Armor Layer Research Articles

The influence of toe geometry on toe armour stability for conventional rubble mound breakwaters

Rubble mound breakwaters have toe structures that provide support to the armour layer and prevent damage to the structure from scouring. In this way, toe failure may be regarded as one of the primary failure modes of rubble mound breakwaters. Several formulae have been proposed for toe stability with conflicting results owing to the neglect of factors such as storm duration and armour layer slope. In the present study, a statically stable rubble mound with rock armoured toe was tested under irregular waves. The effects of wave height, wave period, armour layer slope, water height in front of the structure, water height above the toe, and toe width on the hydraulic stability of a toe structure are investigated. Toe width was found to be ineffective on toe stability, while the relative depth was found as an effective parameter for the toe stability. Greater toe damage was observed by increasing wave height and storm duration. The results highlighted the necessity for a new stability number involving the type of wave breaker on the armour slope with a critical Iribarren value of 4.1. Based on the data from the present study and the findings of another study, new formulae have been developed for estimating toe damage in rubble mound breakwaters. Evaluating the proposed formula using other researchers’ data and formulae highlighted its strengths.

A study on the mechanical behavior of umbilical cables under impact loads using experimental and numerical methods

Accidental impacts affect the structural integrity of umbilical cables during their life cycle. This study investigates the impact behavior of a steel tube umbilical cable using both experimental tests and numerical simulations. A series of impact tests are carried out to elucidate the failure modes and deformation responses of non-bonded multi-layer components. A three-dimensional finite element model is established and verified to capture time-history responses. Through the analysis of time-history responses, the impact energy dissipation mechanisms are investigated, and the impact resistance of armor layers is further evaluated. It is found that the armor layers and polymer sheaths dissipate only approximately one-third of the impact energy, demonstrating limited protection capability, while more impact energy is absorbed by internal functional components. The steel tube may have sustained severe damage, even though the armor layer and polymer sheath exhibit only minor damage. This work has provided a reference for the damage assessment and protection design of umbilical cables.

Multi-scale ceramic self-extinguishing fire retardant coating based on scale armor layer

Currently, designing an efficient and broadly applicable (suitable for foams, wood, steel, plastic) fire-retardant coating remains a significant challenge. This work introduces a multi-scale micro-nanostructured hybrid fireproof coating. The composite features basic fillers that include ceramic glass microspheres, while its interior comprises an inorganic aerogel made from nano black phosphorus and silicon dioxide nanofibers for reinforcement, with a phosphorus-containing acrylic polymer serving as the base. Upon exposure to elevated temperatures, the coating’s surface transforms into a solid char layer resembling scale armor, effectively functioning as a robust fire barrier to protect the underlying substrate. The coating treated rigid polyurethane foam achieved an exceptionally high Limiting Oxygen Index of 45 %, outperforming comparable products. In terms of flame retardancy and smoke suppression, this innovative coating significantly reduces Peak Heat Release Rate (50.3 %) and Total Smoke Production (54.9 %). Notably, it exhibits rapid self-extinguishing capabilities within seconds during butane flame tests at temperatures exceeding 1100 °C, demonstrating remarkable resistance to high-temperature flames. This research offers a straightforward methodology for developing high-performance fireproof coatings, with promising applications across various industrial settings.

Analysis of EFT Transmission Characteristics in Armoured Shielded Cables

Abstract Electrical fast transient pulses (EFT) generated when a gas-isolated substation (GIS) is switched on and off. The EFT is transmitted to the control chamber through the secondary control cable, which will cause the failure of the control equipment. In this paper, the three-dimensional electromagnetic simulation software CST (Computer Simulation Technology) is used to study the transmission characteristics of EFT in armored shielded control cables. First, an EFT analog signal is generated using an interference generator. Analyze the difference between the EFT analog signal and the EFT model in the IEC standard. The conversion method of FFT is used to analyze the spectral characteristics of EFT analog signals. According to the structural parameters, a 20-meter-long model of an armored shielded control cable was built in the CST cable studio The effect of the grounding of the shield and armor layers on the attenuation and crosstalk of EFT signals in the cable is studied. Finally, the EFT experiment of 1m long armored shielded cable is carried out, and the reliability of the research method is verified by comparing with the simulation results.

