Abstract:In order to simulate the aqueduct damage and evaluate the structure safety in a reasonable way, aqueduct failure characteristics were summarized and analyzed based on failure living examples existing research results of numerical simulations and model tests. The typical failure characteristics of aqueducts caused by earthquake, high wind, flood and durability were summarized. The possible failure modes of the pile foundation, the support structure and the aqueduct body for aqueduct structures of simple supported beam typeswere mainly analyzed. Firstly, the failure modes of the pile foundation includes three types, insufficientsoilbearing, insufficient compression strength of the pile and the displacement of the pile tip exceeding limitingvalues. Secondly, bending or shear failure may occur at the pier-bottom. Shear failure may occur at the corbel. Failures tend to occur at the ends of a bent fame column and around the joints of a coupling beam. Thirdly, failure types of bending, shear or shear-bending may occur at the longitudinal beam. The end floor beams, the mid-span and ends of a bottom plate, the bottom of side walls, the bottom of rib plates and the upper tie bars are easy to be damaged. Furthermore, there are many durabilitydamages, such as cracks, concrete carbonation, concrete scaling, leakage, reinforcement corrosion and seal damage.

Abstract:To study the impacts of dam removal on river ecosystems, the response of key ecological components, such as river hydrological conditions, topography, riparian plants, fish, and zoobenthos, to dam removal are analyzed from both the short-term and long-term perspectives. Two currently used major assessment methods are summarized, including assessment of actual removal conditions and numerical modeling forecasting. Field surveying is considered the most direct and convincing research tool, but it is limited by cost and other uncontrollable factors. Numerical simulation has remarkable advantages, such as high speed, low cost, and freedom from scale effects, and can forecast the influence of dam removal and provide decision references for managers. However, the precision and accuracy of simulation need to be improved. It is pointed out that further studies should comprehensively consider the coupling effects among various ecological factors in the process of dam demolition, and the impacts of different demolition times and dam removal phases on river ecosystems require deeper examination in the future.

Abstract:Based on the analysis and identification of the annual runoff sequence components of the Danjiangkou Reservoir, deterministic components such as the trend term, the jumping term and the periodic term were derived by using linear trend regression analysis method, sequential cluster method and variance spectrum method, etc. A stochastic auto-regression model of annual runoff based on Ensemble Empirical Mode Decomposition(EEMD)was proposed(EEMD-AR)and it was applied to the stochastic simulation and prediction of the annual runoff in the Danjiangkou Reservoir. Through the EEMD decomposition, the problem that stochastic simulation and prediction by auto-regression(AR)model cannot be directly applied due to the non-stationary historical runoff sequence of the Danjiangkou Reservoir has been solved. The simulation results show that EEMD-AR model can simulate and predict the annual runoff sequence of the Danjiangkou Reservoir in a good forecast accuracy and it maintain the statistical characteristics of the original historical sequence.

Abstract:Based on the water budget method and a river-network numerical model, the drainage effects of the rainfall-tide-combinations were analyzed through the scenario of a certain tidal polder in Shanghai. Factors involving the drainage criteria, such as the value of rainstorm duration, the determination of drainage degree, the possibility of starting regulation level and pre-reducing water level, the short and long-term implementation of river regulation, the land usage transition and the controlling of the water surface ratio, were analyzed. The results indicate that in the study area of 100 km², the river hydraulic factors and the scales of the drainage facilities calculated by both the water budge method and the numerical model fulfill the engineering accuracy. For a certain drainage scale, the peak water levels and their durations vary under the different rainfall-tide-combinations. The peak water level is relatively large under the “Matsa” case, yet the duration of the high-water-level stage is longer and the water level is higher in the later stage under the “63-year” case. The technical standards of drainage in a plain tidal polder are related to the design rainstorm recurrence interval, the design rainstorm duration, the drainage time, the degree of the drainage, the design tidal level and tidal process. In addition, the rainfall-tide-combinations can highly affect the scale of drainage ability.

Abstract:In order to resolve the water problems, including water resources, water environment, water ecology and water disaster in China, a logic framework of 36 sub-systems was built. This logic framework was based on the ecological carrying capacity theory which contained ecological elastic capability, resources carrying capacity and environmental carrying capacity, and the basic characteristics of water ecological civilization was also considered. The system of water ecological civilization could be divided into four categories, including orderly management of water space, rational utilization and supervision of water resources, effective management of water environment and ecology, evaluation and assessment. Through statistic analysis of the sub-systems for each category, basic problems and solutions were proposed. First of all, there were some problems in the process of pilot. Corresponding solutions should be made to accumulate experience and improve the sub-systems. Furthermore, some sub-systems in laws and regulations were too simple and they should be refined in the future. Last but not the least, some sub-systems contradicted with the present laws, regulations or systems. Before piloting, relevant laws, regulations or systems should be adjusted temporarily.

