• Proceedings of the Korean Geotechical Society Conference
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• 1993.03a
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• pp.41-48
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• 1993

The 2nd phase of Seoul Subway, Lines 5,6,7 and 8, is in progress. To reduce the surface traffic congestion during construction the greater part of the system has been engineered by bored tunnelling. The current tunnelling methodology is based on the New Austrian Tunnelling Method. Serveral collapses have been reported to date. Most of the collapses took place in the area forwed with soft ground. The modes and causes of the collapses were progressive failures in the unsupported surface and sliding failures due to the unfavourable joint direction. The major causes turned out to be the weakness of ground and the sudden influx of ground water from the surface. Some measures to prevent the failures are also presented. To ensure the safe tunnelling ghrough the soft ground the unsupported excavation area has to be minimized and closed as early as possible. Additional support measures such as supporting core, sealing shotcrete, forepoling, spread footing, face rock bolting and grouting should be employed as well depend on ground conditions.

• Structural Engineering and Mechanics
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• v.51 no.3
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• pp.503-518
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• 2014

On October 23, 2011, an earthquake of magnitude 7.0 struck Van, Turkey. This powerful earthquake caused the deaths of 604 people, more than 2,000 injuries, and a considerable loss of property. After this devastating earthquake, on November 9, 2011, another earthquake of magnitude 5.7 occurred. This moderate earthquake caused the deaths of 40 people. Partial and total collapse of the masonry and adobe buildings occurred in the rural areas of Van. In this paper, the acceleration records and response spectrums of the earthquakes were given and the structural deficiencies and reasons of the failures of the rural buildings were evaluated according to the Turkish Seismic Code. The observed failures showed that low quality of structural materials, poor workmanship, lack of engineering services and insufficient detailing of the structural elements are the main reasons of damages.

• International Journal of Highway Engineering
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• v.17 no.2
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• pp.71-78
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• 2015

PURPOSES: This study set out to investigate the current state of microsurfacing in Texas and compared the results with the current state of the practice nationwide. METHODS: For this study, case studies were extracted from the existing literature and compared with the data obtained both from site visits by the research team and data obtained from a survey by Texas Department of Transportation (TxDOT) personnel. The successes and failures of microsurfacing are detailed and explanations of different issues are outlined. Forensic studies from Texas are included in the descriptions of those microsurfacings that failed when configured as part of the cape seals. RESULTS : Microsurfacing has been shown to be an effective pavement preservation technique when applied to an appropriate road, at an appropriate timing, and as a remedy for certain issues. The failures experienced in Texas can mostly be attributed to cape seals and an inability to recognize structurally faulty pavement. CONCLUSIONS : When applied to an appropriate road, at an appropriate timing, and as a remedy for certain issues, microsurfacing has been shown to perform well in numerous case studies. The majority of microsurfacing failures are the result of poor project selection, usually involving the treatment being applied to structurally unsound pavement.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2492-2494
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• 1998

Recently the optical fiber lines have been widely deployed in the trunk lines and digital data service network. The unexpected failures of optical fiber lines by natural disasters and road construction work have increased rear by rear and the number of damaged telecommunication lines per failures is on increasing. In the meantime, it takes long time to recover the optical fiber lines failures. So, it is important to maintain and monitor the status of optical fiber lines for prevention of optical fiber lines failures. Therefore, KT(Korea Telecom) needs efficient and automatic maintenance system to operate and monitor the optical fiber lines. FLOMS(Fiber Line Operation and Monitor System) had been developed in '96 and pilot system was installed at telephone offices in '97. This paper describes the FLOMS which carries out the functions of efficient maintenance and supports for monitoring optical fiber lines and managing facilities in optical fiber lines.

• Journal of the Korean Society of Safety
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• v.26 no.3
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• pp.59-62
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• 2011

Among the accidents and failures that occur during concrete construction, many are formwork failures which usually happen when concrete is being placed. A system of formwork filled with wet concrete has its weight at the top and is not basically a stable structure. Slab formwork consists of sheathing, stringer, hanger and shore. There are several types of adjustable shores. In construction site, pipe supports are usually used as a shore of slab formwork. In this study, pipe support systems with/without horizontal connector were measured by buckling test. Buckling load of respective pipe support system was analyzed by structural analysis program(MIDAS). Buckling load of pipe support with/without horizontal connector was got by test and structural analysis. According to these results, we know that horizontal connector made pipe support system very safe. Buckling load of pipe support with horizontal connector is 56% higher than that without horizontal connector. So horizontal connector is important in slab formwork systems. Finally, the present study results will be used to design slab formwork system safely in the construction sites.

