Spur Dike Research Articles

Counter-toppling force on the composite pile with injected grout for a precast spur dike

In this study, a new design of a precast spur dike is described, and a composite pile with injected grout was introduced to enhance the toppling stability of the spur dike. To investigate the toppling process and counter-toppling force of the pile with injected grout, toppling tests of the composite pile with injected grout in sedimentary beds were conducted in the laboratory. The results indicated that the grouting agent reacted with the soil and formed a bulbous wedge, which significantly improved the counter-toppling force of the pile. Four different stages (incipient stage, slow toppling stage, plastic stage, and pull out stage) in the deformation process of the composite pile were observed and described herein. The horizontal counter-toppling force was found mainly influenced by the pile geometry, penetration depth, soil properties, grout volume, and grout injection rate of the grouting agent. Empirical equations for the shape of the wedge and the horizontal forces at the incipient and critical instants of the pile toppling were developed.

Prediction of Maximum Scour Depth near Spur Dikes in Uniform Bed Sediment Using Stacked Generalization Ensemble Tree-Based Frameworks

The scouring process near spur dikes could jeopardize the stability of riverbanks. Thus, accurate estimation of the maximum scour depth near spur dikes is crucial in river engineering. However, due to the complexity of the scour phenomenon around these structures, it has been a challenge to accurately estimate the maximum scour depth. Few efforts have been made to develop a machine learning (ML) approach for such a purpose. In this study, two novel multilayer stacked generalization frameworks are developed to model the scour depth near a spur dike in a uniform sediment condition. Stacked tree-based frameworks consist of three standalone ML approaches, including multivariate adaptive regression spline, multigene genetic programming, and kernel extreme learning machine as the first layer and the boosting regression tree (BRT) and bagging regression tree (BGT) as meta learners. A total of 186 data points were collected from previous experimental studies, and 32 flume experiments were further conducted under clear water conditions at the Indian Institute of Technology (IIT) Roorkee Laboratory in this study. The performances of the models were assessed using various statistical metrics [e.g., correlation coefficient (R), root-mean-square error (RMSE), and mean absolute percentage error (MAPE)], graphical criteria, and some existing empirical equations. The modeling results demonstrated that the stacked BRT and BGT frameworks were superior to all the standalone ML approaches (R=0.9786, RMSE=0.1654, and MAPE=11.68 for BRT; and R=0.9742, RMSE=0.1831, and MAPE =11.29 for BGT). This finding was also confirmed by a comparison between the empirical correlations and the artificial intelligence models. In addition, the sensitivity analysis proved that the mean sediment size ratio (L/d50) was the most influential variable in estimating the scour depth near spur dikes.

Analysis of local hydrodynamic characteristics of wading buildings under tidal action

The tidal bore is a kind of nonlinear strong discontinuous flow that has a great impact on the wading buildings. During the tidal wave propagation, the local water flow structure of the wading buildings changes significantly. In order to analyze the evolution characteristics of local hydrodynamics of wading buildings under tidal action, a small-scale mathematical model of tidal current is established, and the local hydrodynamic changes of different forms of spur dikes and piers are studied. The results show that the flow velocity fluctuations in front of the non-submerged shoal dam and the dam head are more fluctuating than the submerged spur dikes, and the influence of the tidal dam on the submerged shoal dam area is more severe; the square piers under the tidal wave The turbulent energy and backwater recirculation zones are larger than circular and streamlined piers.

