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The flow occurring at the bottom of a polycrystalline diamond compact (PDC) drill bit involves a complex process made up of drilling fluid and the drilled rock cuttings. A thorough understanding of the bottom-hole flow conditions is essential for accurately evaluating and optimizing the hydraulic structure design of the PDC drill bit. Based on a comprehensive understanding of the hydraulic structure and fluid flow characteristics of PDC drill bits, this study integrates computational fluid dynamics (CFD) with rock-breaking simulation methods to refine and enhance the numerical simulation approach for the liquid–solid two-phase flow field of PDC drill bits. This study further conducts a comparative analysis of simulation results between single-phase and liquid–solid two-phase flows, highlighting the influence of rock cuttings on flow dynamics. The results reveal substantial differences in flow behavior between single-phase and two-phase conditions, with rock cuttings altering the velocity distribution, flow patterns, and hydraulic performance near the bottom-hole region of the drill bit. The two-phase flow simulation results demonstrate higher accuracy and provide a more detailed depiction of the bottom-hole flow, facilitating the identification of previously unrecognized issues in the hydraulic structure design. These findings advance the methodology for multiphase flow simulation in PDC drill bit studies, providing significant academic and engineering value by offering actionable insights for optimizing hydraulic structures and extending bit life. [ABSTRACT FROM AUTHOR]

Abstract Background Climate change associated with droughts has led to widespread forest decline. Hydraulic and carbon-related performances are key physiological processes for the tolerance of trees to environmental changes, yet our current understanding of such physiological performances for forest decline is still limited. Here, we investigated the hydraulic and carbohydrate performances of healthy and declining (canopy dieback) trees in temperate larch (Larix principis-rupprechtii) plantations. Results Relative to healthy trees, the higher native percentage loss of xylem hydraulic conductivity and lower xylem hydraulic conductivity indicated a deterioration of the integrity of the hydraulic system in declining trees. Additionally, the comparable Huber value, intrinsic water-use efficiency, and leaf mass per area between healthy and declining trees suggest a relatively profligate water-use strategy by declining trees. Declining trees had lower nonstructural carbohydrate concentrations in leaves, branches, and twigs but higher soluble sugars concentration in fine roots than conspecific healthy trees. Conclusions Overall, declining trees in larch plantations would be more vulnerable to drought due to the higher risk of hydraulic dysfunction and carbohydrate depletion.

