• Journal of Digital Convergence
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• v.17 no.3
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• pp.205-213
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• 2019

In a construction site, excavation work has a close relation with temporary earth retaining structure. In order to build the underground structure most effectively in a narrow space, prevent soil relaxation of the external behind ground in excavation work, and maintain a ground water level, it is required to install a temporary earth retaining structure that secures safety. To prevent soil washoff in underground excavation work, the conventional method of temporary earth retaining structure is to make a temporary wall and build the internal support with the use of earth anchor, raker, and struct for excavation work. RSB method that improves the problem of the conventional method is to remove the internal support, make use of two-row soldier piles and bracing, and thereby to resist earth pressure independently for underground excavation. This study revealed that through the field application cases of RSB method and the measurement result, the applicability of the method for installing a temporary earth retaining structure, the assessment result, and displacement all met allowable values of measurement, and that the RSB method, compared to the conventional method, improved constructability and economy.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.05a
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• pp.189-218
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• 1997

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.169-176
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• 1999

본 논문은 지하수 흐름하에서의 풍화 잔류토의 세립자 유동특성을 파악하기 위한 수치모델을 개발하고, 실내에서 실시한 수리 모형실험을 통하여 수치모델의 적합성을 규명하였다. 한국의 풍화 잔류토는 점토와 모래의 중간 상태의 특성을 보이는 관계로 기존의 토립자 유동모델중 점토 또는 모래에 적합한 모델에 의해서는 정확한 유동특성의 파악에 한계가 있었다. 따라서, 본 연구에서는 한국의 풍화 잔류토에 적합한 세립자 유동모델을 제시함으로써 풍화 잔류토를 대상으로 시공되는 굴토공사, 댐 축조공사, 그리고 터널공사시 지하수 유입에 따른 세립토사의 유실특성을 이론적으로 규명하였고, 현장에서 배수재로 광범위하게 쓰이고 있는 토목섬유인 부직포의 투수 및 배수특성을 검토하였다

• Geotechnical Engineering
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• v.13 no.2
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• pp.101-124
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• 1997

Adjacent ground surface settlements by deep excavations are analyzed by field observations in the areas where excavations are performed in sandy soils or weathered soils underlain by rocks, First, the magnitude and the distribution of ground surface settlements, which are developed before main excavation activities (e. g., diaphragm wall installation and center pile installation) , are measured and analyzed. Secondly, the magnitude and the distribution of ground surface settlements by main excavation are measured and analyzed. And the results are compared with the predictions obtained by the empirical methods. Through case studies performed on the excavation sites where adjacent ground surfaces or structures are damaged by excavation activities, upper limit location of ground surface cracks are investigated.

• KIEAE Journal
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• v.8 no.1
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• pp.87-92
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• 2008

Sheathing work used for excavation in a crowded downtown is generally a temporary strut method using H-piles and sheathing wall includes lagging, CIP, SCW or slurry wall. A temporary strut serving the support for sheathing wall acts to resist the earth pressure, but it shall be removed when installing the underground structure members. A traditional temporary strut might cause the stress imbalance of the sheathing wall when it is demolished, resulting in time extension and the risk of collapse. A traditional temporary strut method thus needs to be improved for schedule and cost reduction, risk mitigation and for preparation for potential civic complaint. A permanent strut method doesn't require installing and demolishing the temporary structure that will lead to reducing the time and cost and the structural risk during the demolition process. And given the girder, the part of the underground structure, serves the role of strut, it can secure the wider interval compared to the traditional method, which enables to secure the wider space for the convenience of excavation as well as enhance the constructability and efficient site management. The thesis was intended to study the composite girder designed to use the strut as permanent structure so as to reduce the excavation and floor height.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.9-16
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• 2017

To improve concrete-filled tube (CFT) columns, an octagonal concrete-filled tube (OCFT) column was developed. Because the OCFT column requires a small boring diameter, the OCFT column is suitable for Top-Down construction method. In this study, the compression performance of OCFT column to be used as Top-Down pile foundation was verified using centrifuge equipment. Under 12 g centrifugal acceleration, the bearing capacities of the pile foundations of OCFT and H-shaped sections were tested. When the pile foundations were embedded in soil of full depth, 45 % of the design strength, which was assumed to be the construction load, was supported by the OCFT and H-shaped sections in the elastic states. When the pile foundations were embedded in soil of half depth, the buckling of the pile foundations was not investigated. After the loading test, the rock at the bottom of pile foundation, which had a strength of 3.5 MPa, was not damaged due to 45 % of the design strength.

