The safety management for hydropower dam is a work that emphasizes both management and technology, and is an important part of implementing the main responsibility of power enterprises. This study provides an overview of the content and key points of safety management for hydropower dam, in⁃ cluding the implementation of laws and regulations, establishment and improvement of institutional mechanisms, talent cultivation and daily work, which can provide reference for the daily management of power enterprises.

The geological conditions of Kala hydropower station are very complex and there are many re⁃ strictive factors in layout. In the feasibility study stage, tailrace surge chamber is set. In the optimal lay⁃ out of project, the water diversion and power generation system are moved outward as a whole, and the length of water transmission line is effectively shortened. According to the specification, the need of tail⁃ race surge chamber is in a critical state. Therefore, the transition process analysis and justification of cancelling the tailrace surge chamber in Kala hydropower station are carried out. The results show that the transition process of large fluctuation and small fluctuation can meet the requirements of specifica⁃ tion. It is proved that cancelling the tailrace surge chamber is feasible and has significant economic ben⁃ efits, which can provide reference for the design of similar projects.

With the continuous development of basin-level clean energy bases, integrated regulation of hydro-wind-solar power has become an important direction for the development of existing hydropower stations, which presents challenges for the traditional regulation of cascade hydropower centralized con⁃ trol centers, and the introduction of systematic and integrated regulation theory and methods is required. In response to this, a multi-time scale sequential nested regulation architecture for integrated hydrowind-solar system is constructed based on the actual needs of the lower reach of Jinsha river basin. The core business model is analyzed, and an integrated regulation process is established to provide a system⁃ atic solution for promoting the new energy consumption and ensuring the safe and efficient operation of hydropower stations in the clean energy bases.

Based on summary of advantages and disadvantages of common safety inspection methods, technology and equipment of underwater safety inspection are studied and some solutions are proposed, such as miniaturized high-power ROV, multi-beam combined ROV and intelligent unmanned ships. These solutions have addressed challenges of underwater inspection in complex environment such as deep-buried large-diameter long diversion tunnel, high-head multi-bend penstock and high-flow open water area. Moreover, these technologies have been successfully applied to cascade hydropower stations in the Yalong river basin, which is worthy of reference for similar projects.

The static leveling system for dam foundation of Daheiting reservoir has been in operation for nearly 20 years. During operation, abnormal values were detected at measuring points. Through the mon⁃ itoring system test, on- site and monitoring data inspection, and manual observation data comparison and analysis, comprehensive analysis and study of the abnormal conditions existing in operation are con⁃ ducted to find out the cause reasons, and it is determined that the vertical displacement of dam founda⁃ tion is normal and the dam body is operating stably, which can be used for reference to similar projects.

Manwan hydropower dam has been in operation for 30 years. This article reviews the improvement of horizontal control network and the instruments for monitoring of dam horizontal displacement, external slope deformation and dam seepage. As well, the development of automatic monitoring system is introduced. While elaborating on observation methods, data processing and development of automation, the further development direction is also presented, for reference.

The uplift pressure and seepage volume are the most intuitive reflection of the foundation seepage behavior of concrete gravity dam. To get the general variation of the foundation uplift pressure and seepage volume of the gravity dam during operation period, the monitoring data of the main concrete gravity dams in domestic power industry are analyzed. The results show that it is a common phenomenon that the uplift pressure coefficient of partial foundation of the gravity dam exceeds the design value. However, due to the large safety margin in design, the anti-sliding stability of dam foundation could still meet the specification requirements in review and calculation. Under normal conditions, the foundation seepage volume of gravity dam is not greater than 5.0 L/s. The seepage flow of dam foundation of different projects is closely related to geological conditions, seepage control effect and earthquake, but has a weak correlation with dam height or dam crest length. The study results could provide some reference for monitoring data analysis and seepage safety evaluation of concrete gravity dams.