Objectives: Horizontal wells can effectively improve the economic benefits of shale oil and gas development. However, as the horizontal section extends, the rock debris transport efficiency of the PDC drill bit gradually decreases, which can lead to bit balling in severe cases. Consequently, it is costly to directly improve the hydraulic structure of PDC bits. This paper uses a multi-physics field coupling numerical simulation method to analyze the influence of the coupling of different drilling process parameters and drill bit structure parameters on the bottom hole flow field and improves the drill bit hydraulic structure to enhance the rock debris transport efficiency of the PDC drill bit. Methods: Using COMSOL multi-physics field coupling simulation software, a geometric model of the bottom hole flow field of the horizontal well was established. The low Reynolds number k-ԑ model was employed to simulate the coupling of fluid flow and particle motion in the fluid, and iterative calculations were performed. The low Reynolds number k-ԑ model could adapt to different Reynolds number regions, especially the influence of molecular viscosity in the viscous bottom layer in the low Reynolds number region on the mixed phase flow. Parameters close to the actual drilling conditions were used to set the boundary conditions of the coupling model, and the grid independence of the coupling model was verified to reduce simulation error. Changes in the bottom hole flow field and the movement of rock debris by the PDC bit in a horizontal well under different drilling fluid displacement, PDC bit rotation speeds, and rock debris particle sizes were analyzed. Results: In the numerical simulation results of the coupling model, the following findings were observed: (1) From the flow velocity distribution diagram on the bottom hole wall, it was observed that the hydraulic energy distribution on the bottom hole wall became more uniform with an increase in displacement. When the displacement is 35 L/s, the flow velocity distribution effect on the bottom hole wall is optimal. However, the low-speed flow area of drilling fluid at the bottom hole cannot be completely eliminated by increasing displacement. In the comparative analysis of the retention of bottom hole rock debris at different displacements, an increase in displacement can reduce the impact of gravity on the cleaning of bottom hole rock debris. However, once the displacement reaches a certain level, the degree of cleaning of bottom hole rock debris changes relatively little. (2) In the lateral drilling fluid flow line at different rotation speeds, the flow rate gradually increases with an increase in rotation speed, causing a significant deviation in the flow state of the drilling fluid. When comparing and analyzing the accumulation of rock debris particles and the average velocity of rock debris particles, it was found that as the drill bit rotation speed increases, the fluctuation of the average velocity of rock debris particles also gradually increases. Although increasing drill rotation speed raises the average velocity of rock debris particles, it does not improve the migration efficiency of rock debris beyond a certain rotation speed. When the rotation speed is 240 r/min, the rock debris migration efficiency is the lowest. (3) In the comparative analysis of the average speeds of different rock debris particles, the farther they are from the bottom of the well, the faster the speed of large-size rock debris decays due to gravity. The speed change of small-size particles is relatively stable, but the average speed of rock debris particles with mixed particle sizes falls in the middle. (4) With roughly the same displacement area, increasing the number of drill bit nozzles from six to eight significantly reduces the amount of rock debris retention. (5) Compared with the equal diameter nozzle combination, the combination of a large inside and small outside nozzle reduces the transport efficiency of large particle rock debris due to the weakening of the drilling fluid flow rate. However, the flow rate in the central area of the combination of a small inside and large outside nozzle is reduced, which fails to form a strong pressure difference, resulting in an overall reduction in rock debris migration efficiency. Conclusions: Increasing the drilling fluid displacement improves the hydraulic energy and the rock debris transport efficiency at the bottom hole wall, but after the displacement increases to a certain level, it has little effect on the change in the degree of rock debris cleanliness at the bottom of the well. The mismatch between the high speed of the drill bit and displacement increases the average speed of the rock debris, but does not improve rock debris transport efficiency. Within a certain range of rock debris particle sizes, gravity has a relatively small impact on larger-size rock debris due to the influence of rotational force and turbulent kinetic energy. The transport efficiency of larger-size rock debris is higher than that of smaller-size rock debris. However, the farther away from the bottom of the well, the greater the impact of gravity on larger-size rock debris, resulting in greater velocity attenuation than that of smaller-size rock debris. According to the bottom hole flow field state under different drilling process parameters, the number of drill bit nozzles increase from six to eight under roughly the same nozzle displacement area, the hydraulic energy distribution is more uniform and the transport efficiency of rock debris improves. Meanwhile, compared to non-equal diameter nozzle combinations, equal diameter nozzle combinations perform more balancedly.

The results of geophysical and geological field studies of the soil bed of the Zagorsk PSPP-2 during the leveling of the powerhouse are reported. It is shown that the mechanical properties of the bed of a hydraulic structure are improved by leveling injections. The possibility of changing the properties of the soft-soil bed of a structure is confirmed. [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]

High Froude-number open-channel flows can entrain significant volumes of air, a phenomenon that occurs continuously in spillways, in free-falling jets and in hydraulic jumps, or as localized events, notably at the toe of hydraulic jumps or in plunging jets. Within these flows, turbulence generates millions of bubbles and droplets as well as highly distorted wavy air–water interfaces. This phenomenon is crucial from a design perspective, as it influences the behaviour of high-velocity flows, potentially impairing the safety of dam operations. This review examines recent scientific and engineering progress, highlighting foundational studies and emerging developments. Notable advances have been achieved in the past decades through improved sampling of flows and the development of physics-based models. Current challenges are also identified for instrumentation, numerical modelling and (up)scaling that hinder the formulation of fundamental theories, which are instrumental for improving predictive models, able to offer robust support for the design of large hydraulic structures at prototype scale. [ABSTRACT FROM AUTHOR]

