Aiming at the problem of failure path analysis of high arch dams, the current numerical simulation methods still do not take into account the tensile and compressive damage characteristics of dam concrete. Therefore, the concrete damaged plasticity (CDP) constitutive model was used to analyze the damage and failure characteristics of the Laxiwa arch dam under the conditions of static overload, sudden temperature drop and maximum credible earthquake. The results show that the dam body mainly suffers from the tensile failure of concrete at the dam heel and bank slope dam foundation under overload conditions, and loses its bearing capacity after the damage penetration zone is formed; Under the condition of sudden temperature drop, the concrete of the dam body may cause tensile damage in the surface hole and the 1/4 arch dam crest, arch end and dam heel area; While under the earthquake condition, the surface hole near the crown beam of the dam crest downstream surface is mainly used for tensile damage. Tensile failure is dominant, and a horizontal band-shaped failure area is gradually formed and the bearing capacity is lost. The research results clarified the possible damage characteristics and failure paths of the Laxiwa arch dam, and provided a reference for determining the key parts of the Laxiwa arch dam structural safety monitoring analysis.

Investigating the effect of spacing on the effect of staggered-slip permeable spur dike on flow mitigation can provide a theoretical basis for the design of modern shore protection projects. The CCHE2D software was used to conduct a two-dimensional numerical simulation study of the solid flume model in the Xinqiman section of the Tarim River. And then the effect of different spacing on the water surface line, flow velocity and bed shear stress distribution in the upstream permeable spur dike area under the action of staggered-slab permeable spur dike was analyzed. When the relative dam length ratio is 0.21, and the inflow and dam length remain unchanged, the larger the spacing, the better the uniformity of flow and velocity behind the upstream permeable spur dike, and the lower the value of water level and shear stress in the riverbed. When the spacing is 5 times the effective dam length, the flow velocity, water level and riverbed shear stress behind the upstream permeable spur dike tend to be stable. The results of the study can improve the theory of flow mitigation effect in the action area of inserted permeable spur dike.

Aiming at the complicated law of specific energy along stepped chute and the low accuracy and limited application scope of current calculation method of water surface profile, a reliable method of calculating water surface profile was proposed. Based on hydraulic model test, this paper introduced the relative specific energy and made dimensional analysis. Then the dimensionless relative specific energy was systematically studied qualitatively and quantitatively. The results show that the dimensionless relative specific energy is related to the relative critical water depth, spillway slope and dimensionless position. The dimensionless relative specific energy has a good linear correlation along the stepped spillway. Based on the quantitative research results, the empirical formula of dimensionless relative specific energy calculation was given, and a new method of water surface profile calculation was obtained. The analysis of numerical example shows that the calculation method of water surface profile has high accuracy and wide application range, which can provide theoretical reference and technical support for the design of stepped chute.

In order to investigate the influence of the bottom dip angle of contraction section of the dustpan-shaped inlet on the hydraulic performance of the passage, the physical model and hydrodynamic model of the inlet structure of the dustpan-shaped inlet were established. The Reynolds N-S equation and RNG κ-ε turbulence model were adopted to simulate the flow field of the passage with 5 different underside inclinations in the inlet contraction section. The results show that the bottom dip angle increases has a great influence on the velocity distribution of the inlet contraction section and the throat of the winnowed dustpan-shaped inlet passage, and the scheme of the bottom dip angle increases the density of the srteamline distribution and the curvature of the throat, with the increase of flow velocity, the hydraulic loss of the passage is large, and the velocity distribution uniformity of the outlet section of the passage is low; The scheme with small bottom dip angle makes the streamline distribution smooth and the throat streamline curvature becomes slow, the velocity decreases, the hydraulic loss of the passage reduces, and the velocity distribution uniformity of the outlet section of the passage increases; The magnitude of the inclination of the bottom surface of the intake contraction section has no obvious influence on the weighted average angle of the flow velocity of the outlet section of the passage. Hydraulic performance of passage with different bottom dip angles was analyzed. When the bottom dip angle of the inlet contraction section of the dustpan-shaped inlet passage is less than 3°, the water flow in the inlet passage is smooth, the hydraulic loss is small, and the flow pattern at the outlet of the passage meets the water inlet conditions of the pump impeller chamber.

In view of a flood discharge hole of a hydropower station, two types of flip buckets were proposed. The experimental study was carried out with the arc bevel and the new upper and lower composite flip bucket for hydraulic model in flood discharge hole. The parameters of two types of flip buckets such as shape of the water jets, jet trajectory length and the depth of downstream scour hole were compared and analyzed. The test results show that the new type of flip bucket divides the water flow into two parts, forming two upper and lower parallel floors water jets, which fall into the river channel in a parabolic shape, and the width of the two layers of water jets is controlled within the range of the river channel. The trajectory water jets have a stable flow state and are fully diffused in space and plane. Compared with the arc bevel flip bucket, the scour depth of downstream riverbed, the surge height, and the bank flow velocity have all been reduced to a certain extent. Finally, the Ansys Fluent software was used to carry out numerical simulation verification of the designed new flip bucket, and the shape of the tongue, jet trajectory length, turbulent kinetic energy and turbulent kinetic energy dissipation rate under each working condition were obtained. Comparing with the results of numerical calculation and model test, the flow patterns of the two are consistent, and the results of the trajectory length and width of the water jets are basically consistent, which verifies the reliability of the numerical simulation, and provides convenience and technical support for research of ski-jump energy dissipation.

