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Scour of seabed sediments can occur around offshore foundations. For monopile-supported offshore wind turbine structures, the reduction in foundation stiffness due to scour presents certain operational challenges. In cases where scour causes the natural frequency of the structure to become, for example, close to the range of rotor loading frequencies then—due to the increased risk of fatigue damage—turbine support structures are at risk of reduced operation, or even premature decommissioning. In practice, scour protection and/or remediation systems are typically used to mitigate the development of scour. As well as preventing further erosion, scour remediation systems may have a restorative effect on the stiffness of the foundation. This paper describes a one-dimensional (1D) finite-element model for the analysis of natural frequencies for monopile-supported turbine support structures with active scour process around the foundation. The model also incorporates procedures to model the influence of a rock fill scour remediation system on the foundation stiffness. The numerical model is calibrated and validated by comparison with a set of previously described reduced-scale model tests conducted in a flume. The calibrated 1D model is applied to a field case study at a UK offshore wind farm site. [ABSTRACT FROM AUTHOR]

AbstractThis study presents an investigation of the impact of tidal currents on scouring beneath pipelines. To elucidate the role of parameters such as current velocity, time period of each cycle, depth of flow, and number of tidal cycles required to attain equilibrium, 38 tests were conducted in a bidirectional flume for a pipeline. The geometry of pipeline and the flow characteristics of the Persian Gulf were scaled down to a ratio of 1:30 based on the Froud law and used for this study. The tests were carried out in clear water conditions. The experimental findings reveal that a significant portion of the scour depth occurs during the mid-range of each half cycle. This is the case regardless of ebb or flood conditions, and when the current velocity is at its maximum value. Also, the scour hole resulting from bidirectional flow exhibits a symmetrical shape with two dunes on either side. Furthermore, the relative scour depths in daily and semi-daily tidal tests are greater by factors of 1.40 and 1.1, respectively, compared to unidirectional tests when the root mean square values from steady current scenarios are considered. Finally, a series of formulae have been developed based on the experimental results. [ABSTRACT FROM AUTHOR]

Most pier scour monitoring methods cannot be carried out during floods, and data cannot be recorded in real-time. Since scour holes are often refilled by sediment after floods, the maximum scour depth may not be accurately recorded, making it difficult to derive the equilibrium scour depth. This study proposes a novel approach using 16 proximity sensors (VCNL4200), which are low-cost (less than USD 3 each) and low-power (380 µA in standby current mode), to monitor and record the pier scour depth at eight different positions in a flume as it varies with water flow rate. Based on the regression relationship between PS data and distance, the scour trend related to the equilibrium scour depth can be derived. Through the results of 13 local live-bed sediment scour experiments, this PS module was able to record not only the scour depth, but also the development and geometry of the scour under different water flows. Additionally, based on PS data readings, changes in the topography of the scour hole throughout the entire scouring process can be observed and recorded. Since the maximum scour depth can be accurately recorded and the scour trend can be used to estimate the equilibrium scour depth, observations from the experimental results suggest that the critical velocity derived by Melville and Coleman (2000) may have been underestimated. The experimental results have verified that, beyond achieving centimeter-level accuracy, this method also leverages the Internet of Things (IoT) for the long-term real-time observation, measurement, and recording of the formation, changes, and size of scour pits. In addition to further exploring scouring behavior in laboratory studies, this method is feasible and highly promising for future applications in on-site scour monitoring due to its simplicity and low cost. In future on-site applications, it is believed that the safety of bridge piers can be assessed more economically, precisely, and effectively. [ABSTRACT FROM AUTHOR]

Scouring leads to soil loss around piles, which, in turn, changes the ground-vibration characteristics and influences the seismic performance of bridges. In this study, the Xiang'an Bridge was used as a reference for constructing a large shaking-table test model to investigate the dynamic characteristics of the pore-pressure ratio of saturated sandy soils, accelerations, and bending moments of the piles, as well as the horizontal displacements of the pile-top at scouring depths of 10, 20, and 32 cm, with ground-vibration intensities ranging from 0.10-0.45 g. The results indicated that as the scour depth increased, the pile acceleration of the group piles increased and changed abruptly at the variable cross-section and soil-stratum interface. The peak values of the horizontal displacement of the pile-top and bending moment of the pile exhibited an increasing trend. As the ground-shaking intensity increased, the pore-pressure ratio of the saturated sandy soil, pile acceleration of the group piles, horizontal displacement of the pile-top, and bending moment of the pile body gradually increased, whereas the base frequency of the pile foundation gradually decreased. This study can serve as a reference for the seismic design and reinforcement of scour bridges in areas prone to seismic activity. [ABSTRACT FROM AUTHOR]

Few studies have focused on abutments located on curved channels; previous studies have typically focused on straight channels. The present study experimentally examined the local scour that occurs around abutments of different lengths placed on inner and outer banks along a curved channel under clear-water scour flow conditions. The local scour around an abutment in a curved channel is a function of the upstream Froude number, flow intensity, the angle of the bend curvature and the ratios of abutment length to flow depth, abutment length to abutment width and abutment length to channel width. The maximum scour depth around the abutments placed on the outer bank was 1.45 times the scour depth on the inner bank. An empirical equation was developed containing all the dimensional parameters for equilibrium scour depth. The average percentage error of the proposed equation was 2%. [ABSTRACT FROM AUTHOR]

