On the basis of analyzing the hydrogeological and Karst feature of Sifangjing Karst spring watershed, we employed employed regression analysis and dry-season runoff modulus to calculate the natural recharge and recoverable resources according to long-time observations of springs in serious drought of 2009-2010. The results are 15.226 million m3/a and 5.8571 million m3/a, respectively. We also calculated the natural discharge to be 15.338 million m3/a by using runoff modulus and compared it with the assessment result from regression analysis. It’s found that regression analysis has higher reliability .
Global climate change undoubtedly affects the inflow process and supply process of rivers, changes river water quality, water quantity and water system operation, and complicates the sustainable management of transboundary water. However, most of the transboundary water agreements lack important measures to deal with climate challenge and sufficient consideration on the changing social, economic and climatic conditions. Sharing transboundary water leads to conflict between two or more countries, but it also can be a source of cooperation and negotiation. So, sharing climate challenges can be a platform for developing new methods for future transboundary water management. Although there are political and social differences and conflicts of interest among the countries, it is extremely necessary and entirely possible to develop flexible and effective transboundary water agreements. The strategies include ①flexible water allocation strategies ②precise data and information exchange ③comprehensive water quality management ④strategies of response to extreme events ⑤amendment to the original transboundary water agreements ⑥establishment and improvement of joint management institutions.
Water resource has become a bottleneck for the social and economic development of Guanzhong region of Shaanxi province. A model of unit optimal allocation of water resources in Shaanxi’s South-to-North water transfer project is set up, and the model is solved by using Genetic Algorithms (GA). The unit water resources optimization allocation system is established. Comparison between the results of optimal allocation and conventional allocation showed that, on the premises of guaranteeing water supply, the optimal system can reduce the total water shortage by 98.75 million cubic meters. This research provides reference for the reasonable water allocation in this region and the determination of water transfer quantity for the water diversion project from Hanjiang river to Weihe river.
The technology of slope protection by cast-in-situ grids with vegetation is a new ecological slope protection method. In order to research the adaptability and effect of this method in side slope protection, we took Yanqing test area as an example to investigate the growth of vegetation and the physical and chemical properties of soil in the cast-in-situ grids. Results showed that 4 years after the grids construction, the survival rate of Caryopteris clandonensis reached 94.3%. The newborn branch and foliage flourished with the average biomass of each branch reaching 29.3g, the average height 33.07cm and the average coverage 533cm2. Compared with blank plot, the organic matter, total N, available P, and available K of the soil in the grids increased 28.11 g/kg, 0.72g/kg, 11.25mg/kg, 33.74mg/kg, respectively, while pH decreased by 0.71. Moreover, this technology is time-saving and cost-saving with a post-maintenance time of 1-2 years. The research demonstrates that cast-in-situ grids has good performance in soil conservation and vegetation restoration, and is convenient to be applied in slope protection.
Prediction and pre-warning of urban flood is of great importance to secure the normal operation of a healthy city. In order to efficiently improve the risk pre-warning assessment ability for urban flood, it is necessary to utilize the advanced method and technique from overseas. The risk pre-warning assessment ability system for 2-D urban flood and flood situation of drainage area (FRMFS) technique which was introduced into Zhejiang province was at the advanced international standards. In line with the actual situation of China, this technique was absorbed, assimilated and redeveloped. It’s applicability for towns, mid-sized and small cities are verified from the aspects of data acquisition, prediction model, and results display. The achievement of some real cases indicates that this system can efficiently improve the ability of risk pre-warning assessment for urban flood.
The precast concrete slab connected with hinges is a new structure of embankment protection, and has been successfully applied to some embankment protection projects. However, since the size of underwater slab is very small, the underwater layout of concrete slab is difficulty to be detected, which brings about difficulty to the appraisal of underwater construction quality. Through analyzing and comparing various underwater inspection techniques, we present the multi-beam echo sounding with ultra high resolution which is applied to the investigation of embankment protection with hinge-connected concrete slabs in Wuhan segment of Yangtze River. This technique is proved to be advantageous in the inspection of underwater precast concrete slabs connected with hinges, and could also be applied to similar underwater engineering.
The research progress of the hydraulic characteristics of vertical slot fishway, pool-weir fishway, culvert fishway, Denil fishway and combination fishway in China and abroad were reviewed. The flow pattern, characteristics of velocity field, relationship between discharge and water depth, turbulence characteristics, and energy dissipation rate of various fishways were compared and analyzed respectively. The linear relationship between dimensionless discharge and relative water depth in vertical slot fishway was summarized, and the formula expressing the relationship between discharge and water depth in pool-weir fishway was listed. It was pointed out that turbulent kinetic energy, turbulent intensity and turbulence structure would have great impact on the hydraulic characteristics of fishways, the habitat selection and the passage of fish. The research hotspot of fishways is expected to be focused on turbulence characteristics and numerical simulations, especially on the study of turbulence structure. In addition, the influence of hydraulic condition within the fishways on fish passage and its improvements will also be one of the research hotspots in the near future.
By using numerical simulation, the hydraulic parameters inclusive of pressure characteristic, velocity distribution and nappe form in slit-type flip bucket with curved surface were calculated and analyzed. What’s more, detailed information of flow field which cannot be acquired from physical models were obtained. This research serves as a guide for similar engineering.
