Abstract:An improved corridor constraint and IPSO-DPSA algorithm were proposed to solve the problem of morphological distortion of the dispatching line in the reservoir operation optimization process. Based on the hybrid algorithm of particle swarm optimization and dynamic programming successive approximation, this method optimizes the evolution process by introducing improved corridor constraints, special individual evolution mode, external elite set strategy, making the solution set as close as possible to the Pareto-optimal front of the multi-objective problem. The case study of the multi-objective optimization problem of the scheduling graph of the Chitan Reservoir shows that the algorithm can effectively control the morphological distortion of the dispatching line in the optimization process, and has good optimization performance.

Abstract:The wetted perimeter method, Tennant method, Tessman method and month-by-month minimum ecological runoff calculation method were used to calculate the ecological flow respectively. The flow required for fish breeding and spawning was applied to verify the rationality of the four methods. The results show that the Tennant method, Tessman method, and month-by-month minimum ecological runoff calculation method can ensure the minimum flow required for the fish breeding and spawning at the Zumuzu cross section and all the four methods can ensure the minimum flow required at the Dajin section. Tennant method is recommended from March to August and the wetted perimeter method is suggested to use from September to February. The minimum ecological flow process can meet the requirements of fish and habitat protection, and has the smallest impact on human water intake, which can provide reference for the determination of ecological flow.

Abstract:Based on the historical monitoring data from 1960 to 2017, the evolution of chloride concentration in the Dongping Lake was analyzed, and the mechanism of chloride concentration change was discussed. The results show that chloride concentration in the Dongping Lake has been on the rise since 1960, especially since November 2015 after the implementation of the east route of the South-to-North Water Diversion Project. The chloride concentration decreases significantly due to heavy rainfall during the flood season. Before the implementation of the east route of the South-to-North Water Diversion Project, the chloride concentration was mainly affected by the inflow river, saline-alkali soil and shallow groundwater, and after the water diversion, it was mainly affected by saline-alkali soil and shallow groundwater. Therefore, by rebuilding or expanding the salt drainage ditch and cut-off ditch, adding anti-seepage and slope stabilization project, and controlling the pool level of the Dongping Lake, etc. , it is safe as an important hub for the east route of the South-to-North Water Transfer Project and an important water source for the West-to-East Water Transfer Project in Shandong Province.

Abstract:Flow characteristics of serial side weirs in a water distribution well under different inflow discharges were studied based on a 3D numerical simulation of turbulence, in which the free-surface was modeled by VOF method. The results show that evident difference of flow division characteristic exists between low and high discharges. Under low inflow discharge, the impact of adjacent side weirs is larger and the water lever along the distribution well centerline is little with relatively irregular unit discharge. Under high inflow discharge, the impact of adjacent side weirs is weak and the water lever along the distribution well centerline is a backwater curve. According to the characteristic of discharge coefficient, the side weir can be divided into two categories, and the relationship between the corresponding discharge coefficient and the relative head was established, which can be used to predict each weir’s discharge and the overall discharge diversion effect. This study can provide basis for engineering design, safe and efficient operation of water distribution wells in sewage treatment plants.

Abstract:Taking a rockfill dam as a research object, the collapse modes of flood overtopping were considered. The flood process of rockfill dam break was calculated by DB-IWHR model under extreme conditions of the combination for flood limit water level, checked flood water level, checked flood discharge and multi-year average inflow. Flood evolution process was simulated using MIKE 21 to assess the downstream risk of flood inundation by taking the maximum discharge processes of historical floods of tributaries encountered with the flood peak of the main stream. The Centianhe Dam was selected as an example, in which different combinations of inflow floods and dam erosion features were determined according to the reservoir capacity and rockfill material parameters. The results show that the proposed dam break and flood routing models can effectively simulate the process of dam break and the characteristic of flood inundation risk in the downstream region. Finally, suggestions for safe operation of the dam are put forward and plans for flood avoidance and personnel transfer are correspondingly formulated.

