The mechanical properties of hydraulic concrete are an important influencing factor on the stability of hydraulic engineering facilities. A fine damage intrinsic structure model considering the effect of sulfate corrosion was established using a combination of mechanical experiments and theoretical analysis. The results show that the effect of sulfate corrosion increases the damage degree of concrete after damage. With the increase of corrosion time, the compressive strength and elastic modulus show an exponential decay law, and the damage strain tends to increase. From the experimental results, the shape parameter m and scale parameter ε₀ are calculated. Besides, the mesoscopic damage constitutive model considering the effect of sulfate corrosion is solved. The reasonableness of the theoretical model for predicting the stress-strain relationship was verified by experimental data. The constitutive model proposed in this study can provide scientific reference for the accurate prediction of mechanical behavior of hydraulic concrete.

In stone column composite foundations, the Priebe parameter composite method is commonly used to calculate the equivalent shear strength. Most of the existing studies are based on low stresses in conventional embankments, but few studies have been carried out on the applicability of this method under high stresses. This study focuses on the foundation treatment project for a clay core rock fill dam in Rwanda. The stress-strain behavior, micro-failure mechanism and equivalent shear strength of composite specimens with different area replacement ratio were investigated by simulating large-scale triaxle tests with discrete element numerical methods and compared with the widely used parametric composite method. The results show that the stress-strain characteristics of stone column composite foundations at high stresses differ from those at low stresses, and show a strain hardening trend. Composite specimens show a significant non-linear trend in strength at high stresses. The shear strength parameters calculated by the parameter composite method overestimate the strength of composite foundations, and it is recommended that they be discounted in engineering applications.

The Shiliushubao landslide is one of the giant landslides with complex structure in the Three Gorges Reservoir area. Since the dam was filled with water, the landslide has shown signs of revival, causing loss of life and property to several people around. In order to study the deformation failure mode and response mechanism of Shiliushubao landslide under the fluctuation of reservoir water level, the large-scale physical model test was used to accurately control the fluctuation condition of the experimental reservoir water level, and the displacement sensor, earth pressure sensor and pore water pressure were embedded in the slope. The sensor was used to analyze the experimental phenomenon. The results show that the influence of the reservoir water level fluctuation is mainly concentrated at the foot of the front edge of the landslide, and the rapid decline of the reservoir water level has a significantly greater effect on the landslide deformation than the increase of the reservoir water level; The mechanical response of the slope body has a hysteresis, and the effective soil stress increases when the reservoir water rises, the anti-sliding force of the sliding belt increases, and with the increase of the rising rate, the penetration force directed into the slope is larger, which is conducive to the stability of the landslide; Under the condition of the reservoir water level, the deformation and failure mode of the Shiliushubao landslide is sorted as: original slope → Erosion and erosion expansion at the foot of the slope → formation and expansion of the fissure at the foot of the slope → formation of the fissure on the slope surface → local slump, which is a hydrodynamic pressure landslide. The test revealed the deformation mechanism under the condition of reservoir water level, and provided a reference for the study of similar landslides.

In order to realize the effective utilization of winter idle water resources in kariz of Turpan Basin and recharge the regional groundwater, it is urgent to carry out groundwater recharge project in this area and determine the reasonable construction location and effective recharge mode. Firstly, the suitability evaluation system of groundwater recharge was constructed based on the six indexes of kariz flow, recharge source distance, aquifer permeability coefficient, groundwater depth, electromechanical well density and terrain slope. The suitability zoning of groundwater recharge was carried out by using ArcGIS spatial analysis function. Field tests were carried out in the typical recharge suitable areas to study groundwater recharge methods. The results show that there are abundant recharge water sources and storage space in the middle of Gaochang District, the north basin irrigation area of Shanshan County and the northeast part of Toksun County. The overall permeability coefficient is greater than 15m/d, which is suitable for the recharge of kariz winter leisure water. The effective recharge of groundwater can be realized by using the well irrigation method of the electromechanical well recharge, which is suitable for the recharge of the winter idle water in the study area.

To maximize the cost-effectiveness of green infrastructure (GI) implementation, a pilot project in Guangzhou Tianhe Smart City was selected to conduct the study. Setting runoff volume reduction rate, suspended solids load reduction rate, and life cycle cost of GI as optimization objectives, SPEA2 was coupled with SWMM to obtain a series of GI optimal spatial allocation schemes with land utilization as the constraint condition. The results show that with the increase of the rainfall recurrence period, the integrated reduction rate and the range of the GI optimal spatial allocation scheme set gradually reduce. The sunken lawn (SL) is the most cost-effective GI while the green roof (GR) is the least. When the investment is low, the area of SL can be planned to the maximum before planning other GI. If the integrated reduction rate is high with sufficient funds, GR can be considered based on the large allocation area of other GI. The results can provide theoretical support for the implementation of the sponge city program.

