• Structural Engineering and Mechanics
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• v.4 no.3
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• pp.227-242
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• 1996

An important class of problems in the field of geotechnical engineering may be analyzed with the aid of a simple integro-differential equation. Behavior of "rigid" piles(say concrete piles), "deformable" piles(say gravel piles), pile groups, pile-raft foundations, heavily reinforced earth, flow within circular silos and down drag on cylindrical structures (for example the crusher unit of a mineral processing complex) are the type of situations that can be handled by this type of equation. The equation under consideration has the form; $$\frac{{\partial}w(r,\;z)}{{\partial}z}+f(z){\int}^z_0g({\xi})(\frac{{\partial}^2w(r,\;{\xi})}{{\partial}r^2}+\frac{1}{r}\frac{{\partial}w(r,\;{\xi})}{{\partial}r})d{\xi}+h(r,\;z)=0$$ where w(r, z) is the vertical displacement of a soil particle expressed as a function of the polar cylindrical space coordinates (r, z) and the symbols f, g and h represent soil properties and the loading conditions. The merit of the analysis is its simplicity (both in concept and in application) and the ease with which it can be expressed in a computer code. In the present paper the analysis is applied to investigate the behavior of a single rigid pile to bedrock. The emphasis, however, is placed on developing the equation, the numerical techique used in its evaluation and validation of the technique, hereafter called the ID technique, against a formal program, CRISP, which uses the FEM.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.163-172
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• 2003

The engineering properties of composite silicate grout materials that were developed recently were analyzed. In this laboratory tests, OPC (Ordinary Portland Cement) was mainly used as grout materials. Moreover, the properties of composite silica, silica sol and sodium silicate (No.3) acting as coagulating agent were analyzed and compared with each other. For the purpose of finding the engineering properties of composite silicate grout materials, various physical and chemical tests were performed : naked eye measurement, photographing by using SEM, uniaxial compression test and in-situ application test. A series of test results showed that the strength of composite silicate grout materials was about 3～6 times that of ordinary sodium silicate grout materials in 6～24hr. Especially, based on the evaluation of the application of JS-CGM grout to the construction fields, composite silicate grout would be very effective in reducing the coefficient of permeability.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.61-75
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• 2003

Comprehensive review on the determination of critical state parameters in sandy soils from standard triaxial testing was performed to facilitate the application of critical state soil mechanics to the shear behavior of sandy soils. First, semantic differences in literature were clarified, inferring that critical state should be considered as the ultimate state at large deformation. Second, the characteristics of critical state parameters were discussed, and also the uniqueness of critical state line and the sensitivity of quasi-steady state condition were verified in relation to initial state, fabric, loading condition, and drainage condition. Third, as an example, the critical state soil mechanics was applied to evaluate the post-liquefaction shear strength, i.e. the reliable ultimate shear strength in liquified soils, in terms of critical state parameters.

• The Journal of Engineering Geology
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• v.17 no.2 s.52
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• pp.271-277
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• 2007

To find out the anomalous zone in cut slope composed of phyllite and shist, we performed resistivity tomography using a pole-dipole way. The electrical distribution that propagates from a current source in lower part of slope is measured by a potential electrode in upper part of slope. Apparent resistivity data are inverted with an iterative regularized inversion method to reconstruct 3D resistivity image. By comparing with the resistivity images in relation to each section, the images of anomalous zone correspond to their positions represented in cut slope. Therefore, the application of resistivity tomography in cut slope is useful to recognize the extension of anomalous zone.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.883-887
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• 2009

In this study, a new soil retaining system was proposed by soil cement mixing method. The new soil retaining system is based on deep cement mixing method by large diameter reinforcing blocks (piles). Large diameter reinforcing blocks (usually $\varnothing$300-500 mm) have the advantage to make reinforcements over a relatively short depth and thus reduce the amount of reinforcement necessary. A field case has been reviewed for actual application of the soil retaining system at a downtown site. Research was conducted to evaluate the behavior of the installed soil retaining wall, with reinforcing blocks (400 mm in diameter and 4 m in length) placed into a 10 m excavation wall at a $20^{\circ}$ angle. As a result, the potential for applying this method to the downtown excavation site was confirmed.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.987-997
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• 2008

