• Structural Engineering and Mechanics
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• v.57 no.3
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• pp.403-423
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• 2016

The challenges involved with fatigue damage assessment of steel catenary riser (SCR) in the touchdown zone (TDZ) are primarily due to the non-linear behaviour of the SCR-seabed interaction, considerable uncertainty in SCR-seabed interaction modelling and geotechnical parameters. The issue of fatigue damage induced by the cyclic movements of the SCR with the seabed has acquired prominence with the touch down point (TDP) interaction in the TDZ. Therefore, the SCR-seabed response is critical for reliable estimation of fatigue life in the TDZ. Various design approaches pertaining to the lateral pipe-soil resistance model are discussed. These techniques have been applied in the finite element model that can be used to analyse the lateral SCR-seabed interaction under hydrodynamic loading. This study investigates the sensitivity of fatigue performance to geotechnical parameters through a parametric study. In this study, global analyses are performed to assess the influence of vertical linear seabed springs, the lateral seabed model and the non-linear seabed model, including trench evolution into seabed, seabed normalised stiffness, re-penetration offset parameter and soil suction resistance ratio, on the fatigue life of SCRs in the TDZ.

• Geotechnical Engineering
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• v.10 no.1
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• pp.83-102
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• 1994

Design practice of the preloading method, which is one of the most used ground improvement methods, includes quite complicated problems, especially when the draining facilities such as rand drain piles are to be considered. But, such complicated problems can be easily handled once an expert system is developed. The expert system is an interactive computer program which has just succeeded in commercial application. It is a new field of CAE(computer aided engineering), which has developed on application of geotechnical problems in recent years In this study, the expert system which gives practical assistance to engineers is developed by building the knowledge base for the preloading method with vertical drains. In this study, an expert system is built by using CLIPS as a development tool. And the expert system is developed under the workstation environment using UNIX OS.

• The Journal of Engineering Geology
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• v.10 no.2
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• pp.113-133
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• 2000

The role of site investigation for adequate design of civil structure begins from siting to comment on design and providing other available geotechnical data. As the scope of human's life is wider than before, civil works have become conducted at sites of worse geological condition. So, it is necessary to have more adequate comprehension on the geological condition than ever in order to solve complicated geotechnical problems. In this paper, four fault related cases are introduced. Usually faults are the most influential geological structures on civil works. And the analyses with adequate countermeasures to each case are summarized.

• The Journal of Engineering Geology
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• v.24 no.4
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• pp.455-461
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• 2014

The Honam-Jeju, Korea-Japan, and Korea-China subsea tunnel construction projects have drawn significant attention since the early 2000s. These subsea tunnels are much deeper than most existing natural shallow sea tunnels linking coastal areas. Thus, the need for developing new technologies for the site selection and construction of deep subsea tunnels has recently emerged, with the launch of a research project titled "Development of Key Subsea Tunnelling Technology" in 2013. A component of this research, an analysis of deep subsea geological structure, is currently underway. A ground investigation, such as a borehole or geophysical investigation, is generally carried out for tunnel design. However, when investigating a potential site for a deep subsea tunnel, borehole drilling requires equipment at the scale of offshore oil drilling. The huge cost of such an undertaking has raised the urgent need for methods to indirectly assess the local geological structure as much as possible to limit the need for repeated borehole investigations. This study introduces an indirect approach for assessing the geological structure of the seafloor through a submarine bathymetry analysis. The ultimate goal here is to develop an automated approach to the analysis of submarine geological structures, which may prove useful in the selection of future deep subsea tunnel sites.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.475-483
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• 2008

It is necessary to develop a national design method for surface reinforcement of very soft ground because most current design works rely on crude empirical correlations. In this paper, the mechanical behavior of very soft ground that is surficially reinforced was investigated with the aid of a sents of numerical analysis. Several material properties of each dredged soft ground, reinforcement and backfill sand mat have been exercised the numerical analysis in order to compare the result of numerical analysis with those of the laboratory model test. Through the matching process between the numerical and experimental result, it is possible to find the appropriate material properties of the dredged soft ground, reinforcements and backfill sand mat. These verified material properties permit to show the effect of the stiffness of reinforcement and the thickness of sand mat on the overall deformation.

• Geomechanics and Engineering
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• v.17 no.3
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• pp.271-278
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• 2019

In recent years, the crack accidents of earth and rockfill dams occur frequently. It is urgent to study the tensile strength and tensile failure mechanism of the gravelly soil in the core for the anti-crack design of the actual high earth core rockfill dam. Based on the self-developed uniaxial tensile test device, a series of uniaxial tensile test was carried out on gravelly soil with different gravel content. The compaction test shows a good linear relationship between the optimum water content and gravel content, and the relation curve of optimum water content versus maximum dry density can be fitting by two times polynomial. For the gravelly soil under its optimum water content and maximum dry density, as the gravel content increased from 0% to 50%, the tensile strength of specimens decreased from 122.6 kPa to 49.8 kPa linearly. The peak tensile strain and ultimate tensile strain all decrease with the increase of the gravel content. From the analysis of fracture energy, it is proved that the tensile capacity of gravelly soil decreases slightly with the increasing gravel content. In the case that the sample under the maximum dry density and the water content higher than the optimum water content, the comprehensive tensile capacity of the sample is the strongest. The relevant test results can provide support for the anti-crack design of the high earth core rockfill dam.

• Journal of the Korean GEO-environmental Society
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• v.23 no.7
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• pp.11-20
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• 2022

Planetary geotechnical investigation in charge of drilling and soil sampling is of a great importance in providing extraterrestrial geotechnical information. Extraterrestrial subsurface investigation, which includes drilling, soil sampling, and sample transportation, will be loaded in a lander or a rover. Scientists from all over the world are interested in the design and development of a drilling system with various functions due to potential applications in planetary surface exploration mission. However, it is difficult to build a fully functional drilling system in extreme environment conditions. This paper presents engineering considerations for the design and development of soil sampling including drilling and performance verification in extreme environment conditions in detail.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.10a
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• pp.333-340
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• 1997

• Proceedings of the Korean Geotechical Society Conference
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• 1998.10a
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• pp.405-414
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• 1998

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.351-362
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• 2007

Predicted behaviour of a soft clay deposit in design stage is sometimes different from in-situ settlement and pore pressure measured during and after construction. In this paper, characteristics of settlement and pore pressure occurred in soft soil deposits were investigated briefly in order to get a better understanding of time-dependent viscoplastic behaviour and prevent geotechnical problems resulted from long-term settlement, differential settlement, etc.