Copyright of Diamond & Abrasives Engineering is the property of Zhengzhou Research Institute for Abrasives & Grinding and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the severe environment, damages often occur early on hydraulic structures, even in parts submerged in water. This paper presents a study on how the load-bearing capacity of the hydraulic structure is enhanced, once it has been rehabilitated by underwater concreting. A column has been considered as the hydraulic structure. The damaged part of the column was submerged in water, hence, it was repaired by the underwater concrete. For this, the tremie casting method was taken into account. The compression test results pointed out that the damaged column after rehabilitation had a similar loadbearing capacity to the undamaged column, while the not rehabilitated column had reduced load-bearing capacity by 20%. The failure mode of the damaged column after the rehabilitation presented longitudinal cracks along the body of the column, which is similar to that occurred in the undamaged column. Besides, there was no sign of delamination between the protective layer and the existing concrete of the damaged column, proving the feasibility of the selected casting method and concrete mixture for rehabilitation. [ABSTRACT FROM AUTHOR]

The article discusses one of the dangerous geological processes that can cause serious damage to hydraulic engineering construction objects. Using the example of Zagorsk Pumped Storage Power Station-2 (ZaPSPS-2), it is shown how the initial development of suffosion when filling the downstream pool of the hydraulic structure led to the formation of a weakened zone, subsequent destruction, and removal of suffosion-unstable rocks in the contact zone with the reinforced concrete structure. [ABSTRACT FROM AUTHOR]

In recent years, Erbil has faced an elevated risk of floods due to climate change and incorrect land development design and management. To tackle this issue, this study uses Hydrologic Engineering Center River Analysis System (HEC-RAS) software to address flood inundation and reduction by constructing dikes. This involved using a digital elevation model (DEM) in the study area (Mass Village) east of Erbil. The study delineated the catchment area and employed watershed modelling system (WMS) software. Furthermore, Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS) software was used to create a flood hydrograph, which the HEC-RAS software used to estimate flood inundation areas, velocity, and water levels. The study identified water surface areas and velocities prone to flooding in the urbanised area, with water depths ranging from 0 to 5 m. The model was rerun after the construction of the dikes, resulting in water depths ranging from 0 to 7.2 m upstream of the dikes. The modelling results indicated a water depth of 0 m downstream of the dike (protected area), demonstrating that the dike's construction successfully reduced flooding in the urbanised area.

The flow occurring at the bottom of a polycrystalline diamond compact (PDC) drill bit involves a complex process made up of drilling fluid and the drilled rock cuttings. A thorough understanding of the bottom-hole flow conditions is essential for accurately evaluating and optimizing the hydraulic structure design of the PDC drill bit. Based on a comprehensive understanding of the hydraulic structure and fluid flow characteristics of PDC drill bits, this study integrates computational fluid dynamics (CFD) with rock-breaking simulation methods to refine and enhance the numerical simulation approach for the liquid–solid two-phase flow field of PDC drill bits. This study further conducts a comparative analysis of simulation results between single-phase and liquid–solid two-phase flows, highlighting the influence of rock cuttings on flow dynamics. The results reveal substantial differences in flow behavior between single-phase and two-phase conditions, with rock cuttings altering the velocity distribution, flow patterns, and hydraulic performance near the bottom-hole region of the drill bit. The two-phase flow simulation results demonstrate higher accuracy and provide a more detailed depiction of the bottom-hole flow, facilitating the identification of previously unrecognized issues in the hydraulic structure design. These findings advance the methodology for multiphase flow simulation in PDC drill bit studies, providing significant academic and engineering value by offering actionable insights for optimizing hydraulic structures and extending bit life.

An integrated model that considers multiphysics is necessary to accurately analyze the time-dependent response of hydraulic structures on soft foundations. This study develops an integrated superstructure–foundation–backfills model and investigates the time-dependent displacement and stress of a lock head project on a soft foundation during the construction period. Finite element analyses are conducted, incorporating a transient thermal creep model for concrete and an elasto-plastic consolidation model for the soil. The modified Cam-clay model is employed to describe the elasto-plastic behavior of the soil. Subsequently, global sensitivity analyses are conducted to determine the relative importance of the model parameters on the system's response, using Garson's and partial derivative algorithms based on the backpropagation (BP) neural network. The results indicate that the integrated system exhibits pronounced time-dependent displacement and stress, with dangerous values appearing during specific periods. These values are easily neglected, highlighting the importance of integrated time-dependent analysis. Construction activities, particularly the backfilling process, could cause a sudden change in stress and significantly impact the stress redistribution of the superstructure. Additionally, the mechanical properties of concrete have a significant impact on the stress on the superstructure, while the mechanical properties of the soil control the settlement of the integrated system. [ABSTRACT FROM AUTHOR]

