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.

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

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.

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.

With the rapid development of pumped storage power stations, high-head hydraulic tunnels have continued to increase, and the operation safety of headrace tunnels has attracted more and more at- tention. Taking the shallow buried section of headrace tunnel in Huizhou pumped storage power station as an example, the main considerations for safety evaluation of shallow buried tunnel are explained re- spectively. The results show that although the shallow buried section of headrace tunnel has problems of broken surrounding rock and slightly insufficient thickness of overlying rock, the minimum principal stress and seepage stability at each control point can meet the requirements, and measures such as en- hanced consolidation grouting have been taken for the surrounding rock during construction process. Therefore, its safety can be guaranteed at present.

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.

Starting from the characteristics of emergencies and the requirements for emergency decisionmaking, this study treats dam operation emergencies as a continuous dynamic evolution process, propos⁃ es a scenario quintuple description method for dam operation emergencies, and constructs a Bayesian network model based on the evolution phases of target nodes. This model is applied to scenario develop⁃ ment where flood impacts dam operation safety. The approach reveals the intrinsic patterns and evolu⁃ tionary logic of emergencies, thereby enhancing the scientific rigor and operational feasibility of emer⁃ gency measures.

In recent years, several disastrous tailings dam accidents have occurred at home and abroad, caused huge losses to the lives, property and environment downstream. A brief analysis of these typical accidents is conducted to summarize the cause reasons of the dam failure, with the aim of serving as a warning to industry insiders.

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.

Limited by construction conditions, some concrete face rockfill dams have not built down- stream weirs, and only a certain number of osmometers are arranged, which can not reflect the dam seep- age situation through the leakage volume. Due to the complexity of seepage control of concrete face rock - fill dams, it is difficult to obtain the relationship between seepage pressure and seepage volume behind the concrete face by analytical method. In this study, the artificial neural network method is used to es- tablish the relationship model between seepage pressure and seepage volume of the CFRD based on its nonlinear mapping ability, and the measured values are used to verify it. The results by the leakage esti- mation method based on the training samples obtained from the three-dimensional finite element seep- age model are close to the measured results, which can provide a new way for leakage estimation of earth rock dams limited by geological conditions.

The practical weir is common discharge control structure of spillway, and its head loss is an important parameter for calculating the spillway discharge capacity and the water surface line, as well as for the design of energy dissipator. The empirical formula for calculating head loss recommended by cur ⁃ rent specifications has low accuracy. Therefore, using the hydraulic boundary layer theory to derive the calculation formula of head loss of practical weir in spillway is of practical significance.

The opening and closing of transverse joints under strong seismic action have a significant im- pact on the dynamic response of arch dams, which is a key concern in the design of high arch dams. Us- ing the finite element time-history analysis method, taking into account of factors such as the opening of transverse joints in arch dams and the infinite foundation radiation damping, the calculation and simula- tion are conducted based on various working conditions composed of factors including normal reservoir water level and dead water level, design temperature rise and design temperature drop, and seismic loads under site-specific spectra. The analysis results show that the transverse joints in the concrete arch dam undergo repeating opening and closing during seismic response, with a relatively large opening occurring at a certain instant. However, the joint waterstop is not pulled apart. The arch stress of dam body is partially relieved, and the overall high-stress distribution of dam meets the allowable conditions, ensuring the overall stability of dam body after the earthquake.

The anti-sliding stability analysis of gravity dams is one of the key issues in the safety design of dam engineering. Taking Jiaokou river reservoir as an example, based on actual engineering geologi- cal conditions and dam structure, the contact surface between concrete gravity dam and bedrock is deter- mined to be the anti-sliding stability control surface. The anti-sliding stability of the gravity dam foun - dation is systematically analyzed by two methods-theoretical formula calculation and discrete element numerical simulation, and the shear stability safety coefficient and the discrete element displacement contour with different strength reduction coefficients are calculated. The results show that the dam foun- dation is stable under all design conditions. The consistency between the calculated results based on specifications and the numerical simulation results is good. Further suggestions are put forward to strengthen the dam foundation surface treatment and arrange waterproof and seepage prevention facili- ties, which can be technical reference for similar projects.

