The influence of the gas-to-liquid density ratio (DR) on the global wave shape before impact is studied through numerical simulations of the propagation of two different waves in a rectangular wave canal. Two different codes are used: the first one, named FSID, is a highly non-linear 2D bi-fluid potential code initially developed in the frame of SLOSHEL JIP (Kaminski et al. (2011)) to simulate incompressible inviscid free-surface flows without surface tension thanks to a desingularized technique and series of conformal mappings; the second one, named CADYF, is a bi-fluid high-fidelity front-tracking software developed by Ecole Polytechnique Montreal to simulate separated two-phase incompressible viscous flows with surface tension. The first studied wave leads to a flip-through impact while the second one leads to a large gas-pocket impact. Each condition is studied with water and three different gases with increasing densities corresponding to DR = 0.001, 0.003 and 0.005. The global wave shapes are compared a few tenths of second before the impact, before free surface instabilities triggered by the shearing gas flow have developed and also before any gas compressibility matters. Both codes give precisely the same global wave shapes. Whatever the condition studied, it is shown that DR has an influence on these global wave shapes. The trends observed from the simulations are the same as those described in Karimi et al. (2016) obtained from sloshing model tests with Single Impact Waves (SIW) in a 2D tank with a low filling level. A small part of the mechanical energy of the liquid is progressively given to the gas. The larger the DR, the larger this transfer of energy from the liquid to the gas. This explains an increasing delay of the wave front for increasing DRs.
通过对两种不同波在矩形波槽内传播的数值模拟，研究了气液密度比(DR)对碰撞前整体波形的影响。使用了两种不同的代码:第一个代码名为FSID，是一个高度非线性的二维双流体势代码，最初在SLOSHEL JIP框架内开发(Kaminski et al.(2011))，用于模拟无表面张力的不可压缩无粘自由表面流动，这要归功于一种去量化技术和一系列保角映射;第二个软件名为CADYF，是由Ecole Polytechnique Montreal开发的双流体高保真前端跟踪软件，用于模拟具有表面张力的分离两相不可压缩粘性流动。第一个被研究的波导致一个翻转撞击，而第二个波导致一个大的气穴撞击。用水和三种不同密度的气体(DR = 0.001, 0.003和0.005)来研究每种条件。在撞击前的十分之一秒，在剪切气体流引发的自由表面不稳定性发展之前，以及在任何气体可压缩性发生之前，对全球波形进行比较。两种代码给出了完全相同的全局波形。无论研究的条件是什么，都表明DR对这些全局波形有影响。从模拟中观察到的趋势与Karimi等人(2016)在低填充水平的2D水箱中使用单冲击波(SIW)进行晃动模型试验所描述的趋势相同。液体的机械能的一小部分逐渐给了气体。DR越大，从液体到气体的能量转移就越大。这就解释了波前延迟随着dr的增加而增加。
{"title":"Numerical Study of Density Ratio Influence on Global Wave Shapes Before Impact","authors":"S. Étienne, Y. Scolan, L. Brosset","doi":"10.1115/OMAE2018-78624","DOIUrl":"https://doi.org/10.1115/OMAE2018-78624","url":null,"abstract":"The influence of the gas-to-liquid density ratio (DR) on the global wave shape before impact is studied through numerical simulations of the propagation of two different waves in a rectangular wave canal. Two different codes are used: the first one, named FSID, is a highly non-linear 2D bi-fluid potential code initially developed in the frame of SLOSHEL JIP (Kaminski et al. (2011)) to simulate incompressible inviscid free-surface flows without surface tension thanks to a desingularized technique and series of conformal mappings; the second one, named CADYF, is a bi-fluid high-fidelity front-tracking software developed by Ecole Polytechnique Montreal to simulate separated two-phase incompressible viscous flows with surface tension.\u0000 The first studied wave leads to a flip-through impact while the second one leads to a large gas-pocket impact. Each condition is studied with water and three different gases with increasing densities corresponding to DR = 0.001, 0.003 and 0.005. The global wave shapes are compared a few tenths of second before the impact, before free surface instabilities triggered by the shearing gas flow have developed and also before any gas compressibility matters. Both codes give precisely the same global wave shapes.\u0000 Whatever the condition studied, it is shown that DR has an influence on these global wave shapes. The trends observed from the simulations are the same as those described in Karimi et al. (2016) obtained from sloshing model tests with Single Impact Waves (SIW) in a 2D tank with a low filling level. A small part of the mechanical energy of the liquid is progressively given to the gas. The larger the DR, the larger this transfer of energy from the liquid to the gas. This explains an increasing delay of the wave front for increasing DRs.","PeriodicalId":106551,"journal":{"name":"Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126639581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Senthuran Ravinthrakumar, T. Kristiansen, Babak Ommani
