• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.101-104
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• 2007

As the proportion of underground construction increases, the impact of inappropriate selection of a underground construction method for a construction size increases. The purpose of this study is to develop an objective way of selecting an excavation method. There have been several attempts to achieve the same goal using various data mining methods such as the artificial neural network, the support vector machine, and the case-based reasoning. However, they focused only on the selection of a retaining wall construction method out of six types of retaining walls. When we categorized an underground construction work into four groups and added more number of independent variables (i.e., more number of construction methods), the predictability decreased. As an alternative, we developed a decision tree by analyzing 25 earthwork cases with detailed information. We implemented the developed decision tree as a computer-supported program called Dr. underground and are still in the process of validating and revising the decision tree. This study is still in a preliminary stage and will be improved by collecting and analyzing more cases.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10a
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• pp.315-321
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• 2001

Since 1984, block-type reinforced earth wall with geogrid reinforcement has been widely used for retaining wall applications till now in Korea. The use of geogrid as a reinforcement in the reinforced earth wall is steadily increased in an amount over 1,500,000㎡ in a year However, still need exists that some problems in design and construction practices should be made to review, Therefore, this paper reviewed reasonable criteria for selection of backfills, design details considering the effect of the upper soil slope on reinforced earth wall, horizontal displacement of facing block during compaction, and the damage of geogrid reinforcements on the edge part of facing block. Finally, alternative methods of measures on those problems are proposed.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.1
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• pp.1-8
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• 2016

Permanent deformation plays a key role in performance based earthquake resistant design. In order to estimate permanent deformation after earthquake, it is essential to secure reliable response history analysis(RHA) as well as earthquake scenario. This study focuses on permanent deformation of an inverted T-type wall under earthquake. The study is composed of two separate parts. The first one is on the verification of RHA and the second one is on an effect of input earthquake motion. The former is discussed in this paper and the latter in the companion paper. The verification is conducted via geotechnical dynamic centrifuge test in prototype scale. Response of wall stem, ground motions behind the wall obtained from RHA matched pretty well with physical test performed under centrifugal acceleration of 50g. The rigorously verified RHA is used for parametric study to investigate an effect of input earthquake motion selection in the companion paper.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.277-282
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• 2002

The objective of this study is to suggest the optimal method for reinforced earth retaining wall through the appropriate selection of reinforcing materials, development of design criteria. Thus, the efficient land utilization and securing safety in the train operation in service lines could be achieved. For this goal, a large scale shear laboratory test was carried out to evaluate the reinforced effect of earth body reinforced by attachment-type geogrid.

• Journal of the Korea Institute of Building Construction
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• v.8 no.4
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• pp.61-69
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• 2008

The size of the construction projects become huge and complex, and the depth of excavation for the underground structures become deeper. Also the working area is not enough for loading materials and temporary facilities. This is the most case of recent construction projects in downtown area. Top-down is the most useful method for this kind of construction projects. Top-down construction method consists of supporting method, retaining wall type, foundation type and construction direction such as up-down or up-up. construction managers have to select sub-elements for top-down construction method in planning phase. This study is to suggest the sub-elements selection model for the top-down construction method, and the case study is conducted for evaluating this model.

• Geomechanics and Engineering
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• v.20 no.2
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• pp.121-129
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• 2020

In the design of geotechnical structures, engineers choose either peak or critical state friction angles. Unfortunately, this selection is based on engineer's preference for economy or safety and lacks the assessment of the expected level of deformation. To fill this gap in the design process, this study proposes a strain based empirical method. Proposed method is founded on the experimentally supported assumption that higher dilatancy angles result in more brittle soil response. Using numerous triaxial test data on ten different soils, an empirical design chart is developed that allows the estimation of shear strain at failure based on soil's peak dilatancy angle and mean grain diameter. Developed empirical chart is verified by conducting a small scale retaining wall physical model test. Finally, a design methodology is proposed that makes the selection of design friction angle in structured way possible based on the serviceability limits of the proposed structure.

• Geomechanics and Engineering
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• v.21 no.1
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• pp.23-33
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• 2020

An advancing cutting roof for gob-side entry retaining with no-pillar mining under specific geological conditions is more conducive to the safe and efficient production in a coalmine. This method is being promoted for use in a large number of coalmines because it has many advantages compared to the retaining method with an artificial filling wall as the gateway side filling body. In order to observe the inner structure of the gateway cutting roof and understand its stability mechanism, an equivalent material simulation experiment for a coalmine with complex geological conditions was carried out in this study. The results show that a "self-stabilization bearing structure" equilibrium model was found after the cutting roof caving when the cut line deviation angle was unequal to zero and the cut height was greater than the mining height, and the caving roof rock was hard without damage. The model showed that its stability was mainly controlled by two key blocks. Furthermore, in order to determine the optimal parameters of the cut height and the cut line deviation angle for the cutting roof of the retaining gateway, an in-depth analysis with theoretical mechanics and mine rock mechanics of the model was performed, and the relationship between the roof balance control force and the cut height and cut line deviation angle was solved. It was found that the selection of the values of the cut height and the cut line deviation angle had to conform to a certain principle that it should not only utilize the support force provided by the coal wall and the contact surface of the two key blocks but also prevent the failure of the coal wall and the contact surface.

• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.51-61
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• 2000

This paper reviews fundamentals of a pseudo-static seismic design/analysis method for soil-reinforced segmental retaining walls. A comparative study on NCMA and FHWA seismic design guidelines, which are one of the most well known design guidelines for mechanically stabilized earth walls, was also performed. The results demonstrate that there exist significant discrepancies in the results of external stability analysis despite the same calculation model used in the two guidelines, due primarily to different seismic coefficient selection criteria. It is also demonstrated that the internal stability calculation model for NCMA guideline tends to yield larger seismic reinforcement force in the shallower reinforcement layers, resulting in an increased number of reinforcement layers at the top of reinforced wall and increased reinforcement lengths to ensure adequate anchorage capacity. The internal stability calculation model adopted by FHWA guideline, however, leads to redistribution of dynamic force to the lower reinforcement layers and thus results n an opposite trend of NCMA guideline. Findings from this study clearly demonstrate a need for more in-depth studies to develop a generally acceptable design/analysis method.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.686-689
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• 2008

In the past decade, various data mining techniques have been used in construction engineering as a means to make informed decisions through the aid of useful knowledge discovered from historical data. Researchers in the construction domain are often confronted with a challenge to derive a meaningful conclusion with a limited sample of data. However, when the data size is small, the proposed results are often illogical. Even if the derived results are technically flawless, sometimes it is difficult to reproduce these results by using the same analysis method when a different set of data is used. This paper reviews some problems that stem from limited data size, and discusses several recommendations for dealing with these problems.

• Earthquakes and Structures
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• v.26 no.1
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• pp.1-15
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• 2024

Isolation technology has been proven effective in reducing the seismic response of superstructures, where most of the deformation is concentrated in the isolation layer. However, in cases of earthquakes with intensities surpassing the fortification level of the area, or severe near-fault earthquakes, the isolation layer may experience excessive deformation, resulting in damage to the isolation bearings or collisions with the retaining wall or surrounding buildings. In this study, a finite element model using ABAQUS is established and compared with experimental test results to deeply investigate the influence of limit devices on the isolation layer and its response to the superstructure. The findings reveal that a larger limiter stiffness and a smaller reserved gap can achieve a more effective limiting effect. Nevertheless, a smaller reserved gap and a larger limiter stiffness may result in increased response of the superstructure. Therefore, rational selection of the reserved gap and limiter stiffness is crucial to reduce the acceleration response.