Scientific substantiation of dredging volumes on the Ob river - the most important source of water resources in Western Siberia

The purpose of the work is to substantiate the volume of dredging operations intended to ensure navigation on the Ob River. It is particularly important to find an option to reduce the impact of dredging on the river as a source of water resources. The method for determining the optimal dredging is based on theoretical research in the field of channel formation. A retrospective analysis showed the presence of different intensity dredging stages: superintensive dredging in the 80s, extremely low stage in the 90s, and the optimal one, which began in the 21st century. Limiting riffles were determined on the basis of the channel stability criteria. Dredge tracks were outlined and the volumes of dredging operations were calculated to create and maintain guaranteed track dimensions on all transit river fairways. For each of the riffles, options for the location of capital and operational dredge tracks are proposed. In total, it is necessary to develop 79 capital tracks, 86 obligatory annual and operational tracks, to erect 21 longitudinal dams and 31 series of spur dikes. The volume of capital dredge tracks in their various versions should be about 8 million m3, and the minimum required volume of operational tracks in various versions is about 7.6 million m3. The main dredging operations fall on the sections of the Upper and Middle Ob. The volumes are assessed as very significant, but absolutely necessary to stabilize the route of the fairway.

Experimental and numerical investigation of flow over a spillway bend with different combinations of permeable spur dikes

Abstract In this paper, the effects of different combinations of permeable spur dikes installed in the bend section of spillway on flow characteristics and energy dissipation rate were experimentally and numerically investigated. The results indicate that the permeable spur dikes installed in the spillway bend appreciably contributes to the improvement on the water surface uniformity, and the water surface uniformity can reach 90.13% with three permeable spur dikes installed in the bend. The permeable spur dike can lead to different degrees of decrease in the time-averaged longitudinal velocity in each zone of spillway bend. Different from previous study, no circulation zone is formed upstream and downstream of permeable spur dike due to the presence of permeable holes, and the flow upstream of permeable spur dikes could be divided into three distinctly different flow modes according to dye tracing. The presence of permeable spur dikes causes the concentration of TKE zone at concave bank of the spillway bend, except for TKE zone immediately next to the bottom plate. The TKE first increases and then decreases with the increase in the vertical distance from the bottom plate of the spillway bend, exhibiting a typical parabolic distribution. The energy dissipation rate in the spillway bend with permeable spur dike was calculated using a modified integral method, and the dissipation rate can reach as high as 21.08% with three spur dikes installed in the bend.

Numerical and Experimental Investigation of the Effect of Spur Dikes Placement Position on the Hydraulic and Erosion Conditions of Lateral Intakes

Numerical and Experimental Investigation of the Effect of Spur Dikes Placement Position on the Hydraulic and Erosion Conditions of Lateral Intakes

Experimental Study on Flow Structure around Spur Dikes of Different Types

As water damage phenomenon of spur dike exists generally, spur dike must be maintained in order to ensure its regulation function, but its structure changed in the process of maintenance. In order to find out flow structure around the spur dike of different pattens, through generalized flume model tests, variation characteristics of water surface profile and flow velocity around the spur dike of five different pattens were analysed. The results show that the straight head had a greater influence than hook head spur dike on the water surface profile, circular cross-section had smaller effects than trapezoidal cross-section spur dike on the water surface profile; Velocity of Choke area and contraction order from large to small is trapezoidal cross-section and fan straight head dike, trapezoidal cross-section and arc straight head dike, arc section and arc straight head dam, trapezoidal cross-section and fan hook head dike, trapezoidal cross-section arc hook head dike; Cross section vertical velocity distribution from large to small is trapezoidal cross-section and fan hook head dam, trapezoidal cross-section and circular straight head dike, arc cross-section and circular straight head dam, trapezoidal cross-section and circular hook head dike.

Velocity Field and Turbulence Structure around Spur Dikes with Different Angles of Orientation under Ice Covered Flow Conditions

Spur dikes are well-known structures that are widely used in rivers and coastal regions. Depending on their types, sizes, and orientation angles, spur dikes can substantially change flow characteristics. Results of previous studies indicate that the presence of an ice cover in rivers can cause complicated flow structures. The present experimental study investigates velocity fields and turbulence structures in the vicinity of spur dikes under ice cover with different roughness coefficients. The spur dikes were set up at the following three angles of orientation, 90°, 60°, and 45°. Our results show that the strongest velocity fluctuation occurs immediately above the scour hole surface and very close to the dike tip. The increase in the dike angle toward upstream, the velocity component values increase, leads to a larger scour hole. Results show that an increase in dike angle of each 10° (from 45° to 90°) increases the scour depth between 5% and 10%, depending on flow conditions. Furthermore, the increase in the cover roughness coefficient and the blockage ratio of a spur dike leads to a further increase in turbulence kinetic energy and 3D velocity components values. The findings of this study imply that the appearance of an ice cover can increase turbulence intensities up to nearly 30%.