• Journal of the Korean GEO-environmental Society
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• v.11 no.2
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• pp.61-68
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• 2010

Recently, it is a trend of the underground excavation to become larger and deeper for more effective use of available space and with the advent of new excavation technologies. The ground typically has a complex stratigraphy. The excavation can lead to large deformation in the nearby structures and large earth pressure on the wall. This can lead to serious problem in the stability of the wall. For the retaining wall to be safely constructed, it is important that the stratigraphy and engineering properties of the ground be accurately estimated, based on the excavation plan and appropriate excavation method. This study uses the measured field data and numerical results to characterize the characteristics of the lateral deformation of the retaining wall. A touredof six field data were analysed. SUNEX, a numerical program which uses the elasto-plastic model to represent the soil, was used. It was shown that the measured deformations exceeded the proposed values for shallow excavations. Overall, the maximum lateral deformation was within the proposed value and hence, the walls were analyzed as safe.

• Journal of the Korean Geotechnical Society
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• v.22 no.2
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• pp.19-28
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• 2006

Long-term field observations were performed in three excavation sites in order to investigate the displacement behavior of adjacent ground during overall excavation procedure, where the depths of deep excavations were 15 m$\∼$29 m. In this study, ground settlements and lateral displacements of braced wall measured during installation of retaining wall and removal of bracing were specially focused to evaluate the behavior quantitatively according to three-stage-divided procedure, i.e. pre-excavation, main excavation, and removal of bracing. Through field measurements on three excavation sites, lateral displacements induced during removal of bracing are approximate to 40$\%$ of the amount found during main excavation stage and additional adjacent ground deformation during post-excavation procedure ranges from 18$\%$ to 33$\%$ of that found during main excavation stage, based on the settlement volume. In conclusion, it was quantitatively identified in this study that the deformations of adjacent ground during pre- and post-excavation stage were not negligible.

• Journal of Korean Association for Spatial Structures
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• v.11 no.2
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• pp.129-138
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• 2011

Construction methods for underground structure are classified as bottom-up, up-up, and top-down methods depending on the procedure of construction related to a superstructure. In top-down construction methods, building's main structure is built from the ground level downwards by sequentially alternating ground excavation and structure construction. In the mean time, the main structure is also used as supporting structure for earth-retaining wall, which results in the increased stability of the earth-retaining wall due to the minimized deformation in adjacent structures and surrounding grounds. In addition, the method makes it easy to secure a field for construction work in the downtown area by using each floor slabs as working spaces. However top-down construction method is often avoided since an excavation under the slab has low efficiency and difficult environment for work, and high cost compared with earth anchor method. This paper proposes a combined construction method where semi-open cut is selected as excavation work, slurry as earth -retaining wall and CWS as top-down construction method. In the case study targeted for an actual construction project, the proposed method is compared with existing top-down construction method in terms of economic feasibility, construction period and work efficiency. The proposed construction method results in increased work efficiency in the transportation of earth and sand, and steel frame erection, better quality management in PHD construction, and reduced construction period.

• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.367-378
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• 2018

Purpose: The objective of this study is to present a reasonable safety management of the anchored in-situ wall systems constructed in the ground conditions consisting of multi-layered soils underlain by bedrocks in the urban area of Korea. Method: Field measurements collected from collapse case histories with deep excavations were analyzed for the safety management of the wall systems supported by the earth anchors in terms of lateral displacement rates. Results: The average maximum lateral displacement rate in a collapsed zone of the in-situ wall significantly increased upon the completion of the excavation. Particularly, the collapse of the in-situ wall system due to the sliding occurring along the discontinuities of the rock produced a considerably large lateral displacement rate over a relatively short period. Conclusion: For predicting and preventing the collapse of the wall system during or after the excavation work, the utilization of the safety management criteria of the in-situ wall system by the lateral displacement rate was found to be much more reasonable in judging the safety of earthworks than the application of the quantitative management criteria which have been commonly used in the excavation sites.