• Earthquakes and Structures
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• v.26 no.4
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• pp.261-267
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• 2024

With the increase in the exploitation depth of offshore oil and gas, it is possible to control the global buckling of deep-sea pipelines by the snake lay method. Previous studies mainly focused on the analysis of critical buckling force and critical temperature of pipelines under the snake-like laying method, and pipelines often suffer structural failure due to seismic disasters during operation. Therefore, seismic action is a necessary factor in the design and analysis of submarine pipelines. In this paper, the seismic action of steel pipes in the operation stage after global buckling has occurred under the active control method is analyzed. Firstly, we have established a simplified finite element model for the entire process cycle and found that this modeling method is accurate and efficient, solving the problem of difficult convergence of seismic wave and soil coupling in previous solid analysis, and improving the efficiency of calculations. Secondly, through parameter analysis, it was found that under seismic action, the pipe diameter mainly affects the stress amplitude of the pipeline. When the pipe wall thickness increases from 0.05 m to 0.09 m, the critical buckling force increases by 150%, and the maximum axial stress decreases by 56%. In the pipe soil interaction, the greater the soil viscosity, the greater the pipe soil interaction force, the greater the soil constraint on the pipeline, and the safer the pipeline. Finally, the pipeline failure determination formula was obtained through dimensionless analysis and verified, and it was found that the formula was accurate.

• Earthquakes and Structures
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• v.18 no.4
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• pp.423-435
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• 2020

An accurate evaluation of structural damage is essential to performance-based seismic design for the structure across the earth fissure. By comparing the calculation results from three commonly used damage models and the experimental results, a weighted combination method using Chen model was selected in this paper as the seismic damage evaluation. A numerical model considering the soil-structure interaction (SSI) was proposed using ABAQUS software. The model was calibrated by comparing with the experimental results. The results from the analysis indicated that, for the structure across the earth fissure, the existence of earth fissure changed the damage distribution of the structural members. The damage of structural members in the hanging wall was greater than that in the foot wall. Besides, the earth fissure enlarged the damage degree of the structural members at the same location and changed the position of the weak story. Moreover, the damage degree of the structure across the earth fissure was greater than that of the structure without the earth fissure under the same excitation. It is expected that the results from this research would enhance the understanding of the performance-based seismic design for the structure across the earth fissure.

• Structural Engineering and Mechanics
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• v.22 no.1
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• pp.33-52
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• 2006

Three-dimensional description of building structure taking into consideration soil-structure interaction is a very complex problem and solution of this problem is often obtained by using finite element method. However, this method takes a significant amount of computational time and memory. Therefore, an efficient computational model based on subdivision of the structure into building elements such as wall and floor slab elements, plane and three-dimensional joints and lintels, that could provide accurate results with significantly reduced computational time, is proposed in this study for the analysis three-dimensional structures subjected to dynamic load. The examples prove the efficiency and the computing possibilities of the model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5963-5973
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• 2011

Current design and analyzing methods about soil nailing structures, developed on the basis of results obtained from experiments in laboratory or in field and numerical analyses, have applied different interaction mechanisms between the reinforced nails and the surrounding ground, and different safety factors against failure have been obtained. They might be proper approaches if the assumptions about rigidity of nails and ground conditions are met with actual conditions occurred in field. Otherwise, they would result in designing on analyzing in inappropriate ways so that it is needed to evaluate the validity of them. Therefore, in this research using the Centrifugal Model Testing, numerical parameters experiments about soil nailing structures' behavior and failure mechanism were performed. In the numerical parameters experiments, transmuted nail's length, setting angle, nail's front panel, stiffness variously, and increased the level of gravity until wall model was destroyed. Based on experimental results, we compared the effect, failure mechanism caused from parameters changes. By reviewing and comparing centrifugal model test results and methods currently in use, verified validity of existing methods.

• Journal of the Korean Geotechnical Society
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• v.38 no.6
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• pp.17-28
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• 2022

The effect of the soil-structure interaction (SSI) on has been recently evaluated in shaking table tests. However, most of these tests were conducted on single-degree-of-freedom (SDOF) superstructures and a single-pile. This study investigates the inertial interaction effect of a multi-degree-of-freedom (MDOF) superstructure system with a group piles on a large-scale shaking table test. Whereas the SDOF superstructure system shows a single-frequency amplification tendency, the MDOF superstructure system exhibited amplification tendencies of the acceleration phase and frequency responses for multiple frequencies. In addition, the amplification phenomenon between the footing and the column-type superstructure exceeded that between the footing and the wall-type superstructure, indicating a greater inertial interaction effect of the column-type superstructure. The relationship between shear force and inertial force, the relative vertical and horizontal displacements on the footing was figured out. Also, the ananlysis of dynamic p-y curve at each depth was conducted. In summary, the MDOF and SDOP superstructure systems exhibited different behaviors and the column-type superstructure exerted a higher interaction effect than the wall-type superstructure.