One of the most dangerous issues in river engineering is erosion brought on by the flow around bridge piers, which causes failure. As a result, simulating scouring is a crucial technique for assessing the likelihood of scour-related bridge failure. The scour depth surrounding hydraulic structures (non-uniform piers) was investigated using various computational and laboratory models. This study examines the efficacy of the computational fluid dynamics (CFD) model in generating simulations of the scour depth along a bridge pier via the Flow3D software (version 10.1.1.3). k-ε model is built to more accurately consider the generation of turbulent kinetic energy and the anisotropic characteristics of the turbulence. The model's calibration and verification are assessed using statistical metrics (Root Mean Square Error (RMSE), Mean Absolute Error (MAE), and coefficient of determination (R2)). Based on the statistical criteria, it may be concluded that the model's results were promising because the discrepancy between the numerical and experimental models is negligible. The Froude number has been demonstrated to be a crucial factor that must be considered during the construction of piers, since reducing it will result in a decrease in longitudinal velocity and turbulent kinetic energy. Also, the Flow-3D program accurately reproduces the scour depth, flow, and velocity near the pier. [ABSTRACT FROM AUTHOR]

In this study, different geometrical configurations of T-head spur dikes, such as spur dike length (l = 6, 9, and 12 cm), wing length (λ = 0.5, 0.75 l, and l), and wing orientation (θ = 60°, 90°, and 120°) are used to investigate the local scour. The T-head spur dike with l = 9 cm, λ = l, and θ = 90° is found as the optimum configuration. The turbulent kinetic energy flux in the vertical direction is positive in the non-scour zone and negative in the scour zone with a higher magnitude, resulting in the transport of turbulent energy towards the bed that leads to scouring. The sweep events dominate against the ejection events in the scour zones, but in the non-scoured zone, it is the opposite. A regression equation was developed to estimate the scour depth around the spur dike, and satisfactory results were obtained. [ABSTRACT FROM AUTHOR]

AbstractScour occurs inevitably around monopiles of offshore wind turbines (OWTs), negatively impacting the operation of the turbines. For the purpose of ensuring the long-term safety and stability of the foundations, solidified soil which provides higher scour resistance can be used to remediate scour considering its technical convenience. In this study, flume tests were conducted under unidirectional flow conditions to investigate the dynamic remediation of the local scour hole, which was applied to different scour development processes, using solidified soil. Various remediation schemes were simulated by controlling the design elevation of the solidified soil layers to investigate their performance under different conditions. Meanwhile, the phenomenon and characteristics of edge scour during remediation were also analyzed. Results show that different remediation elevations and initiation would lead to varying degrees of edge scour. Early remediation costs less solidified soil but results in severe edge scour, while late remediation needs more materials and experiences milder edge scour. In addition, an evaluation method assessing solidified soil remediation was established. This method was utilized to evaluate the comprehensive benefit and edge scour risk for different remediation schemes. [ABSTRACT FROM AUTHOR]

This study presents a simplified numerical modeling approach that estimates the local scour depths around bridge supports based on the bed shear stresses. It is developed using 3D computational fluid dynamics and coding through ANSYS workbench scripting along with C++ language. The proposed model is called SCFDS (Simplified Computational Fluid Dynamics Scour). The model's main idea is to lower the bed bathymetry at the locations affected by flow obstruction until the shear stresses reach stable target values. The developed model is assessed by applying it to a complex pier of a real bridge over the Nile-River, and its scour data is calculated using the Hec-18 empirical equations. The outcomes of the model's assessment show that it can depict the local scour around complex bridge supports. The developed approach is a novel and efficient tool that can help the designers in simulating local scour in the vicinity of flow obstructions. However, more verification studies are necessary to reach a generalized conclusion. [ABSTRACT FROM AUTHOR]

Examining scouring around bridge piers is crucial for ensuring water-related infrastructure's long-term safety and stability. Accurate forecasting models are essential for addressing scour, especially in complex water systems where traditional methods fall short. This study investigates the application of the HEC-RAS 2D sedimentation model, which has recently become available for detailed sediment analysis, to evaluate its effectiveness in predicting scoring around various pier shapes and under different water conditions. This study offers a comprehensive assessment of the model's predictive capabilities by focusing on variables such as water velocity, shear stress, and riverbed changes. Particular attention was paid to the influence of factors like floating debris and different pier geometries on scour predictions. The results demonstrate that while the HEC-RAS 2D model generally provides accurate predictions for simpler pier shapes—achieving up to 85% precision—it shows varied performance for more complex designs and debris-influenced scenarios. Specifically, the model overpredicted scouring depths by approximately 20% for diamond-shaped piers and underpredicted by 15% for square piers in debris conditions. Elliptical piers, in contrast, experienced significantly less erosion, with scour depths up to 30% shallower compared to other shapes. This study highlights the novel application of the HEC-RAS 2D model in this context and underscores its strengths and limitations. Identified issues include difficulties in modeling water flow and debris-induced bottlenecks. This research points to the improved calibration of sediment movement parameters and the development of advanced computational techniques to enhance scour prediction accuracy in complex environments. This work contributes valuable insights for future research and practical applications in civil engineering, especially where traditional scour mitigation methods, such as apron coverings, are not feasible. [ABSTRACT FROM AUTHOR]