Moonpool resonance is investigated in a two-dimensional setting in terms of regular, forced heave motions of a model with moonpool with different rectangular-shaped recess configurations. A recess is a reduced draft zone in the moonpool. Dedicated experiments were carried out. The model consisted of two boxes of 40 cm width each, with a distance of 20 cm between them. Recess configurations varying between 5 cm to 10 cm in length and 5 cm in height were tested. Different drafts were also tested. The free-surface elevation inside the moonpool was measured at eight locations. A large number of forcing periods, and five forcing amplitudes were tested. A time-domain Boundary Element Method (BEM) code based on linear potential flow theory was implemented to investigate the resonance periods, mode shapes as well as the moonpool response as predicted by (linear) potential flow theory. Dominant physical effects were discussed, in particular damping due to flow separation from the sharp corners of the moonpool inlet and recess. The effect of the recess on the piston-mode behavior is discussed. BEM simulations where the effect of flow separation is empirically modelled were also conducted. The non-dimensional moonpool response suggests strong viscous damping at piston-mode resonance. The viscous BEM simulations demonstrate improvement over inviscid BEM, although further improvement of the method is needed. The piston mode shapes are clearly different from the near flat free-surface elevation for a moonpool without recess, consistent with recently published theory.
{"title":"A 2D Experimental and Numerical Study of Moonpools With Recess","authors":"Senthuran Ravinthrakumar, T. Kristiansen, Babak Ommani","doi":"10.1115/OMAE2018-78326","DOIUrl":"https://doi.org/10.1115/OMAE2018-78326","url":null,"abstract":"Moonpool resonance is investigated in a two-dimensional setting in terms of regular, forced heave motions of a model with moonpool with different rectangular-shaped recess configurations. A recess is a reduced draft zone in the moonpool. Dedicated experiments were carried out. The model consisted of two boxes of 40 cm width each, with a distance of 20 cm between them. Recess configurations varying between 5 cm to 10 cm in length and 5 cm in height were tested. Different drafts were also tested. The free-surface elevation inside the moonpool was measured at eight locations.\u0000 A large number of forcing periods, and five forcing amplitudes were tested. A time-domain Boundary Element Method (BEM) code based on linear potential flow theory was implemented to investigate the resonance periods, mode shapes as well as the moonpool response as predicted by (linear) potential flow theory. Dominant physical effects were discussed, in particular damping due to flow separation from the sharp corners of the moonpool inlet and recess. The effect of the recess on the piston-mode behavior is discussed. BEM simulations where the effect of flow separation is empirically modelled were also conducted.\u0000 The non-dimensional moonpool response suggests strong viscous damping at piston-mode resonance. The viscous BEM simulations demonstrate improvement over inviscid BEM, although further improvement of the method is needed. The piston mode shapes are clearly different from the near flat free-surface elevation for a moonpool without recess, consistent with recently published theory.","PeriodicalId":106551,"journal":{"name":"Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115199069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yichen Jiang, Xiao-jie Zhao, Z. Zeng, T. Sun, Jiawen Li, Z. Zong
The prediction of roll motion of a ship section with bilge keels is particularly difficult because the flow separation and vortex shedding under the hull significantly affect the behavior of roll damping. To predict the roll damping and roll motion directly, the numerical models must simulate the fluid viscosity. Recently, Reynolds-averaged Navier–Stokes (RANS) method and Discrete Vortex Method (DVM) have been applied in this area and show promising results. In this paper, we will use both methods to simulate the free roll-decay motion of a ship section with bilge keels. The numerical predictions of the roll time histories will be compared with experimental measurements. Besides, the numerically-predicted vorticity distributions at different time instants near a bilge keel will be shown and compared. Moreover, the computation times for both numerical methods will also be reported. In this work, we will conduct the comparison for a number of cases that are with different bilge-keel heights and bilge-keel installation angles. Thus, the accuracies and the computational efficiencies will be evaluated comprehensively.