The concrete core samples from four typical locations of a hydropower station that has been in service for sixty years were selected to carry out the study. The compressive strength, impermeability and frost resistance of the concrete core samples were tested according to the specifications. The hydra - tion products, microstructure, porosity and pore size distribution of the concrete core samples were test - ed by the X-ray diffractometer (XRD), scanning electron microscope (SEM) and low-field nuclear magnetic resonance. Moreover, based on the porosity and pore size distribution, the relationship between them and strength was explored. The results showed that the internal carbonization of the concrete core sam- ples was obvious, but the matrix was intact, and the bonding between the aggregates and the hardened paste was good. The results of low-field nuclear magnetic resonance indicated that the porosity of the concrete core sample was between 4.56%~8.40%, and the pore size was basically distributed between 1~ 200 nm. The lower the porosity of the core sample meant the higher the compressive strength and the higher the anti-permeability level. However, the correlation between porosity and frost resistance grade was poor. Compared with the porosity, the proportion of pores between 20~ 100 nm had a better correla- tion with the strength of the concrete core sample, and the correlation coefficient reached 0.954.

In construction of water conservancy and hydropower projects, blasting operations are often involved in the excavation of reservoir area quarries, which may pose a threat to dam safety. This study fo- cuses on Baixianshan concrete face rockfill dam to investigate the impact of blasting on dam structure safety, aiming to provide a basis for safety assessments of similar projects and optimize blasting operation plans. A three-dimensional finite element model of the concrete face rockfill dam is constructed. Consid - ering different dam heights and face slab casting progress during the construction period, the three-di- mensional nonlinear dynamic finite element analysis is performed to evaluate the impact of blasting vibra - tions on dam during both filling and completion stages, and to analyze the blasting intensity that the dam can withstand. The results indicate that the impact of blasting vibrations on dam is limited, with deforma- tion remaining within safe limits. Based on the analysis, appropriate blasting control measures are pro- posed to ensure the stability and safety of dam structures, providing reference for similar projects.

This study aims to evaluate the internal erosion sensitivity of dam core soil of Minjiang navi- gation and hydropower hub project under controlled seepage conditions. The geotechnical properties and dispersibility of soil are analyzed through laboratory tests to reveal the erosion vulnerability mechanism. Based on the measurement results and engineering guidelines, the soil is classified and the erosion sensi- tivity is evaluated. The test results show that the sample size significantly affects the erosion parameters, and there are significant differences between different units. Although the erosion coefficient values vary by test units, according to the engineering criteria, the three types of soil erosion categories are generally similar. It is worth noting that the soil with lower clay content exhibits stronger resistance to internal ero - sion. This study provides important foundation for understanding the internal erosion sensitivity of dam core soil, and reveals the key effects of sample size and clay content on the erosion process.

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 lower reservoir of Huanggou pumped storage power station is the existing Lianhua reser- voir. The inlet/outlet structure of the lower reservoir constructed in early stage has been submerged. The continued project is the first domestic hydraulic structure that adopts underwater construction technolo- gy. A camera system for turbid water is developed during construction, and construction tech such as un- derwater formwork positioning and installation, underwater welding of steel bars and underwater concret- ing by placing machine are used. A underwater sealing device for gate well is designed to achieve dry construction for embedded parts and the phase Ⅱ concrete.

A reservoir project is built on a tributary of the Tarlang river in Turpan city to satisfy the local water supply and irrigation needs. The dam type is embankment dam with clay core. During the opera- tion of reservoir, the contact surface between the dam body and the traditional culvert under the dam is prone to leak, which would threaten the dam safety. So the horizontal directional drilling technology is in- novatively adopted in this project. The water transmission tunnel built by this technology has no direct contact with the dam, which has fundamentally improved the operational reliability of water transmission facilities and the safety of dam structure and is worth reference.