Understanding the scour process around bridge piers and investigating approaches to reduce these phenomena is an important issue for engineers. Side-by-side piers cause lower scour depth compared to a single pier with the same diameter. In this study, the application of downstream bed sill and continuous footing to control the scour depth around single piers and two side-by-side piers is investigated experimentally. The results show that by using a continuous footing with a thickness equal to the pier diameter, the scour depth in front of the pier is reduced by 50% and 55% for single pier and side-by-side piers, respectively. Moreover, when the continuous footing thickness is doubled, no scour depth is observed in front of the pier. Additionally, incorporating a downstream bed sill adjusted to the pier results in a reduction of approximately 30% in scour depth in front of the piers. [ABSTRACT FROM AUTHOR]

Abstract This study presents a simplified numerical modeling approach that estimates the local scour depths around bridge supports based on the bed shear stresses. It is developed using 3D computational fluid dynamics and coding through ANSYS workbench scripting along with C++ language. The proposed model is called SCFDS (Simplified Computational Fluid Dynamics Scour). The model’s main idea is to lower the bed bathymetry at the locations affected by flow obstruction until the shear stresses reach stable target values. The developed model is assessed by applying it to a complex pier of a real bridge over the Nile-River, and its scour data is calculated using the Hec-18 empirical equations. The outcomes of the model’s assessment show that it can depict the local scour around complex bridge supports. The developed approach is a novel and efficient tool that can help the designers in simulating local scour in the vicinity of flow obstructions. However, more verification studies are necessary to reach a generalized conclusion.

Microbially induced carbonate precipitation (MICP) technology is employed to reinforce the surface soil of a dam, aiming to prevent erosion caused by water flow and damage to the dam slope. The relationship between penetration depth, calcium carbonate content, and bonding depth was investigated at eight measuring points on the sand slope surface of a mold under different reinforcement durations. It was observed that as grouting reinforcement times increased, there was a gradual increase in calcium carbonate content but a rapid rise in penetration resistance. Moreover, the bonding depth of sand on the bio-reinforced sand slope increased with higher levels of calcium carbonate content. Microbial grouting reinforcement enhanced soil particle bonding force, requiring water flow to overcome this force for activation of sand particles. Consequently, microbial grouting reinforcement significantly improved shear strength and critical starting flow velocity on sand slope surfaces. The experimental results demonstrated that after MICP surface treatment through spraying, a dense and water-stable hard shell layer composed of bonded calcium carbonate and soil particles formed continuously on sample surfaces, effectively enhancing the strength and erosion resistance of sandy soils. These findings provide reliable evidence for silt slope reinforcement and dam erosion prevention. [ABSTRACT FROM AUTHOR]

Weir, as a hydraulic structure with an upstream and downstream flow pattern, has been of key importance to many researchers in the field of civil engineering. Energy dissipation is considered a challenge that forces researchers to make it high priority. The aim of this study was to examine the impact of the use of different shapes as obstacles at the downstream of a weir on the scour hole depth downstream of its structure. The speculated results were then compared with actual measurements to present the efficiency of CFD techniques to current actual hydraulic-structure problems. The flow 3-D package was considered as the simulation tool in this study. In order to achieve the highest energy dissipation, thus, the minimum scour depth at the downstream, nine various models of different shapes of weirs were numerically and experimentally analyzed. The shapes of the weir models were optimized by numerical simulations then they were physically tested in laboratory experiments. The models have a width of 0.8 m and a height of 0.59 m, while their lengths range from 0.72 to 1.12 m. The bottom of the channel was covered by a sand layer of 0.2 m thickness with a grain gradient rate of 0.002 m. Three different discharge values of 0.015, 0.02 and 0.025 m³ ·s-1 were utilized in the experiments. The experimental and numerical simulation results showed similarities with the maximum depths of scour for all analyses were noted to be between 0.003 m and 0.012 m. Six models have been explored, the SU3 model was found to demonstrate the minimum scour depth ranging from 0.003 to 0.005 m under all flow conditions, In this model, the scour has settled during the first (15) minutes of experiment for the first and second discharges (0.015, 0.020 m³ ·s-1) to be (0.018, 0.02 m) (Table 2) while the scour has settled for the third discharge (0.025 m³ ·s-1) after four hours to reach (0.03 m), therefore, presenting the best performance in terms of energy dissipation. [ABSTRACT FROM AUTHOR]

Collars play an effective role in reducing scour by preventing direct collisions of the flow with the piers. Furthermore, because most rivers meander, this study considered various shapes of bridge piers with collars at various locations along a 180° sharp bend and compared the findings with those of similar cases with no collars installed. The findings show that the aerodynamic shape of the pier and the collar as well as the location of these structures have significant effects on the amount of scouring. The maximum and minimum scour depths which are 2.58 and 0.8 times the pier diameter, occurred in bridge piers with collars at jou.round piers installed at 60° and elliptical piers at 120°, respectively. Moreover, another finding of this study was that use of collars played a significant role in reducing scouring. The greatest effect of the collar was found on the elliptical pier located at the 120º angle with the reduction of the scour depth by 75% and the scour hole volume by 95%. [ABSTRACT FROM AUTHOR]