This study discusses the role of hydraulic simulation in solving issues in designs of island hydraulic structures. It also presents many examples of previous research on this topic; also highlighted are issues whose solution requires special scientific research on two- and three-dimensional models. [ABSTRACT FROM AUTHOR]

Follett et al. (2020, https://doi.org/10.1029/2020gl089346) demonstrated that a large wood jam can be modeled as a porous obstruction with momentum loss proportional to the number, size, and packing density of the logs and jam length. Poppema and Wüthrich (2024, https://doi.org/10.1029/2023gl106348) incorporated uniform flow Froude number, broadening the scope of our work. Here, we demonstrate that Froude number can be directly introduced to equations in the main body of Follett et al. (2020, https://doi.org/10.1029/2020gl089346), without requiring uniform flow. Based on this, we show that a managed increase in upstream depth is possible for conditions below a critical discharge, in which equilibrium upstream depth over uniformly distributed jams can be adjusted with inter‐jam spacing. This design could retain water in low flow conditions, allowing jams to act independently above critical discharge. Finally, we suggest that log orientation can be included in our model by varying both drag coefficient and frontal area perpendicular to the flow. Plain Language Summary: Logjams can increase upstream water surface elevation, creating an upstream pool with slower, deeper water. We demonstrated that the increase in water depth upstream of a logjam is related to the number, size, and packing density of the logs and the jam length. In this Reply to a Comment by Poppema and Wüthrich (2024, https://doi.org/10.1029/2023gl106348), we clarify that our prediction of upstream water depth does not depend on river steepness and sediment size. We go on to show that a progressive increase in upstream depth is possible under some low flow conditions, if logjams are spaced closely enough so that each logjam is impacted by its downstream neighbor. This arrangement could be used to design nature‐based solutions for water retention during drought. In response to Poppema and Wüthrich (2024, https://doi.org/10.1029/2023gl106348), we clarify the observed agreement between our model and a similar model by Schalko et al. (2018, https://doi.org/10.1061/(asce)hy.1943‐7900.0001501) and suggest that the effect of log orientation can be included in our model by varying the drag coefficient in addition to the frontal area perpendicular to the flow. Key Points: Response to Comment by Poppema and Wüthrich (2024, https://doi.org/10.1029/2023gl106348), which re‐writes backwater rise equations in Follett et al. (2020, https://doi.org/10.1029/2020gl089346) using Froude numberFollett et al. (2020, https://doi.org/10.1029/2020gl089346) does not require river slope & roughness, as implied in Comment. We show use of Froude number with main text equationsA series of jams can generate a progressive increase in water depth, allowing for water storage during low flows below a critical discharge [ABSTRACT FROM AUTHOR]

This study focuses on the development of unique geopolymer-based composites made using industrial byproducts and waste materials. The first test variable was the compressive strength grade, where conventional concrete specimens with ordinary Portland cement (OPC) and GPC specimens having three target design strengths (20, 30 and 40 MPa) were prepared and tested. All specimens were tested at different ages, which is the second variable of the study, where early ages (3 and 7 days) and mature age (28 days) were adopted. It is worth mentioning that both geopolymer and concrete samples had the exact quantities of filler and binder materials. Then, the specimens were tested following the procedure of standard ASTM C1138 approach under-water abrasion tests, which were conducted at 6 intervals of 12 h each. The recorded abrasion results revealed higher abrasion losses for specimens with lower design strengths regardless of the type of concrete. Besides, the influence of the sample's age on enhancing the abrasion resistance was more apparent in conventional concrete samples than geopolymer ones since the last gained their design strength early, about three days. The GPC specimens exhibited lower abrasion losses compared to their corresponding OPC ones revealing a better abrasion resistance. The difference was the highest at the age of 3 days due to the early strength development of GPC. The abrasion resistance enhancement of GPC specimens compared to their corresponding OPC ones at 3 days was 72% for the design strength of 20 MPa and around 55% for the higher design compressive strengths.

