• Journal of the Korean Geosynthetics Society
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• v.8 no.3
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• pp.1-7
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• 2009

Earth reinforcement by using geogrids as reinforcing materials are widely applied to several earth structures. The bearing capacity of geogrid reinforced foundation soils is usually examined on based on the rigid plasticity theory or Limit Equilibrium Method. Method of analysis such Limit Equilibrium Method provide no detail information about failure behaviour or strain which develop in the reinforcement or foundation. In this paper the analysis of failure behaviour of strip footing on geogrid-reinforced sand over a soft caly was investigated by using a numerical method. A series of finite element analyses were performed on a geogrid-reinforced strip footing over a soft clay including number of geogrid layers, length, depth. We effectively investigated the failure behaviour and improvement of bearing capacity on the reinforced foundation soil by using FEM program.

• Coupled systems mechanics
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• v.7 no.1
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• pp.27-42
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• 2018

Behavior of soil is usually described with continuum type of failure models such as Mohr-Coulomb or Drucker-Prager model. The main advantage of these models is in a relatively simple and efficient way of predicting the main tendencies and overall behavior of soil in failure analysis of interest for engineering practice. However, the main shortcoming of these models is that they are not able to capture post-peak behavior of soil nor the corresponding failure modes under extreme loading. In this paper we will significantly improve on this state-of-the-art. In particular, we propose the use of a discrete beam lattice model to provide a sharp prediction of inelastic response and failure mechanisms in coupled soil-foundation systems. In the discrete beam lattice model used in this paper, soil is meshed with one-dimensional Timoshenko beam finite elements with embedded strong discontinuities in axial and transverse direction capable of representing crack propagation in mode I and mode II. Mode I relates to crack opening, and mode II relates to crack sliding. To take into account material heterogeneities, we determine fracture limits for each Timoshenko beam with Gaussian random distribution. We compare the results obtained using the discrete beam lattice model against those obtained using the modified three-surface elasto-plastic cap model.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.247-252
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• 2004

To secure stability and availability of Rammed Aggregate Pier method as the foundation of a structure, the bearing capacity and failure behavior characteristics was studied through soil laboratory tests in a model ground. In this study, soil laboratory tests use carried out to find the applicability of RAP method as the foundation of a structure. And bearing capacity and the failure mechanism of RAP method was studied according to relative density($60\%,\;70\%,\;90\%$), diameter(45mm, 60mm, 70mm) of each pier ana depth(5cm, l0cm, 15cm, 20cm, 25cm, 30cm). Earth pressure cell is set up approach RAP and 1.0D space at RAP center. Bearing acpacity and the failure mechanism of RAP is investigated by load test As a result, bulging failure was happened in $5\~10cm\;(1.0D\~2.00)$ depth which the maximum lateral earth pressure is acting. Especially, diameter changing of RAP are in inverse proportion to the relative density and the lateral stress is very much influenced by the lateral earth pressure in every layer and tends to decrease according to depth.

• Journal of the Korean Geotechnical Society
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• v.27 no.3
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• pp.27-40
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• 2011

In this study, we performed model lateral load test for connected-type foundations of transmission tower with bar in clay, and proposed failure standard and measuring method to estimate ultimate lateral bearing capacity. For this study, we performed model lateral load tests in Iksan, Jeollabukdo and analyzed load-displacement characteristic of the model. We manufactured model foundation of transmission tower connected with bar and that considered a change of rigidity. We installed various measuring sensors to find general foundation behavior. From the test results, we measured, compared and analyzed load capacities, and then proposed failure standard to estimate bearing capacity for connecting type foundation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.166-173
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• 2002

Seismic bridge failure due to the combined effects of earthquake and local scour are examined in probabilistic perspectives. The seismic responses of multi-span continuous bridge with deep foundations are evaluated with a simplified mechanical model. The probabilistic local scour depths around the deep foundations are estimated by using the Monte Carlo simulation. From the simulation results, it is found that seismic responses of a bridge slightly increase due to the local scour effect. The effect of local scour on the global motion of the continuous bridge is found to be significant under weak seismic intensity. In addition, the duration to regain its original foundation stiffness is critical in estimating the probability of foundation failure under earthquake. Therefore, the duration in recovering the foundation stiffness should be determined reasonably and the safely of the whole bridge system should be evaluated by considering the scour effect.