Riverbank erosion poses a significant threat to the stability and integrity of river training structures. River training structures such as groynes are important components of sustainable development as they play a crucial role in mitigating flood risks, controlling erosion, and supporting the habitat for aquatic organisms. The habitats vary largely according to the groyne type. A comprehensive comparative analysis of the flow field around the I, L, and T head groynes in the gravel bed is drawn. This study will be of immense use for riverbank protection in hilly terrain where streams are mostly dominated by the gravel bed. Laboratory experiments were conducted in a channel with a sediment bed as gravel of size 9.36 mm. Consistent flow conditions were maintained, with a flow depth (D) of 0.136 m and Froude no (Fr) of 0.61. The performance of these groynes, quantified using Lp (length of bank protection), was investigated. LHG and THG, notably, instigate more profound scour depths, recording values of 0.295 D and 0.29 D, respectively, while IHG trails with the value of 0.21 D. The complex flow field involving velocity peaks, decelerated, and negative flow is discussed and is attributed to flow separation at the groyne tip and the horseshoe vortex. The Lp for each groyne was estimated, with the IHG providing the maximum bank protection of 1.2 L1, L1 being the transverse length of the groyne. The cost–benefit analysis revealed IHG as the most cost-effective structure. These findings contribute to optimization of riverbank stabilization efforts, enhancing the resilience of hydraulic infrastructure and ensuring the safety and wellbeing of affected communities and ecosystems. The results also provide valuable insight into bank protection by various groynes and highlight their contribution to enhancing the resilience of river systems. [ABSTRACT FROM AUTHOR]

In this work, a geophysical characterization of the subsoil of a civil structure corresponding to the basement of a residential complex in Bogotá, Colombia was carried out, using the GPR technique. We were chosen to establish the affectation caused by weeping willow (Salix Babylonica) trees planted near the retaining wall of the structure's foundation and its parking lot platforms. We acquired GPR profiles all throughout the area of the internal part of the basement and the outer retaining wall part. The pieces of equipment used were SIR 4000 and a HS 350 MHz center frequency antenna. The data presented a good and consistent signal. High resolution subsoil images of up to 3m in depth of the area below the parking lots were generated through the analysis of information derived from the processing and interpretation of the data. All of these were compared with information from geotechnical and topographic studies of the area. The results obtained show that the trees' roots are causing scour due to a drying effect of the subsoil, which caused damage to the slab in the parking lot and on the retaining wall. [ABSTRACT FROM AUTHOR]

Recent catastrophic tsunamis, such as the 2004 Indian Ocean and 2011 Tohoku events, have underscored the need for resilient coastal infrastructure. Field investigations in the aftermath of these tsunamis have consistently identified local scour around structures as a critical factor contributing to their failure. Local scour refers to the erosion or removal of sediment in the vicinity of a structure, triggered by the unsteady water flow associated with tsunami inundation. The recognition of the significance of this phenomenon, juxtaposed with the current deficiency of detailed and systematic design guidelines that incorporate the ramification of local scour, has spurred advancements in this area of research. This study has meticulously reviewed state-of-the-art studies on tsunami-induced local scour around structures. The existing design guidelines have been critically assessed, pinpointing their limitations and areas that require further elucidation. Moreover, this critical analysis delineates the current knowledge gaps and outlines prospective directions for future research endeavors aimed at enhancing the resilience of coastal infrastructure, with a particular focus on mitigating the effects of local scour. This comprehensive review aims to deepen the understanding of tsunami-induced local scour and promote more effective, evidence-based design strategies to mitigate the risk of structural failure in high-risk coastal areas. [ABSTRACT FROM AUTHOR]

Offshore structures are deployed extensively to harvest marine resources. Due to the harsh marine environments and heavy-duty working conditions, the risks associated with failure due to scour are high, and the need for accurate prediction of these risks is increasing. Often, pipelines and cables are critical elements of subsea energy transportation and telecommunication, and they are highly susceptible to scour-induced failure. The scour around spheres is relevant to the offshore industry as a simplified three-dimensional representation of subsea structures. This paper presents a numerical study, using FLOW-3D HYDRO, of the scour around on-bottom cylinders and spheres. Whereas most published research investigated scour around stationary solid objects, this paper presents numerical results of a more challenging case of scour around sagging cylinders and spheres. The model was validated against published experimental and numerical results. The scour depth was found to increase with the decrease of the sagging velocity of the solid object. For sagging horizontal cylinders, the scour depth reaches a plateau of 1.1 times the cylinder diameter when the dimensionless sagging velocity is smaller than 0.094. For sagging spheres, the maximum scour depth reaches 0.37 times the sphere diameter when the dimensionless sagging velocity is reduced to 0.0103. The findings provide guidelines for future research on more complicated interactions between flow, solid objects, and the seabed, accounting for the deformation of infrastructure over time. Practical Applications: This paper concerns the flow, sediment transport, and scour around horizontal cylinders and spheres undergoing slow downward motion, which resembles the sagging of on-bottom infrastructure under the influence of gravity and bed erosion. Offshore structures are deployed extensively to harvest marine resources. Pipelines and cables are critical subsea infrastructures that are susceptible to scour-induced failure. Spherical objects are commonplace in the offshore industry, so a sphere can be deemed as an idealized three-dimensional body. This paper provides detailed FLOW-3D simulations and developed empirical relationships between the dimensionless scour depth and dimensionless sagging speed. Most previous research considered only the scour around fixed objects, so this paper provides a novel addition to the existing knowledge on the scour phenomenon. The computational methods established in this study are useful for simulating more-complicated scenarios. The findings provide guidelines for more-realistic predictions of scour and for the design of scour mitigation measures. [ABSTRACT FROM AUTHOR]

The article presents the results of experimental studies of the stability of gabion scour protection near a marine berthing hydraulic structure (hereinafter referred to as HS) under the influence of jets from operating ship propellers. It has been determined that the most critical area is the zone where the scour protection adjoins the structure. [ABSTRACT FROM AUTHOR]