Experimental study on scour characteristics of the sheet-pile groin

Spur dike is widely used to protect river bank in hydraulic engineering. However, the scour around spur dike caused by narrowing flow is often too deep to induce the failure of dike. In this paper, a new type of spur dike: sheet-pile groin is developed and the scour characteristics around it are studied based on experiment. The experiment results show that, compared with the solid spur dike of the same size, the maximum scour depth near the head of the sheet-pile groin reduces by averagely 30% under the same flow conditions. The sheet-pile groin makes the water flow away from itself and the shoreline. When there is an over-dam flow on the top of the spur dike, the sheet-pile groin has a stronger protective effect on the beach behind it than the solid spur dike does. The scouring and silting features of the local riverbed around the sheet-pile groin benefit the stability of the spur dike and the protection of the coastal beaches.

Improving the 2D Numerical Simulations on Local Scour Hole around Spur Dikes

Local scour is a common threat to structures such as bridge piers, abutments, and dikes that are constructed on natural rivers. To reduce the risk of foundation failure, the understanding of local scour phenomenon around hydraulic structures is important. The well-predicted scour depth can be used as a reference for structural foundation design and river management. Numerical simulation is relatively efficient at studying these issues. Currently, two-dimensional (2D) mobile-bed models are widely used for river engineering. However, a common 2D model is inadequate for solving the three-dimensional (3D) flow field and local scour phenomenon because of the depth-averaged hypothesis. This causes the predicted scour depth to often be underestimated. In this study, a repose angle formula and bed geometry adjustment mechanism are integrated into a 2D mobile-bed model to improve the numerical simulation of local scour holes around structures. Comparison of the calculated and measured bed variation data reveals that a numerical model involving the improvement technique can predict the geometry of a local scour hole around spur dikes with reasonable accuracy and reliability.

Installation and adaptive management of T-shaped and L-shaped spur dikes to control bed deformation and diversify physical environment in rivers

This study concerns a method to install spur dikes in the Yodo River, for the purpose of bed deformation control and diversification of physical conditions around the spur dikes. The effects on the physical conditions around the installed spur dikes are evaluated, based on numerical analysis and field survey. The numerical analysis results show that, by installing spur dikes with a focus on hydraulic conditions of not forming sand bars, sediment deposition is suppressed in the main channel. The field survey results demonstrate that sediment deposition in the channel is also suppressed. By installing the spur dikes, some physical conditions around the installed spur dikes can be diversified. By installing spur dikes using large movable sandbags and changing their height after several years, it is possible to maintain the effect of the spur dike installation and diverse bed material conditions for a long period as adaptive management. (For example, by changing the height of the spur dikes 0.3 m lower, bed degradation is produced up to 0.5 m downstream of the spur dikes.) As a result, spur dike in case 8 (shape(c), height 0.7 m from average water level) is better for the present. After several years, changing the height of the spur dikes would be better.

Simulation of flow around a permeable dike using physical and 3D-CFD models

ABSTRACT In this research, complementary numerical and experimental physical models were conducted to investigate flow parameters around an isolated permeable spur dike using ANSYS FLUENT ver. 16.1 software. The volume of fluid method VOF with the help of CFD technique and the turbulence model was used to simulate the complex free-surface flow by applying a geometric reconstruction scheme. Two different mediums with different porosities were used, namely, gravel and glass beads. It was found that, for low flow rate values, there are no significant changes in the water profiles in both longitudinal and lateral directions for both media. Although for high flow rate values, the differences tend to be clearer. Results showed that there is a slight effect of the medium's properties if the dike width is less than 1/3 of width of the channel, in particular with low flow rate values. Good agreement was observed between the computational and the measured results for the water surface profiles. Also, there is an exact match between the lateral velocity distribution of gravels and glass beads. Downstream the dike, the lateral velocity profiles exhibit an S shape curve due to high velocity in the free flow and small flow velocity behind the porous dike. The results show good agreement between the CFD results and the experimental observations of the water surface profiles and velocity distribution according to the statistical analysis using some standard indexes error.