In a uniform flow, critical bed slope can be used to discriminate the flow pattern. The variation of critical bed slope against flow varies with the section’s shape. The formulas of minimum critical bed slope for three different sections were deduced according to theoretical analysis. The results show that these three sections, i.e. rectangular, circular and U-shaped section all has a minimum critical bed slope #em/em#Kmin=26.13n2b1/3,22.335n2d1/3 and 22.335n2(2r)1/3 respectively. The variation in flow pattern can be discriminated conveniently by comparing the actual discharge with the discharge when critical bed slope equals the actual bed slope. This method is simpler and more convenient than the method which determines the flow pattern by calculating critical depth and normal depth.
Inactive and regional fault has developed at the dam site of a hydropower station planned to be built in a gorge area. The fault, passing through the dam foundation at river bankside, can be divided into cataclasite zones and weak tectonic rock zones, of which the cataclasite zone width is about 86m to 92m and the weak tectonic rock zone width is less than 2.1m within the dam foundation. To provide geological data for the hydropower project design, one of the major tasks of engineering investigation is to ascertain the engineering characteristics of cataclasite rockmass, which includes distribution and scales, mineral components, physico-mechanical properties, and engineering properties. Furthermore, the corresponding treatment measures are presented. The research results indicate that slightly weathered and fresh cataclasite rockmass could be used for the foundation of concrete gravity dam whose maximum height is over 200m. It could meet the requirements of dam construction after full-area strengthening and consolidation grouting to depth 15m to 30m under the constructive foundation surface within the dam foundation. The research could provide reference for similar faults and cataclasites of other projects.
Plateau gravel soil is widely distributed in the Tibet Plateau. The shear strength of gravel soil is closely related with the stability of slope. In the present research, large-scale shear tests on gravel soils in China and abroad are reviewed firstly. By using the large-scale indoor and field dual-purpose direct shear apparatus, the mechanical properties of gravel soils in Bangpu mining area in Tibet are analyzed.Furthermore, in association with direct shear test and indoor test results as well as theoretical formulas, a geological model is established in FLAC3D to analyze the slope stability in this area. The research results offer a feasible method for similar analysis on gravel soils.
The present research is to explore the influence of end friction on the strength of rock. On the basis of continuum mechanics, a mesoscale model of rock with nonlinear damaged stress-strain constitutive relations is presented to describe the mechanical behaviors of rock. Furthermore, the Weibull random probabilistic distribution for the heterogeneities of mechanical properties of rock and the damage localization is introduced. Numerical simulation of rock’s uniaxial compression tests with different friction coefficients is carried out. The results indicate that the effect of end constraint occurs during rock’s uniaxial compression test. The uniaxial compressive strength, stress-strain curve and fracture pattern of rock specimen(in particular, short specimen)are significantly affected by the end effect. It is necessary to control the experimental condition to reduce the influences of end effect on measurement results.
To assess the reliability of the lining design for Bakun Hydroelectric Station’s power tunnel in Malaysia, the in situ geostress at three positions along the tunnels were measured by hydro fracturing method.
The actual geometric size of dam foundation is uncertain. In this research, a neural network model for the intelligent identification of the uncertain geometric size of dam foundation is established. The model takes the relative displacement of monitoring points as input, and the dam concrete, rock foundation material parameters and foundation’s geometric size as output. The load distribution of steady seepage body is obtained, and on the basis of material parameters combined according to uniform design principle, the relative displacement of key monitoring points were calculated as the learning samples. The trained network describes the nonlinear relationship among the dam concrete, rock foundation material parameters and the foundation’s geometric size and dam deformation. The water pressure component separated from the measured dam displacement is input into the trained network to automatically identify the dam concrete and rock foundation material parameters and the foundation’s geometric size. Calculation example shows that this model is feasible.
Due to the complex distribution of the displacements and stresses around the crack tip, it is not easy to obtain the Stress Intensity Factor (SIF) with a rapid convergence when using conventional interpolation approaches of numerical methods such as Finite Element Method (FEM). On the basis of Numerical Manifold Method (NMM), a novel method is presented to compute the SIFs via combining analytical solutions with numerical solutions. The Williams expansion is used as the analytical solution, which is formed by applying the constraints of nodal freedoms in the mesh containing the crack tip. High-order polynomial functions are used as the numerical solutions which are connected with the analytical solution via shape functions in the surrounding meshes. Meanwhile, the meshes in NMM need not conform to the physical boundaries including the crack edges, and discontinuous covers are used to allow the cracks arbitrarily align within the meshes, providing the convenience of mesh generation. Numerical example shows the validity of the method. Considering that the Williams expansion is the best approximation for the displacement field around the crack tip, the method has a more rapid convergence than other new methods such as extended Finite Element Method (XFEM).
The lining surface of different parts of canal accepts different solar radiation and has different temperature. In line with the balanced relationship between the amount of solar radiation and net solar radiation, a simple and practical solar radiation model was established for the back analysis of canal lining’s surface temperature. By using MATLAB programming, the atmospheric temperature T 0 at different parts of the canal and the variation of ling temperature T s with time t was calculated taking shaded parts into consideration. The relation between concrete temperature rise at different parts and atmospheric temperature rise were compared. Calculation example revealed that: the variation of atmospheric temperature T 0 and the lining plate temperature T s respectively at canal bottom, shaded slope and sunny slope were in consistency; with the rise of atmospheric temperature, the lining surface temperature increased rapidly and exceeded the atmospheric temperature and reached the maximum. But the range of temperature change varied significantly: sunny slope presents a widest range of temperature rise, followed by canal bottom and shaded slope. The maximum temperature of lining surface came later than that of atmospheric temperature. This model not only conforms with reality and provides a simple and feasible method for the back analysis of lining surface temperature.
