Stability Of Quay Wall Research Articles

Impact of the Thruster Jet Flow of Ultra-large Container Ships on the Stability of Quay Walls

As the size of ships increases, the size and output power of their thrusters also increase. When a large ship berths or unberths, the jet flow produced from its thruster has an adverse effect on the stability of quay walls. In this study, we conducted a numerical analysis to examine the impact of the thruster jet flow of a 30,000 TEU container ship, which is expected to be built in the near future, on the stability of a quay wall. In the numerical simulation, we used the fluid–structure interaction analysis technique of LS-DYNA, which is calculated by the overlapping capability using an arbitrary Lagrangian Eulerian formulation and Euler–Lagrange coupling algorithm with an explicit finite element method. As the ship approached the quay wall and the vertical position of the thruster approached the mound of the quay wall, the jet flow directly affected the foot-protection blocks and armor stones. The movement and separation of the foot-protection blocks and armor stones were confirmed in the area affected directly by the thruster jet flow of the container ship. Therefore, the thruster jet flows of ultra-large ships must be considered when planning and designing ports. In addition, the stability of existing port structures must be evaluated.

Stability of quay wall made on concrete blocks with a formulation based on dredging sand

Port constructions (quay and dike) require an enormous consumption of materials, in particular concrete and its components, as well as sand, hence the need to develop alternative solutions by using port dredging sand, which is evaluated by thousands of tons by its use in the concrete that forms the blocks of quay walls. After having demonstrated in a previous work the possibility of using the dredged sand from the port of Agadir in concrete formulations, the present work consists to show the possibility of using the dredged sand from the port of Agadir in concrete formulations that can be used in the construction of quay wall blocks, by studying the stability of a quay wall at −18 mZH made from concrete blocks derived from a concrete formulation based on the dredged sand, more specifically 50% of the sand used in the formulation is a dredging sand extracted from the port of Agadir, the quay wall stability study will consist of a deep analytical and detailed study of the sliding stability, the overturning and the bearing capacity of the foundation, taking into account the different calculation limit states, the structure of the quay wall studied is the quay wall of the port of Tangier Med II located in the north of Morocco. The eventual use of dredged sand in the concrete of the quay wall will provide enormous gains in the quantities of sand and therefore allow less consumption of construction materials, and will also play a more important role in the preservation of the marine environment by avoiding the dumping of dredged materials, which has a negative impact on the marine fauna and flora.

MINIMIZING BED SCOUR INDUCED BY SHIP BOW-THRUSTERS BY USING QUAY WALL FLOW DEFLECTOR

Recently, the combination of larger bow-thrusters installed with vessels have created higher levels of bed scour action affecting the berthing structure and its overall stability. Therefore, the bed near a quay wall structure must have sufficient strength by placing a bed protection which may cause the cost of the project to rise. This research is carried out to investigate experimentally the effect of modifying the geometry of the quay wall surface on minimizing bed scour. This is done by inserting flow deflectors within the longitudinal direction of the wall surface in order to deflect/minimize the water jet affecting the bed near the quay wall. Experimental tests had been carried out for single and triple deflectors. The results showed that the use of flow deflectors achieved a reduction in bed eroded area in front of quay wall face by about 63%, and causes the start point of erosion to move far away from it; this may improve the stability of quay walls. Therefore, the importance of the present study is testing a new possible measure to improve the stability of quay walls by minimizing the scour in front of the wall and to decrease the cost of bottom protection.

MINIMIZING BED SCOUR INDUCED BY SHIP BOW-THRUSTERS BY USING QUAY WALL FLOW DEFLECTOR

Recently, the combination of larger bow-thrusters installed with vessels have created higher levels of bed scour action affecting the berthing structure and its overall stability. Therefore, the bed near a quay wall structure must have sufficient strength by placing a bed protection which may cause the cost of the project to rise. This research is carried out to investigate experimentally the effect of modifying the geometry of the quay wall surface on minimizing bed scour. This is done by inserting flow deflectors within the longitudinal direction of the wall surface in order to deflect/minimize the water jet affecting the bed near the quay wall. Experimental tests had been carried out for single and triple deflectors. The results showed that the use of flow deflectors achieved a reduction in bed eroded area in front of quay wall face by about 63%, and causes the start point of erosion to move far away from it; this may improve the stability of quay walls. Therefore, the importance of the present study is testing a new possible measure to improve the stability of quay walls by minimizing the scour in front of the wall and to decrease the cost of bottom protection.

Stability Evaluation of a Quay Wall of Large Cylinders

The stability of the quay wall incorporating large diameter cylinders is of great concern at the Yangshan Port, China, owing to severe marine environment. In this study, finite element analysis is carried out to evaluate the stability of a trial quay wall during construction. The single cylinder is examined in terms of turnover failure subjected to a five year design wave action. The case when the cylinder is empty is the critical situation during construction. Filling the cylinder right after the installation is an effective way to increase the stability. After the quay wall has been formed by joining the single cylinders, the safety against overturning is reevaluated. The factor of safety of the quay wall is assessed to be 1.5 under a fifty year design wave action.

Evaluation of seismic displacements of quay walls

A new simplified dynamic analysis method is proposed to predict the seismic sliding displacement of quay walls by considering the variation of wall thrust, which is influenced by the excess pore pressure developed in backfill during earthquakes. The method uses the Newmark sliding block concept and the variable yield acceleration, which varies according to the wall thrust, to calculate the quay wall displacement. A series of 1 g shaking table tests were executed to verify the applicability of the proposed method, and a parametric study was performed. The shaking table tests verified that the proposed method properly predicts the wall displacement, and the parametric study showed that the evaluation of a realistic wall displacement is as important as the analysis of liquefaction potential for judging the stability of quay walls.

Stability of Quay Walls.—Discussion on Paper No. 646

Stability of Quay Walls.—Discussion on Paper No. 646