Study on ballistic impact performance of bionic fish scale protective armor

Composite bulletproof armor used in modern battlefield environments is mostly composed of ceramic/ultra-high molecular weight polyethylene (UHMWPE). In order to further improve its bulletproof performance, this study draws on the superposition of fish scales. The upper layer of the flexible protective armor consists of composite scale layers stacked on top of each other, and the lower layer consists of UHMWPE plates with grooved structures at the corresponding locations of the scales, where a single composite scale consists of an upper SiC ceramic layer and a lower UHMWPE layer. Finite element simulation is used to analyze the protective performance of the protective armor. The effects of back plate thickness, scale tilt angle, and impact location on the protection performance are investigated. The results show that the 8 mm thick back plate can effectively resist the impact of Type 53 7.62 mm armor-piercing incendiary ammunition, and the protective effect is best when the scale tilt angle is 30°. The maximum depression depth of the backplane is 12.4 mm, and the deformation of the backplane is reduced by 3 mm when the bullet hits the overlapping area of the scale compared with the central area of the target scale, accounting for 32.67% of the total deformation. The research work has guided the development of new bionic flexible protective armor.

Partnerships Crucial in Developing Nonmetallic Downhole Tubulars

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 23491, “Role of Ecosystem Partners To Make Nonmetallic Downhole Tubulars a Reality,” by Ahmed Aladawy, SPE, and Ameen Malkawi, SPE, Baker Hughes, and Omar El Shamy, SPE, Novel Non-Metallic Solutions. The paper has not been peer reviewed. Copyright 2024 International Petroleum Technology Conference. _ Nonmetallic (NM) downhole tubulars offer a longer lifetime than their steel counterparts while eliminating corrosion concerns and lowering total cost of ownership. Making them a reality, however, requires a rigorous ecosystem with multidisciplinary skill sets and technology expertise. The complete paper discusses the challenges that face the development of such tubulars starting from academia and research institutes to complement expertise and computer computational power and moving through to material suppliers and manufacturing facilities for pipe prototyping. NM Pipe Construction and Technology Status NM pipes also can include metallic elements, where a hybrid system of NM layers is incorporated into multilayered pipe structures that assume specific roles, similar to a metallic pressure armor layer in subsea flexible risers, jumpers, and flowlines. Another example is polymer-lined steel rigid pipes with glass-fiber reinforced epoxy (GRE), or a dual-layer thermoplastic-lined reinforced pipe (Fig. 1). Composite-based NM pipes can broadly be categorized into reinforced thermoplastic pipe (RTP) and reinforced thermoset pipe (RTR), with glass-fiber reinforced plastic pipe (GRP) and GRE considered a subset of RTR. RTP consists of thermoplastic matrices and layers that can soften after heating and can harden when cooled in a reversible process, thus having the potential to recycle. Because of the flexibility of thermoplastic polymer, RTP pipes up to hundreds of meters long can be spooled on reels and deployed through rigless operation, with reduced system cost and deployment time. This synopsis will concentrate, as does the complete paper, on RTP. RTP pipe design can be classified as unbonded, semibonded, or fully bonded. Essentially, three layers of constituents for RTP exist: the inner layer is a fluid barrier (liner), the second layer is a load-bearing component (reinforcement), and the outer layer is external protection (cover). Unbonded RTP pipe means that the layers are not heat-fused to one another during manufacturing and are free to move between layers. This type of RTP pipe usually is low to medium in pressure rating, especially with regard to collapse rating, but also is lower in manufacturing cost and is suitable in onshore applications for fluid transportation. To increase the pressure rating, semibonded RTP pipes can be considered if pipe thickness is a limitation. For offshore and downhole applications, however, where higher pressure and temperature ratings are required, fully bonded RTP pipes, more commonly known as thermoplastic composite pipes, are preferred to handle high burst and collapse-pressure requirements and more-consistent load transfer across the structure. All RTP types can be manufactured continuously into pipe lengths of hundreds of meters because of their flexibility, but fully bonded RTP may be limited to larger-bend radii than unbonded or semibonded RTP; consequently, a need exists to consider reel-size limitations or even carousels to wind long pipe lengths during manufacturing. Conversely, fully bonded RTP structures may be easier to model and analyze than unbonded pipe.

Review of the Development of an Unbonded Flexible Riser: New Material, Types of Layers, and Cross-Sectional Mechanical Properties.

