• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.2
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• pp.317-325
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• 2019

A suction caisson has been widely used for anchor and foundation of offshore structures due to its broad application, simple installation, and rapid construction. In design of suction caisson foundation, the bearing capacity and the stability of soil are mainly dealt with and analysis methods for them are presented in design codes related to the foundation. On the other hand, the method for structural safety analysis of the suction caisson is not generalized, in particular for load modeling of the caisson under suction. Consequently, there are difficulties in design of the caisson cross section. For this reason, this study analyzed the magnitude and distribution of pore water pressure on inner and outer surface of the caisson using theoretical and numerical seepage analyse, and an approach to reasonably estimate the load applied to the structural analysis of the caisson was presented. Furthermore, effects of penetration depth, anisotropy of permeability, and suction pressure on the pore water pressure were analyzed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.3
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• pp.182-189
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• 2015

The Embedded Suction Anchor (ESA) is a type of permanent offshore foundation that is installed by a suction pile. To increase the loading capacity against pullout, three wings (vertical flanges) are attached along the circumference at 120 degrees apart. Analytical parametric study using the proposed analytical solution method has been conducted to identify the effects of several parameters that are thought to influence the behavior of ESAs. The analysis results show that the pullout capacity increases as the anchor depth and the soil strength increase, and decreases as the load inclination angle increases. The anchor having square projectional area and being pulled horizontally at the middle of its length provides the highest pullout capacity.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.167-173
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• 2014

The embedded suction anchor, ESA, is one type of mooring anchor systems which utilizes the suction pile or caisson to penetrate the anchor into the sea bed and develops its capacity under pullout load. In this study, the numerical analysis using ALE (Arbitrary Lagrangian Eulerian) Adaptive Meshing technique was performed to simulate the pullout behavior of the ESA, and the results were compared to those of the previous research, centrifuge model tests and the analytical method based on limit equilibrium theory. The pullout behaviors of the ESA under horizontal, vertical, and inclined loading were evaluated. The analysis results showed that the maximum horizontal pullout load was developed when the location of loading point was at the mid-point, and the each vertical pullout load gave the similar value regardless of the locations of the loading points. The pullout load decreased as the load inclination angle increased at the mid-point of the anchor.

• Geotechnical Engineering
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• v.23 no.12
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• pp.45-53
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• 2007

• Journal of the Korean GEO-environmental Society
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• v.15 no.6
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• pp.75-83
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• 2014

Suction bucket foundation is installed with the differential pressure created by pumping water out of bucket. Bucket foundation has usually been utilized in mooring anchor for offshore platform or floating oil and gas production facilities in the open sea. After suction bucket foundation successfully was applied as the foundation for offshore wind turbines in Europe, it recently attracts much attention in Korea, too. To estimate the penetration resistance of the suction bucket foundation is one of the important matters that should be considered during its installation. This study carried out a series of model tests to investigate the penetration resistance of suction bucket foundation. And the mobilized soil strength factor was reviewed through comparing the experimental results by two installation ways (e.g., push-in-load and suction) and the results calculated by the conventional equation.

• Journal of the Korean Geotechnical Society
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• v.30 no.10
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• pp.33-44
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• 2014

The preliminary design of suction pile as the supporting system for concrete floating structures was performed for the pilot project of the southwest coast area in Korea. Prior to starting design work, site conditions of the area including ground and hydraulic conditions, and a 100-year return period external force were throughly evaluated. The suction pile for mooring of the offshore floating structures has to satisfy the lateral resistance against external force as well as the penetration ability according to the soil conditions such as soil types, shear strengths, effective stresses, and seepage forces. In the design, the required penetration depths, which were stable for lateral resistance, were evaluated with the diameters of cylindrical suction pile as the final installing ones. And the design suction pressures at each penetrating depths, at which sand boiling did not occur, were assessed through the comparison of penetration and penetrationresistance forces. As a result, it was impossible for suction piles with the diameter range of 3.0~5.0 m to penetrate into required penetration depths. On the other hand, suction piles with the diameter range of 6.0 m and 7.0 m satisfied both the horizontal stability and the penetration ability by design suction pressures at the required penetration depths of 8.5 m and 8.0 m, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2648-2654
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• 2012