• Journal of the Korea Construction Safety Engineering Association
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• s.38
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• pp.79-87
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• 2006

Formwork is a temporary structure that supports its weight and that of freshly placed concrete as well as construction live loads. In constructions site, pipe supports are usually used as shores which are consisted of the stab formwork. The strength of a pipe support is decreasing as it is frequently being used at the construction site. Among the accidents and failures that occur during concrete construction, there are many formwork failures which usually happen at the time concrete is being placed. The objective of this study is to find out the strength change of used pipe support and unused pipe supports according to aging. In this study, 2857 pipe supports were prepared. Among these pipe supports, 2337 pipe supports were lent to the construction companies free of charge. 520 pipe supports were kept on the outside. Compressive strength was measured by knife edge test and plate test at each 3 month. Test results show that the strength of unused pipe supports as well as used pipe supports was decreasing according to age, use frequency and load carrier, and the strength of used pipe supports was lower than the strength of unused pipe supports at the same age. So, the strength of used pipe supports from 191 days to present day was not satisfied the specification of KSF 8001. In this study, the strength of pipe support according to age, use frequency and load carrier was predicted using SPSS 12.0. It was known that the strength of pipe support using for 5 years was reduced to 42.8%. According to these results, it shows that attention has to be paid to formwork design using used pipe supports. Therefore, the present study results will be able to provide a firm base to prevent formwork collapses.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10a
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• pp.337-344
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• 2001

The application of mechanically stabilized earth wall(MSEW) with segmental front panel has been increasing in highway construction due to its cost-effectiveness. However, some failures during construction have been reported and many field engineers are reluctant to select this method for important structure. One of the main reasons may be that there is no moderate specification for design and construction of MSEW yet. This paper discussed the main results of analysis on a case of block-type segmental retaining wall in highway construction. Based on the results, some recommendations on design and construction method of MSEW are presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.401-408
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• 2003

EPS(Expanded Polystyrene) has been used in a variety of applications as a solution of difficult soil conditions encountered in construction activities. Although there has been significant worldwide growth in the use of EPS as a lightweight fill material, it has a few failure cases before and after the construction. This paper described the observed failures of EPS structures up In date around the world. Also, method of quality control was proposed for site monitoring.

• Journal of Construction Engineering and Project Management
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• v.1 no.2
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• pp.11-17
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• 2011

Recent demands from construction industry have emphasized the capability for graduates to have improved skills both technical and non-technical such as problem solving, interpersonal communication. To satisfy these demands, problem-based learning that is an instructional method characterized by the use of real world problem has been adopted and has proven its effectiveness various disciplines. However, in spite of the importance of field senses and dealing with real problem, construction engineering education has generally focused on traditional lecture-oriented course. In order to improve limitations of current construction education and to satisfy recent demands from construction industry, this paper proposes a new educational approach that is Failure-Based Learning for using combination of the procedural characteristics of the problem-based learning theory in construction technology education utilizing failure information that has the educational value in the construction area by reinterpreting characteristics of construction industry and construction failure information. The major results of this study are summarized as follows. 1) Educational effect of problem-based learning methodology and limitation of application in construction area 2) The educational value of the information on construction failure and limitation in application of the information in construction sector 3) Anticipated effect from application of the failure-based learning 4) Development and application of the failure-based learning conceptual model.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.99-106
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• 2011

Recent demands from construction industry have emphasized the capability for graduates to have improved skills both technical and non-technical such as problem solving, interpersonal communication. To satisfy these demands, problem-based learning that is an instructional method characterized by the use of real world problem has been adopted and has proven its effectiveness various disciplines. However, in spite of the importance of field senses and dealing with real problem, construction engineering education has generally focused on traditional lecture-oriented course. In order to improve limitations of current construction education and to satisfy recent demands from construction industry, this paper proposes a new educational approach that is Failure-Based Learning for using combination of the procedural characteristics of the problem-based learning theory in construction technology education utilizing failure information that has the educational value in the construction area by reinterpreting characteristics of construction industry and construction failure information. The major results of this study are summarized as follows. 1) Educational effect of problem-based learning methodology and limitation of application in construction area 2) The educational value of the information on construction failure and limitation in application of the information in construction sector 3) Anticipated effect from application of the failure-based learning 4) Development and application of the failure-based learning model