Unbonded flexible risers consist of several helical and cylindrical layers, which can undergo large bending deformation and can be installed in different configurations to adapt to harsh marine environments; thus, they can be applied to transport oil and gas resources from ultra-deep waters (UDW). Due to their special geometric characteristics, they can ensure sufficient axial tensile stiffness while having small bending stiffness, which can undergo large deflection bending deformation. In recent years, the development of unbonded flexible risers has been moving in an intelligent, integrated direction. This paper presents a review of unbonded flexible risers. Firstly, the form and properties of each interlayer of an unbonded flexible riser are introduced, as well as the corresponding performance and configuration characteristics. In recent years, the development of unbonded flexible risers has been evolving, and the development of machine learning on unbonded flexible risers is discussed. Finally, with emphasis on exploring the design characteristics and working principles, three new types of unbonded flexible risers, an integrated production bundle, an unbonded flexible riser with an anti-H2S layer, and an unbonded flexible riser with a composite armor layer, are presented. The research results show that: (1) the analytical methods of cross-sectional properties of unbonded flexible risers are solved based on ideal assumptions, and the computational accuracy needs to be improved. (2) Numerical methods have evolved from equivalent simplified models to models that account for detailed geometric properties. (3) Compared with ordinary steel risers, the unbonded flexible riser is more suitable for deep-sea resource development, and the structure of each layer can be designed according to the requirements of the actual environment.

High-energy computed tomography for inspection and monitoring of flexible riser

Flexible risers have been widely used in the offshore oil and gas industry and have many applications, such as production, gas lifting, or gas and water injection. The structure comprises several metal and polymer layers, which allow it to withstand a sizeable bending curve and high internal pressure. Therefore, guaranteeing the integrity of flexible risers throughout their useful life is extremely important. It requires developing and applying effective inspection and monitoring techniques, particularly emphasizing the tensile armor layers. This work evaluated the ability of the High-Energy Computed Tomography (CT) Technique to detect internal defects such as cracks, breaks, and fissures in the riser layers. A flexible riser sample of approximately 2 m in length and 281 mm in external diameter was scanned using a tomography system consisting of a 6 MeV Betatron and a set of 14-bit A-Si digital detectors. The images were acquired in 360° with angular steps of 2°. After acquisition, the images were reconstructed, and 3D models were built for qualitative and quantitative evaluation. Through the segmentation process, the metal layers of the flexible riser could be analyzed individually. Defects were found in the tensile armor layers, indicating ruptures and cracks and the onset of pitting. The results strongly suggest that computed tomography can be used as a non-destructive technique for inspecting flexible risers, with good efficiency in detecting defects, and that its application can be extended to field tests.

Nonlinear Slippage of Tensile Armor Layers of Unbonded Flexible Riser Subjected to Irregular Loads

The unbonded flexible riser has been increasingly applied in the ocean engineering industry to transport oil and gas resources from the seabed to offshore platforms. The slippage of helical layers, especially the tensile armor layers of unbonded flexible risers, contribute to the nonlinear hysteresis phenomenon, which is a research hotspot and difficulty. In this paper, on the basis of a typical eight-layer unbonded flexible riser model, the nonlinear slippage of a tensile armor layer and the corresponding nonlinear behavior of an unbonded flexible riser subjected to irregular external loads are studied by numerical modeling with detailed cross-sectional properties of the helical layers, and are verified through a theoretical method considering the coupled effect of the external loads on the unbonded flexible riser. Firstly, the balance equation of each layer considering the effect of external loads is established based on functional principles, and the overall theoretical model of the unbonded flexible riser is set up in consideration of the contact between adjacent layers. Secondly, the numerical modeling of each separate layer within the unbonded flexible riser, including the actual geometry of the carcass and pressure armor layer, is established, and solid elements are applied to all the interlayers, thus simulating the nonlinear contact and friction between and within interlayers. Finally, after verification through test data, the behavior of the unbonded flexible riser under the cyclic axial force, torsion, bending moment, and irregular external and internal pressure is studied. The results show that the tensile armor layer can slip under irregular loads. Additionally, some suggestions related to the analysis of unbonded flexible risers under irregular loads are drawn in the end.

Axial Tensile Ultimate Strength of an Unbonded Flexible Riser Based on a Numerical Method.