To ensure the stability and reliability of gate opening and closing, a dual hydraulic cylinder configuration is typically used to drive the gate. Synchronizing the two cylinders becomes a critical fac⁃ tor when equipping the emergency actuator for the hoist. In this project, the method is applied that multi⁃ ple hydraulic hoists are able to share a single hydraulic emergency actuator for polling display of open⁃ ing during emergency operation. The emergency actuator is movable and once connected to the hydrau⁃ lic lines and cables, it can automatically identify the hoist number. The synchronized operation of two cylinders to open or close the gate is realized through relay interlocking protection, opening collection signal splitting and other mechanisms. The feasibility of using a single emergency actuator to alternately control three hoists is validated through on-site installation, testing and operation, which meets the ex⁃ pected performance and can offer reference for the emergency operation of similar hydraulic hoists in hy⁃ dropower stations.

This study puts forward a vehicle for the inspection of penstocks in hydropower stations, which has been successfully applied to the safety inspection of the penstocks of Unit 4 in Manwan hydro⁃ power station, to ensure the safe operation of penstocks.

Face-slab crack is considered as an influence factor of dam seepage to propose the seepage safety monitoring statistical model and RBFNN model. Combined with the specific project, the seepage monitoring statistical model and RBFNN model of a concrete face-slab rockfill dam are established, and the seepage flow is predicted. The prediction results are close to the actual monitoring values. At the same time, the weight of each influence factor of seepage flow calculated by RBFNN is not significantly different from the results calculated by traditional statistical methods, which shows that the model pro⁃ posed in this study is effective and applicable. The research results are of guiding significance for treat⁃ ment of the abnormal seepage flow mornitoring values of concrete face-slab rockfill dam with cracks.

Personal and property damage caused by water conservancy and hydropower projects, such as flood discharge, has become a common social problem. This paper analyzes various public safety risks in the river channel downstream of a hydropower station and accordingly explores and summarizes various control measures to prevent and resolve these risks in the affected area, for reference.

Using finite element numerical model, combined with the geological conditions, material char⁃ acteristics and seepage field, a deep analysis of the seepage stability status of Luotian reservoir dam is conducted, and the safety performance of the dam is evaluated comprehensively. The results show that the seepage control of Luotian reservoir dam is good under various operation conditions, the saturation line rises as the reservoir water level rises, the seepage flow has little influence on reservoir water stor⁃ age, and the safety factor of anti-sliding stability can meet the requirements of regulations. The research results can provide theoretical support and technical assistance for the safe operation and management of Luotian reservoir dam, and can also provide useful references for the safety evaluation of seepage sta⁃ bility of similar projects.

Concrete dams are affected by changes of water pressure and temperature, resulting in low ac⁃ curacy of combined prediction of deformation. To address this issue, a combined prediction model for concrete dam deformation based on drone oblique photography is constructed. This model calculates the horizontal distance based on the geometric principle of photography, corrects lens distortion and obtains the coordinates. Based on the SIFT feature domain, the local features of the image are extracted, a threedimensional model is constructed, the root mean square error of combined prediction is calculated, and the combined predictive values of variable weights are obtained. The prediction process is designed to realize real-time prediction. The practice results show that the horizontal displacement prediction is ac⁃ curate, and the vertical displacement prediction has the maximum error of 0.5 mm, which has a precise prediction result.

Shape accel array is widely used as it′s automatic, precise and reusable. Combined with the application of shape accel array to the deep deformation monitoring of the slope of a hydropower station, this paper introduces the components and application of shape accel array. The practice shows that the monitoring data are reliable and the system is stable, worthy of promotion to similar projects.

Sanguozhuang reservoir has been in operation for more than 20 years. The situation of sediment in the reservoir area has changed greatly under the influence of human activities. Thus, it is urgent to analyze the reservoir sediment and its influence on normal operation of the reservoir. In this paper, the sediment yield of Sanguozhuang reservoir basin as well as the sediment in front of the dam after 20-year and 50-year reservoir operation are estimated. Then, sediment distribution is calculated. By comparison between the calculation results and the actual sediment situation, the reliability of calculation results is verified. Accordingly, the influence of sediment on dead water level and normal water level of the reservoir are analyzed, to provide basis for the review of the reservoir scale.

