Water conservancy and hydropower projects have the characteristics of long construction period, complex structure, and being greatly affected by natural factors. An accidental factor in operation may sometimes lead to systematic safety accidents of the whole hydropower station. The author summarizes some typical cases of domestic hydropower station accidents in recent years, and analyzes some risk factors needing attention in the construction and operation management of hydropower stations, to provide reference for design, construction and operation management.

The underground powerhouses on the left and right bank of Baihetan hydropower station are all developed from head, which are located in the mountains upstream of dam abutment and close to the upstream reservoir. Based on the hydrogeological conditions, the design experience of similar projects, and comprehensive consideration of the scale and importance of Baihetan hydropower station, the design principle of seepage control system for the underground powerhouse is determined and different seepage control plans are proposed. The seepage field and seepage flow rate are calculated and analyzed by the three-dimensional seepage finite element method, so as to determine a reasonable and economic seepage control system. The research results show that the design scheme can significantly reduce the groundwater level and seepage pressure around the powerhouse and improve the stability of the surrounding rock of tunnels.

From the perspective of the role played by reservoir dams, the importance of reservoir dam safety to the realization of national water security strategy and dual carbon goals is emphasized. The safety operation of reservoir dams is always faced with severe situation and risks. By reviewing and summing up the safety supervision of hydropower dams, some suggestions are put forward.

The rock- bolted crane beam in underground powerhouse of Baihetan hydropower station is designed by use of rigid body limit equilibrium method and checked by finite element method, which verifies the rationality of design parameters of structural section and bolt. Due to the influence of complex geology and high in-situ stress, the excavation of rock-bolted crane beam in local area is difficult, so the technical measures of rock platform excavation and reinforcement are put forward. Analysis of the prototype observation results shows that the bolt stress of rock-bolted crane beam and the opening between crane beam and surrounding rock have met the requirements. During the load test, the increase of monitoring data is small, which verifies the rationality of the design method and construction measures of rock-bolted crane beam.

By inspection of hydraulic technical supervision of dams of Huadian Corporation, the problems and challenges are explained, mainly about management and in the specific equipment. Then plan is made for better hydraulic technical supervision in future. It is particularly important to take high dams, large reservoirs, small hydropower stations and defective dams as key supervision and management objects. Practical and effective measures should be taken to enhance management innovation and technology investment, which can ensure the safe and stable operation of Huadian Corporation dams.

There is a lack of safety and emergency management system and mechanism for cascade hydropower stations in China. To prevent and respond to safety emergencies of dams in the upper reach of Yellow River basin, and to control, mitigate and eliminate adverse effects of emergencies, study on the safety and emergency management of 13 hydropower stations in the reach from Longyang George to Liujia George was carried out by State Power Investment Group Huanghe Hydropower Development Company Limited. The analysis of risk classification matrix and the theory of risk prevention were used to establish the dam safety and emergency management mechanism suitable for hydropower stations in the upper reach of Yellow River belonging to different owners. The study results were of great importance and worthy reference.

Due to the influence of columnar joint basalt, interlayer dislocation zone C4 and C5, fault and high ground stress, the quality of excavation face at the rock-bolted crane girder is poor. In particular, overbreak of the downstream rock wall is common, and the maximum overbreak height below the inflection point of the wall seat is 6 m. Aiming at different defect forms of the rock-bolted crane girder, reinforcement measures are taken, such as support, structure repair and arm support. And the reinforcement measures are analyzed and evaluated.

Local leakage in the inlet and outlet area of upper reservoir of Shisanling pumped storage power station is large, and there may be centralized leakage channels. In order to determine the main part of leakage, five survey lines are arranged in power station. The small loop multi-source and multi-component transient electromagnetic method is used to detect the specific part of leakage. The multi-component data from different emission sources are comprehensively used to carry out joint inversion. Combined with the seepage monitoring and analysis data during operation in the inlet and outlet area, it is obtained that the leakage is mainly occurred in low temperature seasons, which has no obvious correlation with groundwater level. And there is an anomalous leakage area with a length of 10 m in the inlet and outlet area. The detection results provide a technical support for the search and treatment of centralized leakage channels at inlet and outlet. 

The calculation and analysis of dam break flood is an important basic work for dam risk assessment and emergency management. The size of dam break has a great impact on the calculation of dam break flood. At present, most research on the development of dam break is about earth rock dams, while the research on concrete dam break is less. So in the calculation of dam break flood, the geometric size of concrete dam break is usually assumed based on experience. According to the database of historical concrete dam break cases at home and abroad, combined with structural characteristics of concrete dams, the causes and failure modes of concrete dam break are counted and analyzed, and the general principle for estimating the size of concrete dam break is introduced, which provides a reference for determining the parameters of concrete dam break in flood calculation.

