Abstract:The research progress on wave attenuation of coastal ecological vegetation in China was reviewed. Wave dissipation vegetation was taken as the starting point to analyze the effects of stiffness, distribution and inhomogeneity of vegetation on the wave attenuation effect. Then, taking hydrodynamic input conditions as the hitting-point, the similarities and differences of wave dissipation methods under different wave conditions were summarized. Finally, the comparison between traditional breakwater and ecological vegetation wave attenuation was made to discuss the differences in coastal conditions, wave attenuation mechanisms, ecological benefits, engineering maintenance, etc. It is suggested that the problems of plant stiffness, distribution and non-uniformity can be taken as the direction of future study.The combination of wave attenuation by breakwater and ecological vegetation should be attempted, considering the functions of disaster prevention and mitigation, and ecological protection. Keywords: ecological vegetation; wave dissipation test; ecological breakwater; research progress 〖FL

Abstract:The research status of ecological operation of cascade power stations in the upper reaches of the Yangtze River was reviewed. It is considered that the existing research is insufficient in the aspects of research breadth, determination of ecological operation goals, effective interaction between models and experimental research, the impact of climate change, and ecological operation management. It is necessary to further expand the research scope of ecological operation in the upper reaches of the Yangtze River Basin, deepen the research on the formation mechanism of ecological problems related to hydropower development, strengthen the research on the quantitative, intelligent and simulation technology of ecological operation models, and establish a mutual feedback mode between model test and prototype test. According to the formation mechanism of relevant ecological problems, the relationship between ecological operation model and engineering practice, and the impact of climate change, a more specific, scientific and targeted ecological operation scheme can be formed to better promote the construction and operation of conventional ecological operation mechanisms in the upper Yangtze River Basin. Keywords: Yangtze River Basin; cascade hydropower stations; ecological operation; review 〖FL

Abstract:The main factors of rock-concrete interface shear strength deterioration were reviewed, including chemical erosion, temperature effect and load impact. The existing macro and micro test methods of rock-concrete interface were summarized. The degradation models of interface shear strength considering the mechanical properties of rock and concrete, the characteristics of interface roughness, the initial cohesion of interface, and normal external stress were summarized. Given the rock-concrete interface in hydraulic engineering is prone to corrosion degradation under high hydraulic gradients, problems including the shear strength degradation mechanism, shear strength degradation model, and interface crack propagation are proposed to be further studied. Keywords: permeable corrosion; rock-concrete interface; shear strength; deterioration model 〖FL

Abstract:Aiming at the problem of water resources shortage in China, the evaluation index system of regional water resources carrying capacity was constructed in the four dimensions of water resources, virtual water, ecological environment and social economy, in which the new concepts and characteristics of virtual water were combined. Variable weight method was used to determine the weight of evaluation index. The improved matter-element extension model of water resources carrying capacity under the influence of virtual water was constructed and applied to 9 cities in Guangdong-Hong Kong-Macao Greater Bay Area. The results show that the water resources are overloaded in Shenzhen, critically overloaded in Guangzhou and Foshan, and weakly bearable or bearable in other cities. The model evaluation results can provide reference for regional water resources optimal allocation. Keywords: virtual water;water resources carrying capacity;improved matter-element extension model; variable weight method 〖FL

Abstract:Based on the daily meteorological data from 19 meteorological stations in Liaoning Province from 1970 to 2020, the standardized precipitation evapotranspiration index

Abstract:Based on 5 consecutive days of high-frequency measured data of flow velocity, tide level, water depth and Chlorine at three stations in upstream, midstream and downstream of the Qiantang River estuary, the salt flux for each tidal cycle was calculated by the flux mechanism decomposition method. The dynamic mechanism of saltwater intrusion under strong tide was studied. The correlation between salt flux and tidal range, the phenomenon of water and salt transport separation, and the enlightenment of anti-salt were analyzed. The results show that the salt transport in the lower reaches of the estuary is mainly controlled by the Stokes effect, while the upstream is dominated by advection transport and tidal pump transport, and the vertical shear has a very limited impact on salt transport. In the upper reaches of the estuary the phenomenon that the water body is transported downstream and the salt is transported upstream exist, which can strengthen saltwater intrusion in the upstream reaches. The net salt flux to the land has a strong positive correlation with the tidal range. The tidal range can be used as an important indicator for saltwater intrusion and anti-salt scheduling. Keywords: saltwater intrusion; flux mechanism decomposition method; tidal range; Qiantang River estuary 〖FL