The purpose of the present study is to examine the influence of baffles presence at downstream system on weir gate hydraulic response. Two baffles configuration (triangle and angle shapes) are installed in bed flume. Two different spacing are used between the baffles and two different directions for baffles are also adopted. The study tries to investigate the variation in upstream Froude number, downstream Froude number, Reynolds number, actual discharge, discharge coefficient, downstream average water depth and the hydraulic system efficiency which is expressed as function of downstream water depth. It has been shown that the number of baffles has a direct and significant impact on flow hydraulic characteristics of weir-gate structure regardless of the spacing between baffles and the direction of baffles related to flow. Baffles number and spacing have essential impact on the water flow velocity of system and this impact leads to increase the flow resistance. The results clarify that the upstream Froude number, downstream Froude number, Reynolds number, actual discharge and discharge coefficient are decreased with the increase in baffles number except the average downstream water depth which increases with increase in baffles number. The efficiency of hydraulic system gives a good indicator for using baffles with weir-gate structure. At the end this paper shows a fruitful result of efficiency. This experiment run condense on the baffle’s numbers and directions with respect to the water flow direction at the downstream regime. So, the rises in the water level relies on the numbers and directions of the baffles as compare to the case without using baffles at the flume downstream region. The actual discharge and weir-gate discharge coefficient are more sensitive to the increase in the baffles’ numbers and the baffles direction with respect to the water flow direction. [ABSTRACT FROM AUTHOR]

Water resources are of elementary economic and environmental importance, and the observed global transformations as well as regional environmental conditions necessitate activities aimed at providing an optimal amount of water at different levels. One such solution is hydrotechnical infrastructure that permits the precise control of the amount of water in the catchment. This paper presents results concerning changes in the water flow in the Główna River in Poland before (1955–1983) and after (1984–2021) the construction of the Kowalski Reservoir. In the former period, there were no changes in water flow, and the obtained results were not statistically significant (p 0.05). In the period after the construction of the reservoir, a decreasing trend in monthly flow was observed in December, April, July, September, and October. Moreover, a decrease in 1, 3, 7, and 90 day maximum flow was observed. For maximum 30 day flow, the changes were below the threshold of the adopted significance level. Moreover, minimum flow in the period after the construction of the reservoir showed no significant decreasing trend. In hydrological terms, the reservoir served its purpose by contributing to the stabilisation of the water flow. This information is important from the point of view of an increase in retention and corresponds with a broader programme conducted in the territory of Poland. In the context of the construction of further reservoirs, it is important to investigate the current range of changes in water circulation for objects of the type already functioning in the environment, constituting an actual point of reference. [ABSTRACT FROM AUTHOR]

Polymermineral material "PMM" has multiple cycles of swelling and drying. It does not decompose under soil, biological and atmospheric influences and is environmentally safe. By adding the proportion of up to 30 g/kg of PMM additive to soil and tamping, we get a waterproofing material that can be used in urban construction and water supply. Taking into account the fact it is not always technically possible to carry out high-quality ramming when repairing channel walls, the task was to conduct an experimental study in order to determine the total moisture content of the mixture of PMM additive with soil. Experimental results of laboratory studies show that when PMM is added to the soil at a ratio of 30 g/kg under evaporation conditions, the mass of excess water in the substrate increases with time.

Roads, bridges, sewer systems, and other infrastructure failures often result from climate-related incidences along with extensive socioeconomic impacts including human life losses. Infrastructures with frequent experiences are usually replaced, altered, or adopt different Low-Impact Development, Best Management Practice (LID-BMP) approaches. Adapting and recovering from the damages cost a substantial budget. This study reviewed Multicriteria Decision Analysis (MCDA) i.e., risk analysis, hydroclimatic analysis, and Life Cycle Cost-Benefits Analysis (LCC-BA) in the Climate-Resilient Infrastructure Development (CRID). It was carried out following the protocols and guidelines for systematic literature review. Throughout the review, 1D is acclaimed as the best and most suitable to identify critical flooding zones and nodes within the drainage network. The study showed that integrated GIS and 1D hydrodynamic modelling are reliable in waterlogging characterisation and locating suitable floodwater regulating areas, while 2D analysis was found ideal for appropriate damages assessment over different inundation depths, duration, return periods and different climate scenarios. Indeed, about 62.5% of the studies have analysed the LID-BMPs whereby 23.2% integrated hydrologic-hydrodynamic and LCC-BA, and identified optimum performances at different levels. The study showed that, the cost of climatic adaption in infrastructure development results in the benefits optimisation and the effects-attributed cost minimisation. Besides, several studies acclaim the rising of weather-related extremes due to a gradual climate variation. Henceforth, there is a need for adaptation, most importantly, incorporating the changes in infrastructure development, and the necessity of integrating MCDA in CRID. Further, machine learning and deep learning approaches are recommended to overcome challenges and limitations associated with the current multi-dimensional numerical models and big data era demanding huge time and computational power.