Unbonded flexible risers consist of several helical and cylindrical layers, which can undergo large bending deformation and can be installed to different configurations to adapt to harsh marine environments, and is a key equipment in transporting oil and gas resources from Ultra Deep Waters (UDWs) to offshore platforms. The helical interlayer of an unbonded flexible riser makes the structural behavior difficult to predict. In this paper, the axial tensile behavior and the axial tensile ultimate strength of an unbonded flexible riser are studied based on a typical 2.5-inch eight-layer unbonded flexible riser model, and verified through a theoretical method considering the contact between adjacent layers. First, the balance equation of separate layers is deduced by a functional principle, and then the overall theoretical model of an unbonded flexible riser is established considering the geometric relationship between adjacent layers. Then, the numerical model considering the detailed geometric properties of an unbonded flexible riser is established to simulate the axial tensile behavior. Finally, after being verified through the experimental results, the axial tensile stiffness and axial tensile strength of an unboned flexible riser considering the elasticity of the tensile armor layer are studied using the proposed two methods. Additionally, the effect of frictional coefficients is conducted. The numerical and theoretical results show good agreement with the test results, and the friction between adjacent layers would increase the axial tensile stiffness of an unbonded flexible riser.

The application of flexible and porous concrete structures in training works and scour protection

Concrete armour units such as Xbloc have been applied as armour layer for breakwaters and bank protections for years. These smartly shaped blocks were invented to offer efficient protection at more exposed locations by applying blocks that work together with neighbouring units to withstand high wave loads (Interlocking). Also material use was lowered since steeper slopes could be realized compared to conventional rock structures. Xstream and Xstone can be applied in a large range of applications that are traditionally built with loose rock, pitched rock or smooth block revetments such as: - Bed protection (e.g. offshore wind foundations) - River training works - Detached breakwaters - Quay wall protection in harbours - Revetment structures This abstract elaborates on why flexible and porous structures made of these small-scale [0.2 – 0.6m] concrete armour units are an interesting, low CO2 and eco-friendly alternative for bed protections and river training works.

Rehabilitation Of The Afsluitdijk

The ‘Afsluitdijk’ is a 32 km long dam, which divides the Wadden Sea from the Lake IJssel. The dam has been rehabilitated by increasing the crest level to reduce the wave overtopping and reinforce the armour layers on the seaward and lake side of the dam. The Dutch Ministry of infrastructure and Water Management (Rijkswaterstaat division) commissioned Levvel, a consortium of BAM, Van Oord and Rebel, to carry out this renovation. Rijkswaterstaat encouraged contractors to offer innovative design solutions for the rehabilitation works as the dam is one of the icons in Dutch hydraulic engineering history. Levvel proposed two new armour materials to protect the dam against wave action and reduce the wave overtopping over the crest. A combination of Quattroblocks® a product of Holcim Coastal and Levvel-blocs, internationally known as Xblocplus® by BAM have both been introduced for the first time for the design of the dam. The application of innovative materials and/or techniques may incorporate uncertainties and because of the Afsluitdijk is one of the primary sea defenses preventing the Netherlands for flooding the contract included requirements for the Contractor to carry out physical model tests on the main failure mechanisms of the dam. Besides the contractual requirements, Levvel also used physical model tests to optimize the armour elements and the geometry of the dam. The verification of the design has been carried out with large scale 2D physical model tests in the Delta Flume of Deltares and small scale 2D model tests have been used to optimize design solutions.

Numerical Tools For Wave Overtopping At Rubble Mound Breakwaters With Submerged Berms

In the era of climate change, the adaptation of existing coastal structures as a response to potential increasing loads, has become a trending topic in coastal engineering. The combination of sea level rise, storm surge, tides and waves is going to dramatically increase the wave overtopping. In this context, this research is focused on the evaluation of wave overtopping for conventional rubble mound breakwaters, modified by the introduction of a submerged berm. Recent studies illustrated how the introduction of emerged berms on the seaward slope reduces the wave overtopping. The goal then becomes to turn the spotlight on the submerged berms, whose effectiveness has yet to be attested, although it has proven useful in reducing wave loads on the armour layer and seabed pressure under the structure. Therefore, the reliability of two different numerical models in detecting overtopping phenomenon have been assessed. IHFOAM and SWASH have been used (see Figure 1). The first one can solve both Reynolds Averaged Navier Stokes and the Volume Averaged Reynolds Averaged Navier–Stokes equations. The second one solves the non-linear shallow water equations with a non-hydrostatic pressure term, representing a simplified form of the Navier-Stokes equations, with associated limited computational cost. The numerical models have been validated based on experimental tests carried out in a wave flume at the University of L’Aquila.

