In recent years, rainstorm and flood disasters occur frequently in the basin. Accurate and reliable flood forecasting is an important measure to effectively prevent and resist mountain torrents. Taking Lushui basin as the research area, this paper constructed the HSPF semi-distributed model. Choosing the representative floods in the flood data of the basin from 2013 to 2020, the calibration and verification of the model parameters were carried out. The accuracy of flood simulation was evaluated by using indexes of certainty coefficient and relative error. The results show that the model has a good performance in the field flood simulation of Lushui basin. The qualified rates of peak time and peak discharge of 15 flood simulations are 100.0% and 80.0%, respectively, the qualified rates of flood volume and runoff depth are 93.3%, and the average value of certainty coefficient is 0.80. The overall prediction accuracy reaches class B, indicating that the HSPF flood prediction model has good applicability in Lushui basin. The research results can provide basis for flood forecasting in this area.

Aiming at the complicated law of specific energy along stepped chute and the low accuracy and limited application scope of current calculation method of water surface profile, a reliable method of calculating water surface profile was proposed. Based on hydraulic model test, this paper introduced the relative specific energy and made dimensional analysis. Then the dimensionless relative specific energy was systematically studied qualitatively and quantitatively. The results show that the dimensionless relative specific energy is related to the relative critical water depth, spillway slope and dimensionless position. The dimensionless relative specific energy has a good linear correlation along the stepped spillway. Based on the quantitative research results, the empirical formula of dimensionless relative specific energy calculation was given, and a new method of water surface profile calculation was obtained. The analysis of numerical example shows that the calculation method of water surface profile has high accuracy and wide application range, which can provide theoretical reference and technical support for the design of stepped chute.

In view of the difference between the performance of cemented gravel soil under low normal stress and high normal stress, based on the Mohr-Coulomb strength criterion, according to the Mohr-Coulomb strength line of cemented gravel soil before and after yield stress, a polygonal line strength criterion of cemented gravel soil was proposed. The relationship between strength criterion parameters and uniaxial compressive strength and uniaxial tensile strength was deduced. Uniaxial compression test and direct tensile test were carried out to calculate the strength criterion parameters and compare with the strength criterion parameters obtained by triaxial compression test. The results show that the error range between the calculated value and the experimental value is reasonable. The polygonal line strength criterion is suitable for cemented gravel soil.

In order to study the uniaxial tensile behavior of autoclaved aerated concrete blocks (AACB) in static state, the uniaxial tensile test of AACB with different densities was carried out. The tensile failure characteristics and failure mechanism of AACB were analyzed. The change rules of its tensile strength and elastic modulus under different densities were discussed, as well as the relevant formulas of the relationship between uniaxial tensile strength and porosity, compressive strength and splitting tensile strength. The experimental results show that the tensile yield strength and elastic modulus of AACB increase with the increase of density, but the tensile yield strain decreases gradually. The macroscopic failure of AACB under uniaxial tension is mainly controlled by the tensile damage mechanism of the material. It shows obvious brittle failure characteristics. Based on the ideal prediction model of porous materials and the regression analysis of test results, the semi-empirical formula and correction coefficient of AACB uniaxial tensile strength and porosity under the test conditions were fitted. The conversion relationship between AACB tensile strength and its compressive strength and splitting tensile strength was proposed.

In order to study the deformation and internal force of concrete lining structure of expansive soil trapezoidal channel in northern Xinjiang, indoor test and numerical simulation were used to calculate expansive deformation of foundation soil. Based on the beam theory of elastic foundation, a mechanical model was established to calculate the deformation and internal force of concrete lining slab. The deformation and internal force of concrete lining slabs were calculated and analyzed after the operation of the channel with the initial moisture content of the foundation soil being 6%, 9%, 12% and 15%. The results show that the deformation and internal force of the concrete lining plate increase with the decrease of the initial moisture content of the foundation soil. When the moisture content of the foundation soil is 6%, the maximum expansive deformation of the channel floor and slope plate can reach 3.48 cm and 3.94 cm. When the initial water content is constant, the expansion reaction force is the largest at the foot of the slope, and the displacement and bending moment are the largest at the middle of the bottom plate. The displacement of channel slope plate is the largest at one third of the slope foot, and the bending moment is the largest at one sixth of the slope foot. Finally, according to the research results, two engineering measures of "anti-seepage and moisturizing" were proposed.