For the intersection problem of the outlet pipe shared by adjacent units of pumping station, three schemes for the intersection of the outlet pipe of the adjacent units was proposed based on the original scheme of the pump station. The influence of different intersection forms of the outlet pipe on the hydraulic performance of the pump station pipe was investigated with numerical simulation. The results show that the hydraulic losses of plan 2 and 3 were reduced by about 50% compared to the original plan. The flow field distribution before the junction point of the outlet pipes was improved obviously by the three optimization schemes. In the middle flow surface, the pressure and streamline distribution characteristics of plan 3 were better. Compared with the original scheme, plan 1 and plan 2 can improve the flow field of unit 2 and the vortex and secondary flow were reduced before the intersection point. After the intersection point, the flow field distribution of plan 2 was smoother and the hydraulic performance was better. Both the hydraulic performance of each scheme and construction were considered, plan 3 was finally determined as the optimal scheme.

Aiming at the problem of low economic benefits of pump stations caused by unreasonable dispatching, this paper took the pump stations with multiple piping systems as the research object. Considering the impact of peak-valley electricity price, a pump station daily economic optimization model was established by taking the minimum daily operating cost as the goal. The secondary pump station of the connected river reservoir project was taken as a study case to compare constant speed throttling regulation and frequency conversion regulation, which bases on the improved genetic algorithm and dynamic programming method of combined variation. The results show that the improved genetic algorithm is suitable for optimal dispatching of pumping station. At the same time, it is found that when the actual operating points of the pump unit far from the design operating point, adopting frequency conversion regulation has higher economic benefit.

Aiming at the problems of difficult modeling, low prediction accuracy and poor adaptability of the operation trend prediction of cascade pumping station units under the process of multi-factor participation, this study took Yanhuanding Yellow River Project in Ningxia as the research object, introduced the time series analysis method, and put forward the operation trend prediction method of pumping station units based on ARIMA and SVM combination model. The energy consumption and average load in the operation technical parameters of the unit were selected as the test samples. The ARIMA model was used to linearly fit the processed data, and the SVM model was used to predict the residual error to compensate for the nonlinear change in the operation of the unit. The prediction results of the combination model were obtained by combining the two prediction results. The results show that the optimal models are ARIMA (1, 1, 3) and ARIMA (2, 1, 1), and the optimal parameters of SVM model are c=38, g=0.06 and c=68, g=0.18, respectively. The goodness of fit of the combined model for the test samples were 0.999 2 and 0.998 4, R_RMSE were 1.67×10^-5 and 3.9×10^-8, the M_MAPE were 0.036 1 % and 0.074 7 %, indicating that the combined model has high accuracy and good effect in predicting the operation trend of pumping stations. ARIMA-SVM combination model can provide a theoretical basis for the optimization and upgrading of pumping station unit operation condition monitoring system.

Accident pump-stopping water hammer is a technical problem that needs to be highly valued in long-distance pressurized water diversion projects. This paper carried out calculation and analysis of hydraulic transition process on the Oujiang River Diversion Project. The loss of power accident of four pumps under maximum lift was taken as control condition, and the loss of power accident of single pump was taken as verification conditions. The optimization of pump outlet valve closing law was taken as the main water hammer protection measure. The research shows that when the butterfly valve at the outlet of the pump refuses to operate, the pressure and flow in the pipeline fluctuate more violently than that of the single pump during pump trip accident, and the reverse speed of the pump does not meet the specification requirements. By adopting the two-stage broken line closing law of the pump outlet butterfly valve, a better water hammer protection effect can be obtained.

When the pipeline truck moves smoothly, the velocity distribution characteristics of the water flow in the annular gap are related to the interaction between the pipeline truck and the water flow, which will also affect the motion characteristics of the pipeline truck and the hydraulic characteristics in the pipeline. This paper studied the overall and local distribution characteristics of the water flow velocity in the annular gap when the pipeline car moves smoothly by means of physical experiments and theoretical analysis. The relationship between the distribution characteristics of the water flow velocity in the annular gap of the pipeline car with different diameters and the transmission efficiency were compared. The results show that when the pipeline car moves smoothly, the velocity at the inlet section of the annulus is the largest, followed by the middle section of the car, and the velocity at the rear section of the car is the smallest; The flow velocity near the wall of the pipeline truck changes greatly along the way, and the flow velocity near the pipe wall changes less along the process; The distribution of the water flow velocity in the annular gap of the pipeline car with different diameters affects the transportation efficiency of the pipeline car. When the ratio of the water flow velocity in the annular gap to the water flow velocity in the pipeline is close to 1, the transportation efficiency of the pipeline car is the highest.