{"title":"Comparison of RANS Method and Discrete Vortex Method on Simulating the Roll Motion of a Ship With Bilge Keels","authors":"Yichen Jiang, Xiao-jie Zhao, Z. Zeng, T. Sun, Jiawen Li, Z. Zong","doi":"10.1115/OMAE2018-78474","DOIUrl":"https://doi.org/10.1115/OMAE2018-78474","url":null,"abstract":"The prediction of roll motion of a ship section with bilge keels is particularly difficult because the flow separation and vortex shedding under the hull significantly affect the behavior of roll damping. To predict the roll damping and roll motion directly, the numerical models must simulate the fluid viscosity. Recently, Reynolds-averaged Navier–Stokes (RANS) method and Discrete Vortex Method (DVM) have been applied in this area and show promising results. In this paper, we will use both methods to simulate the free roll-decay motion of a ship section with bilge keels. The numerical predictions of the roll time histories will be compared with experimental measurements. Besides, the numerically-predicted vorticity distributions at different time instants near a bilge keel will be shown and compared. Moreover, the computation times for both numerical methods will also be reported. In this work, we will conduct the comparison for a number of cases that are with different bilge-keel heights and bilge-keel installation angles. Thus, the accuracies and the computational efficiencies will be evaluated comprehensively.","PeriodicalId":106551,"journal":{"name":"Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132408716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
All modern drillships are equipped with moonpools, through which drilling and other subsea operations are performed. The operability of the vessel, is the percentage of time that the vessel can perform a specific operation in a specific location not limited by environmental conditions. Specific operations such as lowering a BOP or X-tree through the splash zone, have strict operability criteria and often a drillship is waiting on weather to perform these operations. In this paper, the underwater shape of the moonpool of a drillship is varied and the operability of the vessel is calculated and compared to the original shape. Ten moonpool configurations are used for the study. The GustoMSC “Galene” moonpool shape is used which is comprised of an upper and a lower chamber. The lower chamber or cutout step dimensions such as length, breadth and height are the variables for this study. An analytical method originally proposed by Newman [1] and extended by Chalkias and Krijger [2] is used in this optimization study. The method is comprised of a potential flow radiation/diffraction solver, where the moonpool modes are accounted as additional separate generalized modes. In this way each mode can be damped separately. In order to calculate the damping factors for the moonpool modes used in the potential flow solver, free decay CFD calculations are performed and a P-Q analysis is applied on the resulting time-traces. Additional regular wave CFD calculations are performed for method validation purposes. The efficiency and ease of the proposed method is demonstrated by calculating the responses and operability of multiple shape variations in the frequency domain.
