Abstract:Through the analysis of parameters and structure, it was found that the description of storm water management model(SWMM) on the process of rainfall-runoff formation in urban areas is consistent with urban runoff yield and concentration rule. The physical concept of SWMM is clear because the runoff yield analytical methods are based on hydrology, and concentration analytical methods are based on hydraulics. The parameters of SWMM almost have geometric or physical meanings, but there are some complementary(or dependency) relationships among some parameters. Therefore, it is necessary to reduce the influence of the equifinality for different parameters on parameter calibration. The composition of the process of rainfall-runoff formation in catchment area exit using the method of simultaneous summation shows that the interference between stormflows from different areas is neglected.

Abstract:A one-dimensional river network model was constructed by discretization of Saint-Venant equations with explicit flux-ifference splitting scheme and dealing border with characteristic line method. Meanwhile, the modeling accuracy and stability are enhanced with the application of entropy correction and total variation diminishing(TVD) limiter to local discretion. In a classical numerical example, the model shows its ability in capturing complex flow conditions like trans-critical flow with shock waves. Being applied in the Baguazhou section of the Yangtze River, the model shows its performance in terms of water level and flux with higher accuracy, which is suitable for the real river network. To sum up, the model discretion introduces a new idea about explicit discretion into river network model.

Abstract:Since 1980s, river characteristics in the river network of the Pearl River Delta in Guangdong Province, China, have significantly changed due to large-scale sand mining. Based on measured data, the recent evolution of river characteristics is analyzed from several aspects, such as riverbed evolution, flow and sediment conditions, variations of water level at equal water discharge, variations of flow and sediment diversion in the Xijiang and Beijiang rivers, the volume of river channel, and flood carrying capacity. The results show that since 1980s the riverbed of the river network has downcut severely, and the volume of coming water has slightly changed, while the volume of coming sediment has dramatically declined. Besides, the water level at equal water discharge has significantly dropped, and the flow and sediment diversion in the Xijiang and Beijiang rivers have been adjusted by river sand mining. Moreover, the flood carrying capacity has improved because the volume of river channel has increased. With the decrease of largescale sand dredging operations, river evolution in the river network turned into a new equilibrium stage after 2005.

Abstract:For obtaining the rules of seawater intrusion in the Modaomen Waterway of the Pearl River Estuary, almost half a month, the hydrology and salinity were synchronously measured at the river section from Zhuyin down to Koumen. The results show that the salinity in the Modaomen Waterway generally presents a decreasing trend from downstream to upstream. In Koumen, the average salinity in surface water and at bottom, under different tides and flood-ebb fluctuation, has a large difference with a variation range between 1.7% and 2.4％, whose layering is clearer in dry seasons. Additionally, the difference in ebb period is typically larger than tide rising period. However, in Zhuyin, the salinity in surface water and at bottom, under different tides, has a small difference, with the average salinity lower than 0.1％ under flood-ebb fluctuation. From the perspective of ratio statistics of differences between surface and bottom salinities along the Modaomen Waterway, the average salinity at bottom is 43.1％, 53.4％, and 77.4％ higher than that in surface water in spring, middle, and neap tides, respectively. Furthermore, there exits better corresponding relations between velocities and salinities along water depth, so it is easier for the emergence of gravity flow during the neap tide. Closely to Koumen, salinity linearly decreases with the decrease of water depth; in upstream, salinity demonstrates the index declining rule. In addition, termination points of the two distribution rules are respectively about 23 km under spring tide and 17 km under middle and neap tides far from Koumen.

Abstract:In order to make clear the relationship between coal mining and runoff reduction or even drying-up of the Kuye River, China, we analyzed the variation characteristics of runoff with the daily runoff data and related hydrometeorology data from 1953 to 2010 of the Wenjiachuan station, a control hydrological station at the Kuye River. Then, the impacts of coal mining on surface runoff are quantitative simulated by using monthly water balance model of the Yellow River. The results indicate that the measured runoff data generally present a phase-decreasing trend over the last 60 years with turning points in 1979 and 1999. The runoff reduction ratio due to human activities was 39.44％ during the period from 1979 to 1998, and it quickly increased to 56.50％ during the period from 1999 to 2010, in which the annual average runoff value affected by coal mining reached 29.69 mm, which is equivalent to approximately 2.58×10⁸m³／year. That is, human activities have become the dominant factor causing reduction of surface runoff in the Kuye River.

Abstract:We used the Monte-Carlo method to analyze the influence of network structure on the propagation law of fluctuating pressure of flow within fractures. A replica of the fracture network was created by numerical simulation, which has resembled statistical characteristics with natural fracture network. Taking the replica of fracture network as main space of fissure water, a one-dimensional transient flow model was established to numerically simulate the propagation of fluctuating pressure. And then, the unsteady time process of fluctuating pressure’s propagation of fissure water and the spatial distribution nephogram of fluctuating intensity were generated. We concluded that the propagation of fluctuating pressure in rock fracture network has significant anisotropy. And the transient fluctuating pressure at any node within fractures is determined by the combination of three factors: the hydro-transient effect of fracture line elements connected with the node(especially of those directly connected with the node), the interfering source at fracture entrances, and the reflection source at fracture ends.

