A static dynamic triaxial instrument was used to carry out concrete triaxial dynamic mechanical tests by setting different strain rates (10^-5/s, 10^-4/s, 10^-3/s, 10^-2/s) and different lateral confining pressures (4.5 MPa, 6.0 MPa, 9.0 MPa and 12 MPa). The evolution law of the total energy density, elastic strain energy density and dissipated energy density of concrete with axial strain under dynamic triaxial compression was studied. The influence of lateral confining pressure and strain rate on the energy evolution law of concrete was analyzed. The results show that with the increase of axial deformation, the total energy density and dissipated energy density of concrete increase nonlinearly, and the elastic strain energy density first increases and then decreases. The increase of strain rate and lateral confining pressure improves the specific energy storage limit of concrete, and the energy storage limit of concrete shows a strong rate sensitivity; The relationship of energy storage limit and the lateral confining pressure is approximately linear; With increase of the lateral confining pressure, the rate sensitivity of the concrete energy storage limit shows a decreasing trend.

In recent years, it causes disasters increasingly by too much or too little precipitation. Therefore, accurate prediction of precipitation is of great significance and practical application value to human life and social development. Based on the monthly precipitation data of Zhengzhou from 1990 to 2019, monthly precipitation was forecasted from 2020 to 2021 by utilizing SARIMA, Prophet and LSTM model, respectively. In order to improve the prediction accuracy of the model for monthly precipitation, two combined models of the SARIMA-EMD-LSTM and Prophet-EMD-LSTM were proposed. Empirical analysis shows that the proposed two combined models have higher prediction accuracy and decrease the root mean square error significantly. Furthermore, Prophet-EMD-LSTM model has comparatively better prediction effect. The monthly precipitations in Zhengzhou from April to December, 2022 were forecasted with higher precision.

Based on the monitoring data of 36 meteorological stations in Jiangxi Province from 1960 to 2018, the characteristics of drought change and the correlation between SPEI index and M-K trend test. The results show that the SPEI-12 index showed a slight downward trend, and drought and flood alternated from year to year. The annual drought mainly distributed in the northeast, west and southeast of Jiangxi Province, and most of the drought was global and regional, and the regional drought was more significant after 2000. The seasonal drought occurred in summer and autumn, especially in autumn. The drought degree in spring and winter was light and more frequent in the southern part of Ganzhou. However, after 2001, spring showed an aridity trend, and the SPEI index in summer, autumn and winter showed an upward trend, even easy to cover the province's serious autumn drought. Crop to the affected area and summer and autumn were significantly correlated with SPEI index and summer drought influence on Jiangxi crops than autumn drought. The results can provide reference for drought control and drought resistance in Jiangxi Province.

In order to study the mechanical properties of rocks with prefabricated fissures, rock specimens with intermittent fissures at different angles were prepared. Uniaxial compression test was carried out on the specimens with fissures using uniaxial compression test equipment. It is found that the uniaxial compressive strength of 40° intermittent fissures is the largest, followed by that of 60°and 20°. The PFC2D was used to simulate the test process. The change law of microcrack and stress in the test process was analyzed. It is found that the strength of rock bridge has an important impact on the uniaxial compressive strength of the specimen. Through comparison, the change law of stress-strain curve of numerical simulation is basically consistent with that of physical test.

In order to explore the influence of geographical location (latitude) differences on the water temperature of the reservoir area, the temperate Gongguoqiao Reservoir and the tropical Jinghong reservoir, which are similar in scale and operation mode, were taken the research objects. Based on the prototype observation data, the CE-QUAL-W2 model was established to compare and analyze the water temperature distribution characteristics of the Gongguoqiao and Jinghong reservoir. The results show that the CE-QUAL-W2 model can be applied to the simulation of temperate and tropical reservoirs, and the difference of water temperature changes in reservoirs in different climatic zones can be clarified. The temperature increase and decrease of the surface water temperature in the Jinghong reservoir area obviously lags behind the surface water temperature in the Gongguoqiao reservoir area. Both Gongguoqiao and Jinghong reservoir are weakly stratified reservoirs. Gongguoqiao Reservoir is weakly stratified in spring and summer, while the stratification in autumn and winter is not obvious. Jinghong Reservoir shows weak stratification in summer and autumn, but not in spring and winter. The results can provide reference for water temperature research of similar-scale power stations on the Lancang River.