{"title":"Effect of Moonpool Shape and Dimensions on Drillship Operability","authors":"D. Chalkias, J. Krijger","doi":"10.1115/OMAE2018-77499","DOIUrl":"https://doi.org/10.1115/OMAE2018-77499","url":null,"abstract":"All modern drillships are equipped with moonpools, through which drilling and other subsea operations are performed. The operability of the vessel, is the percentage of time that the vessel can perform a specific operation in a specific location not limited by environmental conditions. Specific operations such as lowering a BOP or X-tree through the splash zone, have strict operability criteria and often a drillship is waiting on weather to perform these operations.\u0000 In this paper, the underwater shape of the moonpool of a drillship is varied and the operability of the vessel is calculated and compared to the original shape. Ten moonpool configurations are used for the study. The GustoMSC “Galene” moonpool shape is used which is comprised of an upper and a lower chamber. The lower chamber or cutout step dimensions such as length, breadth and height are the variables for this study.\u0000 An analytical method originally proposed by Newman [1] and extended by Chalkias and Krijger [2] is used in this optimization study. The method is comprised of a potential flow radiation/diffraction solver, where the moonpool modes are accounted as additional separate generalized modes. In this way each mode can be damped separately.\u0000 In order to calculate the damping factors for the moonpool modes used in the potential flow solver, free decay CFD calculations are performed and a P-Q analysis is applied on the resulting time-traces. Additional regular wave CFD calculations are performed for method validation purposes. The efficiency and ease of the proposed method is demonstrated by calculating the responses and operability of multiple shape variations in the frequency domain.","PeriodicalId":106551,"journal":{"name":"Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128606884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A floating two-dimensional ice plate with a crack on its lower surface is considered. Deflection of the plate is caused by an external impulsive load. The ice floe dynamics is described by thin compound elastic plate equation. Two parts of the plate are of constant thickness and are connected by a torsional spring which models the crack effect on the elastic deflection of the plate. The stiffness of the equivalent torsional spring is given as a function of the plate parameters and the crack length. Both the motions of the ice plate and the stresses near the crack tip are determined without account for gravity and surface tension effects. In the symmetric problem, the crack is always perpendicular to the plate surface. The growth of the crack is governed by the condition of the crack equilibrium at each time instant. The conditions of the impact, the magnitude of the impact force and its duration, which lead to the crack growth are studied within the water impact theory.
{"title":"Impact on an Ice Floe With a Surface Crack","authors":"A. Korobkin, T. Khabakhpasheva","doi":"10.1115/OMAE2018-78273","DOIUrl":"https://doi.org/10.1115/OMAE2018-78273","url":null,"abstract":"A floating two-dimensional ice plate with a crack on its lower surface is considered. Deflection of the plate is caused by an external impulsive load. The ice floe dynamics is described by thin compound elastic plate equation. Two parts of the plate are of constant thickness and are connected by a torsional spring which models the crack effect on the elastic deflection of the plate. The stiffness of the equivalent torsional spring is given as a function of the plate parameters and the crack length. Both the motions of the ice plate and the stresses near the crack tip are determined without account for gravity and surface tension effects. In the symmetric problem, the crack is always perpendicular to the plate surface. The growth of the crack is governed by the condition of the crack equilibrium at each time instant. The conditions of the impact, the magnitude of the impact force and its duration, which lead to the crack growth are studied within the water impact theory.","PeriodicalId":106551,"journal":{"name":"Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130563506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Geißler, P. Cuéllar, G. Hüsken, H. Kühne, M. Baessler
The authors are currently investigating the possibility to apply compaction grouting for offshore pile foundations (Jacket piles as well as monopiles) as a possible retrofitting technique for an optimised foundation concept. In this research project, we are developing a design approach aiming to predict the ideal amount and properties of a grout for a specific soil situation and desired improvement of pile bearing capacity after installation and during service time. Both numerical and experimental tests have been carried out to investigate the injection process during which a highly viscous grout is injected into the soil under high pressure to displace and compact the surrounding soil without fracturing it. The implicit Material Point Method (MPM) based on a mixed formulation is the numerical technique chosen to deal with the expected large deformations and the arbitrary shape of the developing grout bulb. The usage of MPM prevents both the need of remeshing and the numerical instability induced by extensive mesh distortion. For validation with experimental results, we have constructed a testing chamber with one transparent sidewall. This chamber enables us to observe the injection process directly at the transparent vertical window and to measure the in-plane soil displacements and strains by means of the Digital Image Correlation (DIC) technique. The results already reveal the interrelation of soil and grout properties for a successful usage of this common ground improvement technique.