Abstract:To better make the sensor system of sluice floor voiding monitoring on soft foundation to achieve the best balance between costs and performance index, at the same time to solve the problem of traditional effective independence method and damage sensitivity method that cannot consider both modal linear independence and damage sensitivity, a multi-objective approach combined with effective independence method and damage sensitivity method is proposed to optimize the sensor arrangement.To solve the problem of modal data redundancy, the node similarity function is introduced. The influence of the sluice floor voiding on the modal parameters is explored from the aspect of hydrodynamics, and the modal flexibility is determined as the voiding sensitive characteristic quantity. Taking the maximum 2-norm of the Fisher information matrix as the goal, the maximum off-diagonal element of the MAC matrix is used as the evaluation index. The optimal arrangement of measuring points is then realized, and the results of the measuring points have been applied to the voiding inversion of the sluice floor. The results show that the meanrelative error of the recognition accuracy after the sensor optimization is decreased from 28.3%, 15.8%, 39.3% to 1%, 1.9%, 15.9%, respectively, indicating that the reliability of the method is verified. Keywords: sluice on soft foundation; floor voiding; optimal sensor arrangement; effective independence method; damage sensitivity method; modal flexibility 〖FL

Abstract:Aiming at the problem of the influence of seepage hysteresis effect on the accuracy of seepage monitoring models of earth-rockfill dams, considering the difference between the effect of reservoir water level and precipitation on the seepage flow of earth-rockfill dams under different hysteresis effects, the normal distribution function and Rayleigh distribution function were introduced to quantitatively describe the effect of reservoir water level and precipitation on the seepage lag, and a monitoring model of seepage pressure of earth-rockfill dam considering the lag effect was constructed. In order to solve the model parameters, based on the sparrow search optimization algorithm, the optimal values of the model hysteresis parameters and regression coefficients were obtained. Taking a core wall earth-rockfill dam as an example, the accuracy of the seepage monitoring model with and without considering different hysteresis effects were compared and analyzed. The results show that the seepage pressure monitoring model constructed in this study has higher accuracy, closer to the actual situation, and can quantitatively evaluate the hysteresis effect of seepage flow in earth-rockfill dams, which can be used for safety state evaluation of seepage flow and health monitoring of earth-rockfill dams. Keywords: earth-rockfill dam; seepage flow; monitoring model; hysteresis effect; sparrow search algorithm 〖FL

Abstract:On the basis of comprehensive analysis of the characteristics and operating conditions of mountain levees, combined with industry standards and related professional research, a mountain levee safety evaluation system with 17 evaluation indexes was constructed, including rainfall intensity, channel shape, dike material, dike permeability, historical danger, etc. The indexes were weighted subjectively and objectively by improved analytic hierarchy process and CRITIC method based on average difference, and an improved combined weighted cloud model evaluation method was proposed based on game theory. The proposed improved method was applied to the safety evaluation of a mountain levee project in Qingyuan. The calculation and analysis show that the safety score of the mountain levee project is 70.6, and the safety level is basic safety, which is consistent with the actual situation of the project. The reliability and rationality of the levee safety evaluation method proposed in this paper is then verified, and it can be used for the levee safety evaluation in mountain area. Keywords: embankment in mountain area; safety evaluation; cloud model; combination weighting; analytic hierarchy process; CRITIC method 〖FL

Abstract:In order to predict the impact of tailings dam break on the downstream, an improved DB-IWHR model based on the modified Shields curve was established by modifying the calculation of critical shear stress. Through the example of Tangjiashan barrier dam, the higher accuracy of dam break and discharge process evolution of the improved DB-IWHR model was verified. A numerical analysis model for the impact of a tailings dam break was established by using the improved DB-IWHR model and a two-dimensional hydrodynamic model. The submerged range, depth and arrival time of dam break on the downstream were obtained, and the impact of the tailings dam break on the downstream key sensitive points was predicted.The sensitivity of the improved model to the initial width of the breach and erosion parameters was analyzed. The results show that the improved DB-IWHR model, combined with the two-dimensional hydrodynamic model, can better simulate the dam break process of tailings pond and the evolution process of sediment discharge flow. The results conform to the general law of sediment flow movement. The model is not sensitive to the initial breach width, but it is sensitive to erosion parameters. Keywords: tailings pond; dam-break influence; DB-IWHR model;critical shear stress; two-dimensional hydrodynamic model 〖FL

Abstract:Based on the hydraulic model test method, using the hydraulic model of the Yellow River Guxian Water Control Project with a geometric scale of 60, the characteristics of water jet and the pressure characteristics at the floor of the plunge pool of six flip bucket shapes were studied, including continuous, narrow-slit, differential, dovetail, straight edge narrow-slit dovetail and curved narrow-slit dovetail shapes. The experimental results show that the continuous flip bucket water jet has a continuous and concentrated form.The narrow-slit flip bucket of a 30° jet angle does not show a longitudinally stretched water jet shape, with a large internal and external edge trajectory distance and a small water inlet width, and the impact pressure and the fluctuating pressure intensity are larger. The differential flip bucket water jet presents the morphological characteristics of stratified and split strands, the water inlet width becomes larger, and the impact pressure and fluctuating pressure intensity are reduced. The dovetail flip bucket water jet is longitudinally shaped like a broom. The water jet has a large diffusion area, and diffuses, aerates, and dissipates friction fully in the air with a greatly increased water inlet width. No impact pressure occurs in the time-averaged pressure, and the maximum fluctuating pressure intensity is reduced by 59.5%, 69.8%, and 39.4%, respectively, compared with the continuous, narrow-slit and differential flip buckets. The horizontal contraction and longitudinal stretching effects of the curved narrow-slit dovetail flip bucket is better than that of the straight-sided narrow-slit dovetail flip bucket, and the lateral contraction is conducive to the turbulence of the water near the dam and weakens the turbulence of the water in the second dam area. The dovetail flip bucket is conducive to the stability of the plunge pool floor and the downstream energy dissipation and erosion prevention. It has certain reference value in flip bucket shape selection for similar high gravity dams. Keywords: gravity dam; ski-jump energy dissipation; flip bucket shape; water jet characteristics; time-averaged pressure; fluctuating pressure 〖FL

