In this paper, the water supply risk in the area influenced by water transfer project was researched. Taking the middle route of the South to North Water Transfer Project as an example, we investigate the water supply risk in the source region of the project, which is known as the main stream area of middle and lower Hanjiang River. Firstly, we calculated the indicators of water supply risk. With reliability to define the risk probability level and vulnerability to define the water shortage severity level, we proposed a water shortage classification standard and hence classified the risk of water shortage. Furthermore, we calculated the risk sensitivity with water inflow, water demand, and water transfer as three main influencing factors. On the basis of this, we proposed some countermeasures to reduce the risks caused by the influencing factors, in particular, the countermeasures of emergency in dry season.
In order to study the evolution of karst spring system and predict the spring flow, we simulated the evolution of karst dissolution in homogeneous and heterogeneous aquifer system by coupling seepage model and karst dynamic model. It’s found that the water level of the homogeneous aquifer system changes slightly at initial stage and decreases significantly at initial stage at the middle-late stage, while the initial water level of the heterogeneity aquifer system decreased significantly and remains stable at the middle-late stage. In terms of the fracture aperture, the maximum value of the aperture during the same period in the heterogeneous model is 4-5cm larger than that in the homogeneous model. Spring flow of the two systems is small at the initial stage and increases rapidly at the middle-late stage, but the time of increasing and spring flow at each time point are different. The flow of heterogeneous system increases earlier and the flow is larger. The exponential function and polynomial function are employed to fit the curves of the spring flow process in the homogeneous and heterogeneous system. The research provides a new way for simulation of evolution of the karst groundwater system, and also provides scientific basis for groundwater resources evaluation in the karst area at the same time.
In order to study the influence of rainfall forecast error on flood control operation, the short-term rainfall forecast accuracy and distribution for the next 24 hours in Ankang reservoir were analyzed. The probability of flood control operation risk event owing to short-term rainfall forecast error was calculated based on Bayes theorem. Results show that, as for flood operation based on rainfall forecast information of different levels under the current rainfall forecast level, the forecast error at level I (forecasting“no rain”) has little effect on flood operation, hence can be used to guide optimal operation for reservioir; the error at level II (forecasting “light rain”) has great impact on small flood operation and the error at level III (forecasting“no less than moderate rain”) has great impact on large flood control operation, thus can be taken as referenceindex in the flood optimal operation.
The Shibangou landslide was a rainfall-induced large-scale bedding bedrock landslide during the “9.18” floods in 2011 in Nanjiang county. Through field survey and detailed study on the geological environment and geological features of Shibangou landslide, we discussed its geological formation mechanism and deformation evolution in details. it’s found that the surrounding three channels provided a very large catchment, The hidden potential energy caused by super heavy rainfall, the high static water pressure, uplift pressure, and the liquefaction of sliding soil are main causes of the high-speed sliding of the landslide. The landslide experienced four phases the original jointed fissures in the bedrock filled with water and then opened, and troughs initiated in short ranges, then the trough valleys slowly expanded, and finally the water-filled trough valleys slid violently. It’s suggested that during the geological survey, investigation of the microrelief of slopes and the weathered unloading areas should be focused on, it is of great significance for the forecast of such potential bedding bedrock landslide.
The waterway between Three Gorges Dam (TGD) and Gezhouba Dam is tortuous and varied. The unsteady flow caused by the discharge and daily regulation of TGD powerplant complicates the navigation conditions between the two dams. We established a 3-D mathematical model to simulate the unsteady flow caused by the operation of power units. By analyzing the calculation results, we obtained the variation regularity of water surface water gradient and surface water velocity in typical segment between the two dams in the presence of different operation time s and discharges. Results show that with the shortening of the operation time of power units, the increment of surface water gradient in the most hazardous segment intensified, and the maximum surface velocity increased linearly; while with the increase of discharge, the surface water gradient and maximum surface velocity increased linearly.
Flood discharge atomization of high dam projects will have possible negative impact on the hydropower station operation, traffic safety, surrounding environment, and even the stability of the downstream bank slope. Researchers have done much work in this regard, and meanwhile there is still much work to do because of its significance and complexity. This paper presents a full scale review on current study on this issue, summarizes the cognition on its damage, the forming mechanism of the atomization, and the comparison of different experimental and numerical research results. It’s proposed that two aspects should be focused on in the future study: first, advanced measuring equipment and methods should be imported and invented to obtain more particular and accurate information; second, properties of the atomization source should be paid more attention to.