{"title":"Insights Into Compaction Grouting for Offshore Pile Foundations","authors":"P. Geißler, P. Cuéllar, G. Hüsken, H. Kühne, M. Baessler","doi":"10.1115/OMAE2018-77277","DOIUrl":"https://doi.org/10.1115/OMAE2018-77277","url":null,"abstract":"The authors are currently investigating the possibility to apply compaction grouting for offshore pile foundations (Jacket piles as well as monopiles) as a possible retrofitting technique for an optimised foundation concept. In this research project, we are developing a design approach aiming to predict the ideal amount and properties of a grout for a specific soil situation and desired improvement of pile bearing capacity after installation and during service time. Both numerical and experimental tests have been carried out to investigate the injection process during which a highly viscous grout is injected into the soil under high pressure to displace and compact the surrounding soil without fracturing it. The implicit Material Point Method (MPM) based on a mixed formulation is the numerical technique chosen to deal with the expected large deformations and the arbitrary shape of the developing grout bulb. The usage of MPM prevents both the need of remeshing and the numerical instability induced by extensive mesh distortion. For validation with experimental results, we have constructed a testing chamber with one transparent sidewall. This chamber enables us to observe the injection process directly at the transparent vertical window and to measure the in-plane soil displacements and strains by means of the Digital Image Correlation (DIC) technique.\u0000 The results already reveal the interrelation of soil and grout properties for a successful usage of this common ground improvement technique.","PeriodicalId":106551,"journal":{"name":"Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130957819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gravity-based offshore foundations generally consist of a bottom slab and one or more cylindrical shafts on top of it. The geometry of the structure can strongly affect the flow pattern, dynamic wave pressure and further soil response and the liquefaction risk in the vicinity of the foundation. In this work, gravity-based foundations with bottom slabs of cylindrical shape and hexagonal prismatic shape are investigated. An integrated wave-structure-seabed interaction model applied in this work is developed in Open-FOAM, incorporating a nonlinear wave solver, a linear elastic structure solver and an anisotropic Biot’s poroelastic soil solver consisting of consolidation and liquefaction modules. Soil consolidation behavior in the presence of the foundations is investigated. It is found that the corners of the hexagonal foundation cause stress concentration in the soil. Therefore the initial effective stress around the hexagon corners is relatively high. Then, fully nonlinear waves modelled by fifth-order stream functions are simulated. Wave-induced pressure distributions and momentary liquefaction depths around the foundations are predicted.
{"title":"Numerical Analysis of Steep Wave-Induced Seabed Response and Liquefaction Around Gravity-Based Offshore Foundations","authors":"Yuzhu Li, M. Ong, O. Gudmestad, B. Hjertager","doi":"10.1115/OMAE2018-77046","DOIUrl":"https://doi.org/10.1115/OMAE2018-77046","url":null,"abstract":"Gravity-based offshore foundations generally consist of a bottom slab and one or more cylindrical shafts on top of it. The geometry of the structure can strongly affect the flow pattern, dynamic wave pressure and further soil response and the liquefaction risk in the vicinity of the foundation. In this work, gravity-based foundations with bottom slabs of cylindrical shape and hexagonal prismatic shape are investigated. An integrated wave-structure-seabed interaction model applied in this work is developed in Open-FOAM, incorporating a nonlinear wave solver, a linear elastic structure solver and an anisotropic Biot’s poroelastic soil solver consisting of consolidation and liquefaction modules.\u0000 Soil consolidation behavior in the presence of the foundations is investigated. It is found that the corners of the hexagonal foundation cause stress concentration in the soil. Therefore the initial effective stress around the hexagon corners is relatively high. Then, fully nonlinear waves modelled by fifth-order stream functions are simulated. Wave-induced pressure distributions and momentary liquefaction depths around the foundations are predicted.","PeriodicalId":106551,"journal":{"name":"Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131244593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Š. Malenica, Byunghee Lee, N. Vladimir, I. Gatin, C. Monroy, J. D. Lauzon
Green water loading which occurs during the floating body operations in heavy weathers can be very dangerous for the structural integrity of the superstructures and the equipment’s located at the upper decks. The correct modeling of the green water loading and the corresponding structural response is far from trivial and many different physical aspects need to be taken into account at the same time. Depending on the type of the floating body, the overall procedure involves the use of the different numerical tools at different steps. For off-shore type structures the procedure is slightly more complicated than for ships because, in addition to the classical seakeeping simulations, the mooring software also needs to be used. In all cases the final design conditions should be modeled using the complex hydro-structure interaction tools. In the present work the overall methodology is demonstrated and applied to the case of the evaluation of the structural response of the breakwater on the Ultra Large Container Ship (ULCS).
