• Geotechnical Engineering
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• v.4 no.2
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• pp.15-24
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• 1988

To identify the stability of cantilever retaining wall in safe state by the deterministic method, these potential modes of such geotechnical failures as bearing capacity, horizontal sliding and overturning are analysed using Advanced First Order Second Moment (AFOSM) method. All design variables are assumed of the normal distribution and to be statistically independent. Considering the correlations between the single modes, structural system reliability index is 2. 05. Even if the safety factors are larger than the required value in the codes' by the conventional deterministic method, the system reliability of this structure may not be Judged to be safe state since the system reliability index is much lower than general value of 3.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.338-344
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• 2003

The seismic analysis method of spent fuel storage structures for PHWR plant is introduced in comparison with the method for PWR plant. Investigating the structural characteristics of the storage structures, the former is vertically stacked fuel storage trays, while the latter is welded honeycomb type structure. However, as both structures are submerged and free standing, the analysis methods to anticipate the seismic response of both structures are complicated. For the better estimation of actual seismic response, how to model the dynamic properties and the structural behaviour is the key issue. In this paper, the overall procedures of the seismic modelling and stability check for seismic sliding and overturning of the two different storage structures are discussed in the viewpoint of analysis reliability

• International Journal of Railway
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• v.1 no.3
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• pp.99-105
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• 2008

Flow around an ICE2 high-speed train exiting a tunnel under the influence of a wind gust has been studied using numerical technique called detached eddy simulation. A wind gust boundary condition was derived to approximate previous experimental observations. The body of the train includes most important details including bogies, plugs, inter-car gaps and rotating wheels on the rail. The maximal yawing and rolling moments which possibly can cause a derailment or overturning were found to occur when approximately one third and one half of the train, respectively, has left the tunnel. These are explained by development of a strong vortex trailing along the upper leeward edge of the train. All aerodynamic forces and moments were monitored during the simulation and the underlying flow structures and mechanisms are explained.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.235-240
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• 2005

Articulation type container cranes are the boom forms an inverted L shape when raise. The inner boom section is nearly vertical when raise and the outer boom section is nearly horizontal. Articulation type container cranes were developed as a lower height crane to meet aircraft clearance requirements. Because the height of an Articulation type container crane is about 70m, the crane is subjected to the effect of Wind load. Therefore, the problem on the effect of Wind load is receiving carefully study. The researches for the effect of wind load on the structural stability of a conventional container crane are conducted. In this study, we carried out the investigation for an articulation type container crane. When a wind load is applied to a container crane, we analyzed the reaction force distribution at each supporting point of a crane with respect to a wind load direction and the effect of the change of the machinery house location on the structural stability rf a crane by carrying out Finite Element Analysis.

• Journal of the Korean Geotechnical Society
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• v.27 no.3
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• pp.41-54
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• 2011

The present study analyzes the stability of waterfront quay wall under the combined action of earthquake and tsunami. Adopting the limit equilibrium method, the stability of waterfront quay wall is checked for both the sliding and overturning. Forces due to tsunami are compared with the proposed formula and the 3-D one-field Model for immiscible TWO-Phase flows (TWOPM-3D). Variations of the stability of wall are also proposed by the parametric study including tsunami water height, horizontal seismic acceleration coefficient, internal friction angle of soil, friction angle between the wall and the soil and the pore water pressure ratio. The present study about the stability of wall is also compared with the case when earthquake and tsunami are not considered. As a result, the result of numerical analysis about the tsunami force is similar to that of proposed formula. When earthquake and tsunami are simultaneously considered, the stability of wall in passive case significantly decreases and tsunami forces in active case are affected as a resistance force on the wall and so the stability of wall increases.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.251-260
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• 2002

Geotextile tribes are made of sewn geotextile sheet and hydraulically or mechanically filled with dredged materials. They have been applied in hydraulic and coastal engineering in recent years(shore protection structure, detached breakwater, groins, and jetty). Therefore, it is composed of geotextile and confined fill material. Recently, new preliminary design criteria supported by model and prototype tests, and some stability analysis calculations have been studied. The stability analysis of geotextile tube is composed of geotechnical and hydrodynamic analysis. The stability check points are sliding failure, overturning, bearing capacity failure against the wave attack. In this paper are presented the stability analysis method by empirical equation and 2-D equilibrium analysis for geotextile tube. Also, the hydraulic model tests were performed to verify the theoretical stability analysis with geotextile tube shape, filling ratio, significant wave height, and so on. The results of this study show that the stability of geotextile tube depends on the tube shape, contact area, projection area. The theoretical analysis and hydraulic model test show almost the same results.

