• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.72-77
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• 2010

The Incheon Bridge, which was opened to the traffic in October 2009, is an 18.4 km long sea-crossing bridge connecting the Incheon International Airport with the expressway networks around the Seoul metropolitan area by way of Songdo District of Incheon City. This bridge is an integration of several special featured bridges and the major part of the bridge consists of cable-stayed spans. This marine cable-stayed bridge has a main span of 800 m wide to cross the vessel navigation channel in and out of the Incheon Port. In waterways where ship collision is anticipated, bridges shall be designed to resist ship impact forces, and/or, adequately protected by ship impact protection (SIP) systems. For the Incheon Bridge, large diameter circular dolphins as SIP were made at 44 locations of the both side of the main span around the piers of the cable-stayed bridge span. This world's largest dolphin-type SIP system protects the bridge against the collision with 100,000 DWT tanker navigating the channel with speed of 10 knots. Diameter of the dolphin is up to 25 m. Vessel collision risk was assessed by probability based analysis with AASHTO Method-II. The annual frequency of bridge collapse through the risk analysis for 71,370 cases of the impact scenario was less than $0.5{\times}10^{-4}$ and satisfies design requirements. The dolphin is the circular sheet pile structure filled with crushed rock and closed at the top with a robust concrete cap. The structural design was performed with numerical analyses of which constitutional model was verified by the physical model experiment using the geo-centrifugal testing equipment. 3D non-linear finite element models were used to analyze the structural response and energy-dissipating capability of dolphins which were deeply embedded in the seabed. The dolphin structure secures external stability and internal stability for ordinary loads such as wave and current pressure. Considering failure mechanism, stability assessment was performed for the strength limit state and service limit state of the dolphins. The friction angle of the crushed stone as a filling material was reduced to $38^{\circ}$ considering the possibility of contracting behavior as the impact.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.15 no.4
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• pp.281-301
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• 1993

It was revealed that the morphology and projection pattern of terminal arbors from single primary afferent are different among distinct fiber types, functional types and the different subdivision of trigeminal sensory nucleus complex(TSNC). But it was not identified the ultrastructural morphology and synaptic connections of terminal arbors from each primary afferent within TSNC. So we employed the intra-axonal horseradish peroxidase(HRP) injection technique to define the terminal arbors of primary afferent fiber from slowly adapting mechanoreceptors in the periodontal ligament of the cat, and examined 66 labeled terminal arbors within the rostrodorsomedial part(Vo.r) of the trigeminal nucleus oralis, electromicroscopically with 90nm serial sections. All the boutons labelled with HRP contained clear, spherical and uniform sized synaptic vesicles(diameter : $47.66{\pm}3.58nm$ ). Most of the labelled boutons were boutons en passant type and they were connected by unmyelinated axonal strand. In which neurofilament and microtubule was not developed but occasionally contained synaptic vesicle in contrast to the myelinated axon. The size of the labelled bouton was relatively small(long diameter : $1.46{\pm}0.24{\mu}m$, short diameter $0.85{\pm}0.26{\mu}m$, average diameter $1.15{\pm}0.24{\mu}m$) and the shape of which varied from dome to elongated shape, but scalloped glomerulus shape was not developed. Each primary ending in Vo.r made synapse with one or two neuronal propiles(average : $1.11{\pm}0.31$), of which, 89.4% of labelled boutons made synapse with only one neuronal pro pile, the remainder, 10.6% of labelled boutons, made synapse with two neuronal propile. So characteristically they made very simple synapse. Most of labelled boutons(80.03%) made asymmetrical synapse only with dendritic shaft or spine, and 6.1% of labelled boutons received symmetrical synapse from pleomorphic vesicle containing axonal ending(p-ending). So presynaptic inhibiton was relatively scarce. Synaptic triad, in which a p-ending is presynaptic both pre-and post-synaptic element of the axo-dendritic contact from the labelled primary ending was not observed.

