• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.1
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• pp.1-10
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• 2011

Recently harbor remodeling projects are seriously considered to enhance the loading and unloading capability of old container terminals and to make decrepit ports as eco-friendly harbor and waterfront spaces in many countries. In such a case, quantitative and qualitative evaluations on concrete harbor facilities are mandatory to determine the current structural integrity condition of aged materials. Once the remodeling project is determined to be carried out, the reusability of individual structural members and facilities including caissons, cell-blocks, and tetra-pods need to be decided based on the simple and economic visual inspection and/or nondestructive testing. In this study, the systematic quantitative evaluation procedure for determining the structural integrity condition and the reusability is studied based the nondestructive testing and evaluation methods. Conventional methods including Schmidt hammer test and ultrasonicpulse velocity methods and elastic wave based methods including impact echo test and surface wave test are applied to the old harbor facilities in five different sites. The compressive tests are also carried out to determine the elastic modulus and compressive strength of concrete materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.372-378
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• 2016

A mound was constructed to install a caisson and sofa blocks underwater. The mound riprap, which were of uniform grade, size, shape, and specific gravity, formed the foundation for the support superstructure. Also, rubble leveling works were performed before installing structures such as caissons. In this study, underwater construction equipment was developed with a remotely controlled operating system and underwater environment monitoring system for unmanned underwater rubble leveling work. The performance of the developed equipment was verified using on-land and underwater tests. In addition to the performance verification, the construction process and economic efficiency of the equipment should be checked before applying it to the real construction field for commercial purposes. In this paper, a construction process using the developed equipment was proposed and compared with the existing rubble leveling method. The results demonstrated that the new construction method has higher economic efficiency and safety than the existing construction method.

• Journal of Ocean Engineering and Technology
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• v.27 no.6
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• pp.43-55
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• 2013

In general, huge caissons for breakwaters have been constructed on land or a floating dock. In the case of the construction on a floating dock, a 4 step installation procedure is involved: i) construction on a floating dock, ii) transportation by the floating dock to an area near the target sea, iii) launching from the floating dock, and iv) transference by tug-boats to the installation site. It is especially important to pay attention to the dynamic stability of the floating dock against the conditions in the sea during steps i) and iii). In this paper, the static and dynamic stabilities of a caisson on a floating dock are evaluated based on IMO rules during the construction and launching of the caisson on a floating dock by using independent commercial S/Ws such as NAPA, WAMIT, and CHARM3D.

• Journal of the Korean GEO-environmental Society
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• v.22 no.1
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• pp.5-12
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• 2021

Owing to economically efficient and easy installation, bucket foundation is a promising solution for offshore wind turbines. This paper aims at finding the behavior of suction caissons and soil surrounding the foundation by using three-dimensional finite element analysis. Under various loading conditions, a wide range of foundation geometries installed in dense and medium dense sandy soil was considered to evaluate ultimate horizontal load and overturning moment capacity. The results show that the rotation and displacement of the bucket due to monotonic loading are largely dependent on the foundation geometry, soil density and load eccentricity. Normalized diagrams and equations for the ultimate horizontal load and overturning moment capacities are presented that are useful tool for the preliminary design of such foundation type.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.2
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• pp.137-146
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• 2006

This is the second of a two-part paper which describes comparison of reliability design methods by application to Donghae Harbor Breakwaters. In this paper, Part 2, we deal with sliding of caissons. The failure modes of a vertical breakwater, which consists of a caisson mounted on a rubble mound, include the sliding and overturning of the caisson and the failure of the rubble mound or subsoil, among which most frequently occurs the sliding of the caisson. The traditional deterministic design method for sliding failure of a caisson uses the concept of a safety factor that the resistance should be greater than the load by a certain factor (e.g. 1.2). However, the safety of a structure cannot be quantitatively evaluated by the concept of a safety factor. On the other hand, the reliability design method, for which active research is being performed recently, enables one to quantitatively evaluate the safety of a structure by calculating the probability of failure of the structure. The reliability design method is classified into three categories depending on the level of probabilistic concepts being employed, i.e., Level 1, 2, and 3. In this study, we apply the reliability design methods to the sliding of the caisson of the breakwaters of Donghae Harbor, which was constructed by traditional deterministic design methods to be damaged in 1987. Analyses are made for the breakwaters before the damage and after reinforcement. The probability of failure before the damage is much higher than the allowable value, indicating that the breakwater was under-designed. The probability of failure after reinforcement, however, is close to the allowable value, indicating that the breakwater is no longer in danger. On the other hand, the results of the different reliability design methods are in fairly good agreement, confirming that there is not much difference among different methods.