• Structural Engineering and Mechanics
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• v.47 no.5
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• pp.599-622
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• 2013

Seismic response of two dimensional liquid tanks is numerically simulated using fully nonlinear velocity potential theory. Galerkin-weighted-residual based finite element method is used for solving the governing Laplace equation with fully nonlinear free surface boundary conditions and also for velocity recovery. Based on mixed Eulerian-Lagrangian (MEL) method, fourth order explicit Runge-Kutta scheme is used for time integration of free surface boundary conditions. A cubic-spline fitted regridding technique is used at every time step to eliminate possible numerical instabilities on account of Lagrangian node induced mesh distortion. An artificial surface damping term is used which mimics the viscosity induced damping and brings in numerical stability. Four earthquake motions have been suitably selected to study the effect of frequency content on the dynamic response of tank-liquid system. The nonlinear seismic response vis-a-vis linear response of rectangular liquid tank has been studied. The impulsive and convective components of hydrodynamic forces, e.g., base shear, overturning base moment and pressure distribution on tank-wall are quantified. It is observed that the convective response of tank-liquid system is very much sensitive to the frequency content of the ground motion. Such sensitivity is more pronounced in shallow tanks.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.419-426
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• 2000

The purpose of this study is to present the application of WFS co-mixtures for retaining wall as flowable backfill. The fly ash, generated at the Tae-An thermoelectric power plant, was used in this research and was classified as Class F. Green Sand, Furane Sand, and Coated Sand, which had been used at a foundry located in Pusan, were used. Couple of laboratory tests and small scale retaining wall tests were performed to obtain the physical properties of the WFS co-mixtures and the possibility of backfill materials of retaining wall. The range of permeability for all the co-mixtures was from 3.0${\times}$10$\^$-3/ cm/s to 6.0${\times}$10$\^$-5/ cm/s. The unconfined strength of the 28-day cured specimens reached around 550kPa. Results of the consolidated-undrained triaxial test showed that the internal friction angle is between 33.5$^{\circ}$ and 41.8$^{\circ}$. The lateral earth pressure against wall decreased up to 80% of initial pressure within a 12 hours and the total lateral earth pressure is less than that of typical granular soil. It was enough to construct the backfill for the standard retaining of 6m with just two steps, like fill the co-mixtures for half of retaining wall, and then fill the others after 1 day. The stability of retaining wall for overturning and sliding increased as the curing time elapsed.

• Geotechnical Engineering
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• v.2 no.1
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• pp.45-54
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• 1986

An experimental study was carried out in the laboratory on a model of a reinforced earth retaining wall to provide the empirical data for the rational design and the construction methods on a reinforced earth retaining wall. Observed measurements included the variation of tension in the aluminium foil reinforcing strips was monitored by electrical resistance strain gauges pasted on its at different stages of construction. In addition, the lateral movement of the wall was measured by dial gauges and the mode of collapse of the wall was investigated. The measured values are discussed in comparison with the results of the existing studies of the reinforced earth retaining wall. A significant result of the experiments is that the variation of tension in reinforcing strips is non-linear with the maximum tension occuring close to wall face. Attachment of reinforcement to wall increases the stability against overturning.

• Journal of Korea Water Resources Association
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• v.53 no.1
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• pp.29-43
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• 2020

The purpose of this study is to propose the design criteria and detailed design model by reviewing the issues related to geometry, formation process, destruction process, hydraulic function, restoration and ecological function of the step-pool from the existing research results, to apply the step-pool sequences to river restoration. Based on the analysis and review results, the design criteria for the structure and size of the step-pool are presented as ratio of the step spacing and the channel width, ratio of the unit step slope and channel slope, and ratio of step height and the particle size. To ensure structural stability of the step, stability analysis method of overturning based on the keystone theory was proposed as a design criterion. As a detailed design concept, a layout model was proposed by applying the imbricating structure of keystones and arch stones to the planar, longitudinal and transverse configurations of the step-pool.