An Investigation on Human Activities in Shingen Bank Japan Centred on Spur Dike

River space is one of the precious open spaces that human beings can contact with nature. Respecting, complying with and protecting nature is the essence of river landscape construction. In the process of natural river construction, the spur dike is an indispensable element for the stability of river banks, the formation of natural environment of ecological system and human activities, and its various functions are widely recognized. In this study, the spur dike in the Shingen Bank is taken as the center to investigate the forms of riverside activities of residents on the spot, to understand the impression of residents on the river, and on this basis, to investigate the spatial structure characteristics along the river and its relationship with human activities, with a view to providing some help for future urban river and riverside space reconditioning.

Investigation and Analysis on the Function of Space Formation of Spur Dike for Around Shingen Bank Japan

The Shingen Bank is famous for its flood control in Japan. Spur dike is skilfully used in river management, which creates good conditions for the human activities. In this paper, using the representative of the river regulation buildings in the Shingen Bank as the object to analyze the space formation function of Spur dike and examine human activities at the water edge. Firstly, by analyzing the ecological function and utilization of Spur dike in river space, the relationship between the Spur dike and human activities is clarified. And then, the configuration method of spur dikes in the course of river management was put forward, which could provide reference for the management and landscape planning of the near natural rivers.

Numerical Simulation of Meandering Effects on Velocity Field and Separation Zone past a Spur Dike in Rigid Bed

This study presents a numerical model to simulate two-dimensional flow field near a vertical impermeable spur dike in a sine-generated rigid bed meandering channel. Comprehensive study of resultant velocity and separation zone past the spur dike on five different channels with meandering angles 0°, 15°, 30°, 45° and 60° were carried out and compared. The CFD model Nays 2D was used to simulate the flow field. Cubic- Interpolated Pseudo-Particle (CIP) method was used as finite difference method to analyze the advection terms. The study reveals that unlike straight channel, flow field and separation zone past the spur dike are influenced by the position of spur dike and angle of meandering. For meandering angle equal or greater than 60° and position of spur dike at s*=0.5 with reference to the straight rectangular channel from the upstream end on the right bank, significance of spur dike as a flow deflector does not prevail. With the same flow parameters and channel characteristics, the velocity amplification is maximum to angle of meandering equal to 30°.

Effect of T-shaped spur dike length on mean flow characteristics along a 180-degree sharp bend

Abstract An open channel flume with a central 180-degree bend with a rigid bed is designed to obtain a better understanding of the complex flow pattern around a T-shaped spur dike located in a sharp bend. The 3-dimensional velocities are measured by using an acoustic Doppler velocimetry under clear-water conditions. This study’s primary objective is to compare variations of the mean flow pattern along a 180-degree bend with a variety of T-shaped spur dike lengths. In order to do so, parameters such as streamlines, the maximum velocity distribution, and the secondary flow strength under the influence of three T-shaped spur dike lengths will be analyzed and then compared with the case where no spur dikes are implemented. The results show that with the spur dike placed at the bend apex, the mean secondary flow strength at that range increases by approximately 2.5 times. In addition, a 67% increase in the length of the wing and web of the spur dike leads to a 27% growth in the mean secondary flow strength along the bend.