Currently, the electricity market is undergoing a new round of reform, and deviation assessment mechanisms have been introduced in various places to promote fair competition. In the face of the new market rules, the traditional dispatching model with maximum generation cannot be applied, and hydropower companies need to take market factors into account to control deviations. In order to save hydropower companies from paying costs, a study was conducted on the deviation control rules, and a bi-level optimization model with the objective of maximizing generation capacity and minimizing deviation was established to facilitate trading decisions. Taking the Three Gorges hydropower plant and Hubei province electricity market as examples, the Harmonic Search algorithm was used for analysis. The results show that the deviation rate in each interval is within the deviation control range, and the hydropower plant is exempt from deviation control. Thus, the bi-level optimization model mentioned above is feasible.

Based on the SRTM digital elevation DEM model, using the hourly precipitation data of Chongqing from May to September 2017 to 2021, this paper analyzed the temporal and spatial distribution characteristics of short-term heavy precipitation under different terrains in Chongqing, and discussed the relationship between the frequency and intensity of short-term heavy precipitation and topographic factors. The results show that the spatial distribution of short-term heavy precipitation in Chongqing is uneven. The overall average frequency high value area of the previous year and stations ≥ 60mm/h are mainly located near Huaying Mountain in Northwest Chongqing, Daba Mountain in Northeast Chongqing and Wuling Mountain in Southeast Chongqing; For the station average frequency of short-term heavy precipitation in Chongqing, the monthly variation shows a significant single peak type, and the frequency is the most in July; The diurnal variation is bimodal, with the main peak occurring most frequently at 03:00-05:00 and the secondary peak occurring more frequently at 16:00-19:00. The frequencies of the north and west slopes are slightly more than those of the other slopes. The frequency of flat slope and gentle slope is more than that of other slopes. The frequency of 500-1 000 m and > 1500 m is more than that of other altitudes; The fluctuation ≤30 m and 30-200 m are more frequent than other fluctuations; When slope ≤15°, altitude ≤1 000 m, and undulation ≤200 m, stations with precipitation intensity ≥100 mm/h appear, indicating that appropriate mountain topography is conducive to the increase of short-time heavy rainfall intensity. The research results can provide reference for near early warning, disaster prevention and reduction of short-term heavy precipitation in Chongqing.

As a diversion tunnel, the pressure distribution of the tunnel body, the top and the bottom of the tunnel is very important to avoid cavitation, vibration and other undesirable phenomena. Taking the diversion tunnel of Yebatan Hydropower Station as the research object, this paper simulated the pressure distribution of the diversion tunnel based on the physical model test, as well as the three-dimensional numerical model established by the RNG k-ε turbulence model and the VOF method. The reliability of the three-dimensional numerical simulation was verified by the experimental data. The results show that the main flow of the diversion tunnel, the pressure distribution of the tunnel body at the sudden change of hydraulic boundary such as the inlet chamber section, the turning section and the plug section, as well as the variation trend of the bottom and top pressure along the way were analyzed. The research results show that the pressure distribution along the bottom and top of the diversion tunnel shows a downward trend, but at the sudden change of hydraulic boundary such as the sluice chamber section, the plug section and the turning section, the pressure value will show a large fluctuation of rapid increase or decrease.

The structural joints of face rockfill dam are the most important part and the weakest link of the seepage control system of dams. Taking a face rockfill dam as an example, the position, width, length of vertical failure joints and permeability coefficient of cushion area were simulated by finite element method. And then the seepage field law and permeability stability after water stop failure were studied. The results show that in the case of single fracture failure, the position, width, length of fracture and permeability coefficient of cushion are positively correlated with control factors of seepage flow, and the length of vertical fracture and permeability coefficient of cushion are the most significant. When multiple joints fail simultaneously, the seepage flow at cracked panel can be calculated by summing the failure results of single joints, and the results are safety. At the same time, it is suggested that the permeability coefficient of cushion should be 1×10^-5m/s or slightly smaller. The results can provide reference for the design and construction of similar projects.

Flexible mattress is a beach protection measure which is widely used in the waterway regulation projects in the middle and lower reaches of the Yangtze River. The in-situ service condition of the flexible mattress has a great impact on the protection efficiency for the beach and shoal. Aiming at the difficulty of identifying and quantifying the deformation of the bulge of the flexible mattress, a model test was carried out to study the strain response characteristics of the bulge deformation. The result shows that the strain under bulging deformation presenting a parabolic strain distribution characteristic on the cross-section, and the area with the largest strain is located on the top of the bulging body. Based on the strain distribution characteristics of bulge deformation, the shape prediction formula was proposed. Furthermore, the bulge deformation identification method and shape inversion method were put forward. The results can provide the reference for the deformation monitoring and assessment of the flexible mattress.