Journal of Waterway, Port, Coastal, and Ocean Engineering

This paper sheds light on the mechanism of post equilibrium sea bed scour around dynamically active marine structures such as wind turbines. Exposure of a fully developed scour hole (at equilibrium state) around a wind turbine mono-pile to the cyclic movement of the structure leads to the backfilling and deformation of the scour hole. The existing approaches to scour prediction for foundation design of offshore wind turbines generally consider wind turbines as static structures and ignore the physical impact of the cyclic movement of the pile on the supporting soil and, hence, on the scour process. Through an experimental program, this paper explains the influence of the cyclic movement of the pile on the local scour in noncohesive sediments. A series of flume tests at two scales were conducted. Simple hydrodynamic conditions and bed sediment configurations were adopted to highlight the effect of pile movement. The results obtained indicate that a mechanism exists by which the scour hole can be significantly deeper and wider in extent than that predicted by conventional methods. This arises through a multistage process consisting of periodically alternating cyclically loaded and unloaded stages simulating a sequence of storms.

Stability formulas for rock armor and Tetrapods were developed using multigene genetic programming, which is one of the machine learning methods. The developed formulas are shown to be more accurate than previous empirical formulas and neural network models. They are also compared against a few independent data that were not used in the development of the formulas. To give an idea of the confidence of the formulas, the equations for 90% prediction error band are presented. The formula for Tetrapods is somewhat less accurate than that for rock armor, probably because the experimental data for rock armor were produced by a single author, whereas those for Tetrapods were produced by several authors, so the data were inhomogeneous. The formula for rock armor includes the crest freeboard of the structure, which was not considered in previous studies, so it can be used for low-crested structures as well.

A laboratory experiment was conducted in a wave flume to compare sand beach profile evolution and wave overtopping of a sand berm for the three cases of (1) no structure, (2) a stone revetment protecting the steep sand berm, and (3) a stone sill reducing wave action on the berm. The revetment reduced onshore sand transport on the fronting beach but was effective in protecting the sand berm and reducing wave overtopping. The revetment crest was damaged during major wave overtopping. The sill reduced the beach profile change but was not very effective in reducing wave overtopping and berm erosion when the sill crest was submerged sufficiently. An existing numerical model (CSHORE) was upgraded for its application to the sill test where the emerged sill crest became submerged during the test. The upgraded model was compared with the measured wave transformation, wave overtopping, and overwash rates and beach profile evolution in the three tests consisting of 90 runs with each run lasting 400 s. The model was also used to predict the settlement of the revetment and sill for the case of no filter below the stone structure. The limited experiment and numerical modeling quantified the capability and limitations of the revetment and sill.

This paper presents the results of a centrifuge model test performed to study the behavior of a plumb-pile-supported wharf under yard-heaped loads. A bent composed of a slab, girders, and six rows of equally spaced plumb piles was chosen for the demonstration. The horizontal and vertical displacements of the bent, the earth pressures around the piles, and the bending moments of the piles were investigated. The failure mode and mechanics of the wharf under yard-heaped loads were analyzed. Test results indicate that the horizontal displacement of the bent was significantly larger than the vertical settlement, both of which rapidly increased after reaching a threshold load value. Maximum values of earth pressures occurred at distances of $2/3$ of the pile length from the pile cap in the middle and rear (landside) sections of the bent. The piles on the side facing the sea were in tension in the upper part and generally in compression in the middle and lower parts. The excessive yard-heaped loads caused a large integral translation of the slope, and thus piles were pushed by the surrounding soil and deformed, primarily leading to the tilting failure of the plumb-pile-supported wharf.

A mathematical model of the interaction of an oblique wave and rectangular submarine trench in an ice-covered ocean is given using linearized potential theory. The motion in the fluid is characterized by velocity potentials, which are expressed in terms of eigenfunctions. The continuity of the velocity potentials at the boundary of the trench produces a set of singular integral equations. These equations are solved using a multiterm Galerkin approach. A numerical study on the amplitude of reflection and transmission coefficients has been carried out to illustrate the influence of incidence angle, flexural rigidity of ice, and geometry of the trench. Known results in the absence of ice cover are covered as a special case.