Designing hydraulic structures requires careful consideration of local scouring downstream. This study investigated the performance of trapezoidal labyrinth weirs in controlling flow and mitigating scour in straight channels through physical model experiments. Sixty configurations were examined, using weir apex angles of 20°, 45°, 60°, and 80°, heights of 30 cm, 35 cm, and 40 cm, and flow rates of 50–200 L/s. A linear weir served as a reference. The results showed that the 60° apex angle consistently outperformed other configurations, reducing scour depth by up to 41% and scour length by up to 50% compared to the linear weir. It also decreased deposition depth by 40% and length by 50%. Lowering weir height from 40 cm to 30 cm led to reductions of 35% in scour depth and 40% in scour length at low discharges. These improvements remained significant even at higher flow rates, with a 29% reduction in scour depth and 25% in scour length at 200 L/s. This study provides evidence-based recommendations for optimizing labyrinth weir designs to define the relationship between hydraulic efficiency and erosion control. It offers valuable insights into weir geometry, flow conditions, and the resulting scour and deposition patterns. These findings contribute to the optimization of labyrinth weir designs to minimize downstream bed configurations. The tests were conducted under limited flow conditions. [ABSTRACT FROM AUTHOR]

In this study, the effects of the grain size and gradation of riprap, the overtopping flow depth, and the downstream slope of the embankment on the scouring and deposition characteristics at the downstream toe of the embankment were investigated. For the experiment, three different downstream slopes (1:2, 1:3, and 1:4), three different overflow depths (1, 2, and 3 cm), and three different sizes of riprap particles (d50 of 16.41 mm, 8.48 mm, and 3.39 mm, herein referred to as coarse gravel, medium gravel, and granule, respectively) were used in the laboratory. The experimental results demonstrated that the scour depth and deposition height increased with increasing energy head for each downstream slope condition. Among the three particle sizes, coarse gravel shows the lowest scour depth and the highest deposition height. For the 1:2 slope, the coarse gravel particle size was 62% and 75% less resistant to scouring than the medium gravel and granule particles, respectively. For the 1:3 slope case, this was 31% and 46%, and for the 1:4 slope case, this was 39% and 49% less than the medium gravel and granule size particles, respectively. [ABSTRACT FROM AUTHOR]

Investigating different pier shapes and debris Finteractions in scour patterns is vital for understanding the risks to bridge stability. This study investigates the impact of different shapes of pier and debris interactions on scour patterns using numerical simulations with flow-3D and controlled laboratory experiments. The model setup is rigorously calibrated against a physical flume experiment, incorporating a steady-state flow as the initial condition for sediment transport simulations. The Fractional Area/Volume Obstacle Representation (FAVOR) technique and the renormalized group (RNG) turbulence model enhance the simulation's precision. The numerical results indicate that pier geometry is a critical factor influencing the scour depth. Among the tested shapes, square piers exhibit the most severe scour, with depths reaching 5.8 cm, while lenticular piers show the least scour, with a maximum depth of 2.5 cm. The study also highlights the role of horseshoe, wake, and shear layer vortices in determining scour locations, with varying impacts across different pier shapes. The Q-criterion study identified debris-induced vortex generation and intensification. The debris amount, thickness, and pier diameter (T/Y) significantly affect the scouring patterns. When dealing with high wedge (HW) debris, square piers have the largest scour depth at T/Y = 0.25, while lenticular piers exhibit a lower scour. When debris is present, the scour depth rises at T/Y = 0.5. Depending on the form of the debris, a significant fluctuation of up to 5 cm was reported. There are difficulties in precisely estimating the scour depth under complicated circumstances because of the disparity between numerical simulations and actual data, which varies from 6% for square piers with a debris relative thickness T/Y = 0.25 to 32% for cylindrical piers with T/Y = 0.5. The study demonstrates that while flow-3D simulations align reasonably well with the experimental data under a low debris impact, discrepancies increase with more complex debris interactions and higher submersion depths, particularly for cylindrical piers. The novelty of this work lies in its comprehensive approach to evaluating the effects of different pier shapes and debris interactions on scour patterns, offering new insights into the effectiveness of flow-3D simulations in predicting the scour patterns under varying conditions. [ABSTRACT FROM AUTHOR]

This study examines the scouring effect downstream of a type-A trapezoidal stepped Piano key weir using experimental methods. The experiments were performed on weirs, both with and without steps at the outlet keys, while considering various discharge rates, tailwater depths, and bed material sizes. The study scrutinized three unique weir configurations, each with different dimensions and step counts at the outlet keys: the first, second, and third weirs had 5, 10, and 15 steps respectively. The findings indicate that the maximum scour depths in the Piano key weirs with 5, 10, and 15 steps were, on average, 17.5%, 31%, and 19% less than those in the non-stepped weir. It was also noted that an increase in discharge and a decrease in tailwater depth and bed material size led to an increase in the maximum scour depth. Moreover, an increase in the number of steps and a decrease in the size of the bed materials resulted in a reduction in sediment ridge height. The analysis suggests that the average scour index values in the 10-stepped weir were about 21% lower compared to the non-stepped weir. These insights contribute to the design and optimization of hydraulic structures to effectively mitigate scouring effects. [ABSTRACT FROM AUTHOR]

