• Communications for Statistical Applications and Methods
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• v.8 no.1
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• pp.15-27
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• 2001

One proposal is made for constructing nonparametric estimator of slope parameters in a regression model under symmetric error distributions. This estimator is based on the use of idea of Johns for estimating the center of the symmetric distribution together with the idea of regression quantiles and regression trimmed mean. This nonparametric estimator and some other L-estimators are studied by Monte Carlo.

• Geomechanics and Engineering
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• v.16 no.5
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• pp.513-525
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• 2018

Slope stability of sensitive clayey soils is particularly important when subjected to strength loss and deformation. Except for progressive failure, for most sensitive and insensitive slopes, it is important to review the feasibility of conventional analysis methods based on peak strength since peak strength governs slope stability before yielding. In this study, as a part of efforts to understand the behavior of sensitive clay slopes, a total of 12 centrifuge tests were performed for artificially sensitive and insensitive clay slopes using San Francisco Bay Mud (PI = 50) and Yolo Loam (PI = 10). In terms of slope stability, the results were analyzed using the updated instability factor ($N_I$). $N_I$ using equivalent unit weight to cause a failure is in reasonable agreement shown in the Taylor's chart ($N_I$ ~ 5.5). In terms of dynamic deformation, it is shown that two-way sliding is a more accurate approach than conventional one-way sliding. Two-way sliding may relate to diffused shear surfaces. The outcome of this study is contributable to analyzing stability and deformation of steep sensitive clay slopes.

• Journal of the Korean Society for Railway
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• v.12 no.2
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• pp.321-328
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• 2009

A optimal reinforcement in the joint rock slope excavation adjacent to an existing tunnel would be influenced by excavation distance from the tunnel, slope angel, and joint conditions but has been empirically determined so far. In this study, large scale model tests were conducted to find out the relationship between load translation on the excavation surface and bebavior of the tunnel according to excavation steps of the jointed rock slope. Consequently, two main parameters, joint dip and sloped angle were investigated in those model tests. From the test results, it was found that tunnel deformation was the largest one when the excavation of joints located closer to the tunnel crown or invert. Stability of the slope and the tunnel were varied in a certain excavation stage related to the angle of slope. In the future, based on results of this study the reinforcement method for the tunnel and slope safety in a jointed rock mass will be demonstrated.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.543-550
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• 2000

Rock slopes along the road or railroad are affected by temperature and therefore experienced iterative freezing-thawing process between winter and early spring. The purpose of this study is to analyze the stability of rock slopes which are influenced by the deterioration due to the freezing-thawing. The analysis is the homogenization method which evaluates the strength property of discontinuous rock mass, and as a strength failure criterion, Drucker-Prager failure criterion is used. The deterioration property of real rock is obtained by a freezing-thawing laboratory test of tuff and this property of deterioration is quantitated and used as a basic data of stability analysis for rock mass. To evaluate the deterioration depth due to the freezing-thawing in situ rock slope, one dimensional heat conductivity equation is used and as the result I can find that the depth of which is affected by a temperature. After the freezing-thawing depth of model slope is determined, we analyze the pattern of rock mass stength value of rock slope model which excesses the limit of self-load.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.3
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• pp.85-90
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• 1988

A probabilistic model for the failure in a homogeneous soil slope is presented. The Safety of the slope is measured through its probability of failure rather than the customary factor of safety. The safety margin of slope failure is assumed to follow a normal distribution. Sources of uncertainties affecting characterization of soil property in a homogeneous soil layer include inherent spatial variability., estimation error from insufficient samples, and measurement errors. Uncertainties of the shear strength-along potential failure surface are expressed by one-dimensional random field models. The rupture surface, created at toe of a soil slope, has been considered to propagate towards the boundary along a path following an exponential (log-spiral) law. Having derived the statistical characteristics of the rupture surface and of the forces which act along it, the probability of failure of the slope was found. Finally the developed procedure has been applied in a case study to yield the reliability of a soil slope.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.2
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• pp.149-157
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• 2001