Investigation Of Coastalock Performance On A Breakwater With Porous Core

Hard stabilization methods have traditionally been employed to mitigate coastal erosion. Concrete armour is widely used due to its high level of dependence, robustness, ease of production and cost effectiveness (Cooke et al., 2020; Pikey and Cooper, 2012). It is inevitable that coastline ‘armouring’ will continue to rise because of the growing human population and urbanization, desire for and value of coastal property, opposed to predicted climate change (Chapman and Underwood, 2011). The environmental impact of such 'armouring' on coastal systems can be detrimental, resulting in a degradation or destruction of habitats and the loss of ecologically trivial species (Gittman et al., 2015). The CoastalockTM, a single-layer armour unit, aims to blend coastal protection with marine habitat creation. This armour unit is designed to mimic inter- and sub-tidal habitats, with chemical composition of substrate and micro and macro features that provide niches for various species. The key feature of CoastalockTM is the cavity that is integrated into the design, that caters to diverse marine life needs depending on its orientation (ECOncrete Tech Ltd., 2019). CoastalockTM's hydraulic performance is under research. Preliminary tests conducted in the Hydraulic Engineering Laboratory (HEL) of the Technical University of Delft (TUD) on a 2V:3H impermeable slope in deep water conditions highlighted that with tight placement of the units significant pressure gradients across the top layer led to damage. The introduction of spacings between units for enhanced permeability improved stability significantly (Gutiérrez et al., 2023). A redesign of the unit was proposed incorporating protrusions to enforce the spacings between the blocks (Molenkamp, 2022). This research focuses on evaluating the influence of a porous core on the hydraulic performance of a CoastalockTM armour layer, specifically assessing its stability, overtopping, and reflection on a 2V:3H breakwater slope in deep water conditions—from the toe to just below the crest. A pivotal aspect of this research is the investigation of the impact of protrusions on the hydraulic performance. Furthermore, the study explores the influence of different toe configurations, aiming to comprehend the vulnerability of the armour layer to sliding. Toe scour falls outside the scope of this study.

Deformation of vegetated channel bed under ice-covered flow conditions

A common feature of cold regions is the presence of ice cover on water surface. In the presence of vegetation in the channel bed which is normally leafless in winter, interaction between river ice and vegetated channel bed becomes very complex. In the present study, the impacts of ice cover and submerged leafless vegetation on channel bed deformation and flow resistance have been investigated based on 144 experiments conducted in a large-scale outdoor flume. The independent variables associated with the maximum scour depth around vegetation elements have been assessed and equations have been developed. Results indicate that the most important variable affecting the maximum scour depth around vegetation under ice-covered flow conditions is the ratio of the ice cover roughness to the bed roughness (ni/nb). However, under open channel flow conditions, the flow Froude number is the most important variable influencing the maximum scour depth. The methods based on the law of the wall provide reliable Manning's coefficient for both smooth and rough ice covers in the presence of submerged vegetation in the channel bed. As the vegetation density increases, the size of scour holes becomes smaller. With the increase in vegetation density, the median grain size of the armour layer in scour holes decreases correspondingly. When vegetation elements are placed in a staggered configuration, the median grain size of the armour layer in scour holes is less than that of squared configuration of vegetation elements. Regardless of the roughness of ice cover on water surface and the grain size of sediment in the bed, the maximum depth of scour holes always occurs at the upstream front face of each vegetation element. Under the rough ice-covered flow condition, the maximum depth of scour holes is more than that under the smooth ice-covered and open flow conditions.

Wave Pressures Acting On The Pavement Behind The Sloping Revetment

A physical experiment was performed to seek an empirical equation predicting the wave force acting on the upper surface of the pavement behind the revetment parapet due to wave overtopping as well as the uplift force acting on the underlayer of the pavement induced by the wave pressure passing through the core layers of the revetment. The experiment was carried out by installing pressure transducers along the upside and downside of the pavement with different configuration of the parapet, water depth, relative freeboard, and armor layer thickness. Then, the wave pressure and force on the pavement was analyzed under various incoming wave conditions. Based on the analysis results, major parameters affecting the wave forces were identified and an empirical equation for evaluating the forces on the pavement is suggested.