{"title":"Green Water Assessment for Marine and Offshore Applications: Structural Response of the ULCS Breakwater","authors":"Š. Malenica, Byunghee Lee, N. Vladimir, I. Gatin, C. Monroy, J. D. Lauzon","doi":"10.1115/OMAE2018-78432","DOIUrl":"https://doi.org/10.1115/OMAE2018-78432","url":null,"abstract":"Green water loading which occurs during the floating body operations in heavy weathers can be very dangerous for the structural integrity of the superstructures and the equipment’s located at the upper decks. The correct modeling of the green water loading and the corresponding structural response is far from trivial and many different physical aspects need to be taken into account at the same time. Depending on the type of the floating body, the overall procedure involves the use of the different numerical tools at different steps. For off-shore type structures the procedure is slightly more complicated than for ships because, in addition to the classical seakeeping simulations, the mooring software also needs to be used. In all cases the final design conditions should be modeled using the complex hydro-structure interaction tools.\u0000 In the present work the overall methodology is demonstrated and applied to the case of the evaluation of the structural response of the breakwater on the Ultra Large Container Ship (ULCS).","PeriodicalId":106551,"journal":{"name":"Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121216535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Young-ho Hong, Daesung Lim, Doowon Seo, J. Jeon, Kwangseok Chae, Jong-Sub Lee
For the most proper solution of annual increase of solid and other waste treatment in the limited landfill site, the global leading countries develop and keep expanding operation of the offshore waste landfill sites. In this report, we examined the most proper mix ratio of the water cut-off materials for the prevention and enforcement of the performance of the existing cut-off wall inter-connection parts of the offshore waste landfill site, which might be deteriorated by the external force inherent in the sea area. For acquiring the most proper mixed ratios in back-up water cut-off materials, we examined and evaluated the physical characteristics of the applied back-up water cut-off materials — on-site marine clay materials, which might be possible to be acquired near to site, admixtures and bentonite. Also, we applied those back-up water cut-off materials into the new concept applied to the vertical cut-off wall connection parts and investigated variation of the water cut-off performances throughout the changes of the permeability coefficient before and after deformation of the inter-connection joints of the vertical cut-off walls. For the investigation of the permeability performances, we carried out half sized mock-up tests in the laboratory and checked the variation of permeability coefficients referred to the changes in the applying location of back-up water cut-off materials and finally reach to application of back-up water cut-off materials as a proper solution of water cut-off performances in the inter-connection parts of the vertical cut-off wall at offshore waste landfill site.