Flow Dynamics Around Permeable Spur Dike in a Rectangular Channel

In this study, numerical simulations were performed to investigate the flow and turbulence characteristics of rectangular spur dikes with varying permeability using the Reynolds stress turbulence model developed by three-dimensional (3-D) numerical code FLUENT (ANSYS). In this research, both permeable and impermeable spur dikes were investigated with varying permeability (25%, 37%, 49%, 62%, and 74%) to show its effect on the flow structure. At zh=3.5 cm (where z is the maximum flow depth, and zh is mid of flow depth), 3-D flow velocities and depth-averaged velocities were measured in the horizontal plane. Different velocity profiles and contours, turbulent intensities (T.I), and turbulent kinetic energy (TKE) were analyzed at various selected positions. The findings indicate that an increase in the permeability of the spur dikes up to 74% had a reciprocal effect on the mean stream-wise velocity. Moreover, the recirculation regions created within the impermeable spur dike field decreased with increased permeability of spur dikes. The permeable spur dike head showed a significant decrease in T.I, and TKE compared to the impermeable spur dike. Therefore, to protect the spur dike head from severe turbulent flow during floods and reduce the spur dike field’s recirculation region, a permeable spur dike is preferred.

Experimental study of local scour around T-shaped spur dike in a meandering channel

Abstract A spur dike is mainly constructed as a river-training structure and is primarily used to prevent bank erosion. The restriction to flow caused by the construction of a spur dike promotes local scour around the structure. In the case of a dike placed in a channel bend, the scour becomes more aggressive. The literature review found that the research work related to local scour around a spur dike located in a meandering channel is very limited or minimal. Therefore, an experimental investigation was conducted to study the local scour process around a T-shaped spur dike placed at different locations along the outer bank (or concave) of a reverse-meandering channel. Non-dimensionalized empirical equations for temporal and maximum local scour depth were developed as the function of the Froude number of approach flow and spur dike location. It is observed that local scour around the dike increases with the increase in Froude number and location in the meander (measured from the entry to meander). The formulation for the maximum scour depth was further evaluated with the experimental data related to the 180° bend, from literature, and it was found that the proposed equation's application is very much limited.

Measurement and Characteristic Analysis of Turbulent Flow near Permeable Spur Dike

To disclose the turbulence features near a permeable spur dike, this paper measures the three-dimensional (3D) instantaneous velocity at different vertical lines and depths around the permeable spur dike through acoustic Doppler velocimetry (ADV). The relative turbulence intensity and Reynolds stress were calculated for each measuring point, and the distribution features of different turbulence structures were analyzed along the water depth. Experimental results show that: within the length of the dike, the turbulence intensity and Reynolds stress in the downstream of the dike are much greater than those in the upstream. In the downstream of the dike, the turbulence intensity in the root and body regions peaks in the dike crest layer, but that at other positions minimizes in that layer (but peaks on the water surface or river bottom). In the upstream, ejection and sweeping are the dominant turbulence structures; the two structures also dominate near the free layer at the bottom in the downstream; outward and inward interactions dominate near the dike crest layer in the downstream.

Evaluation of impact of spur dike designs on enhancement of aquatic habitats in urban streams using 2D habitat numerical simulations

Although channelized urban streams provide aesthetic and economic value, they reduce biodiversity and alter the habitats of aquatic organisms. Spur dikes not only prevent the erosion of riverbanks, but also generally improve aquatic habitats. River 2D is widely used to analyze the aquatic habitats. However, the model often faces a challenge of lacking sediment and riverbed evolution module, which is difficult to predict the change of aquatic habitats. In this study, a depth-averaged habitat model, which couples a two-dimensional water-sediment shallow water model with an Instream Flow Incremental Methodology (IFIM), was provided to evaluate the impact of spur dikes on the improvement of aquatic habitats in the Jinjiang Stream in Chengdu, China.The potential value of aquatic habitats was quantitatively evaluated by a weighted useable area (WUA). Under different spur dike scenarios, the WUA is greater than under natural conditions, that is, the construction of spur dikes is beneficial for improving the habitat of aquatic organisms in urban rivers. In addition, further analysis from the simulation results shows that the three-spur dike scenario with a flow of 40 m³/s represents the best layout of spur dikes. Our study indicates that adjusting the spur dike layout is an effective instrument to enhance aquatic habitats, and can provide a certain reference for water ecological restoration and river management.