Aiming at the problems of difficulty in determining the optimal parameters and low accuracy of the deep learning method in dam prediction, the sparrow search algorithm (SSA) was improved, and the parameters of the gated recurrent unit (GRU) were optimized by the improved sparrow search algorithm (ISSA). Then a dam deformation prediction model based on the ISSA-GRU was constructed, and this model was applied to the deformation prediction of the Longyangxia Dam of Qinghai Section in the upper reaches of the Yellow River. The results show that the dam deformation prediction model based on ISSA-GRU has higher prediction accuracy and stability, which can be used as a reference for dam deformation prediction.

In order to explore the impact of river level and total rainfall duration on the drainage performance of rainwater pipe network, an integrated SWMM generalized model of pipe network and river in a certain industrial park was constructed. Based on the rainfall events with a return period of 5 years and the total rainfall duration of 2 h and 24 h, the drainage conditions of rainwater pipe network and river in industrial parks with different initial river levels were simulated and analyzed. The results show that when the initial river level is low and the outlet is free outflow, river level has little impact on the drainage performance of the rainwater pipe network. When the outlet is submerged, with the increase of the initial river level, the proportion of overloaded pipelines and overflow nodes in the drainage system increases, the overload time and overflow time are prolonged, the peak flow of outlets and pipeline nodes decreases, and the peak flow of node which is closer to outlet decreases more sharply. Based on the same rainfall return period and the initial river level, compared with the short duration rainfall, the proportion of overloaded pipelines and overflow nodes in the long-duration rainfall is larger, the overload time and overflow time are longer, and the peak flow of outlets and pipeline nodes decreases greatly. When designing the storm water drainage system with river-pipe network, it is advisable to check the drainage performance of storm water drainage system for 24 h rainfall and different river levels.

In order to study the distribution of the annular gap flow field during the bend start of the pipeline vehicle under different loading conditions. Numerical simulation combined with physical model test verification was used to study the annular gap flow field during the horizontal bend start of duct trucks with different loads. The results show that the increase of load does not change the overall distribution of the gap flow field velocity, but only changes the magnitude of the gap flow field velocity; Under different loading conditions, the axial flow velocity of the gap flow field of the pipe vehicle in the horizontal bend has the law of increasing and then decreasing from the inner wall of the pipe to the outer wall of the pipe vehicle. The circumferential flow velocity is more uniformly distributed at the section of the pipe vehicle gap inflow port and the section in the vehicle, but the opposite distribution of flow velocity on both sides of the sealing cover appears at the section of the gap flow outlet. The radial flow velocity is more uniformly distributed as far away from the support body and the seal cover, and the flow velocity increases significantly at the support body in the slit flow outlet section of the pipeline vehicle. This study explains the reasons for the formation of annular gap flow field distribution law and obtains the flow velocity distribution law of the gap flow field when the pipe vehicle is started at the bend with different loads. While improving and enriching the theory of annular gap flow, it provides theoretical basis for the application of hydraulic conveying in cartridge loading pipeline.

The proposed Longweizhou junction is a low-head hydro-junction project that focuses on navigation, flood control, water resources, and protection of the aquatic ecological environment. There are two continuous bends upstream and downstream of the dam site, and the straight section where the dam site is located is also short, so the river boundary conditions are not conducive to smooth flood discharge after the project. To demonstrate and optimize the general layout of the proposed hydro-junction, an integrated hydraulic-physical model with a scale of 1∶80 was adopted. On the basis of hydrodynamic similarity verification, a detailed experimental study was conducted on the discharge capacity of the hydro-junction, revealing the characteristics of flow velocity distribution and flow distribution in the original design scheme under typical flood conditions, clarifying the shortcomings of the original scheme and corresponding optimization ideas, putting forward the measure of cutting the side beach to improve discharge capacity. The optimized scheme test verified that the discharge capacity could meet the design requirements. The research results may serve as reference for the design of this project and other similar projects.

For underflow energy dissipation, the arrangement of the grille shortens the length of the stilling pool and makes it easier to adapt to changes in terrain conditions. The two-phase flow of water and gas in the round-bore Γ-shaped grille type stilling pool was numerically simulated by the aeration model in FLOW-3D. The results show that the concentration of longitudinal bottoming gas decreased (31.3% →8.0%) along the way, and decreased significantly at the grid position, the minimum number of holes in front of the grid (^#6 section) was 5.6, the number of holes near the grid was about 9.0, and the number of holes behind the grid was much greater than 9.0. The bubble size near the bottom of the grid front axis increases along the course (0.9 mm→8.1 mm), and the bubble size of the near bottom plate after the grid decreases along the way (1.6 mm decreases to close to 0 mm). It can be considered that the bubbles with smaller diameters in large flow velocity areas play a major role in aeration corrosion reduction, which has obvious protective effect on the solid boundary of concrete, and the structure of the stilling pool including the grid is not easy to occur cavitation erosion damage.

