• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.390-400
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• 2010

BNWF(Beam on Nonlinear Winkler Foundation) method has long been adopted for lateral behavior analysis of pile foundation and widely recognized for its simplicity and accuracy up until now. However, due to lateral load tests which were done in limited conditions and theory-based input Parameter estimation, the applicbility of p-y curve has not been fully examined. Accordingly, we researched on the applicability of conventional input parameter estimation and the p-y curve to be determined by the estimation through inverse analysis based on lateral load tests.

• Geomechanics and Engineering
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• v.22 no.1
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• pp.97-108
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• 2020

The time-consuming and less objectivity are the main problems of conventional micromechanical parameters calibration method of Particle Flow Code simulations. Thus this study aims to address these two limitation of the conventional "trial-and-error" method. A new calibration method for the linear parallel bond model (CM-LPBM) is proposed. First, numerical simulations are conducted based on the results of the uniaxial compression tests on limestone. The macroscopic response of the numerical model agrees well with the results of the uniaxial compression tests. To reduce the number of the independent micromechanical parameters, numerical simulations are then carried out. Based on the results of the orthogonal experiments and the multi-factor variance analysis, main micromechanical parameters affecting the macro parameters of rocks are proposed. The macro-micro parameter functions are ultimately established using multiple linear regression, and the iteration correction formulas of the micromechanical parameters are obtained. To further verify the validity of the proposed method, a case study is carried out. The error between the macro mechanical response and the numerical results is less than 5%. Hence the calibration method, i.e., the CM-LPBM, is reliable for obtaining the micromechanical parameters quickly and accurately, providing reference for the calibration of micromechanical parameters.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.418-423
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• 2005

In designing underground structure such as tunnels, estimating geotechnical characteristics of the ground is one of the most important and difficult tasks. In this paper, a methodology that can identify geotechnical parameters using only field-measured relative convergence displacements is presented. By using only relative convergence measurement data, inevitable errors in absolute convergence estimation can be avoided and in turn the parameter estimation process can be simplified. The methodology utilizes sensitivity relationship between static displacement measurements and geotechnical parameters. The feasibility and applicability of the proposed methodology is verified via a 3-d numerical example of a tunnel structure.

• Journal of the Korean Geotechnical Society
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• v.25 no.11
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• pp.87-103
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• 2009

To determine the reliable probabilistic distribution model of geotechnical properties, outlier and randomness test for analysis data, parameter estimation of probabilistic distribution model, and goodness-of-fit test for model parameter and probabilistic distribution model have to be performed in sequence. In this paper, the probabilistic distribution model's geotechnical properties of Songdo area in Incheon are estimated by the above proposed procedure. Also, the coefficient of variation (COV) representing the variability of geotechnical properties is determined for several geotechnical properties. Reliable probabilistic distribution model and COV of geotechnical properties can be used for probability-based design procedure and reasonable choice of design value in deterministic design method.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.792-802
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• 2008

If a tunnel is constructed below the groundwater level, the groundwater flow will occur inducing the seepage force toward the tunnel and will result in the increase of tunnel convergence. The longitudinal deformation during tunnel excavation will also be increased due to seepage pressure. A back-analysis methodology in underwater tunnel was proposed in this study based on the relative longitudinal deformation measured in-situ. Geotechnical parameters can be estimated utilizing the proposed method where the prior estimate as well as the measured convergence can be reasonably combined by adopting the Extend Bayesian Method.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.785-789
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• 2009

It is essential to carry out appropriate site investigations for the accurate prediction of the geo-structure. However, the importance of the site investigation is often overlooked due to the time and expense constraints. In this study, several cases of geotechnical design perfromed in United States are introduced with the lessons about how the site investigations are planned, performed and applied for the actual design parameter determination. Based on the case studies presented herein, experienced geotechnical engineer should participate in site investigations from the planning stage through the final boring logs and utilize all the laboratory and field tests to have consistent input parameters for the soil constitutive models. Furthermore, it is also desired to have close relationship between construction industry and the academia to compensate their needs.

• Geotechnical Engineering
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• v.12 no.2
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• pp.43-58
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• 1996

In spite of drastic development of underground technology too many uncertainties still exist in design and construction of underground structures. Estimation of ground parameters might be one of those uncertainties in design of underground structures. It is not an easy task to estimate the parameters reasonably well in advance in the design stage. The main purpose of this paper is the best parameter estimation in the underground structures. In order to estimate unknown model parameters from the in-eitu measurements as well as prior estimates, the Extended Bayesian Method(EBM) is utilized and implemented with Finite Element Program. The parameter estimation model utilized in this study is applied to two underground structures : the one Pusan subway tunnel: and the other Darlington intake tunnel in Canada, and the effectiveness of the proposed model is illustrated.

• Proceedings of the Korean Geotechical Society Conference
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• 1996.03a
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• pp.155-166
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• 1996

• 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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• 1994.09a
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• pp.191-198
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• 1994

This paper deals with a feedback system for the estimation of geotechnical parameters in underground construction works. The Ordinary Least Square (OLS) Optimization Method is utilized and combined with Finite Element Program so that optimum values of ground properties can be estimated. The preperties that can be estimated are Young's and Brown's failure criteria is proposed.