Hydraulic structures can be a promising place for tidal energy extraction due to the high flow velocities, easy access to the power grid and easy access for maintenance. However, quantification of the impacts of a tidal power plant in a hydraulic structure is not straight forward. In 2015 a pilot plant consisting of an array of five Tocardo tidal turbines was installed in the Eastern Scheldt Storm Surge Barrier in the Netherlands. This pilot was accompanied by monitoring studies to verify that the operation of the plant had no adverse impact on the barrier and its surroundings. This paper presents the assessment of the hydraulic impact of the tidal power plant in the storm surge barrier based on an analysis of water level and current measurements, combined with numerical modeling and followed by an assessment of the environmental impact with emphasis on the effects on the intertidal areas in the estuary. This validation approach by a pilot plant is imperative to understand the interaction between tidal turbines and the hydraulic structure on the local scale. This understanding gives extra credibility to the predictions of the extrapolated large-scale and large array assessments which will always be fully numerical. [ABSTRACT FROM AUTHOR]

Poplar plantations can acclimate to drought stress in semi-arid areas, where the variation of stand age may result in varied water adaptation strategies presented as hydrodynamic performance. In this study, nine mature Populus simonii Carr. individuals were targeted as sampling objects in plantations characterized to three stand ages: young (9 yr), middle-aged (17 yr), and near-mature (29 yr) stages in a semi-arid area of western Liaoning, Northeast China. Hydraulic traits were investigated as parameters of leaf pressure-volume curves, xylem embolism vulnerability curves, hydraulic structure, and wood density (WD). Results showed that osmotic potential (Ψtlp) and relative water content at the turgor loss point and cell-wall bulk elastic modulus were lowest in middle-aged stands (−2.19 MPa; 86.71%; 13.75 MPa). Stem and leaf-specific hydraulic conductivity (Ks and LSC) were all the highest in middle-aged stands. Xylem embolism vulnerability (P50) and lethal water potential of trees (P88) increased with the growth of stand age. Young stands faced minimal risk of hydraulic failure according to the stomatal safety margin (SSMtlp, Ψtlp minus P50), which was consistent with the comprehensive evaluation results of the principal component analysis. WD was related to P88 (R2= 0.51; p < 0.05). P50 was related to drought avoidance traits Ψtlp (r = 0.76; p < 0.05) but not to xylem efficiency (Ks). Overall, WD can be an excellent proxy for hydraulic safety monitoring. Young and middle-aged Populus simonii populations are more adaptable to drought conditions than near-mature populations, and near-mature stands should receive intermediate cuttings to avoid exposure to drought stress. [ABSTRACT FROM AUTHOR]

The sky-jump spillway is an economical solution to return water to rivers, but an unsuitable flip bucket design might jeopardize the spillway, the dam, or other appurtenant works. Characterizing in advance, during the design phase, the position, size, and shape of the erosion basin would be useful to ensure that water flow is returned to the river in a safe way. Also, it would be useful for the safety assessment throughout the exploitation phase when erosion has not yet reached its maximum extension. Here, based on experimental laboratory work, the location, size, and shape of the erosion basin are analyzed, and a procedure is given for its characterization according to the design of the sky-jump spillway. [ABSTRACT FROM AUTHOR]