In order to study the influence of high tidal current velocity on the dynamic characteristics of horizontal axis tidal turbine under free wave conditions, STAR-CCM+ was used to establish a numerical calculation method for the hydrodynamic characteristics of tidal energy turbines under sea wave conditions. The law of wave influence on the rotation of tidal energy turbines and the characteristics of wake flow generated during the rotation were obtained. The results show that the amplitude and frequency of the angular acceleration of the tidal energy turbine are affected by the waves, but the fluctuation amplitude is less than the wave amplitude, the variation frequency is higher than the wave frequency. The wake flow produced by the rotation of the hydraulic turbine will make the flow field around the next hydraulic turbine more chaotic, and will have an impact on the blade rotation, turbine shaft load and energy utilization efficiency. Based on the analysis of the changing trend of pressure fluctuation, it is considered that the wake flow has little effect on the fatigue damage of hydraulic turbine.

Based on Hopf bifurcation theory, the stability of pumped storage power station considering asymmetric water passing system is studied. Firstly, the mathematical model of the speed regulation system of the pumping and storage unit of the one-pipe two-machine asymmetric water passing system with the upstream surge chamber is established. On this basis, the Hopf bifurcation analysis is carried out to obtain the theoretical stability region of the speed regulation system, and the dynamic response characteristics of the unit under different control parameters are analyzed to verify its theoretical stability region. Furthermore, the multi-scale oscillation characteristics and its generation mechanism of the dynamic response of a pipe double pump storage unit are revealed. Finally, the influence laws of flow inertia time constant, turbine inertia time constant and surge chamber time constant on system stability are explored. The results show that the Hopf bifurcation of the speed control system of the pumping and storage unit of the one-pipe two-machine asymmetric overflow system with the upstream surge chamber is supercritical, and its stability region is determined by two bifurcation lines; The hydraulic interference between the surge chamber and the units makes the response characteristics of the units show obvious multi-scale oscillation characteristics; Larger flow inertia time constant and smaller turbine inertia time constant are beneficial to system stability, and the influence of surge chamber time constant on system stability presents saturation characteristics. The research results have important guiding significance for the intelligent control of pumping and storage units and the design optimization of water passing system in power stations.

Aiming at the shortcomings of low efficiency and time-consuming when using the ANSYS parametric design language (APDL) to carry out the three-dimensional finite element design of the gate structure, this paper proposed a APDL design-analysis program based on VB, and performed nephogram results on a certain project. The results show that the program can improve the design and analysis efficiency of steel arch gate, and programmers can flexibly debug related to practical project cases, so that the designed steel arch gate can meet the needs of project construction.

In order to deeply understand the impact of the alteration of different opening angles of the two stage flap valves on outflow, a two- stage flap valve of a certain pumping station was taken as an example. Choosing four opening angle schemes widely used in practical projects, the three-dimensional flow pattern behind the two stage flap valve under different flow rates was simulated. The influence of flow streamline, velocity uniformity and hydraulic loss in culvert on the flow pattern was analyzed. The results show that the resistance loss coefficient along the outlet culvert is inversely correlated with the opening angle, to be specific the larger the opening angle of the flap valve, the less the hydraulic loss of the water flow in the outlet culvert pipe, and disparity degree becomes more obvious with the increase of the flow rate. When the flow rate is 2 m³/s, the hydraulic loss of the outlet culvert pipe in scheme 4 decreases by 49.6% compared to that of scheme 1; When the flow rate is 16 m³/s, the hydraulic loss of the outlet culvert pipe in scheme 4 decreases by 79.1% compared to that of scheme 1. To conclude, the larger the opening angle of the flap valve, the better the flow pattern in the culvert and when the flap valve is opened to 46°for the upper flap valve and 64°for the lower flap valve in scheme 3, the flow pattern in the culvert has tended to a better state.

The "reinforced concrete shield and riverbed" junction or pre-excavated pits at the end of the apron of a gate dam with supercritical flow connection mode are often damaged by foundation erosion, which not only leaves the apron in a suspended state, but may also cause the flow pattern at the end of the apron to deviate from the designed supercritical flow pattern, or even form a hydraulic jump like large-scale rolling and scouring riverbed, but there are few relevant research results. For the scenario that suspended foundation at the end of apron caused by local generalized scouring, the detailed observation and computational analysis of the flow patterns near the scour pits of different sizes at the end of the apron were carried out using physical model experiments and three-dimensional turbulence numerical modelling methods. Compared to the supercritical flow pattern at the end of the apron when the foundation is not scoured, the results show that the scour pits change the flow pattern significantly, and can be divided into three categories. The first category is the hydraulic jump upstream of the apron, the second category is the mixed flow in the scour pit and the third category is the quasi-periodic flow pattern consisting of the first two categories. The results of the flow evolution study can provide technical support for the analysis of large-scale damage to the retaining structure downstream of the dam apron, which has certain engineering application value.