The experimental evaluation of the performance of a corrugated apron under free flow subcritical and submerged conditions was conducted, with a focus on scour patterns over the apron. Comparative analysis with a smooth rigid apron revealed an increase in scour depth upon the application of the corrugated apron under free and submerged jet flow conditions. The implementation of a corrugated apron resulted in a considerable reduction in scour depth and length compared to a smooth rigid apron. The maximum reduction in scour depth and length amounted to 79% and 83%, respectively, while the minimum reduction observed was 13% in scour depth and 11% in scour length. Additionally, investigations into velocity and turbulence characteristics over both smooth and corrugated aprons were conducted. It was observed that the rate of turbulence intensity increase within the scour hole due to the presence of a smooth apron surpassed that of the corrugated apron. Scour downstream of the corrugated apron exhibited distinct delineations, including regions of jet diffusion, transition, acceleration, and a recirculating zone near the bed of the scour hole. [ABSTRACT FROM AUTHOR]

Scour is a significant concern for bridge design/maintenance, and scour countermeasures are often used to prevent or reduce erosion caused by scouring. The W weir is a grade control structure serving many purposes, including scour control at bridge piers. A series of laboratory experimental runs was conducted, changing the size, height and location of the pier in relation to the weir to optimise the structural configuration of the downscaled W weir. These experiments revealed that the scour hole profile upstream of the downscaled W weir changes with weir height. At a weir height of 1.0D (D = diameter of pier), two small depressions of almost identical size were observed inside the main scour hole, one just in front of each upstream apex of the W weir. One cone-shaped scour hole was observed when the W weir height was 0.5D with its maximum depth in between the upstream apexes. Reduction of scour in front of the pier was greater when the weir height was 1.0D. The maximum scour control achieved among all different structural combinations of downscaled W weir was 47.66%. This was achieved when the downscaled W weir was 2.0D in size and 1.0D high, placed 2.0D distant from the pier. [ABSTRACT FROM AUTHOR]

Rock-sills are instream low-head structures generally used to stabilize the riverbed. Their presence causes the formation of pools and riffles along the river, thus improving the aquatic habitat and creating resting spots for aquatic species. In this study, the riverbed morphology due to the rock-sill configuration installed at river bends was experimentally analyzed under clear-water condition, with a uniform, granular bed material. Tests were conducted by varying the inclination of sills with respect to the radial direction in three curved bends. Experimental evidence confirmed that the curvature of the channel bend plays a fundamental role, i.e., scour features significantly differed from those occurring in straight channels. Likewise, the inclination of the sill and its shape affect the scour morphology. The presence of the sill and the curvature of the channel caused an asymmetric distribution of the flow in the radial direction, possibly resulting in a shift of the scour hole toward the center. The analysis of experimental data allowed us to provide practitioners with a useful formula to predict the maximum scour depth. Finally, interesting insights on scour dynamics and features at equilibrium are also presented. [ABSTRACT FROM AUTHOR]

The significant rainfall in October 2018 in northern Iran caused devastating flooding that caused considerable economic losses and claimed at least nine lives. Following the flooding, several bridges have suffered different levels of damage. Immediately after the event, the authors conducted a field investigation to study the performance of RC bridges during the flood. This paper presents the failure modes of flood-affected bridges and provides reasons for every failure case. The results revealed that scour around foundations, pier tilting, flexural failure of piers, and superstructure unseating were the most significant failure modes observed. Pile-supported bridges performed notably better than those with shallow foundations. In addition, observations have revealed that structural integrity plays a crucial role in the general stability of bridges during flooding. Pier ductility is another significant parameter that affects the performance of bridges during flood events. Finally, fragility curves were developed based on the empirical data set provided from the post-flood status of the bridges in the affected region. The river flow velocity (Vs), maximum flow discharge (Qp), and Qp normalized to the 10-year average river discharge (Qm) were considered intensity measures of the fragility analysis. The correlation analyses revealed that despite Vs and Qp/Qm , the flow discharge was not an appropriate intensity measure for generating fragility curves. [ABSTRACT FROM AUTHOR]

Over the last 15 years, microbially induced calcite precipitation (MICP) has emerged as a possible solution to mitigate coastal erosion. To date, most MICP soil treatments that have been studied involve column injection using a pump. In recent years, MICP application through surface percolation has gained traction as an alternative technique, but data using this technique are limited. More recently, a new treatment recipe/technique was developed, and this technique was termed bioslurry. Like most MICP studies, research with bioslurry has concentrated on the column injection method, and surface percolation has received very limited attention. This paper discusses the treatment of Florida beach sand by surface percolating bioslurry. Researchers experimented with variations of the bioslurry recipe to optimize erosion resistance, which was assessed using a pocket erodometer combined with physical measurements. In addition, treated specimen morphology was preliminarily examined using X-ray diffraction and scanning electron microscopy. Results showed that erosion resistance was maximized when 15% to 25% of the specimens' pore volumes were filled with bioslurry and that this erosion resistance may be sufficient to withstand worst-case storm events after only one treatment. In addition, previous researchers always used a relatively long (i.e., ∼12 h) stir time when preparing bioslurry. Results presented here show that it may be possible to produce comparable data with much shorter stir times (i.e., 1 to 2 h). [ABSTRACT FROM AUTHOR]