• Geotechnical Engineering
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• v.12 no.3
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• pp.127-148
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• 1996

Recently, foundations of heavy structures such as bridge abutments have been built on slopes or near the crest of slopes at an increasing rate. Because the bearing capacity of such foundations is considerably lower than the bearing capacity of the same soil on a level ground, deep footings such as piles and caissons are often used. However, the costs of such methods are generally very high. One of the new techniques to overcome the problem is to place reinforcing members such as geosynthetics or metal strips horizontally at some depths beneath the footings. Rational methods of analysis to predict the bearing capacity of footings in reinforced slopes are therefore needed. This paper proposes an analytical method for estimating the increase in bearing capacity gained from the included horizontal strips or ties of tensile reinforcing in the foundation soil below the footing built near the crest of a slope. A failure mechanism, including the concept of'wide slab effect', adopted in the present study for analyzing the bearing capacity of foundations in reinforced slopes, is established through the observed model test behaviors described by Binquet SE Lee and Huang et al, and the Boussinesq solutions. The analytical results are then compared with the experimental data described in the paper by Huang et al. Also in order to properly evaluate the soil reinforcement interaction, typical pullout test values of the apparent friction coefficient, which usually vary with depths owing to both the increase of the shearing volume and the increase in local stress caused by soil dilatancy, are analyzed and related functionally. Furthermore, analytical parametric studies are carried out to investigate the effect and significance of various pertinent parameters associated with design of reinforced slope foundations. Keywords : Bearing capacity, Reinforced slope, Slab effect, Friction coefficient.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.6
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• pp.495-507
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• 2009

The expected sliding distance for the lifetime of a caisson breakwater has a limitation to be used as the stability criterion of the breakwater. Since the expected sliding distance is calculated as the mean of simulated sliding distances for the lifetime, there is possibility for the actual sliding distance to exceed the expected sliding distance. To overcome this problem, the exceedance probability of the allowable sliding distance is used to assess the stability of sliding. Latin Hypercube sampling and Crude Monte Carlo simulation were used to calculate the exceedance probability. The doubly-truncated normal distribution was considered to complement the physical disadvantage of the normal distribution as the random variable distribution. In the case of using the normal distribution, the cross-sections of Okgye, Hwasun, and Donghae NI before reinforcement were found to be unstable in all the limit states. On the other hand, when applying the doubly-truncated normal distribution, the cross-sections of Hwasun and Donghae NI before reinforcement were evaluated to be unstable in the repairable limit state and all the limit states, respectively. Finally, the shortcoming of the expected sliding distance as the stability criterion was investigated, and we reasonably assessed the stability of sliding of caissons by using the exceedance probability of allowable sliding distance for the caisson breakwaters in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.510-518
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• 2020

With the promotion of digitalization in the construction industry, BIM has become an indispensable technology. On the other hand, it has not been actively utilized in practice because of the difficulty of BIM modeling. The reason is that 3D modeling is less productive not only because of the difficulty of learning BIM software but also the modeling work is done manually. Therefore, this study proposes a method and system that can improve the productivity of BIM-based modeling. For this reason, in the study, a slit caisson, which is a typical structure of a port, was selected as a development target, and various parameters were derived through interviews with experts so that it could be used in practice. This study presents a UI construction plan that considers user convenience for efficient management and operation of diverse and complex parameters. Based on this, this study used visual programming and Excel VBA to develop a BIM-based design automation system for slit caissons. The developed system can use many parameters to quickly develop slit caisson models suitable for various design conditions that can contribute to BIM-based modeling and productivity improvement.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.4
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• pp.280-293
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• 2005

In this study, a model to calculate the expected total construction cost has been developed by combining a model to calculate the sliding distance of a caisson of a vertical breakwater and a model to calculate the rehabilitation cost of a caisson. The optimal cross-section of a caisson of a vertical breakwater is defined as the cross-section that requires a minimum expected total construction cost within the allowable limit of caisson sliding. Two allowable limits are considered: 0.1 m of the expected sliding distance during the lifetime of the breakwater and 0.1 of the probability that the cumulative sliding distance during the lifetime of the breakwater is greater than 0.3 m. A discount rate has also been introduced to convert the future rehabilitation cost to the present value. The introduction of the discount rate reduces the expected total construction cost for the caissons designed for shorter return periods due to frequent rehabilitations. The present design method requires a smaller cross-section than the conventional deterministic method in shallow water depths, enabling us to design a caisson more economically. On the other hand, the above-mentioned allowable limits of caisson sliding show similar results for smaller water depths, while, for larger depths, the former requires a larger cross-section than the latter.

• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.83-91
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• 2020

In this study, the characteristics of support behavior according to the change of ground condition of the cast-in-place pile and the large Caisson foundation, which are increasingly used as foundations of large structures and bridges. the allowable bearing capacity calculated using the yield load analysis method was analyzed to calculate similar allowable bearing capacity for each method. In addition, the allowable bearing capacity calculated by the ultimate load analysis method was found to have a large difference in bearing capacity for each method. Through this point, it can be usefully used as an empirical formula for evaluating the settlement characteristics of piles in future design and construction. In addition, as a result of examining the ground force distribution during sedimentation of large caissons, the section of the weathered rock layer showed almost constant ground force distribution as ground forces decreased after yield occurred at the base corner. And in the bed rock layer section, the foundation's center was transformed into a ground force in the form of a convex downward due to an increase in the ground resistance of the central part. Using these results, the theory previously presented by Fang (1991) and Kőgler (1936) was proved.