This paper provides a systematic summary of the current status and development direction of the standards system, regulatory system, management mode and technology for dam safety of China′s hy⁃ dropower stations. Responsibility shared among power enterprises, government departments and Large Dam Safety Supervision Center is established as the dam safety management mode of China′s hydropow⁃ er stations. China has released 101 effective standards and formulated a system table for dam safety stan⁃ dards. China has established a regulatory system centered around Regulations on the Supervision and Management of Operation Safety of Hydropower Dams. In the future, China will revise regulations, im⁃ prove standards and develop technologies to enhance the emergency response capability, informatiza⁃ tion, intelligence and internationalization level of dam safety, and promote the stable and far- reaching development of dam safety management.

After the reinforcement of Longshan reservoir, there is a problem of settlement, which leads to cracks on the dam crest and has unknown impact on the dam operation safety. This study comprehensively uses pit exploration, drilling and geophysical exploration methods to evaluate the dam operation safety, analyze the current situation of dam filling, investigate and analyze the causes of cracks and settlement problems. Meanwhile, the impact of the infiltration line lowering caused by reinforcement is considered to conduct a preliminary evaluation of settlement. The results indicate that the settlement of Longshan reservoir is mainly due to the low filling quality in some areas of dam body and the infiltration line lowering, which leads to the consolidation settlement of filling material. Although the settlement situation still meets requirements, the risk of continued settlement cannot be ruled out. It is necessary to excavate the non- dense soil and rerun the thickening and reinforcement project. The relevant survey methods and analysis can provide reference for similar dam settlement problems.

The safety technical standard system for hydropower dams serves as the safeguard mecha ⁃ nism for dam safety. In this regard, China has established specialized organizational bodies responsible for the planning, development and management of safety standards for hydropower dams. In nearly three decades of progress, standard development has been carried out in key areas such as safety monitoring, safety management and evaluation, safety risk assessment and emergency management, safety informati ⁃ zation and decommissioning management, gradually improving and refining the safety technical standard system for hydropower dams. This paper outlines the development history and achievements of hydro ⁃ power dam safety standards, elaborates future directions and tasks of standardization efforts, and intro ⁃ duces the latest released standards.

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.

The safety of hydropower dams is of significance for the lives and property of people, energy security, and the stability of economy and society. The dam safety monitoring system serves as the eyes and basis for supervising and evaluating dam safety, while routine monitoring and inspections of dam safety are a major task in the operation of hydropower stations. Timely detection of anomaly during dam operation requires not only a reliable dam safety monitoring system but also the practice of standardized and orderly monitoring and supervision. The former relies on technological advancement and progress while the latter depends on the continuous improvement of regulatory framework, technical standards, management concepts, as well as the competence and capabilities of personnel involved.

Based on the digital twin platform, the intelligent engineering safety analysis and early warn⁃ ing system is studied and designed. The mechanism model of engineering safety monitoring is studied by using the data mining, intelligent analysis and diagnosis technology. To obtain early warning indexes for specific project, the evaluation system and criteria are developed, which has realized intelligent safety analysis and early warning. Moreover, it has been applied to a project and resulted in improvement of the accuracy and timeliness of early warning, enhancement of the level of intelligence, and decisionmaking support for the operation management department.

The purpose of online dam safety monitoring of hydropower stations is to dynamically evalu⁃ ate the dam safety status in real time, which can provide technical support for preventing dam break, overtopping and major structure damage. The online dam safety monitoring system should be practical, effective and useful. It is necessary to develop and approve a practical and effective monitoring plan be⁃ fore system development. Based on the statistics and analysis of the causes of dam failures in the dam en⁃ gineering history worldwide, this paper explains the risk identification and monitoring elements of dam operation safety, and proposes suggestions for the content, items and information organization of online monitoring, to provide reference in the development of online monitoring plan.

In order to enhance the real-time capability of flood risk analysis and adapt to the dynamic characteristics of flood evolution, a 3D real-time flood risk analysis system based on the B/S architec⁃ ture has been designed. This system employs a coupled approach of the breach flow calculation software BREACH and the 2D hydrodynamic numerical model for dam-break flood calculation and simulation. It integrates WebSocket technology for real-time data transmission and utilizes Cesium 3D visualization platform to display the flood evolution. The core functional modules of this system are scenario manage⁃ ment, real-time calculation and calculation result analysis of dam-break flood, which can support dy⁃ namic management, real-time calculation and result visualization of the dam-break process. The system was validated through the case study of a reservoir. The results showed that the system can effectively re⁃ flect the flood inundation process, obtain reasonable calculation results, and enhance the intuitiveness of flood risk analysis and the decision-support capability through visualization technology

In recent years, a large number of pumped storage power stations have been built in China, and the reservoir engineering geological conditions determine the feasibility of the construction. Through on-site geological surveys and tests, the leakage and bank slope stability of the proposed upper reservoir are evaluated. Research has shown that the project is located in an area with prominent leakage problems. It is recommended to deal with the problems of dam foundation leakage and seepage around dam during the anti-seepage of upper reservoir basin. The engineering slope is generally stable. For the broken rock body affected by faults, as well as disadvantage blocks formed by the cutting and combination of faults, interlayer joints and dominant joints, the effective support measures should be taken in time according to the excavation exposing situation.

At present, the intelligent and smart safety management for hydropower dams in China is still at an early stage. Numerous institutions in the industry have carried out extensive explorations in intelli ⁃ gent operation and maintenance of hydropower dams, leading to the preliminary formation of an intelli ⁃ gent technical system for dam safety operation. This paper systematically analyzed the current status and practical demands of intelligent construction for hydropower dam operation safety. By examining the ap ⁃ plication of statistical models, neural networks, deep learning, knowledge graphs and AI large models, this study reviewed and discussed recent advances and future prospects in intelligence research of hy ⁃ dropower dams from the perspectives of intelligent information sensing, data-driven analysis, structural health diagnosis and intelligent decision support, aiming to provide some insights and reference ideas for smart dam development in future.