• Geotechnical Engineering
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• v.5 no.4
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• pp.17-26
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• 1989

The creep ratio, which has been applied as a measure to prevent piping failure in designing embankments, has been originally proposed for the protection of masonry or concrete dam from piping along the boundary surface between the foundation soil and the bottom of the structure. In this study, it has been investigated whether this creep ratio could be applied for the earth embankment through the model test and we reevaluated the required creep ratio in the present design criteria. Based on this research, it was concluded that a piping failure would always occur within the embankment body and not through the boundary surface between the embankment and foundation. Therefore it could be said that the present design criteria are illogical to determine the design creep ratio according to less permeable soil no matter whether the soil forms embankment or foundation.

• Earthquakes and Structures
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• v.21 no.6
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• pp.641-652
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• 2021

Digging well foundation has been widely used in railway bridges due to its good economy and reliability. In other instances, bridges with digging well foundation still have damage risks during earthquakes. In this study, a new type of digging well foundation with prefabricated roots was proposed to reduce earthquake damage of these bridges. Quasi-static tests were conducted to investigate the failure mechanism of the root digging well foundation, and then to analyze seismic behaviors of the new type well foundation. The testing results indicated that these prefabricated roots could effectively limit the rotation and uplift of the digging well foundation and increase the lateral bearing capacity of the digging well foundation. The elastic critical load and ultimate load can be increased by 69% and 36% if prefabricated roots were added in the digging well foundation. The prefabricated roots drived more soil around the foundation to participate in working, the stiffness of the bridge pier with root digging well foundation was improved. Moreover, the root participation could improve the energy dissipation capacity of soil-foundation-pier interaction system. The conclusions obtained in this paper had important guiding significance for the popularization and application of the digging well foundation with prefabricated roots in earthquake-prone zones.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2757-2762
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• 2012

Sewage pipelines are one of important infra-structures. The main reasons of sewage pipelint failure are improper backfill materials and compaction controls in field. Especially, it is very difficult to compact the lower part of circula pipelines. In order to overcome these problems, the prefabricated light-weight plastic foundation was developed. Couple of load-displacement tests were carried out to get the characteristic of failure. From the limited laboratory loading tests, the use of prefabricated light-weight plastic foundation is an alternative to solve the difficulty of backfill materials and compaction control.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.237-242
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• 1993

The bearing capacity of the sand foundation including a thin dense sand layer depends on the stiffiness, thickness and the location of the dense sand layer. In this paper was the influence of the dense sand layer on both the bearing capacity and the failure configuration is studied by means of K.E.M(Kinematic Element Method). K.E.M was implemented to get the excat solution starting from the upper bound of the analysis. The result show that the bearing capacity of the foundation and the failure configuration is greatly influenced by the dense sand layer, when the layer is located not deeper than 3/5 of the foundation width.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.3
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• pp.435-451
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• 2015

Evaluation of the performance of aging structures is essential in the oil and gas industry, where the inaccurate prediction of structural performance can have significantly hazardous consequences. The effects of structure failure due to the significant reduction in wall thickness, which determines the burst strength, make it very complicated for pipeline operators to maintain pipeline serviceability. In other words, the serviceability of gas pipelines and elbows needs to be predicted and assessed to ensure that the burst or collapse strength capacities of the structures remain less than the maximum allowable operation pressure. In this study, several positions of the corrosion in a subsea elbow made of API X42 steel were evaluated using both design formulas and numerical analysis. The most hazardous corrosion position of the aging elbow was then determined to assess its serviceability. The results of this study are applicable to the operational and elbow serviceability needs of subsea pipelines and can help predict more accurate replacement or repair times.