Queueing theory has been used in port management since the early 60s as a support, among others, to determine the optimal number of berths based on the occupation rate of the berths and the expected waiting time for vessels operating in them. Depending on the type of terminal involved, different authors have provided solutions for various $E_k/E_k/n$ systems. While the equations characterizing some of these systems can be analytically resolved, and it is possible to calculate exact solutions for them, other systems are not resolvable, and only approximate solutions are presented in the form of graphs or tables. In the present work, a simple analytical methodological scheme is presented for one of these systems with approximate solutions ($M/D/n$) deduced from a system in which the exact analytical solutions exist ($M/M/n$). This new approach is proposed to be used in private container terminals without regular services and in bulk terminals in which quasi-constant size vessels arrive.

Efficient vessel scheduling through a channel can improve the operational efficiency of ports. Additionally, many large vessels with a deep draft have delays related to tidal cycles when passing through tidal channels. Therefore, it is of great practical significance to study the vessel scheduling problem through a channel for which the depth is affected by the tide. In this paper, a model and an algorithm to solve the vessel scheduling problem is presented. The vessels entering the tidal channel are ordered to ensure the shortest total waiting time. The model and algorithm are then verified using actual data from the Yangtze River estuary. The results show that the scheduling efficiency is higher than other strategies, including first come first served (FCFS), random scheduling, larger draft vessels priority scheduling, and manual scheduling. Additionally, the proposed model and algorithm can be modified slightly and used for vessel scheduling through other channels with tide-affected depth.

Researchers have underscored the importance for a pipeline to safeguard against adverse effects resulting from its displacement in the vertical, axial, and lateral directions because of the low shear strength of the soil. The seabed may sometimes consist of soft or very soft clay soil with high water content and low shear strength. Dissipation of the water content from the soil void increases its effective stress, with a resultant increase in the soil shear strength. The electrokinetic (EK) concept has been applied to increase soil bearing capacity with barely any study conducted on its possible application on pipe–soil interaction. The need to explore more options merits further research. The EK process for the pipe–soil interaction consists of two main stages: the electroosmotic consolidation process and dynamic analyses of the pipe–soil interaction. The present study numerically investigated the impact of EK-treated soil on pipe–soil interaction over the non-EK process. The results of dynamic pipe–soil interaction on EK-treated soil when compared with non–EK-treated soil indicate a significant increase in the force required to displace a pipeline.

This paper analyzes the modeling of the hydro- and morphodynamics of bichromatic wave groups on an intermediate beach with an initial $1:15$ slope. The nonhydrostatic version of XBeach was used to simulate two incident wave conditions of the experiments carried out within the HYDRALAB-IV Coupled High Frequency Measurement of Swash Sediment Transport and Morphodynamic (CoSSedM) project. The chosen forcing conditions have different strengths of swash–swash interaction. A procedure was developed to generate boundary conditions for the model that are able to fully account for both the bound and free long waves measured during the experiments. Using the normalized root-mean-squared error as a measure, this paper finds a higher accuracy of the nonhydrostatic version of XBeach in simulating swash–swash interaction from the hydrodynamics point of view, and worse performances in capturing the details of intragroup sediment transport. Nevertheless, the model is able to distinguish the relative difference in offshore swash sediment transport among different types of swash–swash interaction, and it is overall more successful in simulating beach morphodynamics when the swash sediment transport is of the same order of magnitude as the surf zone one.

The wave forces acting on a rigid cylinder are investigated in the presence of multiple outer porous cylindrical barriers by assuming the linear water wave theory. A Bessel series solution is obtained for the boundary value problem by using the methods of eigenfunction expansion and least-squares approximation. Two configurations of outer porous barriers are considered, namely bottom-standing and surface-piercing. As a special case, the effect of fully extended barriers is studied. The wave loads exerted on the cylinders, free surface elevations, and flow distribution around the structures are computed and analyzed for different physical parameters. The present theory is ratified with the result available in the literature for a single fully extended outer porous barrier. The study reveals that the hydrodynamic forces exerted on the inner impermeable cylinder are reduced significantly as the number of outer porous barriers is increased. Thus, multiple outer fully extended or partial porous barriers can be set up to protect the inner rigid cylinder.

