In order to improve the aerated concentration of the stepped energy dissipator, mitigate the damage of cavitation and cavitation erosion, and improve the energy dissipation rate, the stepped energy dissipator with segmented piers was proposed. The influence of the arrangement of the front pier and the reverse pier of the energy dissipator on the hydraulic characteristics of the stepped energy dissipator with segmented piers was studied by numerical simulation. The results show that the stepped energy dissipators with segmented piers generate hydraulic jump near the energy dissipators in the flat and straight section of the terrace. The arrangement of the main pier has better effect of hydraulic jump aeration, higher concentration of aeration along the way, and better effect of cavitation erosion mitigation; The flow velocity along each stage increases gradually, and the arrangement of the main pier has lower flow velocity and better energy dissipation effect; A large range of positive pressure is formed on the upstream area and the upstream area of the energy dissipation pier, and negative pressure is generated on the top and back surface of the energy dissipation pier. The arrangement of the positive pier has a high blocking effect on the water flow, and the arrangement of the reverse pier has a large negative pressure; Under each flow condition, the energy dissipation rate of the two arrangement forms is higher, and the energy dissipation rate of the positive pier arrangement form is higher when the flow is larger, which has better energy dissipation effect. The arrangement of the main pier has better effect in reducing the cavitation damage of the step and improving the energy dissipation rate, which can provide a reference for the structural design of the stepped energy dissipator with segmented piers.

Prediction of the vibration trend of hydropower units is an important measure to ensure the normal operation of the unit. However, due to the complexity and non-stationarity of the vibration signal of the unit, accurate prediction becomes a difficult problem. To this end, this paper proposes a combined trend prediction model based on adaptive variational modal decomposition and temporal convolutional network (TCN). Firstly, the Whale Swarm Algorithm (WOA) was used to optimize the parameters of Variational Mode Decomposition (VMD) to avoid the drawbacks of blindly selecting parameters, and to achieve adaptive decomposition of vibration signals. And then each decomposed component signal was normalized to establish TCN for trend prediction. Finally the original vibration signal prediction was obtained by superimposing the results. The proposed model was demonstrated and tested with the actual operation data of a domestic power station. The results show that the proposed model has high prediction accuracy and can be used in engineering practice.

In hydro-generator units, the thrust bearing oil tank has the largest volume and the internal structure is relatively more complex. Therefore, there are many oil mists in the oil tank, and there are often internal and external oil spills, which have a great impact on the safe and stable operation of the unit. Based on the basic theory of computational fluid dynamics, the calculation model of thrust bearing in a power station was established, and the number of pressure oil blade was changed. The ICEM was used to mesh the three-dimensional model, and Fluent was used to calculate. The CFD-POST was used to analyze the oil mist related parameters of thrust bearing oil tank. The results show that in the design of hydro-generator units, the number of pressure oil blade can be appropriately increased, so as to increase the temperature difference between the upper and lower blades, reduce the oil temperature below the blade and increase the pressure, so as to better inhibit the occurrence of internal oil rejection and effectively prevent the diffusion of oil mist due to low pressure.

The diversion tunnel plug is a key project for the safety of water conservancy and hydropower projects. Wedge-shaped plugs are widely used in engineering. There are many calculation methods for columnar plug, but not so much for the wedge-shaped plug. Based on the design scheme of the diversion tunnel plug in Karot power station, this paper carried out the theoretical and numerical simulation analysis. Through the force analysis of the wedge, the calculation method of the hydraulic pressure bearing capacity of the wedge-shaped plug was proposed. The comparative analysis of wedge and columnar plug safety was carried out by three-dimensional elastoplastic numerical simulation. The result shows that the maximum deformation under the calibration water level of the wedge-shaped plug was 0.8 mm, and its overload safety factor was 1.08 times that of the columnar plug. By comparing the numerical simulation with the formula calculation results, the rationality and accuracy of the calculation method for the bearing capacity of the wedge-shaped plug were verified. The research results have important guiding value for the design of wedge-shaped block.

In order to explore the energy evolution law of rock failure process in the excavation process of diversion tunnel, this paper selects magnetite ore and carries out conventional triaxial and triaxial pre-peak constant axial pressure unloading confining pressure tests. The results show that in the conventional triaxial test, the rock is dominated by elastic strain energy storage and dissipative strain energy consumption before the peak stress, and the elastic strain energy release and dissipative strain energy consumption after the peak stress. With the increase of confining pressure, pre-peak shear fracture energy is higher than post-peak shear fracture energy. In the unloading confining pressure test, the dissipated strain energy increases exponentially. The faster the unloading rate, the shorter the unloading period is, and the higher the rate of energy increment per unit time between the unloading point and the drop point. Based on the M-C criterion of rockburst dynamics, the loss of rock cohesion and the dissipated strain energy of rock under unloading path, the damage variable in the process of rock unloading is defined, and the damage degree of rock deformation and failure is revealed from the perspective of energy.