From the weakly nonlinear mild-slope wave equations introduced by Nadaoka et al.(1994, 1997), a set of weakly nonlinear wave equations for rapidly varying topography are derived by including the bottom curvature and slope-squared tenns ignored in the original equations ofNadaoka et al. To solve the linear version of extended wave equations derived in this study one-dimensional finite difference numerical model is con¬structed. The perfonnance of the model is tested for the case of wave reflection from a plane slope with various inclination. The numerical results are compared with the results calculated using other numerical models reported earlier. The comparison shows that the accuracy of the numerical model is improved significantly in comparison with that of the original equations ofNadaoka et al. by including a complete set of bottom curva1w'e and slope¬squared terms for a rapidly varying topography.

• Journal of Forest and Environmental Science
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• v.30 no.1
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• pp.113-119
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• 2014

To examine the soil reinforcement by the shrub with shallow root systems for slope stability, we developed insitu apparatus for direct shear test and conducted the insitu field tests for Lespedeza cyrtobotrya, a representative revegetation species for artificial hillslopes. The insitu field tests were conducted for two different soil conditions (the rooted soils and non-rooted soils) and we then compared the experimental values with those calculated from the Wu model. The results showed that the soil reinforcement derived from the insitu field tests ranged from 0.01525 to 0.1438 $kgf/cm^2$ while the one calculated from the Wu model ranged from 0.1952 to 0.2696 $kgf/cm^2$. Our finding suggests more field tests are needed to collect the related parameters in the model application thereby predicting the reliable soil reinforcement by the shrub root systems.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.2
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• pp.173-182
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• 1994

A numerical experiment on the effective discharge of waste materials caused in recirculating aquaculture basins was performed. The numerical model used in this study was a 4-level hydrodynamic and advection-diffusion model. Flow structures and settling processes of ss in the various mathematical model basins are discussed. The calculated flow fields of the numerical basin corresponded well with the measured velocity in field basin. In the cases of steep bottom slopes in 4/30, the non-dimensional tractive force($U{\ast}/U{\ast}_c$) which is all important parameter for the deposition pattern of waste materials was stronger than with the mild slope one. The settling pattern of ss depended considerably on the degree of bottom slope of basin. To concentrate deposited waste materials into the center discharge pipe, it is useful to design a cylindrical basin with a steeply conical bottom. In addition, to prevent movement of the deposit area away from the center, it is necessary to locate the circulating ducts at diametrically opposed points on the basin sides.

• Journal of Korean Port Research
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• v.7 no.1
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• pp.79-88
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• 1993

This study deals with the case of a fixed floating structure(FFS) at the mouth of a rectangular harbor under the action of waves represented by the linear wave theory. Modified forms of the mild-slope equation is applied to the propagation of regular wave over constant water depth. The model is extended to include bottom friction and boundary absorption. A hybrid element approximation is used for calculation of linear wave oscillation in and near coastal harbor. Modification of the model was necessary for the FFS. For the conditions tested, the results of laboratory experiments by Ippen and Goda(1963), and Lee (1969) are compared with the calculated one from this model. The cases of flat cylinderical structures, both fixed and floating, were taken to be in an intermediate water depth.

• The Journal of Engineering Geology
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• v.11 no.1
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• pp.13-23
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• 2001

Rock slope near the road or railroad is affected by the outside temperature and iterative freezing-thawing process during winter and early spring. The purpose of this study is to analyze the stability of rock slope which is iniluenced by deterioration due to the freezing-thawing. Method of analysis is homogenization method which find the strength property of discontinuous rock mass and as a strength failure criterion, Drucker-Prager failure criterion is used, The deterioration property of real rock is obtained by a freezing-thawing labordtory test of tuff and this quantitative property is used as a basic data of stability analysis of rock mass. To evaluate the deterioration depth due to the freezing-thawing in the field rock slope, one dimensional heat conductivity equation is used and as a a result we can find the depth of which is affected by a temperature. After determined the freezing-thawing depth of model slope, the pattern of rock mass strength value of model rock slope which excess the limit of self-load is analyzed.