• Earthquakes and Structures
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• v.8 no.1
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• pp.275-304
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• 2015

The objective of this paper is to investigate the validity of transmitting boundaries in dynamic analysis of soil-structure interaction problems. As a case study, the proposed Baghdad metro line is considered. The information about the dimensions and the material properties of the concrete tunnel and surrounding soil were obtained from a previous study. A parametric study is carried out to investigate the effect of several parameters including the peak value of the horizontal component of earthquake displacement records and the frequency of the dynamic load. The computer program (Mod-MIXDYN) is used for the analysis. The numerical results are analyzed for three conditions; finite boundaries (traditional boundaries), infinite boundaries modelled by infinite elements (5-node mapped infinite element) presented by Selvadurai and Karpurapu, 1988), and infinite boundaries modelled by dashpot elements (viscous boundaries). It was found that the transmitting boundary absorbs most of the incident energy. The distinct reflections observed for the "fixed boundaries" disappear by using "transmitted boundaries". This is true for both cases of using viscous boundaries or mapped infinite elements. The type and location of the dynamic load represent two controlling factors in deciding the importance of using infinite boundaries. It was found that the results present significant differences when earthquake is applied as a base motion or a pressure load is applied at the surface ground. The peak value of the vertical displacement at nodes A, B, E and F (located at the tunnel's crown and side walls, and at the surface above the tunnel and at the surface 6.5 m away from tunnel's centre respectively) increases with the frequency of the surface pressure load for both cases 1 and 2 (traditional boundaries and mapped infinite elements respectively) while it decreases for case 3 (viscous boundaries). The modular ratio Ec/Es (modulus of elasticity of the concrete lining to that of the surrounding soil) has a considerable effect on the peak value of the horizontal displacement at node B (on the side wall of the tunnel lining) increase about (17.5) times, for the three cases (1, 2, and 3).

• Journal of the Korean Geotechnical Society
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• v.27 no.5
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• pp.17-31
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• 2011

This paper presents the results of a numerical investigation on the behavior of earth retaining wall system with emphasis on the groundwater lowering. Using the 2D stress-pore pressure coupled analysis, the effects of ground excavation and groundwater interaction were examined using wall horizontal deformation, ground surface movement, plastic strain pattern, effective stress distribution and axial stress of strut. In addition, based on the results from a parametric study on a wide range of soil profile and initial ground water table level, the ranges of wall displacement and ground deformation were suggested quantitatively.

• Journal of the Korean Geotechnical Society
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• v.25 no.4
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• pp.19-29
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• 2009

In this study, a numerical analysis was performed to predict the sequential behavior of anchored retaining wall where the failure accident took place, and verified accuracy of prediction through the comparisons between prediction and field measurement. The emphasis was given to the wall behaviors and the variation of sliding surface based on the two different methods of elasto-plastic and finite element (shear strength reduction technique). Through the comparison study, it is shown that the bending moment and the soil pressure at construction stages produce quite similar results in both the elasto-plastic and finite element method. However, predicted wall deflections using elasto-plastic method show underestimate results compared with measured deflections. This demonstrates that the elasto-plastic method does not clearly consider the influence of soil-wall-reinforcement interaction, so that the tension force (anchor force and earth pressure) on the wall is overestimated. Based on the results obtained, it is found that finite element method using shear strength reduction method can be effectively used to perform the back calculation analysis in the anchored retaining wall, whereas elasto-plastic method can be applicable to the preliminary design of retaining wall with suitable safety factor.

• Journal of the Korean Geotechnical Society
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• v.33 no.11
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• pp.83-95
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• 2017

This study examined the magnitude and distribution of earth pressure on the excavation wall in jointed rock mass by considering different groundwater conditions under various rock types, joint inclination angles, and earth pressure coefficients. Based on a physical model test (Son and Park, 2014), extended studies were conducted considering rock-structure interactions based on the discrete element method, which can consider the joints characteristics of rock mass. The results showed that the earth pressure was highly influenced by the groundwater condition as well as the rock type, joint inclination angle, and earth pressure coefficient. The results were also compared with Peck's earth pressure for soil ground, and clearly showed that the earth pressure in jointed rock mass can be greatly different from that in soil ground.

• Journal of the Korean Geotechnical Society
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• v.34 no.11
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• pp.43-55
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• 2018

AGF (Artificial Ground Freezing) method is a temporary ground improvement method which can apply to all types of soil with the purpose of high stiffness and low hydraulic conductivity. However, the groundwater flow and the heterogeneity of the ground increase the uncertainty of the ice-column formation which hinders the reliability of this method. The effects of groundwater flow and layered heterogeneity on ice-wall integrity by AGF method were analyzed using finite element analysis program for a coupled thermo-hydro phenomena in the freezing ground. Groundwater flow changes circular ice-column into elliptical shapes and increases the time required for the formation of ice walls. The previous theoretical formula overestimated the completion time of the ice wall and the critical groundwater velocity by neglecting the thermal interaction between adjacent ice-columns. Numerical results presented the corrected formula and verified the proposed equation for the dimensionless ice-wall completion time. In the layered heterogeneous ground, the thickness of the layer with higher hydraulic conductivity and its relative magnitude were found to be important factors in the ice-wall completion time and critical velocity.