• Journal of the Korean GEO-environmental Society
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• v.21 no.8
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• pp.5-13
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• 2020

During the construction of underground space expansion of old facilities, it is necessary to secure temporary residence space for existing residents as well as noise and vibration issues during construction, and in the case of commercial, industrial, and social use, damage is expected from suspension of the use of facilities. There is a need for a technology that minimizes noise and vibration during underground expansion, enabling the use of existing facilities even during construction. In this study, a practical underground extension model is proposed by analyzing the behavior of the temporary structure and the surrounding ground as a result of measurement at each construction stage for a actual construction site. In order to solve the problems that occurred during construction, the basement slabs were placed in advance after the initial excavation. The measurement results (building inclinometer, crack measurement system, structure inclinometer and surface settlement meter) at the site were reviewed to analyze the behavior of the temporary structure and surrounding ground. As a result, it was confirmed that the inclinometer of the building and the structural inclinometer showed a tendency that the displacement after the slab line was placed was reduced or converged. The placement of basement slabs during underground extension not only relived the noise and vibration problems during construction, but also secured the stability of structures.

• Journal of the Korean GEO-environmental Society
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• v.14 no.9
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• pp.5-12
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• 2013

In this study, each top-down load test and bi-directional load test has been performed on the 480mm diameter of two rock socketed drilled shafts, which are located next to each other, and the results have been compared. The result shows that the settlement from the equivalent load-settlement curve of bi-directional load test is smaller than one from top-down load test, because elastic is not considered in equivalent load-settlement curve of bi-directional load test. Therefore elastic shortening should be considered to obtain appropriate equivalent load-settlement curve. Three existing methods used to obtain equivalent load-settlement curve with consideration of elastic shortening has been compared with the result of top-down load test. The result shows that those existing methods are sufficiently applicable to the design. In addition, result of comparison between top-down load test and bi-directional load test shows that bi-directional load test was found to overestimate bearing capacity because it does not consider pile body failure.

• Geomechanics and Engineering
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• v.35 no.1
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• pp.29-39
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• 2023

As the intensity of urban underground space development increases, more and more tunnels are planned and constructed, and sometimes it is inevitable to encounter situations where tunnels have to underpass the river embankments. Most previous studies involved tunnels passing river embankments perpendicularly or with large intersection angle. In this study, a project case where two EPB shield tunnels with 8.82 m diameter run parallelly underneath a river embankment was reported. The parallel length is 380 m and tunnel were mainly buried in the moderate / slightly weathered clastic rock layer. The field monitoring result was presented and discussed. Three-dimensional back-analysis were then carried out to gain a better understanding the interaction mechanisms between shield tunnel and embankment and further to predict the ultimate settlement of embankment due to twin-tunnel excavation. Parametrical studies considering effect of tunnel face pressure, tail grouting pressure and volume loss were also conducted. The measured embankment settlement after the single tunnel excavation was 4.53 mm ~ 7.43 mm. Neither new crack on the pavement or cavity under the roadbed was observed. It is found that the more degree of weathering of the rock around the tunnel, the greater the embankment settlement and wider the settlement trough. Besides, the latter tunnel excavation might cause larger deformation than the former tunnel excavation if the mobilized plastic zone overlapped. With given geometry and stratigraphic condition in this study, the safety or serviceability of the river embankment would hardly be affected since the ultimate settlement of the embankment after the twin-tunnel excavation is within the allowable limit. Reasonable tunnel face pressure and tail grouting pressure can to some extent suppress the settlement of the embankment. The recommended tunnel face pressure and tail grouting pressure are 300 kPa and 550 kPa in this study, respectively. However, the volume loss plays the crucial role in the tunnel-embankment interaction. Controlling and compensating the tunneling induced volume loss is the most effective measure for river embankment protection. Additionally, reinforcing the embankment with cement mixing pile in advance is an alternative option in case the predicted settlement exceeds allowable limit.