 Recharge는 UNSAT 1(numerical model)을 통해 얻은 결과와 비교할 때 서로 상이한 결과를 보였다. 또한, Recharge의 계산에 있어서 지하수위의 변화에 따른 영향을 알아보기 위해 Sensitivity Analysis를 수행하였다. 즉, 고정수위(fixed groundwater table)로 가정했을 때 발생되는 오차를 한개의 수리학적 계수(hydraulic parameter)의 함수로 보고 계산을 했으며 이 결과를 그림으로 나타내어 보았다. 이 연구의 결과는 Model Simulation에 있어서 수리학적 경계조건을 결정하는데 큰 도움이 될 것이며, 또한 이 연구에서는 Unsaturated-Saturated Flow Model이나 Drainage Model을 함께 병행시켜 Simulation을 수행하는데 촛점을 두고 있다.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1204-1211
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• 2008

Compression index is one of the important characteristic numbers in soft soil engineering. Since 1940's, many researchers have suggested various practical solutions to define the compression index of clay using other soil properties. But, these results are only can give us an outline of soft soil behavior. In this study, the relationships between pore water pressure dissipation test results and compression index were suggested using comparison results of both tests. This relationships are based on basic concept of consolidation phenomena, essential difference between pore water pressure dissipation test and consolidation test, and disagreements between theoretical time factor and real time factor. To identify proportional factor of proposed equation, Geotechnical investigation results of Kwang-Yang(KY) site and Busan New Port(BN) site were used. The proportional factor was 0.0031 from 20 to 50% of consolidation rate where correlation parameter($R^2$) is 0.9051.