The assessment of scour depth downstream of weirs holds paramount importance in ensuring the structural stability of these hydraulic structures. This study presents groundbreaking experimental investigations highlighting the innovative use of baffles to enhance energy dissipation and mitigate scour in the downstream beds of rectangular piano key weirs (RPKWs) and trapezoidal piano key weirs (TPKWs). By leveraging three state-of-the-art supervised machine learning algorithms—multi-layer perceptron (MLP), extreme gradient boosting (XGBoost), and support vector regression (SVR)—to estimate scour hole parameters, this research showcases significant advancements in predictive modeling for scour analysis. Experimental results reveal that the incorporation of baffles leads to a remarkable 18–22% increase in energy dissipation and an 11–14% reduction in scour depth for both RPKWs and TPKWs. Specifically, introducing baffles in RPKWs resulted in a noteworthy 26.7% reduction in scour hole area and a 30.3% decrease in scour volume compared to RPKWs without baffles. Moreover, novel empirical equations were developed to estimate scour parameters, achieving impressive performance metrics with an average R2 = 0.951, RMSE = 0.145, and MRPE = 4.429%. The MLP models demonstrate superior performance in predicting maximum scour depth across all scenarios with an average R2 = 0.988, RMSE = 0.035, and MRPE = 1.036%. However, the predictive capabilities varied when estimating weir toe scour depth under diverse circumstances, with the XGBoost model proving more accurate in scenarios involving baffled TPKWs with R2 = 0.965, RMSE = 0.048, and MRPE = 2.798% than the MLP and SVR models. This research underscores the significant role of baffles in minimizing scouring effects in TPKWs compared to RPKWs, showcasing the potential for improved design and efficiency in water-management systems. [ABSTRACT FROM AUTHOR]

Monopile foundations are commonly constructed for offshore wind turbines and installed at depths shallower than 30 m. However, preventing scouring and erosion around the pile foundation due to waves is critical, as this can cause instability of the foundations and supported structures. In this study, model and numerical tests were conducted to investigate wave-induced scour and erosion around a monopile foundation and clarify the fundamental mechanisms involved. Numerical tests were conducted and validated against physical model tests for a bare sea bed, and good reproducibility was obtained. When a monopile foundation was installed in both the numerical and physical tests, the flow velocity on the seabed in the offshore and inshore directions increased on the side of the foundation perpendicular to the direction of the wave motion. In the model test, scouring occurred at the same location, indicating that scouring may have been caused by the flow velocity; however, this scouring occurred locally, suggesting the need for a detailed analysis of the associated factors. [ABSTRACT FROM AUTHOR]

In this study, the effects of the grain size and gradation of riprap, the overtopping flow depth, and the downstream slope of the embankment on the scouring and deposition characteristics at the downstream toe of the embankment were investigated. For the experiment, three different downstream slopes (1:2, 1:3, and 1:4), three different overflow depths (1, 2, and 3 cm), and three different sizes of riprap particles (d50 of 16.41 mm, 8.48 mm, and 3.39 mm, herein referred to as coarse gravel, medium gravel, and granule, respectively) were used in the laboratory. The experimental results demonstrated that the scour depth and deposition height increased with increasing energy head for each downstream slope condition. Among the three particle sizes, coarse gravel shows the lowest scour depth and the highest deposition height. For the 1:2 slope, the coarse gravel particle size was 62% and 75% less resistant to scouring than the medium gravel and granule particles, respectively. For the 1:3 slope case, this was 31% and 46%, and for the 1:4 slope case, this was 39% and 49% less than the medium gravel and granule size particles, respectively.

Scouring is one of the most important factors in the destruction of bridge piers. One of the ways to reduce scouring depth is to use a slot in the bridge pier. In this research, the Flow 3D model was used to simulate the effect of a slot with the same dimensions in two positions parallel to the bed and close to the water surface. The tests were performed at two relative speeds of 0.87 and 0.92. Uniform and non-cohesive bed sediments with a geometric standard deviation of 1.4 and an average diameter of 1 mm were used. The results showed that the slot created in the pier of the bridge weakens the eddies around the pier and is effective in reducing scour depth. The slot close to the surface, on average, about 6%, and the slot parallel to the bed, about 26%, are effective in reducing the maximum scour depth compared to the control pier. Also, with the increase of Froud number from 0.376 to 0.380, scour depth has increased by 11% on average.

Scour around bridges present a severe threat to the stability of railroad and highway bridges. Scour needs to be monitored to prevent the bridges from becoming damaged. This research studies the feasibility of using green laser for monitoring the scour around candidate railroad and highway bridges. The laboratory experiments that provided the basis for using green laser for underwater mapping are also discussed. The results of the laboratory and field experiments demonstrate the feasibility of using green laser for underwater infrastructure monitoring with limitations on the turbidity of water that affects the penetrability of the laser. This method can be used for scour monitoring around offshore structures in shallow water as well as corrosion monitoring of bridges.

Hydraulic structures at river crossings, especially culverts in ephemeral streams, are susceptible to damage during floods due to culvert scour, caused by various factors. It is essential to implement preventive measures to ensure the longevity and safety of these structures. This paper aims to present a comprehensive review of the factors influencing local scour downstream of culverts, offering a thorough understanding of this phenomenon. Consequently, a thorough review of the experimental studies and their corresponding outcomes documented in the literature is conducted. The analysis is divided into two main sections. The first section discusses dimensional analysis, while the second section delves into the key parametric factors affecting scouring, including flow regime, scour time, and experimental studies documented in the literature. The methods used in the second section are categorized into three distinct categories: channel and culvert dimensions, flow conditions, and sediment characteristics. This article not only provides a platform for researchers to conduct laboratory research but also assists hydraulic engineers in identifying crucial factors in culvert design. [ABSTRACT FROM AUTHOR]