Due to the uncertainty of runoff, there are certain risks when formulating hydropower station power generation plans. In this paper, the concept of spectral risk measurement in economics was introduced in reservoir dispatch to quantify risk, and a benefit-risk equilibrium optimization model was established, which can reflect the attitude of decision makers to risk through different risk aversion coefficients and confidence values according to the actual situation of the power station. Taking the Three Gorges Power Station as an example, the results show that compared with the traditional model of maximum power generation benefit, the proposed benefit-risk equilibrium optimization model can effectively reduce the risk caused by the uncertainty of inflow in hydropower stations under the condition that the loss of power generation income is extremely small.

Research and exploration on intelligent grouting technology has been conducted in some hydro-power stations in recent years. Intelligent grouting equipment has been invented and intelligent control strategies for conventional geological conditions have been developed. However, the existing technology lacks the intelligent control strategies for pressure sensitive and weak stratum, and is not suitable for grouting construction under complex geological conditions. Relying on the Xiong'an regulation and storage reservoir project and based on the empirical research method, this paper has carried out researches on new intelligent strategies for weak strata such as lift sensitive and split sensitive. The field test results show that the intelligent grouting technology meets the needs of field construction, in which the water pressure and grouting construction process can be intelligently completed, and the lifting and splitting situation can be handled. The research is conducive to ensuring the quality of grouting projects and improving the level of intelligent construction.

The mechanical effect of plant roots on soil is an important factor in improving the erosion resistance of slopes, and the relevant research on the impact resistance of plant roots under water flow at home and abroad is in a blank spot. In this paper, the common soil and water conservation plants tall fescue and dogtooth roots were selected as the research objects, and the jet erosion test was carried out on the slope of the plant model, and the erosion failure mechanism of the root slope of different species of plants was compared. The main conclusions are as follows: the variation law of the average erosion depth ΔD_AE of high fescue slope, dogtooth root slope and plain soil slope under different working conditions is similar and consistent, and it increases exponentially as a function with the increase of erosion flow velocity and linear function with the increase of erosion angle. The average erosion depth under various working conditions was generally as follows: high fescue< dog tooth root< plain soil; The average erosion depth of high fescue at each flow rate decreased slightly ΔD_AE slightly greater than that of dog tooth root. When the scouring angle was fixed, the ΔD_AE of each angle was the largest when the flow rate was 1.6 m/s, and the flow rate was higher than 1.6 m/s, and gradually decreased. When the erosion flow rate is constant, there is a decreasing tendency ΔD_AE increase with the increase of the scouring angle.

In order to understand whether the power frequency electric field level generated by the UHV AC power transmission and transformation project meets the relevant requirements, this paper uses the EFA-300 power frequency field strength meter to conduct the cross-section of the substation and transmission line of the Ximeng-Shengli 1 000 kV AC power transmission and transformation project, and evaluate the uncertainty of the measurement results. The results show that the maximum measured value of the substation boundary is (3.65±0.18) kV/m, k=2, which is lower than the electric field limit of the substation boundary, 4 kV/m; the maximum measured value of the line cross-section is (5.41±0.28) kV/m, k=2, which is lower than the electric field limit below the overhead transmission line, 10 kV/m, which meets the requirements of relevant national standards. It is found that the error of the field strength meter has a great influence. The uncertainty of the power frequency electric field measurement can be reduced by improving the calibration accuracy of the power frequency field strength meter. This work is supported by the Science and Technology Project of the Headquarters of State Grid Corporation of China-Research on Power Frequency Electric Field Calibration Technology (GYW1720200201).

Water footprint evaluation is of guiding significance for the rational development of regional water resources. The input-output method was used to account for the water footprint of Hubei Province from 2007 to 2017, and the driving factors of water footprint changes were analyzed using the structural decomposition model. The results show that the virtual water content in Hubei Province decreased significantly, and water use efficiency improved from 2007 to 2017. The total water footprint showed a trend of rising and then falling, with a net increase of 19.9%, and the main growth sectors were construction and services. Technology level and economic scale were the main factors inhibiting and promoting the increase of water footprint, respectively. However, their effects on water footprint changes gradually weakened, and both showed a reduction effect. From 2007 to 2017, the sectoral linkages changed from positive to negative driving force, and the inhibitory effect on water footprint was revealed, which shows that optimizing the industrial production process helps carry out water conservation. The impact of driving factor on different sectors showed heterogeneity. The adjustment of industrial structure inhibited the increase of water footprint in high water-consuming sectors such as agriculture while promoting the increase in construction and services. In the future, the industry scale and residential demand in sectors producing high-value-added products will grow, such as services, and water-saving technology development should be shifted to these sectors promptly.