Abstract:Based on the practical implementation of initial water rights allocation in Dalinghe River Basin, the initial water rights allocation research progress was summarized from four aspects, such as allocation scopes, allocation mechanisms, allocation principles and allocation models. Combined with the characteristics of Dalinghe River Basin and the index system of water resources allocation in China, a new evaluation index system of water rights allocation is designed from four dimensions, including the fairness, efficiency, sustainable development, and macroeconomic regulation & control. The effectiveness of initial water rights allocation is evaluated comprehensively in Dalinghe River Basin based on the coupling models of Delphi method, Topsis method, and Coordination degree evaluation method. The evaluation results show that under the action of macroeconomic regulation and the control of both the central government and water administration department in Dalinghe River Basin, water rights allocation in Dalinghe River Basin is matched with its social and economic development. In addition, the coupling coordinated development validity reaches a higher level by strengthening democratically political consultation among different provinces and cities in Dalinghe River Basin. The effectiveness of the method is verified by the case analysis.

Abstract:According to the independent, scientific, system level and operational principles, an indicator system for the evaluation of water conservancy management and service ability of modernization development level in Zhejiang is constructed. The system is based on the full analysis of a large number of domestic and foreign related indicators, combined with the actual situation of Zhejiang Province, preferably including six criteria layers, flood & typhoon control and drought management, water conservancy project management, water management, water conservancy projects, talents guarantee ability and the financial security ability. On the basis of fuzzy clustering iterative scientific method, the index weights were determined, and the development level comprehensive evaluation model was constructed. The level of modernization of the water resources management and service ability in Zhejiang in 2015 was evaluated using this model. The results are compared with the expected values in 2020. Solutions and suggestions are put forward according to the problems and weak links.

Abstract:The closing process of high-head plain gates was numerically simulated with the RNG k-ε model, VOF method, and dynamic mesh division technique. The reliability of the numerical method was verified with measured data. The trend term of bottom edge pressure was extracted using empirical mode decomposition(EMD), a processing technology of a nonstationary random process. The relationships between the bottom edge type, flow fluctuation, and holding force were examined. The optimal bottom edge type was determined through comprehensive consideration of the pressure fluctuation, cavitation, and holding force characteristics of the bottom edge. The results show that the type of bottom edges of gates has a significant influence on the opening and closing forces, and a bottom edge with a front inclination leads to the minimum opening and closing forces, lower pressure fluctuation, and less cavitation damage.

Abstract:Three-dimensional flow fields of submerged dams with four permeable rates(0. 1, 0. 2, 0. 3, and 0. 4)were numerically simulated based on the OpenFOAM open source package, and the influence of the permeable rate and discharge on the three-dimensional flow characteristics around permeable submerged dams was examined. The results show that, under constant discharge conditions, with the increase of the permeable rate, the reflux behind the dam is weakened; the upwelling height, the range of the slow-flow area, and the vorticity decrease; and the turbulent kinetic energy in the dam and near the permeable circular hole behind the dam increases. Under constant permeable rate conditions, with the increase of the discharge, the range of the slow-flow area behind the dam increases, the reflux is gradually weakened, the mixing is aggravated, and the vorticity and turbulent kinetic energy as well as their influence ranges increase.

Abstract:Based on the hydrological and water quality data during 2005-2014, runoff division method, rainfall deduction method and runoff deduction method were used to evaluate the non-point source pollution respectively in the upstream of Lijiang River. Compared with rainfall deduction method and runoff deduction method, the accuracy of runoff division method is the highest. The relationship between pollution load difference and runoff difference in wet and dry period can be described by a linear equation, with R² values greater than 0. 88. The calculated values of pollution load using runoff division method were significantly correlated with the measured values, and the R² reached 0. 91. Compared with NH₃-N and COD_Mn, the ratio of non-point source pollution to total pollution load of TP calculated by the different methods showed strong stability. The Average value caculated by runoff division method showed that the ratio of non-point source pollution to total pollution load of COD_Mn, NH₃-N and TP was 0. 70, 0. 73 and 0. 74 respectively. It shows that non-point source pollution load highly contributes to the water quality in the upstream of Lijiang River.

Abstract:Experiments were conducted to investigate the effect of injection times and particle sizes on particle transport in porous media. Two experimental series were performed under two different flow velocities. Injections of 392 mL particle suspensions into the porous media were repeated 13 times for each experimental series. The study reveal that injection times, particle sizes and seepage velocities have great impact on the characteristics of particle transport. Under steady seepage velocity, the transport curves of the injected particles have a normal distribution and the pore volume corresponding to the descent portion of the curve is larger than the value of ascent portion. Besides, the peak concentrations increase with injection times for low flow velocity conditions. However, peak concentrations hardly vary with the injection times for high flow velocity conditions. The amount of the deposited particles decreases with increased depth for particles of 3. 40 μm median diameter. The quality ratio of the deposited particles under 0. 085 cm/s flow is greater than those under 0. 170 cm/s flow. When the seepage flow rate is low, the effect of gravity increases for larger size particles, and the corresponding particle transport velocity is also higher. However, when the seepage flow rate is high, particle transport velocity is mainly controlled by hydrodynamic forces. The screen effect on particle deposition is more obvious for particles of larger grain sizes, resulting in a higher deposition rate.