Concrete is widely used in various large construction projects owing to its high durability, compressive strength, and plasticity. However, the tensile strength of concrete is low, and concrete cracks easily. Changes in the concrete structure will result in changes in parameters such as the frequency mode and curvature mode, which allows one to effectively locate and evaluate structural damages. In this study, the characteristics of the curvature modes in concrete structures are analyzed and a method to obtain the curvature modes based on the strain and displacement modes is proposed. Subsequently, various indices for the damage diagnosis of concrete structures based on the curvature mode are introduced. A damage assessment method for concrete structures is established using an artificial bee colony backpropagation neural network algorithm. The proposed damage assessment method for dam concrete structures comprises various modal parameters, such as curvature and frequency. The feasibility and accuracy of the model are evaluated based on a case study of a concrete gravity dam. The results show that the damage assessment model can accurately evaluate the damage degree of concrete structures with a maximum error of less than 2%, which is within the required accuracy range of damage identification and assessment for most concrete structures. [ABSTRACT FROM AUTHOR]

A design system suitable for hydraulic structural modeling of inland river ship locks is developed based on the parametric modeling advantages of BIM technology. The system is composed of 29 sub-modules with the functions of modelmaking, automatic arrangement and rapid modification. The problems in insufficient specialization of platform software, low modeling efficiency and difficulties in guaranteeing the quality of the modeling are solved by using the software architecture conforming to the design process. The system has been successfully applied to practical projects and has been verified with good effect and broad prospects. [ABSTRACT FROM AUTHOR]

Discordance and concordance play a significant role in the hydraulic response for the flume, open channel, hydraulic structure, and flow field measurement. Bed discordance and bed concordance are regarded as common problems in open channels. Discordance is the dominant one, which could have an effect on the hydraulic structure that is constructed inside the channel. This paper deals with the impact of bed flume discordance on hydraulic flow characteristics at the weir-gate downstream hydraulic regime. Four configurations with different lengths and heights of the bed flume discordance are adopted here to investigate the impact of these configurations on the hydraulic characteristics. In addition, one configuration of the bed flume concordance is adopted to compare with the other four configurations. At downstream, the average water depth becomes dimensionless by dividing by upstream water depth, vertical distance between weir and gate, length of downstream, length of concordance, and length of discordance in order to evaluate the inequality in the distribution of Froude number. On one hand, certain results appear strongly between Reynolds number and Froude number at downstream, actual discharge and flow velocity at downstream, flow area past the gate and Froude number at downstream. On the other hand, there was a complex dramatic relation between the weir-gate discharge coefficient and Froude number at downstream. Overall, the study shows that there is a good relationship between specific energy, water depth, and flow speed. Doi: 10.28991/HIJ-2022-03-03-09 Full Text: PDF

A preliminary assessment of the strength of earth dams under dynamic loads is one of the most important tasks associated with the design of such massive hydraulic structures. The present study is devoted to predicting the deformation of earth dams under the influence of strong earthquakes, which are possible in the immediate vicinity of the dam location. Recently, a number of large earthquakes have occurred in the world, which led to severe destruction and indicate high seismic risks associated with the potential instability of existing large earth dams. Under intense seismic impacts, the response of the dam depends on various factors, including its geometric dimensions, as well as the type of structure. A number of existing dams, which were designed and built according to the normative rules of their time, do not take into account modern real operating conditions, in particular, potential seismic loads. This article examines the influence of these factors on the stability and strength of earth dams, taking into account the real properties of the soils of the dam body and the base of the bottom of the hydraulic structure in accordance with the new regulatory requirements. On the basis of the proposed mathematical model, verification calculations for the strength and stability of such earth dams located in the seismic zone were carried out. To assess seismic safety of high earth dams built and operating in regions of complex climatic conditions, including frequent earthquakes, the proof of the method choice capable of reliable and valid results in terms of adopted assessment criteria is required. Correct mathematical model choice ensures, on the basis of computations, strength indices of the hydraulic structure under study. In particular, comparison and analysis of calculated date obtained in case of the plane calculation model and spatial model with the field measurements results and spectral analyses of the Sarsang dam accelerograms showed the suggested calculation models provided reliable strength indices results for the earth dams in the operating reservoirs. The use of more complex models of the physical and mechanical properties of the dams’ soil leads to reliable results that are in good agreement with real field tests.