Abstract:In order to study the problem of site vibration induced by flood discharge of high dams, a method combining finite element numerical simulation and hydraulic model test is proposed to calculate the site vibration response. Taking a domestic project as an example, the vibration response of the concerned area under different working conditions was calculated. The influence of flood discharge and flood discharge scheduling mode on the site vibration was analyzed, and the propagation law of vibration wave under different rock conditions was revealed. The results show that the life of the surrounding residents cannot be affected by any kinds of flood discharge methods of the project. The larger the discharge, the greater the vibryation response of the downstream site can be. When the flood discharge conditions of the three spillway tunnels are the same, the No. 2 tunnel discharge is the most unfavorable. Under the same flood discharge conditions, the vibration response of the four tunnels is less than that of the designed opening. The main reason for amplifying the vibration wave in the model range is the difference nature of the rock mass around the fault, the existence of faults further increases the amplification effect.

Abstract:In order to investigate the variation of shear characteristics of rock fractures after seepage erosion and its evolution mechanism, shear tests were conducted on two groups of specimens in different states. One group was fresh and the other was after a 120 h seepage-erosion experiment. The variations of shear test curve, peak shear strength, residual shear strength and initial shear stiffness were analyzed. The results show that the shear stress-strain curves and normal displacement-shear displacement curves of rough fractures after seepage erosion change little compared with the fresh rough fractures, but the shear contraction displacement decreases and the shear dilation displacement increases. The seepage erosion increases the surface roughness of the fracture, leading to an average increase of the peak shear strength by 8. 83%, but with no significant change in the residual shear strength, indicating a declined ratio of residual strength to peak strength. The initial shear stiffness increases by 10. 84% on average after seepage erosion.

Abstract:Taking the engineering groups built in tidal reaches of the Yongjiang River Basin in Ningbo City as an example, the cumulative influence of bridge and wharf groups on flood propagation under typical flood and tidal conditions was studied based on the numerical model of Delft3D. The results of the influence of a single type and two types of engineering groups on flood level and flow velocity were contrastively analyzed. The results show that bridge and wharf groups have a cumulative influence on flood propagation, which is located in the reaches of the Yongjiang River upstream of Ningbo University, the Fenghua River and the Yao River. In the region of water level (velocity) both increase or decrease by the single type of bridge or wharf groups, the water level (velocity) has a higher variation amplitude by the combined action of bridge and wharf groups, but the changed value is not a simple superposition of the influence amplitude of two engineering groups. In the region of water level (velocity) changes in opposite by the single type of bridge and wharf groups, the variation amplitude of water level (velocity) is reduced by the combined action of bridge and wharf groups.

Abstract:The pseudo-potential lattice Boltzmann method (LBM) with a tunable surface tension source term was applied to study a droplet impacting on a moving thin film. The effects of Reynolds number, Weber number and liquid film velocity on the evolution process of the liquid crown were analyzed. The results show that the initial liquid film velocity aggravates the kinematic discontinuity at the upstream liquid crown after impacting, leading to a dramatic deformation of the upstream liquid crown. However, the kinematic discontinuity in the liquid film at the downstream liquid crown is reduced, which can suppress the evolution of the downstream liquid crown. The upstream crown height increases with the increase of Reynolds number, but does not change with Weber number. The downstream crown height decreases with the increase of both Reynolds number and Weber number but the evolution process of the crown radius is not affected. Furthermore, with the increase of the initial liquid film velocity, both the upstream and downstream crown heights decrease, but the radius of the crown increases. The simulation results of LBM agree well with the experimental results and theoretical analysis, which proves that the pseudo-potential LBM is a robust and effective tool to simulate the process of a droplet impacting on a liquid film under complex conditions.