Rocking Of Single Layer Armour Units Measured By Embedded Sensors

Single layer randomly placed armour units are used in many rubble mound breakwaters around the world. For these armour layers, breakage of armour units due to rocking could be a major damage mechanism, but no good methods exist to evaluate and quantify rocking. The aim of the study is to quantify the rocking impact velocities for irregularly placed single layer armour units. This study utilizes embedded Rocking Sensors to obtain the first measurements of rocking impact velocities of single layer armour units. More generally, the paper (Hofland et al. 2023) shows how novel measurement techniques can be used for the investigating the stability of single layer armour layers.

Concrete Armour Unit Breakwater Physical Model Monitoring With 3D Modeling Tools

SEABIM® is a patented scan to BIM process that can generate a reliable and complete 3D model of a rubble-mound breakwater precast protective layer (Xbloc®, Accropode™, Core-loc™ etc.). Using computer vision techniques, the known 3D shape of the Concrete Armour Units (CAU) is detected in a high-resolution point cloud, which allows to obtain the position and orientation of each unit relative to the cloud. By superimposing 3D models produced from different scans at different dates, the movement of each block can then be quantified and represented as a vector. For natural riprap armours, a point cloud segmentation algorithm is applied. Each rock is identified, and then geometric characteristics of the armour can be computed (apparent rock diameters, placement density), and the movement between each scan can be monitored. This tool has been applied to numerous real-scale projects since 2019, both in the monitoring of newly built infrastructures and in the asset management phase (Aberdeen South Harbour, Calais port 2015, Nouvelle Route du Littoral etc...). Breakwater physical models in laboratories, in wave flumes or basins, also require monitoring of the movement of reduced-scale blocks between each wave series. With SEABIM® this movement can be computed with accuracy for each CAU, allowing for a consistent evaluation of the armour layer response to wave loads. The automatic block detection process can be launched on the point cloud from a survey of the initial physical model, obtained either by photogrammetry or LiDAR. Then a new survey is done after each wave series in order to create a sequence of 3D models. Those models can be compared by computing the displacement vectors of the centers of gravity of the units. The vectors can be visualized using color graded arrows within the 3D model. All the information can then be exported to a spreadsheet for further analysis. Using this technique, settlement, rocking and sliding effects can be identified. In this paper we will discuss in detail the adaptation of the survey techniques from real scale to laboratory projects (difference in scanning technique, scale effect on point cloud density etc.). Then we will explain the 3D modeling process and the applications of the 3D models for engineering analysis purposes.

Study Of The Hydraulic Response Of A High Permeable Breakwater Using Physical Modelling

Physical modelling tests were conducted in the wave flume of Artelia’s hydraulic laboratory to study the hydraulic response/stability of a rubble mound breakwater made with a non-standard core composed of crushed concrete blocks (tetrapod). This design carried out by EDF, is aimed at having high permeability and fits in an eco-design approach, through the reuse of existing materials already on site. Eventually, the hydraulic efficiency of three different sections were tested and compared, all sections having the same armour layer and the same main dimensions but different {core; filter} systems : core only made with crushed tetrapod, core and underlayer made with crushed tetrapod (no filter layers with rocks) and baseline design (quarry run core and rock underlayer). Several responses were studied: armour layer stability, overtopping and transmission of the structure and head loss on both sides of the structure with an inflow/outflow system in the rear side basin set up in the wave flume. This case study illustrates 1) the importance of the physical modelling approach to testing unusual structures, as part of an eco-design approach, where the use of standard design formulas does not allow to verify the hydraulic behaviour of a high permeable breakwater and 2) also shows that unconventional design can lead to satisfactory hydraulic results.

Hydraulic Stability Of The New Cubilok™ Armour Unit On A 3:4 Slope

The Cubilok™ (or Cubilok) is a new trademarked armour unit that has been developed in South Africa by PRDW Consulting Ports and Coastal Engineers to accommodate a wide range of breakwater designs. The Cubilok is still in its early stages of development and therefore it has not yet been applied or tested in prototype conditions. 2D Physical model tests were conducted as part of a master’s research project to investigate the stability and behaviour of the Cubilok on a 3V:4H slope. From this study, it was observed that the wave steepness has a significant influence on the performance of the Cubilok, where superior stabilities were recorded during conditions with shorter wave periods. When placed on a 3V:4H slope and with a packing density of ɸ = 0.63, the stability of the Cubilok is comparable to that of other concrete armour units, however, it is susceptible to severe settlement. Some results also showed that the settlement of the armour layer can probably be significantly reduced when the armour layer is constructed on a milder 1V:2H slope or when the packing density is increased to ɸ = 0.65.