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.

In order to study the applicability of recycled aggregate in hydraulic asphalt concrete, the mix proportion test of recycled aggregate hydraulic asphalt concrete was carried out, and its mix proportion parameters were determined through uniaxial compression, splitting test and permeability (porosity). The asphalt aggregate ratio is 7.0%, the grading index is 0.37, the filler content is 13%, and the replacement rate of recycled aggregate is 50%. The recycled aggregate was modified with modifiers of different concentrations. The water absorption, apparent density, crushing index and adhesion of the recycled aggregate were analyzed to determine the modifier concentration that meets the test requirements. The modifier concentration in this test is 10% of water glass and 12% of silane coupling agent. Based on the above research, the applicability of recycled aggregate in hydraulic asphalt concrete was studied through water stability coefficient, thermal stability coefficient and permeability coefficient. The results show that the application of recycled aggregate in hydraulic asphalt concrete can meet the requirements of the specification, which can provide a reference for the popularization and application of recycled aggregate in hydraulic asphalt concrete.

In the long service process of the deep excavated expansive soil channel slope, the real-time identification of the service behavior of the channel slope by means of displacement monitoring index is an important means to ensure the safe operation of the channel slope. Therefore, it is of great significance to formulate reasonable monitoring indexes for the safety of canal slope engineering. The POT model was presented in this paper. On the basis of introduction of 2 σ criteria and chauvenet principles, the threshold T and the corresponding relation between monitoring index was established. Through the best solution to satisfy the relationship between threshold, a canal slope displacement monitoring index for improved POT model was established to apply to the Taocha section of South-to-North Water Transfer Project of deep excavation expansion earth canal in slope engineering. Compared with the traditional POT model, the results show that the improved POT model based on 2σ -chauvenet criterion can effectively avoid subjectivity and random error, and it has higher calculation accuracy. The proposed displacement monitoring index is more safety, which has stronger guiding significance to prevent the risk of canal slope and ensure the safe long-term operation of canal slope.

In order to solve the heat dissipation problem of heat pipe rectifier cabinet for excitation system of giant hydropower station, the working principle of loop heat pipe and the processes of development and improvement of loop heat pipe rectifier cabinet were introduced. The advantages of integrated loop heat pipe and horizontal symmetry structure, as well as its application in Wudongde Hydropower Station were analyzed. The practice shows the loop heat pipe rectifier cabinet adopting completely self-cooling heat dissipation mode is in a thermal stable state after long-term operation in the field, and a series of problems, such as dust, noise, power supply, maintenance, can be solved from the design principle. Meanwhile, it can improve the safety, reliability and automation level of the equipment and reduce the energy consumption, the benefits of energy-saving and environmental protection are obvious.

For the 1# bulb tubular unit of Baisha Hydropower Station, the prestress vanishment of the rotor bracket and hot sleeve of the spindle could results the scratching of the generator and the uneven air gap between stater and rotor, which generates the excessive unilateral magnetic pull. This problem may lead to a serious accident in runaway or load rejection conditions. According to the experiential and theoretical analysis, the solution points to the fastening connection by a pin arrangement between rotor bracket and main shaft. Consequently, the unit has been running steadily under various working conditions. As there are numerous large, medium and small units in China facing the similar problem, the treatment scheme and design calculation methods proposed in this paper could be considered as a typical solution reference.

Aiming at the problem that many measured thermometer data are not effectively used in the previous prediction of crack opening and closing time series data, and there are multiple correlations between their variables, considering the advantages of principal component analysis (PCA) in dealing with multidimensional data and gate recurrent unit (GRU) neural network in dealing with complex time series data, this paper constructed the PCA-PSO-GRU combined prediction model. Taking the monitoring data of the opening and closing of the left inducing joint of a concrete gravity arch dam as a sample, the principal components of the input variables were extracted to reduce the dimension of the input data. And then the model training and multi-step prediction were carried out. The mean absolute error and root mean square error were used to evaluate the prediction accuracy of the model. The prediction results were compared with PSOGRU, PCA-PSO-BP and the traditional statistical regression models. The results show that the PCA-PSO-GRU combined prediction model has higher accuracy in the prediction of inducing joint time series data, which can provide guidance for the evaluation of opening and closing degree of dam inducing joints.

To avoid flow surface morphology change caused by wear and cavitation erosion of turbine movable guide vane and the unit efficiency decrease, ultrasonic vibration cavitation machine, high-speed jet of gaza's grinding apparatus and circle grinding apparatus were used to carry out cavitation erosion test for epoxy mortar, mortar composite resin and polyurethane and movable guide vane base material of ^#45 steel. Based on the test results, the cavitation erosion resistance and impact wear resistance of different materials were analyzed, and the service life of materials under strong cavitation erosion was predicted. The influence of flow rate, attack angle and sand content on material wear was studied, and the prediction model of material wear was established. The results show that the corrosion resistance of the materials is as follows: polyurethane > composite resin mortar > epoxy mortar; The abrasion loss of material has a linear or exponential relationship with the increase of velocity. The relationship between wear and sand content is linear. When the attack angle increases gradually, the impact wear first reaches the peak value and then decreases gradually. The critical attack angle of different materials is different.

Aiming at the difference of the runoff fluctuation regime after the construction of reservoir, this paper adopted several fluctuation quantification methods to analyze the difference of downstream runoff fluctuation regime after the construction of Three Gorges reservoir from the dispersion, tendency and steepness change degrees on the basis of nearly 70-year long time series of runoff data at Yichang hydrologic station. Compared with the natural runoff regime, the results show that the dispersion degree of runoff decreases (mostly in flood control storage capacity reservation period), the tendency change degree of runoff increases and the steepness reduces (mainly in drawdown period), and totally the fluctuation regime changes intricately.

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.

Taking Jinghe River Basin in Gansu Province as the main research object, the Jinghe River trunk canal irrigation area in the upper reaches of Jinghe River was selected as a typical experimental irrigation area. The irrigation return water, farmland water content and crop growth trend of Jinghe River trunk canal irrigation area were monitored. The water consumption of Jinghe River trunk canal irrigation area was tested by the combination of diversion and drainage difference method and multi-level soil water balance model (VSMB model). According to the monitoring experiment, the total water diversion volume of Jinghe River main canal irrigation area in 2018 is 20.76 million m³, and the total water return volume is 5.23 million m³. The water consumption coefficient of Jinghe River main canal irrigation area is 0.56 by using the diversion and drainage difference method. The total annual water diversion of typical plots in Gannong experimental field is 1 901 m³, and there is no retreating water on the surface. The water consumption coefficient obtained by diversion and discharge difference method is 0.75, and the water consumption coefficient obtained by VSMB model is 0.71. The research results provide reference for the study of water consumption coefficient of other agricultural irrigation areas in Jinghe area, and have certain guiding significance for irrigation area planning and design and high-efficiency agricultural irrigation pilot work.