For the pressurized water supply project of a long distance, large flow and high lift pumping station, the pump trip was simulated. Combined with the characteristics of the engineering terrain, the combined protection method of air-cushion surge chamber and one-way surge tank was proposed. And then the sensitivity analysis of the closing rule of the valve after the pump and the throttle orifice of the surge chamber was carried out according to the requirements of pipeline pressure control. The results show that the air cushion surge chamber could effectively protect the water hammer of the pump trip and the water hammer of valve shutdown caused by the rapid closure of the pump valve. The one-way surge tank solved the problem of local high pressure caused by the continuous water refill of the air cushion surge chamber, and protected the safety of the high point pipe section. The combined protection scheme could significantly reduce the volume of air cushion surge chamber and saved the engineering cost. In addition, the closing rule of the pump valve and the throttle orifice area of the air cushion surge chamber has a great impact on the water hammer pressure of the pipeline. Too fast valve closing or too large throttle orifice area will lead to the positive pressure of the pipeline exceeding the standard. Too slow valve closing or too small throttle orifice area will lead to large negative pressure in the pipeline. The specific project needs to be optimized in combination with transition process simulation. For this project, after simulation and optimization, the diameter of the throttle orifice was 0.8m, and the valve of the pump was closed by 5s straight line, and the results met the requirements of regulation guarantee calculation.

In order to accurately judge the start and end time of snowmelt period, the upstream of the Danba basin, the main source of snowmelt runoff in Daduhe River, was taken as an example. Based on hydrometeorological data from 2009 to 2020, set pair analysis method, systematic clustering method and K-means clustering method were used to calculate the snowmelt period in the dry season (November to the next May), and the rationality of the staging results was evaluated. The division scheme of final snowmelt period in the basin was determined. The results show that the main snowmelt period is from January 11 to May 10, the preceding period is from November 1 to January 10, and the following period is from May 11 to May 31, which is the beginning period of rainfall runoff (there is still some snowmelt runoff). The research results can provide reference for the classification of snowmelt periods in high latitude areas.

As an important factor in the ecological environment of lakes, aquatic plants play a key role in the restoration and management of lakes. The water blocking effect of aquatic plants has a significant impact on the flood storage and discharge process of lakes, so the impact of aquatic plants on the roughness has become an important part of the hydraulic research of ecological lakes. The height of aquatic plants is closely related to the roughness of lakes. The elastic modulus of aquatic plants is an important mechanical property parameter for calculating its deformation. The stem of aquatic plants is simplified as a cantilever beam with variable cross-section. Through the bending deformation test of eight aquatic plants, the tensile force, displacement and other parameters are measured, and the elastic modulus value is calculated. The basic range of the measured elastic modulus change of eight aquatic plants is obtained. The comparison shows that the elastic modulus of these aquatic plants increases with the growth age or total length.

In order to study the seepage characteristics evolution of rock mass in the water level-fluctuating zone under condition of water-rock interaction, the dolomite in the reservoir area of Wudongde Hydropower Station was selected as the research object in this paper. The variation law of fracture seepage characteristics was obtained through the single fracture seepage test. With the help of SEM and 3D surface contour scanning technology, the variation law of fracture surface microstructure and surface morphological characteristics was studied, and the influence mechanism of fracture seepage characteristics evolution law was discussed. The results show that in the process of water-rock interaction, when the seepage pressure is constant, the seepage decreases exponentially with the increase of confining pressure; When the confining pressure is constant, the seepage increases linearly with the increase of seepage pressure; With the increase of water-rock interaction period, the seepage of fractures decreases rapidly at first and then slowly, and then increases slowly and tends to be stable. The water-rock interaction softens and dissolves the minerals at a certain depth of the fracture surface, and changes the micropore structure and surface morphological characteristics. Under action of confining pressure, the fracture surface is more closed. The further reduction of effective crack width is the main reason for the decrease of fracture seepage.

In order to study the effects of plants on the migration and accumulation of nitrogen in the biological retention system, and promote the vegetation construction of rainwater biological retention system in loess distribution area, 5 groups of biological retention system simulation devices were constructed by selecting Iris, Hemerocallis, Sedum, Ophiopogon and non-plants. The migration of nitrogen in fillers and the accumulation of nitrogen in each medium under different plant treatments were investigated. The results show that there was a close relationship between plant nitrogen accumulation and plant biomass increase during the experiment, which was as follows: Sedum> Iris>Hemerocallis> Ophiopogon. The nitrogen absorbed by plants was mainly accumulated in the upper structure of plants. The distribution difference of in the five groups of biological retention system fillers is not significant and the content of is low. is mainly removed in the upper part of the packing layer by adsorption, and each system has a good removal effect on . Plants have a significant effect on the distribution of in the packing and the migration of in the system. Compared with the non-plant group, the system with plants can reduce content in the filler, and the lower the content in the filler before influent, the lower the effluent concentration. The average TN removal rates of 5 treatments were as follows: Iris (50.59%)> Sedum (43.99%)> Hemerocallis (37.85%) Ophiopogon > (30.51%)> non-plant (26.09%).