Considering the lack of research on the ventilation characteristics of open flow spillway tunnels under high flow velocity conditions, based on a 50 m/s high-speed jet test device, this paper investigated the effects of flow velocity, ventilation tunnel area, and relative height of spillway tunnels on the ventilation volume and wind speed distribution in ventilation tunnels. By analyzing 44 sets of prototype observation data and 28 sets of experimental data, an empirical formula for calculating ventilation at high flow rates was proposed. The results show that the measured value of ventilation is 2.1-9.6 times of the standard value when the water flow velocity is 18.0-37.2 m/s. As the area of the ventilation tunnel increases, the rate of increase in ventilation volume gradually decreases, and the distribution of wind speed inside the ventilation tunnel is related to the area of the ventilation tunnel. The ventilation volume first increases and then decreases with the increase of the height of the spillway tunnel, and the change in the relative height of the spillway does not change the wind speed distribution characteristics. The calculated ventilation value by the improved formula is relatively close to the actual measurement value, with 3/4 of the data within the 20% error line range. Research results can provide guidance for engineering practice.

The change of hydrological situation and the operation scheduling of the downstream of the hub make the water level at the inlet and outlet of the fish channel change at all time, and the fish channel is running improperly. The insufficient inlet water depth will cause water drop and hinder the backtracking of fish. The integrated model was used to analyze the hydraulic characteristics under different water level combinations at the inlet and outlet of the fishing channel. The results show that the hydrodynamic changes of the fish tunnel tank chamber are mainly concentrated in the pool chamber near the inlet, and the greater the influence is closer to the downstream. When the inlet water level decreases, the water drops at the inlet and it is difficult for fish to trace; When the inlet water level rises, the inlet velocity slows down rapidly. In view of the design inlet flow velocity is 0.60 m/s-1.00 m/s, the maximum drop between the outlet of the fish channel and the inlet water depth is recommended to be controlled at 1.00 m. At the same time, appropriate water replenishment measures should be taken according to the water depth of the inlet to form effective lure flow rate at the inlet, and there is a good linear relationship between the supplementary water flow and the inlet water depth.

Under the condition of low flow ratio, the flow structure of the inlet area of tributaries is very complicated. Based on physical model test and PIV particle image velocimetry technology, the average velocity distribution and three-dimensional velocity spatial distribution of open channel tributaries under different intersection conditions were observed, and the variation law of the flow field of tributaries was analyzed. The results show that when the confluence is relatively small, the surface water of the tributaries will have reverse reflux phenomenon to varying degrees due to the top supporting effect of the main stream water, while the bottom water flows downstream to the main stream, and there is a relatively obvious oblique mixing interface. With the increase of the confluence ratio, the influence of the main stream on the flow structure of the left bank of the tributary decreases gradually. When the intersection angle is 30° and 90°, the water flow structure near the right bank section is most affected by the water top support of the main flow. When the intersection angle is 150°, the tributaries are basically in reverse reflux state, and the maximum reflux velocity area is formed at the intersection. The results can provide theoretical support for the study of frequent bloom caused by nutrient enrichment in tributaries of reservoir area.

The groundwater level in the deep foundation pit project close to the river shows a dynamic characteristic of long-term low water level but high water level during flood season. Foundation pit dewatering leads to the complexity of the seepage field in the surrounding stratum environment, destruction of enclosure structures, accidents include piping and instability at the bottom of the pit. Therefore, this paper simulated the excavation-precipitation process of deep foundation pit project based on the HS-Small constitutive model, analyzed the sensitivity of precipitation influencing factors (precipitation depth, mode, rate and water stop curtain) to the surrounding environment deformation and their relationship. Compared the analysis results with the measured results, it can be found that the settlement of the top of the foundation pit, the soil outside the pit and the surrounding buildings gradually increases, and the dewatering has a more obvious influence on the deformation during the excavation and dewatering of the foundation pit; Fractional precipitation can effectively reduce the settlement deformation of surrounding buildings and ground surface; It is recommended that the dewatering depth of foundation pit should be controlled within 0.5-2.0 m below the bottom plate; The precipitation rate has a relatively small impact on the total settlement of the surrounding environment, but has a great impact on the settlement rate. When the precipitation rate reaches the optimal value, it is beneficial to the stability control of the foundation pit. The embedded depth of water-proof curtain in this project is more than 30 m, which has no obvious effect on controlling the settlement of surrounding buildings. The research results can provide reference for the dewatering design and construction of similar deep foundation pit projects closed to the river.

To ensure the structural safety of the double row steel sheet pile cofferdam and control its water use area, the single-factor sensitivity analysis method was carried out to study the impact of various items on the deformation of cofferdam, and the PLAXIS software was used to implement the 2D and 3D finite element calculation. The results show that the elevation and tension of tie rod, and the specification of steel sheet pile have little impact on the deformation of cofferdam in soil; Compared with the width of the cofferdam itself, the deformation of cofferdam is more affected by the width of inner foot, so the width of the inner foot should be increased as much as possible; The depth of the outer sheet pile has no obvious impact on the deformation of the cofferdam, so that it can be reduced appropriately, and the depth of the inner sheet pile can be increased; The effect of the transverse structure on controlling the deformation of the cofferdam is not obvious, and other measures can be taken to strengthen the connection between the inner and outer sheet pile. The research ideas and calculation results can provide reference for structural design optimization of steel cofferdam in similar projects.