Abstract:A two-dimensional numerical wave flume model was set up using the open source CFD software OpenFOAM to solve the continuity and momentum equations for viscous incompressible fluid based on fluid finite volume method. The numerical wave flume was verified by the experimental data of wave elevations, pressures and the bottom velocity from the physical model test of a baffle structure under regular waves. The transmission coefficients and the bottom velocity of the battle structure in different incident wave conditions were computed and compared alone with the relative depth. It shows that the transmission coefficients can be less than 0. 5 if the relative depth is greater than 0. 8. The bottom velocity of the oscillating flow can obviously be enhanced with the increase of the relative depth and extra attention should be focused on by engineering technicians.

Abstract:Taking the frame seawall in Wenzhou as an example, the finite element strength reduction method was used to analyze the influence of dense-row piles and filling height of the downstream slope on the deformation and stability of the seawall. The results show that compared to double-row pile cases, the horizontal displacement of the piles near the top of piles in single-row pile cases decreases, the overall stability safety factor of frame seawall decreases substantially. With the increase filling height at the downstream slope, the horizontal displacement of the dense-row piles increases continuously with the maximum increase rate at the top of piles, and the overall stability safety factor of the frame seawall decreases sharply.

Abstract:In view of the high adiabatic temperature rise and rapid hydration heat release rate of pumped concrete, a hydration temperature rising rate model based on hydration degree (hydration degree model) was constructed combined with the adiabatic temperature rise tests. Parameter inversion of hydration degree model, hyperbolic model, single exponential model and compound exponential model was performed and compared by the ABC (artificial bee colony) algorithm. The hydration degree model was applied to the fitting of five sets of adiabatic temperature rise test results, and the four temperature rise models were performed a feedback simulation analysis on the temperature field of a concrete test block in a pump gate project in Shanghai. The simulated results show good agreement with the experimental data. Hydration degree model can fully describe the characteristics of the hydration heat release in different stages, and the parameters are fitted in steps, which can greatly avoid the over-fitting problem when too many parameters exist. The model can provide more accurate temperature simulation results for intelligent temperature control during the construction of pumped concrete structures.

Abstract:A new economical type of pre-cast flashboard spur dike with consolidation piles is introduced, of which the main anti-overturning component is the consolidation pile. The overturning resistance characteristics of the consolidation piles were intensively investigated by indoor experiment and 3-D scanning technology on a fine sand foundation bed. The results show that the grouting agent can react with the ambient soil and a large rigid bulbous body around the toe of the pile forms after the consolidation of the injected grouting agent, which can significantly improve the anti-overturning force of the pile. The toppling process of the consolidation pile can be divided into four different stages, including slight-tilting stage, tilting stage, toppling stage, and out-pulling stage. The anti-overturning force is mainly affected by the structural geometry, penetration depth, soil properties, grout volume and injection rate of the grouting agent. Formulas of the critical horizontal anti-overturning force and critical angle of inclination were proposed based on dimensional analysis and experimental data fitting.

Abstract:Dredged silt has the characteristics of high moisture content, difficult consolidation and large volume, and polluted by heavy metals, leading to slow drying, hard utilization and soil hardening, which is unbeneficial of plant growing. To solve the above problems, dredged silt polluted by copper, lead, and cadmium was taken as a study object, which was mixed with fiber, lime, fly ash, kaolin, sodium silicate, sodium carbonate, ferric sulfate and magnesium sulfate. Then polluted silt stabilization and planting tests were performed. The results show that the permeability coefficients after soil solidification are increased by 2 or 3 orders of magnitude. Eight leaching amounts of heavy metals are obviously decreased, which can meet the national standards. The kale grown in solidified silt has faster growing rate with healthier leaf appearance. The optimum proportion of planting is 10% mixtures of fly ash, lime, kaolin, and fiber combined with 6% mixtures of sodium carbonate and ferric sulfate. Using the optimum scheme, the kale has lower heavy metal contents with higher reduction rate of heavy metal leaching amounts compared with other four groups, which can absorb more nitrogen and phosphorus.