Inclined pile foundations are commonly adopted in the support of wharf, harbor, bridge, and wind turbine structures. In the context of offshore wind turbines, inclined piles are typically arranged symmetrically around a circle with an elevated pile cap above sea level, referred to as an elevated pile-cap foundation. However, limited research exists on the impedances of inclined pile foundations with elevated pile caps. In this study, a theoretical model was developed that incorporates a homogeneous soil half-space and an inclined pile foundation with an elevated pile cap. The pile and soil half-space were modeled as Euler-Bernoulli beams and linear-elastic continuum, respectively. The soil's contribution to the pile's dynamics was represented by the receptance matrix, established at discrete interactions points along the pile's embedded section. The effects of the rake angle and scour depth on the dynamic impedances of the inclined pile foundation with an elevated pile cap were investigated. It was observed that the peak frequency of impedance shifts to a lower value as the scour depth increases; whereas the peak frequency shifting effect is less prominent when the rake angle changes. The impedance of the elevated pile-cap foundation is more sensitive to the pile's rake angle compared to the scour depth. [ABSTRACT FROM AUTHOR]

Scour around bridges present a severe threat to the stability of railroad and highway bridges. Scour needs to be monitored to prevent the bridges from becoming damaged. This research studies the feasibility of using green laser for monitoring the scour around candidate railroad and highway bridges. The laboratory experiments that provided the basis for using green laser for underwater mapping are also discussed. The results of the laboratory and field experiments demonstrate the feasibility of using green laser for underwater infrastructure monitoring with limitations on the turbidity of water that affects the penetrability of the laser. This method can be used for scour monitoring around offshore structures in shallow water as well as corrosion monitoring of bridges. [ABSTRACT FROM AUTHOR]

Numerous offshore wind turbines (OWTs) with bucket foundations have been installed in seismic regions. Compared to the relative development of monopiles (widely installed), seismic design guidelines for bucket-supported OWTs still need to be developed. Moreover, scour around bucket foundations induced by water–current actions also creates more challenges for the seismic design of OWTs. In this study, a simplified seismic analysis method is proposed that incorporates the soil–structure interaction (SSI) for the preliminary design of scoured bucket-supported OWTs, aiming to balance accuracy and efficiency. The dynamic SSI effects are represented using lumped parameter models (LPMs), which are developed by fitting impedance functions of the soil–bucket foundation obtained from the four-spring Winkler model. The water–structure interaction is also considered by the added mass in seismic analysis. Based on the OpenSees 3.3.0 platform, an integral model is established and validated using the three-dimensional finite element method. The results indicate that the bucket-supported OWT demonstrates greater dynamic impedance and first-order natural frequency compared to the monopile-supported OWT, which has an increased seismic response. Seismic spectral characteristics and intensities also play an important role in the responses. Additionally, scour can change the bucket impedance functions and the frequency characteristics of the OWT system, leading to a significant alteration in the seismic response. Scour effects may be advantageous or disadvantageous, depending on the spectral characteristics of seismic excitations. These findings provide insights into the seismic response of bucket-supported OWTs under scoured conditions. [ABSTRACT FROM AUTHOR]

Tsunamis continue to pose an existential threat to life and infrastructure in many coastal areas around the world. One of the risks associated with tsunamis is the formation of deep scour holes around critical infrastructure and other coastal buildings, compromising their structural integrity and stability. Despite its importance, tsunami-induced scour is still given limited and simplified consideration in design guidelines for coastal structures. To further improve the understanding of tsunami-induced scour processes, and thus provide the basis for safer design of coastal structures, novel large-scale laboratory experiments have been conducted. The experiments featured a unique combination of boundary conditions, including a square coastal structure on a sloping and dry sandy beach. Single broken solitary waves were used to simulate tsunami bores. The spatiotemporal scour development directly at the square column was monitored by a high-resolution camera system, allowing a detailed description of the highly dynamic flow and scour process. Differences in the scour process between the wave runup and drawdown phases are described, and maximum and final scour depths are given as a function of inundation depth, wave height, and distance of the column from the shoreline. The scour process is characterized by several distinct phases of varying intensity and scour rate, the sequence of which varies depending on the location on the sides of the column. It is shown that the drawdown phase has a large influence on the overall scour development, adding up to 58% to the scour depth obtained during the wave runup phase. As a result of significant sediment infilling during the drawdown phase, the maximum scour depths achieved during the drawdown phase are up to twice the final scour depths at the end of a test. This discrepancy between final and maximum scour depths is greater than in previous studies using a flat sediment bed. The results of this study therefore help to interpret scour depths measured during field investigations after a tsunami event and provide a basis for extending design guidelines for coastal structures. [ABSTRACT FROM AUTHOR]

Weirs and gates are hydraulic structures installed in canals, mainly for controlling the discharge. Because of their existence, unfavorable influences regarding the downstream bed configurations were recorded. This study experimentally explores the combined effect of simultaneous flow through a hydraulic device consisting of a V-notch sharped weir with an inverted V-shaped gate, aiming to minimize the downstream bed scour. Eighty-one runs were carried out using nine weir-gate models with three different vertex angles. The tests were executed considering three upstream and three downstream water depths. A V-notch weir with an angle of 120º was tested under similar hydraulic conditions and was used for comparison. The results revealed that the length of backflow was increased by the decrease in weir angle under a fixed 120° gate angle. The bed configurations were sensitive to gate angle. The combined device showed a significant decrease in bed disturbances regardless of the angles used compared to the traditional V-notch weir. Simple formulas were developed to predict the scour parameters. [ABSTRACT FROM AUTHOR]