Tension wire alignment is commonly used in monitoring of horizontal displacement in the upstream and downstream direction of linear concrete gravity dams. The floating vessel should match with wire diameter and the distance between measuring points, or the size of floating vessels should be specifically designed. Otherwise, deflection and large draught of the floating vessel may cause system error of the tension wire alignment. For the case as the distance between measuring points is 35 m, the forces on the floating vessel are analysed, and accordingly, the vessel size is enlarged. On-site test on the accuracy of the measured values shows that it can meet the error requirements of the specifications.

Hushan reservoir dam is a sand dam with clay core wall located on gravel sand foundation. Over the past 50 years of operation, concentrated seepage was observed downstream of the riverbed section of the dam, which was caused by seepage in the dam foundation. Based on the engineering geology and hydrogeological conditions of dam foundation, finite element and flow network were used to analyze the seepage of the dam foundation and the clay covering. As well, the seepage stability of dam foundation was analyzed. Then the concrete anti-seepage wall scheme and the high-pressure jet grouting scheme were compared for seepage prevention of dam foundation. The results showed that the use of concrete anti-seepage wall to treat dam foundation was suitable, worth reference.

Acquiring dynamic material parameters of concrete dams is of great significance for verifying their seismic safety performance. At present, a common approach involves identifying the modal parameters of concrete dams from strong motion observation data and then constructing an objective function based on this information to optimize the material′s dynamic parameters. In this paper, modal parameters are identified based on strong motion observation data while simultaneously time-domain indicators from the seismic response sequence are extracted. A joint inversion of material dynamic parameters is conducted by constructing an objective function that combines both time-domain and frequency-domain information. Since the two objective functions differ in units and dimensions, a multi-objective optimization calculation is performed using the fast non-dominated sorting genetic algorithm with elitism strategies to obtain the Pareto optimal solution set for the dynamic material parameters of the concrete
dam. Inversion analysis of a specific engineering case demonstrates that the joint inversion method for concrete dam material dynamic parameters based on time-frequency domain information exhibits strong parameter identification performance and high stability, offering good application prospects in practical projects.

Based on the the overstressing on rock support system in the excavation of tailwater surge chamber of Yangfanggou hydropower station, combined with on-site geology, support scheme and monitoring scheme, the dynamic feedback analysis model is established. Analysis results show that the main reason for the overstressing on rock support system is, on one hand, local unloading and relaxation caused by the exposure of dominant joints with middle and high angles on the side wall and along the chamber. On the other hand, the construction blasting exerts great influence on the bolt stress as the monitoring instruments are close to the excavation boundary. By analysis and according supplementary support, the deformation and bolt stress of the area tend to converge. The evaluation method can be used to analyze the the overstressing on rock support system.

The deformable body of Guobu slope is on the right bank of Laxiwa hydropower station, 0.9~1.7 km upstream the dam. It is an ultra-large granitic rock slope with a volume of 102 million m 3 , affected by various deformation mechanism, mainly toppling deformation, and is classified as Class B Grade I. After the reservoir impoundment in March 2009, obvious deformation of Guobu slope is observed. Hence, scientific research, safety monitoring and risk control measures are carried out, including geological exploration, deformation monitoring, numerical calculations using various methods, and stability analysis. Due to the high deformation rate of Guobu slope in the early stage of reservoir impoundment, the deformable body of Guobu slope was assessed as a major hazard of Grade Ⅱ. In 2018, based on study results, Guobu slope was reclassified as a safety risk of Grade Ⅱ (acceptable risk of Grade Ⅱ). In October 2015, the reservoir water level reached the normal impoundment level of 2 452 m. Long-term monitoring data since then show that the deformation of Guobu slope has slowed down after the reservoir water level stabilized between 2 450 m and 2 452 m. The daily deformation rate by the monitoring point at the maximum deformation decreased to less than 2 mm/d. Currently, the deformable body of Guobu slope is generally stable, and the risk is controllable. This paper introduces the specific measures and achievements in the treatment of the deformable body of Guobu slope of Laxiwa hydropower station, for reference.