• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.4
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• pp.313-322
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• 2003

This research work presents 3-D behavior of adjacent structures due to tunnelling induced ground movements by means of field measuring data and nonlinear FEM tunnel analysis. The results of the analytical methods from Mohr-Coulomb model are compared with the site measurement data obtained during the twin tunnel construction. It was found that the location and stiffness of the structure influence greatly the shape and pattern of settlement trough. The settlement trough for Greenfield condition was different from the trough for existing adjacent structures. Therefore the load and stiffness of adjacent structures should be taken into account for the stability analysis of the structures.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.3
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• pp.251-261
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• 2007

This study is to investigate the damage assessment of adjacent structures due to tunneling in urban environment. Model tests were carried out with two-story masonry building structures in various shapes and locations. The damage level of adjacent structures were very differently estimated in accordance with the shape ratio (L/h) of structures, construction stages, and various locations. The results of model tests were plotted on the damage level graphs in order to predict the direction of damage levels for the different types of structures (i.e. stiffness of structures, L/h). The progressive crack development mechanism at various construction stages was revealed through model tests and crack size indicated more conservative side of damage level on the damage level graph.

• Journal of the Korean Geotechnical Society
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• v.34 no.8
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• pp.15-26
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• 2018

Recently, as the seismic performance based design methods have been introduced, dynamic numerical analyses need to be performed to evaluate the actual performance of structures under earthquakes. The verification of the numerical modeling is the most important for the performance based design. Therefore, 2-dimensional numerical analyses were performed to simulate the seismic behavior of a pile-supported structure, to provide the proper numerical modeling and to determine of input parameters. A dynamic centrifuge test of a pile group in dry loose sand was simulated to verify the applicability of the numerical model. The numerical modeling was carefully made to reflect the actual condition of the centrifuge test including dynamic soil properties, soil-pile interaction, boundary condition, the modeling of the group pile and structure and so on. The predicted behavior of the numerical analyses successfully simulated the acceleration variation in ground, the moment and displacement of the pile, and the displacement and acceleration of the structure. Therefore, the adopted numerical modeling and the input parameters can be used to evaluate the seismic performance of pile groups.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.3
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• pp.19-27
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• 2001

In this seismic analyses of structures, it is well recognized that the effects of soil-structure interaction can not be ignored and seismic responses of a structure taking into account the stiffnesses of a foundation-soil system show the significant difference from those with a rigid base. However, current seismic analyses of apartment building structures were carried out with the rigid base ignoring the characteristics of the foundation and the properties of the underlying soil. In this study, seismic analyses of wall-slob type apartment buildings which have a particular structural type were carried out taking into account the soft soil layer comparing seismic response spectra of a flexible base with those of a rigid base and UBC-97. Low-rise or middle height wall-slab type apartment buildings built on the deep soft soil layer showed a rigid body motion with the reduced seismic responses due to the base isolation effect, indicating that it is considerably safe but uneconomical to utilize the design spectra of UB-97 for the seismic design of wall-slab type apartment buildings due to conservative design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.24-33
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• 2017

Domestic urban railway underground station structures, which were built in the 1970s ad 1980s, had been constructed as Cut-and-Cover construction system without seismic design. Because the trends of earthquake occurrence is constantly increasing all over the world as well as the Korean Peninsula, massive human casualties and severe properties and structures damage might be occurred in an non-retrofitted underground station during an earthquake above a certain scale. Therefore, to evaluate the retrofit effect and soil-structure interaction of seismic retrofitted underground station, a centrifugal shaking table test with enhanced stiffness on its structural main member are carried out on 1/60 scaled model using the Kobe and Northridge earthquakes. The seismic retrofitted members, which are columns, side walls, and slabs, are evaluated to comparing with existing non-retrofitted centrifuge test results Also, to simulate the scaled ground using variation of shear velocity according to site conditions such as ground depth and density, resonant column test is performed. From the test results, the relative displacement behavior between ground and structures shows comparatively similar in ground, but is increased on ground surface. The seismic retrofit effects were measured using relative displacements and moment behavior of column and side walls rather than slabs. Additionally, earthquake wave can be used to main design factor due to large structural deformation on Kobe earthquake wave than Norhridge earthquake wave.

