This paper summed up the main experiences and lessons of 200 m grade rockfill dam construction,analyzed 4 typical projects of 300 m grade dam, put forward the scientific research and key technical problems of 300 m grade dam.
This paper makes a systematic research on the properties of dam materials for HCRFD (High Core Rock Fill Dam), and initiates with a modification method of static & dynamic constitutive model; a study on the compaction property of materials mixed with gravel soil, compaction standard and the detecting methods for filling quality; the papers has also explored into the new technology to realize a comprehensive, real-time, online and automatic monitoring on the various parameters of filling construction and compaction via transmission network by adopting technologies of PDA、GPS、GPRS.
This paper introduces the major domestic achievements on underground projects and technology. As cities are faced with a series of social and environmental problems, such as speeding up of urbanization, shortage of resources, worsening of environment and soil declination, underground space will soon be developed and utilized as a new form of national resources, and the demand for underground projects has a huge potential. The paper elaborates on the fundamental scientific and critical technological problems in the research of underground project technological innovations.
The quality control and schedule control are the significant technical problems in high core rock-fill dam and high concrete dam construction. The conventional quality control methods exhibit difficulty to ensure construction quality of high core rock-fill dam and to control timely schedule of high concrete dam under high-intensity continuous construction. Real-time compaction quality monitoring technology of high core rock-fill dam, real-time entire-process monitoring technology of dam materials transportation and real-time acquisition technology for dynamic information of construction quality using personal digital assistant devices (PDAs) are proposed, which realize the precise automatic online entire-process monitoring of compaction and transportation. In addition, based on an established mathematical model of concrete dam schedule real-time control, the method of timely warning and dynamic adjustment of construction schedule is proposed to provide means for schedule prediction, appropriate warning, dynamic adjustment and optimization of high concrete dam construction schedule. Furthermore, system integration technique for digital dam on Internet is presented, and a digital dam system is developed, which provides a supporting platform for dam final acceptance, safety assessment and operation management. The above-mentioned technologies have been applied to more than 10 major hydro-electric projects with achieving remarkable economic and social benefits.
Based on the overall analysis of roller compaction system of high core rock-fill dam, the theory of construction simulation for roller compaction is put forward and the simulation model is set up which can actually reflect the uncertainties of the rock-fill dam roller compaction to ensure the simulation to be more close to the actual construction. This study achievement has been applied to the filling unit construction process of the Nuozhadu high core rock-fill dam to verify the reliability of the simulation model, which gives important guidance to the project. Meanwhile , the technical support is applied for the schedule control and management.
Based on the monitoring data, a practical information management system of safety assessment and warning for Nuozhadu earth-rockfill dam is developed. The system includes system management module, safety criteria module, monitoring data and engineering information module, numerical calculation module, back-analysis module, safety warning and contingency plan module, and data base and management module. The numerical calculation and back-analysis modules are the key parts, which perform analysis of seepage, stress and deformation of dam, crack of dam, dynamic response and slope stability. The parameters of constitutive model are back-analyzed by using the monitoring data and the behaviors of the dam at some important time are predicted.
In the long-term service period, many factors may lead to serious damages and deficiencies to the structure, such as complicated working conditions, inadequate investigation and design, poor management, aging of structure, etc. Therefore, it's very important to study the online monitoring method for flood discharge. According to the special advantages of HHT in instantaneous characteristics analysis and signal processing, an online monitoring method for flood discharge structure damage based on HHT is put forward in this paper. Firstly, after obtaining the HHT energy spectrum of measured responses, the energy distribution vector, defined as ηi , can be calculated. Then, because of the η i differences between undamaged and damaged situations, we determine the structure anomaly indexes and the warning threshold. Finally, having been calculating the anomaly indexes of adjacent time periods, the damage online monitoring can be realized. The results from the numerical simulation test of a guide wall demonstrate that the anomaly indexes mentioned above can accurately identify the structure damage and have anti-noise ability to some degree. However, the further research for estimating the damage location and degree need to be developed in the next period.
The vibration of powerhouse structures is mainly induced by hydraulics factors, mechanical and electromagnetic factors of the generating unit. It nonlinearly couples with the generating unit. Based on prototype observation data of Ertan Hydropower Station, the paper analyzes the coupling effect between vibration of units and powerhouse,and then the vibration response forecasting model of the powerhouse is built based on LS-SVM optimized by particle swarm optimization algorithm, and the prediction results are coincide with the observed data. Further, the paper introduces the running water head as an input divisor into the intelligent prediction model while the forecasting range is extended, and the result is satisfactory.
In order to consider the time-dependent characteristic of risk factors of hydropower project, the method of stochastic process simulating structure resistance and load effect is adopted. On the basis of analyzing the structure characteristics and mode of operation, the operation safety risk rate assessment model of hydropower project is established on the comprehensive application of the improved analytic hierarchy process, the time-dependent reliability theory and the risk rate threshold. A scheme to demonstrate the time-dependent risk rate assessment method for an example of the earth-rock dam is particularly implemented by the proposed approach. The example shows that operation safety risk rate is closely related to both the service period and design standard; considering the effect of time-dependent, the risk rate increases with time and the intersection of them reflects the technical service life of structures. It could provide scientific basis for the operation safety and risk decision of the hydropower project by predicting the trend of risk rate via this model.