The major dam shell of Xiaolangdi water conservancy project is filled with rockfill materials containing siltstone, clay rock and other soft rocks. After years of operation, the soft rocks on dam surface have weathered into fragments, and part of soft rocks have been eroded into rockfill voids, which will have a certain impact on the physical and mechanical properties of rockfill materials in the dam shell, such as the permeability coefficient and shear strength, and may also affect the stability of upstream and downstream dam slopes. At the same time, Xiaolangdi dam has large dam height, complex and deep overburden, many kinds of dam materials and complex operating conditions, so it is necessary to study the properties of rockfill materials in dam shell. Through in-situ excavation and sampling, relevant tests of the grading, compactness and permeability of rockfill materials and original rock character and strength are carried out to conduct the experimental study on properties of rockfill materials in the major dam shell. The results show that the main character parameters of rockfill materials in the major dam shell slightly changed, and the weathering degree and compressive strength of rockfill materials have limited influence.

Taking factors affecting the accuracy of static leveling as the starting point, this paper analyz⁃ es the degree of influence of temperature difference and barometric difference in pipeline, pipe diame⁃ ter, etc, and proposes corresponding solutions. Also, this paper analyzes bubbles, liquid corrosion, dew condensation on float surface, contact friction, sensor measurement error and other factors, and proposes corresponding optimization methods. The error propagation rule of the static leveling system is explained and the pipeline test process is described, which can check whether the static leveling system works nor⁃ mally. Through comparison and analysis of artificial leveling observation data and automatic static level⁃ ing data of a typical project, it is concluded that after taking various methods, the measurement accuracy can meet the requirements of specifications.

Work summary and practical considerations on online safety monitoring technology for hydropow ⁃ er station dams// by ZHANG Xiuli// Dam Safety Monitoring Center of National Energy Administration Abstract: The author summarizes the progress and achievements of the Dam Safety Monitoring Center of National Energy Administration in promoting online monitoring technology development for hydropow ⁃ er dam safety over the past two decades, highlighting that online dam safety management is an essential component of the dam safety lifecycle management system. It is crucial to promote and implement online dam safety management widely. The author emphasizes that the development of online dam safety moni ⁃ toring system should focus on practicality, and proposes four key recommendations of prioritizing practi ⁃ cality, emphasizing research on monitoring schemes and indicators, ensuring meticulous and accurate processing of routine dam safety monitoring data and inspection results, and paying close attention to the planning, design and oversight of online monitoring platform development.

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.

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 Jiudianxia water conservancy project is located in the high altitude and cold area. Its dis⁃ charge tunnel on the left bank is easy to freeze due to the low temperature and the wind through tunnel. The durability of lining concrete in the tunnel is seriously damaged by the freeze-thaw cycle, which af⁃ fects the service life of the tunnel. This paper puts forward a design scheme of installing flat insulation gate at the opening of underground tunnel to solve the problems of seepage water freezing and cyclic freeze-thaw damage to the lining concrete.

Under the new situation of hydropower development, Yangfanggou hydropower station is the first large hydropower project under the EPC contract mode in China. During construction of the dam site slope, due to the characteristics of complex geological conditions, high and steep slope, huge scale and tight construction period, it was urgent to systematically carry out research on the key technologies of dynamic feedback design and stability control of high rock slope excavation. Relying on the integrated and efficient management mode and the mutual trust mechanism of this project, an interconnected man- agement system that deeply integrates design, construction and digitization was proposed, and a techni- cal team and innovation platform that closely integrate construction, design, geology, monitoring, scientif- ic research and information were established, which provided an important guarantee system for the sci- entific, safe and efficient construction of slope. Through systematic research and development of com- plete sets of complex technical problems in engineering, a method system of dynamic feedback analysis and decision optimization for large-scale complex high rock slope during construction period was estab- lished, which guaranteed the engineering safety and stability of the 300 m high rock slope in this mil- lion-kilowatt hydropower station. The relevant technical methods and research results have been summa- rized and refined to form a practical standardized method, which has the value of popularization and ap- plication.

The design task of pumped storage project is heavy, the time is limited, and there are many disciplines involved. Therefore, traditional design methods are unable to satisfy the current situation and requirements. Using BIM technology, through meticulous application planning, the collaborative design is carried out, covering surveying, civil engineering, mechanical and electrical engineering, and other re - lated disciplines. It can significantly improve the rationality of design schemes, enhance the accuracy and quality of design results, increase the diversity of results, liberate the productivity of designers, and provide a solid foundation for the application of digital twin pumped storage power stations. This study briefly describes the way to choose a suitable 3D digital collaborative design solution for pumped storage power stations and carry out 3D digital design, as well as the value and advantages of 3D digital technol- ogy in the design stage of pumped storage power stations.

Due to the relatively concentrated timing of water distribution periods, in order to meet the needs of water allocation within the year and improve the water supply guarantee rate, the Xinjiwa reservoir is constructed in Zouping city, as supporting works for the first phase of the East Route Project of South-to-North Water Diversion. This project can realize the water supply goal of South-to-North Water Diversion Project and provide support for the regional national economic development. Focusing on the construction of dams for the reservoir, the design schemes are compared and selected from two aspects: reservoir storage depth and dam foundation seepage interception scheme. The selected design scheme can meet the requirements of the reservoir, and can provide reference for reservoir construction in water supply areas along South-to-North Water Diversion Project.