Abstract:In order to investigate the effects of slot position on the hydraulic characteristics of a vertical slot fishway pool, the RNG k-ε turbulence model and velocity-pressure coupling SIMPLE algorithm were used to numerically simulate the fishway under different working conditions. The results indicate that the slot position rarely influence the pattern of mainstream flow, the attenuation of velocity along main stream, and the velocity distribution at the vertical slot section. The slot position affects the distribution, area, and flow field of the recirculation zone by changing the location of the mainstream zone. When the distance between the vertical slot and the sidewall is 25% to 35% of the pool width, the flow pattern in the fishway is reasonable and the efficiency of fish passing is significantly improved.

Abstract:Through analysis of the pumping test data, which were affected by errors, an aquifer was investigated in order to present a new method for estimating the aquifer parameters. Based on the self-paced learning method in the machine learning field, a self-paced learning method based on the differential evolution algorithm was established and applied to the determination of aquifer parameters. This method was compared with other methods under errors of different levels. The numerical experimental results show that under errors of different levels, the differences between the values estimated with this method and traditional methods are small, and there are minor differences between the simulation data and original data. The results of the self-paced learning method, which was used for estimation of aquifer parameters based on pumping test data, are effective and reliable. The established algorithm is highly stable and it is seldom affected by data errors.

Abstract:Arching effects easily occur for a concrete face rockfill dam(CFRD)built in a narrow valley. In this paper, the Maerdang power station engineering was used for a case study. 3D finite element models of the CFRD under different valley slope schemes were established. Distributions of the static and dynamic displacement, stress of the dam under different slope angle schemes were obtained by finite element(FE)analysis. In addition, the effect of slope angles on the stress and deformation characteristics of the dam was analyzed. Meanwhile, the influence of the valley slopes on the structure stability of the dam under earthquake action was studied. Results indicate that the valley slope is approximately 50°when evident stress arch effect occurs inside the rockfill of the dam so that the critical angle of the valley should be 50°. A negative correlation is observed between the slope angles and the dam settlement. In the situation of arching effect, the earthquake action has no significant negative effects on the dam.

Abstract:In order to promote the application and deep research of MgO-admixed concrete, the conditions of concrete deformation, configuration and construction of induced joints for 8 arch dams in Guizhou Province were analyzed. These arch dams were constructed with MgO-admixed concrete in the whole dam body and have been in operation for more than a year. Results show that the statically indeterminate property of the arch dam structure provides a good constrained environment for MgO-admixed concrete to form compressive pre-stresses during the concrete expansion process. The amount of MgO in the concrete can be determined by cement mortar autoclave method or one-grade concrete autoclave method. The measured expansion capacity of dam concrete with such amount of MgO is about 50×10^-6~150×10^-6, which does not reach the expected value to fully compensate the shrinkage crack induced by temperature drop. Configuration of induced joints is an efficient measure to take full advantage of the MgO-admixed concrete damming technology. Once the MgO materials is mixed into the roller compacted concrete(RCC), the fast and economical superiority of RCC and MgO-admixed concrete in dam construction can take great effect.

Abstract:The CCS Hydropower Station headrace tunnel in Ecuador was constructed by a large diameter double-shields tunnel-boring machine(TBM)with an excavation diameter 9. 11 m. The cutterhead was blocked due to the collapse of the surrounding rock in a fault fracture zone when it reached K16+127. 0 m. Based on the results of geophysical prospecting by seismic method along with borehole core analysis, the width of the fault fracture zone and its influencing zone was determined to be about 70 m. The main composition of the surrounding rock was graded as class Ⅳ and class Ⅴ locally, indicating a very poor stability. The upper part of the segment 16. 26 m behind the cutterhead was removed to excavate flank tunnels along the two sides of the main tunnel wall. When the flank tunnels reached the cutterhead, the pilot tunnel was enlarged along the headrace tunnel axis as far as it passed through the fault fracture zone. The advanced anchor bolts and consolidation grouting were used for advanced support before the pilot tunnel excavation. Steel arch, system anchor bolts, hanging net and shotcrete were used for system support after the pilot tunnel excavation. With these support methods, top arch collapse of the pilot tunnel could be prevented during TBM tunneling. When TBM tunneling in fracture zones, the consolidation grouting to the surrounding rock ahead of the tunnel face should be performed at every tunnel cycle to prevent rock collapse. With the employment of above technologies, the TBM was back in normal operation and it successfully passed through the fault fracture zone.