• Geomechanics and Engineering
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• v.34 no.1
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• pp.29-41
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• 2023

The 3D geospatial modeling of geotechnical information can aid in understanding the geotechnical characteristic values of the continuous subsurface at construction sites. In this study, a geostatistical optimization model for the three-dimensional (3D) mapping of subsurface stratification and the SPT-N value based on a trial-and-error rule was developed and applied to a dam emergency spillway site in South Korea. Geospatial database development for a geotechnical investigation, reconstitution of the target grid volume, and detection of outliers in the borehole dataset were implemented prior to the 3D modeling. For the site-specific subsurface stratification of the engineering geo-layer, we developed an integration method for the borehole and geophysical survey datasets based on the geostatistical optimization procedure of ordinary kriging and sequential Gaussian simulation (SGS) by comparing their cross-validation-based prediction residuals. We also developed an optimization technique based on SGS for estimating the 3D geometry of the SPT-N value. This method involves quantitatively testing the reliability of SGS and selecting the realizations with a high estimation accuracy. Boring tests were performed for validation, and the proposed method yielded more accurate prediction results and reproduced the spatial distribution of geotechnical information more effectively than the conventional geostatistical approach.

• 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.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1113-1117
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• 2009

• Geotechnical Engineering
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• v.12 no.6
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• pp.139-152
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• 1996

In order to treat flow problems for unsaturated soils, it is necessary to obtain the soil-water characteristic curves which show nonlinear relationship between metric suction and volumetric water content. With two different pleasuring devices, measurements of the matric suction were taken for Jumoonjin sand, Hangang sand, and weathered granite soils with different fined. Experimental parameters which can describe experimental formulas for the soil-water characteristics were determined by using the data obtained from the experiment. Among experimental formulas of previous researchers, that of van Genuchten(1980) agreed well with the results of experiments. For weathered granite soils, the parameters increased with the increase of fine contents, Therefore, the soil-water characteristic for a weathered soil can be estimated by using Parameters corresponding to its fine contents.

• Journal of the Korean Geotechnical Society
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• v.24 no.2
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• pp.15-25
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• 2008

A soft ground improvement method is used for structures which are constructed on soft ground to decrease settlement and Increase bearing capacity. The Floating Base Plate has been developed for such purposes. In this study, the load-settlement characteristics were investigated by numerical analysis on various Floating Base Plate shapes to select an optimum shape, different from the conventional shape. The selected optimum shape was used to perform plate bearing test and numerical simulations. It was found that the Floating Base Plate is very effective In reducing the settlement and increasing the bearing capacity.

• Journal of the Korean Geotechnical Society
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• v.25 no.8
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• pp.23-32
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• 2009

In this study, the reliable and simple analysis method was proposed to predict the settlement characteristic of composite ground in stage of design and construction of sand compaction pile (SCP). Model parameters could be obtained by the optimization process based on genetic algorithm. In order to examine the proposed method, laboratory consolidation tests on the settlement characteristic of SCP composite ground were performed for various replacement ratio of sand such as 0 (no replacement), 20, 36, and 56%. The proposed model showed very good agreements with measured data in the relation of void ratio-log scaled stress and time-compression far each replacement ratio.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.563-574
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• 2008

Most of earthquake-induced geotechnical hazards have been caused by the site effects relating to the amplification of ground motion, which are strongly influenced by the local geologic conditions such as soil thickness or bedrock depth and soil stiffness. In this study, an integrated GIS-based information system for geotechnical data, called geotechnical information system (GTIS), was constructed to establish a regional counterplan against earthquake-induced hazards at an urban area, Daejeon, which is represented as a hub of research and development in Korea. To build the GTIS for the area of interesting, pre-existing geotechnical data collections were performed across the extended area including the study area and a walk-over site survey was additionally carried out to acquire surface geo-knowledge data. For practical application of the GTIS used to estimate the site effects at the area of interesting, seismic microzoning map of the characteristic site period was created and presented as regional synthetic strategy for earthquake-induced hazards prediction. In addition, seismic zonation for site classification according to the spatial distribution of the site period was also performed to determine the site amplification coefficients for seismic design and seismic performance evaluation at any site in the study area. Based on the case study on seismic zonations at Daejeon, it was verified that the GIS-based GTIS was very useful for the regional prediction of seismic hazards and also the decision support for seismic hazard mitigation.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.119-131
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• 2005

Seepage analysis through unsaturated zone based on the theory of unsaturated flow is commonly performed to evaluate dam safety. However, the concepts of unsaturated soil behavior have not been transferred into the hands of practicing geotechnical engineers since the problems involving unsaturated soils often have the appearances of being extremely complex. The behavior of dam such as seepage rate and the pore water pressure distribution is different according to the unsaturated hydraulic properties, but nevertheless simply assumed properties have been used due to insufficient data from domestic soils. In this paper, the effect of unsaturated hydraulic properties on the behavior of dam was studied through a series of numerical analyses, and then the results were discussed. It is observed that water table moves at a (aster rate, as the values of unsaturated soil parameter a and n increase. The value of m showed opposite trend. The sensitivity calculated using the approximation form showed maximum values near the water table. And the value of n that is related to the slope of soil water characteristic curve gives greatest influence on the change of sensitivity with time.

• Journal of the Korean Geotechnical Society
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• v.22 no.4
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• pp.73-83
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• 2006

Seepage analysis through unsaturated zone based on the theory of unsaturated flow is commonly performed to evaluate dam safety. However, the concepts of unsaturated soil behavior have not been transferred into the hands of practicing geotechnical engineers since the problems involving unsaturated soils often have the appearances of being extremely complex. There is variability and uncertainty associated with the unsaturated hydraulic properties that in turn will lead to variability in predicting unsaturated soil behavior such as seepage rate and the pore water pressure distribution. In this paper, measurements of the soil-water characteristic curve and saturated hydraulic conductivity for the core material of dam were conducted. Then, finite element stochastic analysis was used to capture the effect of unsaturated hydraulic properties on the seepage behavior of dam. It is observed that the amount of seepage increases, as the values of unsaturated soil parameters a and n increase. The values of m and p showed opposite trend.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.932-937
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• 2008

The asphalt waste has been collected more than ten thousands' ton from repairing works on the road and excavation repair works, most of them are disposed on land of reclamation. Only a few percentage of wasted asphalt recycled to new one. Therefore, In this study, usage of wasted asphalt and has been done engineered characteristic test for recycling materials of sub-grade and structure. To know the characteristic of asphalt waste, tamping test, bearing-ratio test, permeability test and direct shear test was done using asphalt-sand mixture. The test results shows that, mixed asphalt materials with sand can be used for materials of subgrade-soil and structure.