Abstract:Baihetan Hydropower Station has a huge capacity of single unit with the layout of two units sharing a common tailrace surge chamber and tailrace tunnel.Since various and complex flow pattern sexist in the tailrace tunnel, analysis and control of hydraulic disturb transition is an important prerequisite to ensure safe and stable operation of the system. Based on the Method of Characteristic for pressurized water conveyance system, the characteristic implicit format of free-surface flow analysis was introduced, and the mathematical model of the free-surface-pressurized flow in tailrace tunnel was derived.The stability analysis and regulation model of water conservancy and hydropower system was constructed considering the frequency regulation mode of the governor and stability analysis of hydraulic disturb was analyzed. The results show that the transition process of hydraulic disturb in Baihetan Hydropower Station is stable with the effect of various flow patterns in tail tunnel system. With the increase of unit operating head, the tailwater system transits from completely pressurized state to free-surface-pressurized flow state and free-surface flow state.The length of pressurized part decreases, and the water level of the tailwater surge chamber and the dynamic process of tailwater system decay faster, which is conducive to improve the regulation performance of the disturbed units. Both the two different unit types meet the stability requirements on hydraulic disturb of water conveyance and hydropower system, and the regulation performance of the disturbed units is basically the same. Keywords: water conservancy and hydropower system; hydraulic disturb; stability analysis; free-surface-pressurized flow;Baihetan Hydropower Station 〖FL

Abstract:Considering the structural characteristics and operation characteristics of high-arch dams, and based on the shortcomings of existing research in the aspects of fractional-order element models, physical and mechanical parameter inversion of concrete dams, and deformation safety monitoring development of concrete dams, a research proposal is developed based on the fractional-order modeling theory to scientifically monitor the deformation behavior of high arch dams in operating conditions. Fractional-order numerical simulation of deformation characteristics of high arch dams and fractional-order model-based deformation safety monitoring approaches of single observation point and observation point group are two interrelated scientific problems of the research proposal. The main research process is as follows, fractional element model construction, physical and mechanical parameter inversion, deformation monitoring of single observation point, deformation monitoring of observation point group.Basic to in-depth, simple to complex, phenomenon to essence, theory to application, local to whole, one-dimensional to multidimensional are the research principles. Three key scientific and technical problems should be solved to realize the research proposal, which are fractional-order element model of accelerated rheology of high arch dams in three-dimensional high stress state, elastic and viscoelastic parameter inversion of fractional element model, and fractional-order analysis model of time-dependent deformation of high arch dams. Keywords: fractional-order modeling; high arch dam; deformation behavior; safety monitoring; numerical simulation; parameter inversion 〖FL

Abstract:A deeply excavated expansive soil slope of a canal section with high groundwater level in the Nanyang basin of a water transfer project was investigated. According to the data of geological survey and the data during the construction and operation periods, the appearance disaster characteristics of the canal slope after deformation were summarized. The depth and the geometry of the potential shear deformation zone of the deformed body were described. The deformation mechanism was comprehensively analyzed from the internal and external factors such as engineering geology and hydrogeology

Abstract:In order to find an alternative admixture of fly ash in roller compacted concrete

Abstract:Aiming at the problems of steel pipe segmentation in long-distance water transfer projects, such as low efficiency, poor accuracy, and difficulty in checking model data, building information modeling

Abstract:In order to realize the simulation of the filling progress of core walls in ultra-high core rockfill dams in high-altitude area, the influences of material supply for warehouse surface construction, meteorological characteristics of high-altitude area, and construction parameters of warehouse surface on the construction progress of core wall filling were comprehensively considered. A simulation model of the core wall filling progress of ultra-high core rockfill dams in high-altitude area with self-adaptive adjustment of simulation parameters of meteorological forecast, material supply intensity, and construction machinery configuration, etc. was established. The simulation model was applied to filling progress control of the core wall of an ultra-high core rockfill dam. The results show that the deviation between simulation results and the actual construction progress is 2.17%, which is more in line with the actual construction situation than those of the traditional simulation method, and the model can be used for on-site simulation analysis of construction progress. Keywords: ultra-high core rockfill dam; self-adaptive control theory; progress simulation; meteorological forecast; high-altitude area 〖FL

Abstract:In order to realize reasonable analysis of dam deformation trend, a comprehensive analysis method integrated with Kalman filter, fractal and long short-term memory neural network