{"title":"Experimental Study of Water Cutoff Performance of Steel Pipe Sheet Piles With Interlocked Joint","authors":"Young-ho Hong, Daesung Lim, Doowon Seo, J. Jeon, Kwangseok Chae, Jong-Sub Lee","doi":"10.1115/OMAE2018-78124","DOIUrl":"https://doi.org/10.1115/OMAE2018-78124","url":null,"abstract":"For the most proper solution of annual increase of solid and other waste treatment in the limited landfill site, the global leading countries develop and keep expanding operation of the offshore waste landfill sites. In this report, we examined the most proper mix ratio of the water cut-off materials for the prevention and enforcement of the performance of the existing cut-off wall inter-connection parts of the offshore waste landfill site, which might be deteriorated by the external force inherent in the sea area. For acquiring the most proper mixed ratios in back-up water cut-off materials, we examined and evaluated the physical characteristics of the applied back-up water cut-off materials — on-site marine clay materials, which might be possible to be acquired near to site, admixtures and bentonite. Also, we applied those back-up water cut-off materials into the new concept applied to the vertical cut-off wall connection parts and investigated variation of the water cut-off performances throughout the changes of the permeability coefficient before and after deformation of the inter-connection joints of the vertical cut-off walls. For the investigation of the permeability performances, we carried out half sized mock-up tests in the laboratory and checked the variation of permeability coefficients referred to the changes in the applying location of back-up water cut-off materials and finally reach to application of back-up water cut-off materials as a proper solution of water cut-off performances in the inter-connection parts of the vertical cut-off wall at offshore waste landfill site.","PeriodicalId":106551,"journal":{"name":"Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics","volume":"62 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113986306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effect of the mobile jack-up spudcan penetration and extraction on adjacent platform piles is an important issue in ocean engineering. Residual moments along piles will exist due to strata plastic deformation after spudcan extraction. If the residual response is large, the combination of the residual load and extreme environmental load may become the controlling load case for the piled structure. In order to understand the variation of the pile responses during spudcan penetration and after extraction, adjacent pile responses are calculated using the Coupled Eulerian Lagrangian (CEL) finite element method. Two kinds of typical seabed, clay and fine sand, are considered during calculation. The effects of the spudcan penetration depth, the spudcan-pile clearance, the shear strength of strata and the pile head constraint on adjacent pile responses are analyzed during spudcan penetration and after extraction. Calculated results show that residual responses of adjacent piles depend on the penetration depth, the clearance, the shear strength and the pile head constraint. The residual response of piles in soft clays is different from that in sands. For piles in soft clays, the residual response of adjacent piles will increase with decrease of the shear strength and the maximum residual pile shaft moment is larger than that during spudcan penetration. For piles in sands, the maximum residual pile shaft moment is about 70–80% of that during spudcan penetration. Therefore, the residual response of piles should be considered when the effect of spudcan penetration on adjacent platform piles is evaluated.
{"title":"Numerical Simulation on Residual Responses of Adjacent Piles After Spudcan Penetration and Extraction","authors":"Jianhua Wang, Yifei Fan, Haibo Ji","doi":"10.1115/OMAE2018-77788","DOIUrl":"https://doi.org/10.1115/OMAE2018-77788","url":null,"abstract":"The effect of the mobile jack-up spudcan penetration and extraction on adjacent platform piles is an important issue in ocean engineering. Residual moments along piles will exist due to strata plastic deformation after spudcan extraction. If the residual response is large, the combination of the residual load and extreme environmental load may become the controlling load case for the piled structure. In order to understand the variation of the pile responses during spudcan penetration and after extraction, adjacent pile responses are calculated using the Coupled Eulerian Lagrangian (CEL) finite element method. Two kinds of typical seabed, clay and fine sand, are considered during calculation. The effects of the spudcan penetration depth, the spudcan-pile clearance, the shear strength of strata and the pile head constraint on adjacent pile responses are analyzed during spudcan penetration and after extraction. Calculated results show that residual responses of adjacent piles depend on the penetration depth, the clearance, the shear strength and the pile head constraint. The residual response of piles in soft clays is different from that in sands. For piles in soft clays, the residual response of adjacent piles will increase with decrease of the shear strength and the maximum residual pile shaft moment is larger than that during spudcan penetration. For piles in sands, the maximum residual pile shaft moment is about 70–80% of that during spudcan penetration. Therefore, the residual response of piles should be considered when the effect of spudcan penetration on adjacent platform piles is evaluated.","PeriodicalId":106551,"journal":{"name":"Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics","volume":"212 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134302314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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