Successful design, construction and maintenance of geotechnical structure in soft ground and marine clay demands prediction, control, stability estimation and monitoring of settlement with high accuracy. It is important to predict and to estimate the compression index of soil for predicting of ground settlement. Lab. and field tests have been and are indispensable tools to achieve this goal. In this paper, Artificial Neural Networks (ANNs) model with Levenberg-Marquardt Algorithm and field database were used to predict compression index of soil in Korea. Based on soil property database obtained from more than 1800 consolidation tests from soils samples, the ANNs model were proposed in this study to estimate the compression index, using multiple soil properties. The compression index from the proposed ANN models including multiple soil parameters were then compared with those from the existing empirical equations.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.514-527
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• 2007

Earth reinforcement techniques are used worldwide and offer proven solutions to a wide range of geotechnical engineering problems. Here in this paper, recent developments of three major reinforced soil retaining wall methods in Japan were introduced in order to show how the current situation of this technique in Japan is. And the statistical data for the volume of the use was also shown, such as the total volume of the use, the scales of the structures, layout of the earth reinforcement, fill materials, and foundation conditions. Some of the case histories were also introduced with photographs and figures. And then, as one of recent research activity by the author, the study on the application of X-ray CT for the problem of earth reinforcement method combined with other method such as piling and soil improvement was introduced. In this study, a series of model test for several reinforced ground with geogrids was conducted using a newly developed test apparatus. Then, the behavior in the soil box was scanned after settlement using X-ray CT scanner. Based on these test results, the reinforcing effect by the geogrids and the soil arching effect over the pile heads was discussed precisely and those are done in 3-D with nondestructive condition. Finally, the effectiveness of the use of X-ray CT scanner in geotechnical engineering was promised.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.362-371
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• 2006

The behaviour characteristics of Granular Compaction Pile(GCP) are mainly governed by the lateral confining pressure mobilized in the matrix soft soil to restrain the bulging failure of the granular compaction pile. The GCP method is most effective in soft soil with untrained shear strength ranging from $15\sim50\;kPa$. However, the efficiency of this method is falling down in the more compressible soil conditions, which does not provide sufficient lateral confinement. In the present study, the GCP method reinforced with uniformly graded permissible concrete is suggested for the extension of application to the soft ground. Also, large triaxial compression tests are conducted on composite- reinforced soil samples for verification of availability of the suggested method and the settlement estimation method of the reinforced GCP is proposed. Further, for the verification of a validity of the proposed method, predicted settlements are compared with results of numerical analyses. Tn addition, parametric studies are performed together with detailed analyses of relevant design parameters.

• Journal of the Korean Geotechnical Society
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• v.27 no.3
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• pp.95-102
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• 2011

A model of solid-water-air coupling in triphasic mixture is compared to that of solid-water coupling in biphasic mixture with an application to partially saturated soils. Based on thermodynamics, the mathematical framework governing the behavior of a partially saturated soil is derived by using balance equations, and numerical implementation through drainage experiment of a sand column is carried out to validate the obtained formulations. The role of the air phase in the hydro-mechanical behavior of triphasic mixture can be analyzed from the interaction among phases and from the solid skeleton's constitutive behavior, and the three-phase model found applications in geotechnical engineering problems, such as $CO_2$ sequestration and air storage in an aquifer.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.977-986
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• 2009

Sampling disturbance can introduce considerable errors in the laboratory estimation of geotechnical properties of soils, and the results obtained from sophisticated sampling and careful laboratory testing are not matching with field behavior. Therefore, it is advantage to adopt in-situ testing techniques for the estimation of geotechnical parameters. Therefore, Screw plate loading test, one of new field test technologies, has been investigated in this study. This test can be utilized to find out important properties of soils such as load-displacement, elastic modulus, and shear strength. The screw plate loading test modified from the plate loading test is an experiment underneath ground by inserting a spiral type of auger screw. The structure and characteristics of the screw plate loading test device was examined in detail. In addition, The new screw plate loading test device was manufactured to refer the previous studies. The reliability of developing screw plate loading test was examined through the analysis of the laboratory test.