Fishways are essential hydraulic structures to ensure the migration of fish and other aquatic organisms in the area of cross structures in river systems. In this context, the present study focuses on vertical slot fishways with specific geometries and their discharge coefficients. A comprehensive data analysis was performed, aiming on the development of new fitting parameters in conjunction with their respective approaches for practical design procedures. In addition, validity ranges and parameter dependencies were defined. Using the new fitting equations, it is possible to determine accurate discharge coefficients to design functional strutures for a defined validity range. Results show that discharge coefficients are highly dependent on the basin geometry. Comparing newly developed fitting parameters have shown that investigated fitting equations can be used to determine discharge coefficients. However, it should be noted that newly developed fittings can only be applied in practice for the defined range of validity for investigated exemplary geometries. [ABSTRACT FROM AUTHOR]

Floating dikes have several advantages over spur dikes including less influence on riverine sediment transport, bed topography, and ecosystems, and a good adaptability to fluvial conditions. Despite these advantages, floating dikes have not been used in many river regulation schemes due to the limited understanding of the 3D flow structures around floating dikes. In this study, a series of experiments were conducted to investigate the 3D flow structures around floating dikes. Results show that, after installing a floating dike on one side of a flume, the surface water flow is deflected to the opposite side of the flume, and a backflow develops around the outer and downstream side of the dike, where both the vertical turbulent intensity and the absolute magnitude of the Reynolds stress are relatively large. Due to the blocking effect of the dike, the cross-sectional area decreases, causing an increase in velocities below and alongside the dike, as well as a decrease in velocities upstream of the dike. Increasing the submerged depth or length of the dike results in an increase in flow velocity adjacent to the dike, as well as an increase in the vertical or lateral scale of the backflow. On the contrary, increasing the dike thickness leads to a weakening or disappearance of the backflow, along with a decrease in the acceleration rate of flow adjacent to the dike. [ABSTRACT FROM AUTHOR]

Subcritical flows over highway and railway embankments, commonly encountered during flood events, can be treated like submerged flows over trapezoidal-shaped weirs. In earlier studies, the equation of the submerged-flow discharge for such types of weirs was developed as a function of the degree of submergence and free-flow discharge. However, the application of this equation in practice requires a pre-determined discharge from experiments performed under free-flowconditions. In this study, a discharge equation was deduced from the streamwise momentum balance equation, which overcomes the drawback of the previous approaches. The results of the validation demonstrated that the proposed equation is capable of predicting the submerged-flow discharge of a trapezoidal-shaped weir within ±6.0% of the measured value. Furthermore, the most prominent features of the submerged overflows were examined by systematically analyzing the experimental data. For such flows, the free-surface and bed-pressure profiles are self-similar only over the upstream face of the weir. Results of this investigation confirmed that the degree of submergence and the slope of the downstream weir face significantly affect the characteristics of the submerged flow, but the effect of the latter on the non-modular discharge is marginal. [ABSTRACT FROM AUTHOR]

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This paper describes a method for determining the initiation and unstable toughness of fully graded concrete of arbitrary specimen size. The method first predicts the initiation and peak loads of concrete specimens of any size, as well as crack length-to-height ratios based on the fracture test results of concrete specimens with limited sizes or crack length-to-height ratios. Then, combined with the fracture extreme theory, the fracture toughness of concrete with varying size or crack length-to-height ratios is determined. Finally, in order to verify the applicability of the method, it is used to calculate the fracture toughness of small aggregate concrete and fully graded concrete with different sizes or crack length-to-height ratios, and its prediction accuracy is evaluated through indices such as mean absolute percentage error, root mean square error and reliability index a15. The results show that the proposed method can meet the needs of practical engineering applications and can provide theoretical basis for the optimization of the fracture test method of fully graded concrete and the determination of fracture parameters in crack stability or propagation analysis. [ABSTRACT FROM AUTHOR]

Water plays a pivotal role in various agricultural and industrial activities through the construction of hydraulic structures like dams, canals or hydroelectric power station. Geophysical logging and tracer study form an integral part of Non Destructive Technique (NDT) towards delineation of probable zones of seepage through hydraulic structures. Application of radioisotope(s) as a tracer has made it a versatile tool in deciphering the path of seepage in integration with other techniques. Tritium (3H) is one such radiotracer which has been used extensively in groundwater hydrology over the past few decades. With the same principle, tritium is used as a tracer for seepage detection studies through hydraulic structures. In this paper a few intricate problem(s) of seepage through hydraulic structure(s) is briefed, where along with chemical tracer(s), tritium was used to determine the direction of seepage, permeability of formation etc.