Aiming at the problem of low economic benefits of pump stations caused by unreasonable dispatching, this paper took the pump stations with multiple piping systems as the research object. Considering the impact of peak-valley electricity price, a pump station daily economic optimization model was established by taking the minimum daily operating cost as the goal. The secondary pump station of the connected river reservoir project was taken as a study case to compare constant speed throttling regulation and frequency conversion regulation, which bases on the improved genetic algorithm and dynamic programming method of combined variation. The results show that the improved genetic algorithm is suitable for optimal dispatching of pumping station. At the same time, it is found that when the actual operating points of the pump unit far from the design operating point, adopting frequency conversion regulation has higher economic benefit.

For underground powerhouse in high geostress area, the excavation of the lower powerhouse cavern after the completion of the pouring of the rock-anchored crane beam may have an adverse impact on the crane beam. Aiming at this problem, three-dimensional elastoplastic finite element method was used to analyze the stress and deformation, the stress of the anchor and the stability of the crane beam of an underground powerhouse during construction and operation period. The results show that in the high geostress field, the rock-anchored crane beam will have large deformation, and the joint surface between the beam and the surrounding rock will have large tensile stress. After the crane beam is poured, the stress and deformation of the beam will increase greatly in three stages. As the excavated part is far away from the beam, the stress and deformation of the beam will become gentle, and the safety factor of the joint surface between the beam and the wall will be large, which can provide a reference for the crane beam pouring and cavern construction in similar projects.

Based on the climatic conditions and flood characteristics of the Puhe River Basin, this paper used Tank model to simulate 10 rainstorm flood processes in the basin from 2019 to 2020, constructed a conceptual rainstorm flood meteorological risk early warning model suitable for the basin, and carried out simulation and accuracy evaluation. The results show that the improved water tank model can intuitively simulate the water level change process curve of Shijiao hydrological station under different time scales and different basic water levels, reduce the uncertainty of area rainfall threshold, and the prediction accuracy is class B; Meteorological risk warning is issued level by level according to the simulation results, and the skill score and hit rate are 100%; The average early warning release time is more than 3 hours in advance, which can be substituted into the predicted precipitation to further extend the flood forecast period.

Anti-dip layered rock slope is a common type of slope in hydropower engineering. Its stability is controlled by slope geometry, rock characteristics and structural plane properties. To reveal the influence of multiple factors on the stability of such slopes, taking the safety factor and displacement as dependent variables, the significance of six main factors, namely slope angle, slope height, rock inclination angle, rock thickness, rock quality and structural plane quality, was studied based on the approaches of discrete element modelling and orthogonal test design. Moreover, the deformation and failure laws of typical modes for anti-dip slopes were analyzed. The study can provide a reference for the optimal design of anti-dip layered rock slopes.

Accident pump-stopping water hammer is a technical problem that needs to be highly valued in long-distance pressurized water diversion projects. This paper carried out calculation and analysis of hydraulic transition process on the Oujiang River Diversion Project. The loss of power accident of four pumps under maximum lift was taken as control condition, and the loss of power accident of single pump was taken as verification conditions. The optimization of pump outlet valve closing law was taken as the main water hammer protection measure. The research shows that when the butterfly valve at the outlet of the pump refuses to operate, the pressure and flow in the pipeline fluctuate more violently than that of the single pump during pump trip accident, and the reverse speed of the pump does not meet the specification requirements. By adopting the two-stage broken line closing law of the pump outlet butterfly valve, a better water hammer protection effect can be obtained.