• 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.

• Journal of the Korean Geotechnical Society
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• v.29 no.3
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• pp.41-50
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• 2013

There always exists uncertainty which is mainly due to uncertainty of the evaluation of a geotechnical structure at a site. The uncertainty in the geotechnical analysis can be considered in the probabilistic analysis using the Monte Carlo Simulation. It needs various soil profiles which could be possible at the target site. In this study, a new method is proposed to generate soil profiles which are probable at the site. The proposed method analyzes a structure of a site and generates one dimensional soil profiles for a probabilistic analysis. Through the field application, the applicability of the prosed method was shown.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.03a
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• pp.143-152
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• 1995

• Journal of the Korean Geotechnical Society
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• v.16 no.2
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• pp.79-89
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• 2000

The application of stabilization method has increased because of short construction periods, no environmental problems with dumped and replaced soil, assurance of required strength and economical effect with mid to small size construction. The unconfined and triaxial(UU-condition) compression tests were executed with each mixing sample for the study of the improvement effects and the effect of design-parameters by the stabilization methods. Three typical stabilizers, which are representative in Korea, were applied in this study, and three common soils(very soft clay, general weathered soil, common clay), which are common in Korea, were used in this study. In this study, the effect of engineering factors(soils, stabilizers and water contents, etc.) which are important parameters for the improvement effects of mixed ground by stabilizers, was analyzed. As results, the tendencies of design-parameters(unconfined compression strength, deformation modulus and strength parameter) are presented and the criteria of the application of stabilization methods are suggested.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.147-179
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• 2002

The important role of observational method in geotechnical engineering are emphasized together with the direction of future development, concerning successful application of the technique on the site investigation, design and feed back at various construction stages. Case histories on the application of feed back are introduced in order to achieve the most economical and reliable construction for tunnel, rock slope and deep excavations through feed back system at design and construction stages. Also the limitations and advantages of the observational method and the role of feed back system are discussed for construction of tunnel, rock slope and deep excavation in hard ground such as layered ground conditions including weathered, soft and hard rocks.

• Geotechnical Engineering
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• v.14 no.1
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• pp.29-36
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• 1998

The application of a multiple rock classification method, which is a generalization of a binary rock classification, is studied in this paper. In particular, this paper shows how to incorporate qualitative data through a case study. The method suggested in this paper can be effectively used for a systematic multiple rock classification such as RMR system developed by Bieniawski. It will be very useful for rock classifications. In addition, it is known that the expected cost of errors can be atopted to indicate how well a investigation plan is made.

• Interaction and multiscale mechanics
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• v.4 no.1
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• pp.49-64
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• 2011

A methodology for jointed rock mass characterization starts with a research based on geological data and tests in order to define the geotechnical models used to support the decision about location, orientation and shape of cavities. Afterwards a more detailed characterization of the rock mass is performed allowing the update of the geomechanical parameters defined in the previous stage. The observed results can be also used to re-evaluate the geotechnical model using inverse methodologies. Cases of large underground structures modeling are presented. The first case concerns the modeling of cavities in volcanic formations. Then, an application to a large station from the Metro do Porto project developed in heterogeneous granite formations is also presented. Finally, the last case concerns the modeling of large cavities for a hydroelectric powerhouse complex. The finite element method and finite difference method software used is acquired from Rocscience and ITASCA, respectively.

• Earthquakes and Structures
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• v.13 no.6
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• pp.519-529
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• 2017

The surrounding rocks of underground openings are natural materials and their mechanical behavior under seismic load is different from traditional man-made materials. This paper proposes a framework to comprehensively model the mechanical behavior of surrounding rocks. Firstly, the effects of seismic load on the surrounding rocks are summarized. Three mechanical effects and the mechanism, including the strengthening effect, the degradation effect, and the relaxation effect, are detailed, respectively. Then, the framework for modelling the mechanical behavior of surrounding rocks are outlined. The strain-dependent characteristics of rocks under seismic load is considered to model the strengthening effect. The damage concept under cyclic load is introduced to model the degradation effect. The quantitative relationship between the damage coefficient and the relaxation zone is established to model the relaxation effect. The major effects caused by seismic load, in this way, are all considered in the proposed framework. Afterwards, an independently developed 3D dynamic FEM analysis code is adopted to include the algorithms and models of the framework. Finally, the proposed framework is illustrated with its application to an underground opening subjected to earthquake impact. The calculation results and post-earthquake survey conclusions are seen to agree well, indicating the effectiveness of the proposed framework. Based on the numerical calculation results, post-earthquake reinforcement measures are suggested.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1075-1082
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• 2008

Recently, coal ashes which are increasing annually are buried in ash ponds as industrial wastes. However, buried coal ashes can pollute ground water and ground due to leachate from coal ashes, which are serious environmental problem. Even though a lot of researches on recycling of coal ashes have been conducted, only 15% of coal ashes are recycled up to now. And those recycled coal ashes are not bottom ashes but fly ashes. So in this study, it was proved that Bottom Ash can be used as an alternative material to O.P.C(Ordinary Portland Cement) according to laboratory test results and test field construction. Also bottom ash is more economical and environmentally friendly than O.P.C.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.113-118
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• 2008

Among the geophysical methods, Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT) comprise the most promising techniques in resolving buried archaeological structures in urban territories. In this work, two case studies which involve an integrated geophysical survey employing the surface three dimensional (3D) ERT and GPR techniques, in order to archaeologically characterize the investigated areas, are presented. Totally more than 4000 square meters were investigated from the test field sites, which are located at the centre of two of the most populated cities of the island of Crete, in Greece. The ERT and the GPR data were collected along dense and parallel profiles. The subsurface resistivity structure was reconstructed by processing the apparent resistivity data with a 3D inversion algorithm. The GPR sections were processed with a systematic way applying specific filters to the data in order to enhance their information context. Finally, horizontal depth slices representing the 3D variation of the physical properties were created and the geophysical anomalies were interpreted in terms of possible archaeological structures. The subsequent excavations in one of the sites verified the geophysical results, enhancing the applicability of ERT and GPR techniques in the archaeological exploration of urban territories.