This study aims to examine the effects of massages using various tools being frequently applied in skin care centers. It suggests the most effective method based on the comparative analysis on the body heat changes before and after the massages and also provides foundational data to develop back treatment programs. This research conducted manual, ultrasonic device, and also suction massages from July 3rd till 10th, 2011 to women at the age of 35 to 45 living in Gwangju, Jeonnam. And five of them were arranged for each tool. The body heat changes before the massages and after the 20-minute massages were measured with the body heat diagnostic device of thermograph DITI IRIS-XP. The collected data went through the t-test using SPSS 18.0. According to the result, the body temperature increased significantly before and after the manual massage from $30.82{\pm}0.52$ to $35.06{\pm}0.36$ (p<.001). The body temperature also increased significantly before and after the ultrasonic massage from $30.66{\pm}0.53$ to $35.14{\pm}0.39$ (p<.001). And the body temperature increased significantly before and after the suction massage from $30.93{\pm}0.47$ to $39.25{\pm}0.19$ (p<.001). The hand, ultrasonic device, and also suction were all effective as massage tools in terms of increasing body temperature, and the suction massage was shown to have the greatest effect in body temperature increase. Thus, the suction was analyzed as the most effective tool to be used to develop back treatment programs.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.2
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• pp.161-168
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• 2018

This paper presents the design procedure of the suction bucket used to support a subsea manifold. The soil-suction bucket interaction numerical analysis technique was verified by comparing the present results with a reference data. In order to simulate the soil-bucket interaction analyses of a subsea manifold structure, various material data such as undrained shear strength, elastic modulus, and poisson ratio of soft clay in Gulf of Mexico were collected from reference survey. We proposed vertical and horizontal design loads based on system weights and current-induced drag forces. Under the assumption that diameter of the suction bucket was 3.0 m considering real dimension of the subsea manifold frame structures, aspect ratio was decided to be 3.0 based on reference survey. The ultimate bearing load components were determined using tangent intersection method. It was proved that the two design load components were less than ultimate bearing loads.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.1
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• pp.31-36
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• 2022

This paper presents the measuring process of dynamic properties of offshore wind power foundation and provides consideration of each step. This Guideline enables to maintain consistent measuring procedure and therefore increase the reliability of test results. Small scaled suction bucket foundation was fabricated to represent the commercial support structure installation mechanism and two cases(free-free, free-fixed) of dynamic tests were performed at workshop. From the tests, the importance of dynamic properties of connection part between suction bucket and tower was figured out. More over, types and configuration of measuring devices are recommended which can help find the natural frequency of wind turbine foundation correctly. In field test, it was found that the natural frequency of suction bucket foundation was increased linearly with the penetration depth due to the confining effect of ambient soil. Meanwhile, it was not easy to get an enough excitation force with normal impact hammer because the N.F of suction bucket model was in the lower range of 0 Hz ~ 5 Hz. Therefore, new excitation method which has enough force and can excite lower frequency range was devised. This study will help develop safety check procedure of suction bucket foundation in field at each installation stage using the N.F measurement.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.71-81
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• 2020

The large circular steel pipe for a marine bridge foundation has been developed as a construction method capable of performing the role of the working platform and cofferdam. The objective of this study is to demonstrate the wireless remote sensing system for monitoring the stability of the large circular steel pipe during construction and operation through field tests. The artificial seabed ground with an water level of 4 m is constructed for field tests. The large circular steel pipe with a diameter of 5 m and height of 9.5 m is installed into the ground by suction, and the embedded depth is 5 m. The inclinometer and strain gauges are installed on different surfaces of the upper module, and the tilt angle and stress are monitored throughout the entire construction process. As results, tilt angles are measured to be constant during the suction penetration. However, the tilt angle is larger in the x-axis direction. In addition, even when installed on different surfaces, the tilt angle in the same axial direction is measured to be almost the same. The stresses measured by strain gauges increase during suction penetration and decrease during pull-out. Based on measured stresses, it is found that the eccentricity is acting on the large circular steel pipe. This study shows that a wireless remote sensing system built with an inclinometer and strain gauge can be a useful tool for the stability monitoring of the large circular steel pipe.