In order to enhance the ability of emergency response to storm surge disaster and ensure moistureproof safety, the 3D unsteady k-ε model coupled with the volume of fluid (VOF) method of water-air two-phase flow is established. The model adopts the method of equivalent roughness to deal with urban intensive building groups, in which the effect of water resistance and water storage are both taken into consideration. One hundred years frequency storm surge is analyzed based on the numerical simulation and analysis of floodwater evolution with storm tide between the Haihe River and the Yongdingxinhe River of the new coastal region of Tianjin. The severity of different frequencies of the storm surge are compared and analyzed. The results show that the flooded area and the water depth decrease with the increasing of storm surge frequency. The researches provide theoretical foundation and technical support for the safety management of the sea wall and scientific assessment of storm surge disaster.
In thermally stratified reservoir, a multi-level intake structure is usually adopted in hydropower station to reduce the negative effect of releasing lower-temperature water to the environment in downstream reach. And a simple and practical formula of water temperature released is need. In this paper, based on Nuozhadu Hydropower Station, a model test is conducted to model the thermal stratification of this reservoir, and measure the temperature of water released from the intake structure. A prediction formula of water temperature released is put forward based on the experimental data. The formula is validated by the experimental results of water temperature released from the intakes of Jinping No.1 Hydropower Station.
In this paper, the northern mountainous area of Fuzhou City which is an ungauged basin has been taken for example to discuss the method of design flood calculation by means of combining the DEM (digital elevation model) and the Xin'anjiang model (three components). The problem of estimating the parameters of the runoff model has been solved by using the parameters of the reference station. In the convergence calculation, the isochrones are obtained by DEM which helps to avoid the cumbersome work of drawing them on the map. With the establishment of the digital elevation model throughout the country, it is practically significant to use it in the hydrological estimation.
In the paper, the concept and realization process of intelligent compaction for high roller compacted concrete dam construction was presented, as well as the theory of real-time monitoring and intelligent feedback control. Based on the analysis of real-time compaction index, a multiple regression model of the dam compactness was established and a real-time estimation method of compaction quality of the entire work area for roller compacted concrete dam was proposed finally. The adaptive adjustment of the roller work parameters was achieved, with the speed, exciting force, the rolling pass and the compacted thickness meeting the standard during the entire construction process, and the compaction quality and construction efficiency can be both improved as a result. What's more, the research provides a new way for the construction quality control of roller compacted concrete dam.
In this paper, 3D simulation model for the river closure is established by making use of virtual reality and 3dsmax technique. With the analysis of the dynamic hydraulic characteristics at the closure-gap, a VR-based 3D dynamic visual-simulation of method for the complex process of river closure is presented. In this visual epresentation, comparison among different schemes of river closure is achieved easily. Therefore, a powerful visual tool for aiding river closure design and management can be provided.
A method of applying system integration theory to real-time control on high arch dam construction was proposed to fit the strong complexity and randomness in the construction process. A system integrated framework of real-time control on high arch dam construction was designed. Then, the implementation process of the system integration was illustrated in detail from four aspects of information integration, function integration, technique integration and monitoring index integration. Finally, a real-time control system based on the network platform was built up. The application result shows that the theory and the system can realize integrated control and analysis dynamically, and improve the dam construction management level effectively.
In this paper, on the basis of research on high core rock-fill dam filling construction characteristics, the process control index architecture is established; the method of process monitoring is determined; the solution scheme is proposed; the monitoring system of core rock-fill dam filling construction process, with the characteristics of real-time, high precision, automation and all weather, is developed in order to achieve monitoring on process of transportation to dam and rolling on dam surface. The monitoring system is applied in the construction field of the highest earth rock-fill dam in Asia, Nuozhadu core rock-fill dam, as the core component of the construction process control architecture, achieving refining, all-whether and real-time control on key links of dam filling construction, which improves quality control level and efficiency of construction process.
Long diversion tunnel is often featured by great embedded depth, long tunnel line, large hole diameter and extremely complicated geologic conditions. The engineering quantity of each process is large, and the influence is enormous; therefore, the internal and external environment and constraint condition are changed in the actual construction, leading to the deviation between formerly construction schedule plan and actual construction schedule plan. If the deviation isn't corrected timely, the formerly plan can not guide the actual construction. In this paper, using computer simulation technology, control theory and virtual reality technology, the whole construction process real-time schedule control and visual analysis of the long distance diversion tunnel based on simulation are proposed. The feasibility study and scientific basis is provided for the real-time control of construction schedule.
Based on multi-source data, a fitting geological surface is required to achieve the balance among accuracy specification, continuity and storage. An approach of complex geological surface reconstruction which combines interpolation with approximation based on NURBS(non-uniform rational B-splines) technique is presented. The algorithm adopts the skinning method for densely and uniformly distributed data in the key region, and it ensures that all original data are on the built surface strictly. For the discrete data in the peripheral region, NURBS approximation fitting method is used to construct the corresponding surface, which approximates the data fully under the required accuracy. Finally, the integrated surface is analyzed and modified by checking the rationality of geological structure, geometry and accuracy. The instance shows that the approach can satisfy practical demands of engineering geologists and offer elements to further 3D geological modeling.
Considering the shortage of the experience and expert in construction claim of large water transfer project, case-based reasoning (CBR) and rule-based reasoning (RBR) in artificial intelligence are used in claim management. The knowledge-based claim decision support system is designed and implemented, in which the previous cases of hydraulic engineering claims are stored structurally. The system is used for the construction management of a trans-basin water transfer project.