Tsunamis, impulse waves, and dam-break waves are rare but catastrophic events, associated with casualties and damage to infrastructures. An adequate description of these waves is vital to assure human safety and to generate resilient structures. Furthermore, a specific building geometry with openings, such as windows and doors, reduces wave-induced loads and increases the probability that a building withstands. However, waves often carry a large volume of debris, generating supplementary impact forces and creating debris dams around buildings, limiting the beneficial effects of the openings. Herein, a preliminary study on the three-dimensional (3D) effect of debris dams on postpeak wave-induced loads under unsteady flow conditions is presented based on laboratory experiments. Both wooden logs (forest) and shipping containers were tested, showing different behaviors. Shipping containers were associated with severe impact force peaks, whereas the interlocking nature of forest-type debris provoked a compact debris dam, leading to higher and longer-lasting hydrodynamic forces. The arrangement of the debris also had an influence on the resulting structural loading. All tested scenarios were analyzed in terms of horizontal force, cantilever arm, and impulse acting on the building. This study presents a methodology to support the evaluation of postpeak debris-induced loads for the design of safer resilient buildings.

This paper reports results of the impact of a quayside floating system on overtopping. The approach is experimental and analytical. Rectangular floaters in heave motion were considered at various distances from a vertical wall. Floaters with different widths and heights were tested. The effect of the draft and the floater’s distance to the wall on overtopping quantification was considered in intermediate water conditions. First, overtopping evolution as a function of the wave period was found to be correlated with the floater behavior. The overtopping increased at the resonance period of the floater but decreased at larger periods. The experimental results were then compared with a linear analytical model based on potential flow theory, where the wave height at the seawall was given using the Van der Meer formula. An improvement of the analytical model was obtained by introducing a term corresponding to pressure losses between the floater and seawall. The experimental results are in good agreement with the corrected analytical model: the evolution is similar, with an averaged standard deviation of 1.2 for large wavelengths. The present results show that the wave period and distance of the floater to the vertical wall are significant parameters for overtopping. Overtopping is reduced by the presence of the quayside floater for small distances to the vertical wall and large wave periods when the floater follows waves.

This paper deals with the evolution of the engineered mouth of the Vistula River, Poland, influencing the growth of its delta. The considered delta is a coastal form typical for semiclosed nontidal seas, like the Baltic. The delta shape, close to symmetrical, results from the significant predominance of the riverine hydrodynamics and dynamics of sediment over the respective marine processes. Two versions of the model of a simplified geometry of the delta are presented, as well as the shoreline evolution model. The models are supplemented by the analysis of the sediment budget at the river mouth. The influence of the outlet breakwaters on long-term morphodynamics of the delta is taken into account. The multidecade forecast of delta development is carried out.

This paper presents the risk identification process, a checklist of 215 different risks, and an associated risk breakdown structure (RBS) for the design and construction phases for a shipping port and associated container terminal. The case study project scope for the research includes a 3,500-m breakwater, 80 ha of reclaimed land, a 1,000-m-long quay wall, port equipment, and buildings. The checklist is categorized according to the project work breakdown structure (WBS) and includes risks associated with (1) breakwater, (2) reclaimed land, (3) entrance canal and basin, (4) quay wall, (5) container yard and buildings, (6) power supply, and (7) project management office. Since the research outcome was developed by subject matter experts during an actual project, it can be used during risk identification, as a completeness check after risk identification on similar projects, or for individual activities (e.g., quay wall construction) per the required project scope. The research also includes a list of risks that specifically relate to marine construction.

A simple formula to determine the wave breaking depth index for regular waves is proposed. In the literature, there are several formulas for determining the breaker depth index, which, over the years, have gradually evolved by improving advanced measurement tools. The proposed formula has been obtained by means of dimensional analysis and incomplete self-similarity, and it has been calibrated and verified by using a large breaker depth index database yield fairing good predictions for a wide range of wave conditions and beach slopes. The application of some existing formulas for determining the breaker depth index has been examined by using previous published laboratory data compared with the new formula.