With the development of information technology, the traditional paper-based hydraulic patrol inspection work is gradually transformed into a patrol inspection management system (module). At present, the patrol inspection system still has some problems. For example, the patrol inspection objects are not abstractly classified, the defects are not objectified, and the functions of patrol inspection App are simple. Aiming at the above-mentioned problems, the optimization design scheme is proposed and applied to the patrol inspection module in the dam safety information management system for Yalong river basin. Web terminal and mobile terminal (App) are mainly included in this module and functions such as viewing tasks, patrol inspection, result recording and query, defect tracking and query are available. With the help of information management means, this system can optimize the information management mode of hydraulic patrol inspection and further improve the level of dam safety information management.

A hydropower dam in northeast cold area suffers from structural joints damage on the overflow surface, which will seriously affect the dam safety and durability. The repair scheme of low temperature and large deformation is adopted to carry out the function repair by epoxy mortar and surface protection for structural joints on overflow surface. After treatment, the surface of structural joints is in good condition without damage during flood discharge, worth reference for treatment of similar concrete defects in cold area.

During investigation, design, construction and operation of tunnels, due to constraints and mistakes, failures happen. There are 10 cases at home and abroad presented in this paper, as well as the cause reasons and the lessons learned, for reference.

Xikeer reservoir is located in an area with frequent occurance of earthquakes. Since its completion, the reservoir has experienced six strong earthquakes, each of which has caused varying degrees of damage to the reservoir dam. Analysis of seismic damage characteristics and seismic safety of the dam can provide reference for the design of hydraulic structures in highly seismic region. Firstly, the seismic damage characteristics are summarized based on seismic damage data of the reservoir dam. It is found that cracks and sand boil occur in the dam during each earthquake, and the seismic damage severity is closely related to the earthquake magnitude. Secondly, based on the mechanics test results about dam foundation and dam body, the seismic safety is analyzed from the aspect of liquefaction possibility of dam foundation and cracks in dam body. The results show that the foundation of main dam and auxiliary dam may be liquefied locally, and the dam body is prone to crack by earthquake. Finally, some suggestions on reinforcement measures are put forward.

Patrol inspection is an important means to ensure the safety of hydropower stations. Based on summary of the advantages and disadvantages of traditional patrol inspection schemes, combined with digital inspection methods, this paper proposes an optimized scheme and a new online inspection system scheme is formed. Upgrading of inspection functions, the optimization of inspection types and content as well as the optimization of inspection systems are realized. After the scheme optimization, the degree of data structuring has been improved, the data redundancy has been significantly reduced, and the defect management function has been added. Moreover, the online inspection system designed based on this scheme has been applied to Ertan hydropower station.

The“1·12”water inrush accident of Guanzhou hydropower station reflects the problems that the main responsibility of safety management is not implemented, the procedures of bidding and procurement are chaotic, and the quality of pipe bulkhead is poor. Enterprises in charge of the operation and management of hydropower stations should learn from this accident. In order to eliminate risk factors and ensure the operation safety of power stations, responsibilities of relevant departments should be fulfilled, technical management should be strengthened, and the sensitivity and responsibility of operation management personnel should be improved.

Aiming at the problems such as low work efficiency, weak professional level, and poor timeliness existing in the manual analysis, information technology is adopted and a set of dam safety monitoring data diagnosis and analysis system is designed and developed, which has obvious advantages in monitoring data preprocessing, distribution map drawing, engineering analogy, abnormous situation feedback, and et al. As well, it can realize the automatic generation of monthly reports, quarterly reports, annual reports, earthquake express reports and comprehensive monitoring data analysis reports. The application shows that the system can significantly improve the efficiency and quality of dam safety monitoring data diagnosis and analysis work, and it is worthy of promotion in dam safety management industry.

Intelligent dam management platform based on online dam safety monitoring and BIM modeling for Xinfengjiang hydropower station has modules such as three-dimensional display of the dam, online dam safety monitoring and controlling, management of dam safety monitoring, intelligent patrol inspection, management of defect and hidden danger, intelligent report compilation, account and document of hydraulic equipment, task management and other functions. By use of the platform, the integration of information from various dam safety businesses is realized and the problems in traditional dam management are solved. This paper introduces the construction principles, development mode, system framework, database design and function modules of the platform, as well as the time node of system construction. Further, the operation of each module of the platform is analyzed.

Seepage monitoring is important for dams. Combination of water measuring weir and monitoring instruments is mainly adopted worldwide, which is more applicable to the cases when the flow is greater than 1 L/s, while its effect is not ideal when the flow is less than 1 L/s. Combined with the application of tipping bucket flowmeter in the automatic seepage flow monitoring system of Jicun dam, the application scenario, function principle, installation and debugging, and daily operation of tipping bucket flowmeter at measuring points with small flow are described, worth reference.