At present, most of the domestic parallel pump groups adopt a single-objective control model, and only pay attention to the energy efficiency optimization of operating conditions and operating costs in the process of use, and cannot adjust the operation strategy under the real-time working conditions of the pump group according to the comprehensive energy efficiency state of the pump group in the whole life cycle. A multi-objective pump group energy efficiency optimization control model can be independently adjusted according to the energy efficiency state of the current pump set in the whole life cycle. The weight coefficients of three objective functions can be autonomously adjusted, which improves the energy efficiency of the pump set throughout its life cycle and extends the life of the pump set. The objective function was determined by the ideal point value and distance deviation method. The multi-objective ideal point model was solved by LINGO. The optimal solution with the highest total system efficiency, the lowest pump group specific energy consumption and the highest system reliability was obtained. Experimental results show that the improved multi-objective ideal point model can adjust the target weight combination according to the real-time state of the pump group, so as to adjust the real-time control strategy of the pump group.

In order to reveal the process and mechanism of outbreak of flash floods and causing disasters in ungauged areas, a numerical model of the transport of loose bodies under heavy rainfall floods was established in the Xiangxi River subbasin of Zhangshu City, Jiangxi Province. The process of heavy rainfall and the law of sediment transport were analyzed. The results show that for the river, the flow velocity is higher at the high terrain, slope drop change and the confluence area, and for the area with gentle slope and large catchment area, the increase of flow velocity at the confluence point is especially significant compared with other areas; The local water accumulation at the beginning of the basin, surface runoff occurs in a short period of time, and the gathered water scours out several gullies, and sediment is mostly deposited at the downstream outlet; The water depth and flow velocity of the basin are related to the rainfall. The greater the rainfall, the greater the water depth and flow velocity is, the more significant the scouring situation is. This study has positive significance for flash flood warning in the region.

Fissure distribution has a significant effect on mechanical properties and damage failure of layered rock mass with complex fissures. Based on the uniaxial compression test and DIC technique, the influence of fissure location and fissure angle on the mechanical properties and failure of the composite fissure rock sample composed of sandstone-like and martial-like rocks was analyzed. The results show that the mechanical properties of composite fissure rock samples increase with the change of fissure location from sandstone, interface and marble and the increase of fissure angle. Influence of fissure location on rock sample failure: When the fissure is in marble, the initial crack is easy to be the far-field crack in sandstone, and the surface spalling occurs in both sandstone and marble, but the failure is more obvious in sandstone, is prone to "H-shaped failure". When the fissure is at the interface and sandstone, it is easy to produce wing crack and anti-wing crack at the crack tip of sandstone. Exfoliation occurs only in sandstone, "1γ shape failure" and "y shape failure" are easy to occur, respectively. At the same time, the stress-strain levels σ and ε corresponding to the initial crack generation at the same fissure angle increase with the change of fissure position from sandstone, sandstone to marble and marble. Influence of fissure angle on rock sample failure: When α=90°, the tip is not easy to crack, and when α=45°, the tip is easy to crack. When the fissure location is the same, the σ and ε of α=90° are the largest, while the σ and ε of α=0° and α=45°are the smallest. "H-shaped failure" occurs when α=0° and "y-shaped failure" occurs when α=90°. The research results are instructive for practical engineering construction and design.

In order to explore the influence of water-binder ratio, fly ash, slag powder content and age on the compressive strength of full aeolian sand concrete, the compressive strength test of full aeolian sand concrete was carried out. The microscopic characterization of its physical composition was implemented in combination with XRD results. The compressive strength prediction model of full aeolian sand concrete was established by multiple linear regression. The results show that the compressive strength of full aeolian sand concrete increases first and then decreases with the increase of water-binder ratio. When the water-binder ratio is 0.4, the compressive strength is the largest. The growth effect of fly ash on compressive strength of aeolian sand concrete is not as significant as that of slag powder. The incorporation of fly ash and slag powder is easier to convert AFt into AFm. The established compressive strength prediction model has high accuracy and is suitable for sand concrete. The research results can provide theoretical basis and technical support for the engineering application of full aeolian sand concrete.

In order to solve the sliding failure problem caused by the wet expansion and dry shrinkage of expansive soil in the North Xinjiang water supply project, lime, cement and sand and gravel were used as the main curing materials. Through unconfined compressive strength test, direct shear test, compression test and SEM test, the influence of test dosage on the mechanical properties of improved expansive soil and the formation mechanism of microstructure strength under different improvement methods were studied by combining macro and micro. The test results show that with the continuous increase of the amount of lime and sand gravel, the soil strength increases steadily, while the peak value of cement improved soil appears when the amount of lime and sand gravel is about 7%. For lime and sand gravel, when the amount of lime and sand gravel is about 6% and 30% respectively, the overall compressibility of the improved soil is low, the cohesion is large, and the shear and compressive strength is high, which can meet the requirements of engineering application. The SEM analysis of lime and cement stabilized soil with the best mix ratio shows that a large number of curly flake hydrated gel materials are generated, which significantly reduces the pores compared with the original expansive soil, and the aggregates are closely cemented. From the macro mechanical properties, the mechanical properties and stability of the solidified soil are greatly improved.