Soft rock with expansion properties is distributed widely along the highway in Yanbian area which gave rise to instability of slopes and brought about great damage in this area. In order to describe the strength and stress-strain characteristics of the geotechnical dielectric material in this area, the stability of Xinyan landslide on the Wangqing-Yanji highway in Jilin Province was analyzed and parameters of the support work were provided. Indoor consolidation-undrained shear test was carried out on the soil samples taken from the construct site. Results revealed that the stress-strain curves of the samples were typical hyperbola under low confining pressure, the soil exhibited weak strain hardening; while under high confining pressure, the soil displayed obvious strain hardening behavior. In association with Duncan-Chang model, the test results were analyzed to obtain parameters of the model. On the basis of this, the normalized behavior of expansive soil in this area was studied, and the results showed that the normalized degree was highest when the normalization factor was (σ1-σ3)ult. Furthermore, the normalized equation of strain-stress curves was established, which would well predict the variation trend of stress-strain relation.
Excavation and construction of hydraulic structures and other human activities in natural slope disturb the original stability of the slope, change the original structure of the slope and then form a more complex hydraulic slope. At the same time, the stability of the hydraulic slope is directly related to the safety of hydraulic structures, and even affects the safety construction and normal operation of the entire project. In this paper, the stability of the surge shaft slope in a hydropower station is analyzed with both rigid limit equilibrium method and finite element method from two-dimension and three-dimension perspectives. The results show that when studying the stability of slopes which have shafts, the three-dimensional analysis is required. When studying the stability of these slopes with two-dimensional method, the position of selected sections should be considered. If the selected sections cross the shafts, the results are usually different from the actual situation and show the slope is unstable while the slope is actually stable. So if two-dimensional method is employed to research the stability of these slopes, the stability of both sections which crosses the shaft and sections beside the shaft should be considered comprehensively. This research serves as a reference for the stability analysis of complex hydraulic slopes with shafts.
To research the mechanical properties of soil in the sliding zone of rainfall induced landslide, we investigated the stress strain relation, shear strength index and initial deformation modulus by triaxial shear tests. The results indicated that the water content has remarkable impact on the development mode of stress strain relations. When the water content is smaller than the plastic limit, the stress strain relation experienced a process from elastic deformation to strain hardening, to peak value emergence, then to strain softening, and finally to shear failure surface; while when the water content is larger than the plastic limit, the mode of strain stress relations generally developed from strain hardening swell at strength decreases, which can be divided into three phases: when the water content is smaller than the plastic limit, the variation of shear strength is not obvious; when the plastic limit is 17% (in the vicinity of the average value of liquid limit and plastic limit), the shear strength reduces most rapidly; and afterwards, the decrease of shear strength slows down. With the increase of water content, the cohesion decreases in an approximate bilinear relation.
The strength of prestressed concrete lining of Yellow-River-crossing tunnel was analyzed and verified by using 3-D non-linear finite element model. According to the features and action mode of the double composite lining structure, the prestress loss caused by the friction between steel strand and duct, the anchorage device deformation and the inward shrink of steel was taken into account. The distribution of effective prestress in prestressed steel strand was obtained. The distribution of hoop stress in the inner and exterior surface of the lining, as well as the average hoop stress respectively under the stretched steel strand condition and the design waterhead condition was also acquired. The calculation results indicate that the loss of prestress is severe when the steel strands are stretched. The tension stress and other factors affecting the loss of prestress should be controlled strictly so that the effective prestress could meet the strength requirement. Under the above two conditions, the whole section of the concrete lining is totally pressed and its stress distribution is also feasible enough to assure the tunnel’s long-term running. The basic variation and key parameters such as the stress parameters of the numerical calculation results are consistent with those of the full-scaled simulation model test.
It’s proposed that pico-hydropower is an important means to enhance the socio-economic development and to improve the income and living standard of farmers in the agricultural and pastoral areas of East Tibet. SWOT (strengths, weaknesses, opportunities, threats) is employed to analyze various factors and external conditions for the development of pico-hydropower. The strength, weakness,opportunity and challenge of developing pico-hydropower in this region are elaborated. By matching the internal and external factors, basic strategies and policies suitable for the pico-hydropower development in this region are given.
Because of complex shape and multiple working faces, it’s difficult to ventilate and dissipate smoke in the large gallery-type surge chamber of Luding Hydropower Station. To improve the ventilation and secure the construction, a numerical simulation method based on fluid mechanics theory is applied to the research of airflow distribution and harmful gas diffusion of different ventilation options in the first and second construction stage. The optimum ventilation scheme of the first and second construction stage is given, and the corresponding reasonable time of ventilation and smoke dissipation is put forward. The research result serves as a theoretical basis and technical support for the determination of ventilation time in the construction of hydropower station.
The piping volume metering is an important infrastructure work for water resource management, water conservation, levying water resource fees by volume and scientific allocation of water resources work. Based on the project of “piping water on-site measurement and calibration technology research”, the working principle of water piping volume measurement traceability, as well as rationality assessment method of using on-site standard flow-meter in the traceability calibration is described in this paper. Application analysis illustrates that rationality assessment method of using on-site standard flow-meter in the traceability calibration is feasible and ideas for further research are proposed.