• Journal of the Korean GEO-environmental Society
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• v.20 no.10
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• pp.39-46
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• 2019

The interaction between the ground and structures should be considered for seismic design of group piles supporting the superstructure. The p-y curve has been used widely for the analysis of nonlinear relationship between the ground and structures, and various researches have conducted to apply the dynamic p-y curve for seismic design of group piles. This curve considers the interaction between the ground and structures under the dynamic load such as an earthquake. However the supported effect by the pile cap and the interaction by inertia behavior of superstructures. Therefore, the shaking table test was conducted to verify the effect of the change of the pile cap in group piles supporting superstructures embedded in sandy soil. The test condition is that the arrangement and distance between centers of piles are fixed and the length of the pile cap is changed for various distances between the pile cap side and the pile center. The result shows that the distance between the pile cap side and the pile center have an effect on the dynamic p-y curve and the effect of group piles.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.1
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• pp.37-45
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• 1990

An analytical procedure is proposed for the seismic analysis of a soil-structure interaction system with besemat uplift, including the effects of concurrent vertical seismic ground motion, nonlinear distribution of bearing soil pressure under the basemat, and 3-dimensional behavior of the system. The soil-structure interaction system is assumed to have rectangular-shaped basemat on elastic half-space. Nonlinearity of soil spring constants and soil damping coefficients induced by the base mat uplift is modeled by considering not only the reduction of contact area between soil and structure but also the effects of rigid body rotational motion of the superstructure, and the shift in the point of action of the resultant reaction on the basemat. Throught various parametric studies. it has been confirmed that the seismic responses of the superstructure reduce notably while response at the basemat increases considerably. The results also show that the effects of concurrent vertical ground motion. nonlinear soil pressure distribution under basemat, and 3-dimensional behavior of the system shall be included in uplift analysis in order to obtain the correct structural responses.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.3
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• pp.249-257
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• 2005

There are basically two methods for the seismic design of underground structures ; analytical or pseudo-static, and dynamical method. In pseudo-static analysis approach, the ground deformations are imposed as a static load and soil-structure interaction does not include dynamic or wave propagation effects. However the behavior of soil structure interaction is nonlinear, it needs to consider nonlinear soil-structure interaction effects. In this study simplified seismic analysis method to consider soil-structure interaction by iterative procedure is proposed and the results are compared and analyzed by a finite difference computer program.

• Journal of the Korean GEO-environmental Society
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• v.11 no.1
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• pp.27-34
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• 2010

A finite element analysis has been conducted to clarify the behaviour of a single pile in heaving ground related to ground excavation. The numerical analysis has included soil slip at the pile-soil interface, analysing the interaction between the pile and the clay has been studied. The study includes the upward movement of the pile, the relative shear displacement between the pile and the soil and the shear stresses at the interface and the axial force on the pile. In particular, the shear stress transfer mechanism at the pile-soil interface related to a decrease in the vertical soil stress has been rigorously analysed. Due to the reductions in the vertical soil stress after excavation, the relative shear displacement and the shear stress along the pile have been changed. Upward shear stress developed at most part of the pile (Z/L=0.0-0.8), while downward shear stress is mobilized near the pile tip (Z/L=0.8-1.0) resulting in tensile force on the pile, where Z is the pile location and L is the pile length. Some insights into the pile behaviour in heaving ground analysed from the numerical analyses has been reported.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.757-772
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• 2018

Recently, earthquakes have occurred in large cities such as Gyeongju and Pohang, and seismic analysis studies have been actively conducted in various fields. However, since most of the previous seismic analyses have dealt with ground structures and the ground separately, there is a lack of a study on the complete soil-structure dynamic interaction. Therefore, in this study, a sensitivity analysis is conducted with MIDAS GEN and MIDAS GTS NX to apply the underground structure fixed-end model considering only the building and the complete system model considering both the building and the ground, respectively and the validity of dynamic analysis considering SSI is examined. As a result of the study, in most conditions it is found that the maximum horizontal displacement of the tall building in case of the underground structure fixed-end model is estimated to be smaller, the bending stress is larger, and the range of the weak part is smaller than that of the complete system model. Therefore, it is expected to be more reasonable to use the complete system model considering soil-structure interaction in seismic analysis.