Abstract:A series of supersaturated total dissolved gas (TDG) release tests, under different wind speeds, were carried out in laboratory and the impacts of wind speed on supersaturated TDG release process were studied. According to available release models, we estimated the release coefficients and derived a quantitative formula to describe the relationship between the release coefficient of supersaturated TDG and wind speed. Results showed that, under the condition that temperatures were among 8.5℃ and 9.5℃, the release rate was fairly slow for low wind speed, but the release rate of supersaturated TDG remarkably augmented as wind-speed increased. The release coefficient of TDG was 0.00542 h^-1 under windless condition, and others were between 0.00709 h^-1 and 0.06668 h^-1 with wind speeds ranging from 1.08 to 11.33 m／s. And, at the same time, the relative release coefficients were within the range of 1 to 12.303 in the experiment. Thereafter, a fitted quantitative formula between relative release coefficients and wind speeds was obtained, whose calculation deviation ranged from -11.76％ to 10.21％.

Abstract:In order to establish the mechanics constitutive models of ice in different conditions (i.e., temperature, loading rate, and confining pressure), through the theoretical analysis and experimental research, we compared the characteristics of ice stress-strain curve in uniaxial compression test and triaxial compression test under proportional loading condition. Then, we described the relationship between stress and strain of ice by adopting the mechanics constitutive model of power hardening. Moreover, according to the data from the triaxial compression tests, we established the mechanics constitutive models in the two test conditions by using least squares curve fitting. Overall, the error analysis showed that the mechanics constitutive model of ice is comparatively accurate.

Abstract:In order to deeply understand the concept of seepage force in porous media, its mechanical essence is analyzed and its definition is exactly given. From the perspective of micromechanics, the mechanical characteristics of soil particle under percolation condition is analyzed, and the calculation method of singular particle’s seepage force under percolation condition employed in particle flow code in three dimensions(PFC3D) is discussed. Additionally, the analysis model of mesoscopic particle flow for calculating seepage force value is built. By using the fluid-solid coupling analysis function of PFC3D, the features and values of soil seepage force of porous media under percolation condition are studied. Through comparing the value of seepage force obtained by numerical method with that by analytical solution, the results indicate that it is feasible to study the macro-characteristics of driving force in porous media under percolation condition with PFC3D, which is based on mesoscopic theory. Moreover, the seepage force is a synthesis result of normal stress and shear viscous stress acting on the surface of soil particles.

Abstract:Taking the annual maximum flood peak flow, rainfall intensity, drainage area, river length, and river slope at different periods of 122 hydrological stations in Zhejiang Province as indicators, the regional regression equation is established. Then, the regression equation is used to calculate the annual maximum flood peak flow at those hydrological stations. Comparing the calculated values with observations, the results show that the relation between them significantly follows the regionalization rules. Therefore, Zhejiang Province can be divided into two flood calculation zones. Points where the calculated value is bigger than the measured focus on the areas such as the middle and upper reaches of the Qiantang River, the middle and upper reaches of the Ou River, the Puyang River, and the Cao’e River, and the points account for 69.5％ of whole points in the zone; points where the calculated value is smaller than the measured focus on the areas such as the Tianmu Mountain, Kuaiji Mountain, Siming Mountain, Tiantai Mountain, Dapan Mountain, Kuocang Mountain, and the North and South Yandang Mountain, distributing as “7” glyph, and the points account for 73％ of whole points in the zone. The result matches the zonings of plum rains (East Asian rainy season), typhoon rain, land utilization, vegetation, etc., in Zhejiang Province, which reveals that the zoning result is reasonable and the zoning method is feasible.

Abstract:At present, there is no fixed uniform standard for the size of anti-seepage curtain in various hydraulic design criteria as well as engineering practices. On the premise of keeping the seepage stable and conforming the seepage flow control standards, and based on seepage control principle, this paper presents the equilibrium seepage control method to optimize the structure of anti-seepage curtain in the order of depth, length and thickness. First, this method provides the depth of anti-seepage curtain by taking seepage quantity and slope as the standard, and then determines the length when the maximum bypass seepage velocity on two sides is equal to that in the formation of upstream and downstream of anti-seepage curtain. Finally, the method regulates the thickness when the maximum seepage velocity through anti-seepage curtain is equal to the maximum bypass seepage velocity in the formation of upstream and downstream of anti-seepage curtain. This optimal design not only ensures the best impervious effects, but also reduces financial costs. Overall, the optimized calculation results of engineering examples show that the proposed method is simple in terms of computation process and the results are reliable.

Abstract:In order to improve the operating efficiency of a suspending type axial-flow tidal current turbine, which can be self-adaptive according to the direction of ocean current, a three-section duct with outer envelope has been installed around the turbine. The hydrodynamic performances of this duct have been analyzed with numerical simulation method and the results have been verified by model tests. It has been found that the duct with fold line shape, where the attacked angle of constringent section and proliferation section is 15°, has excellent hydrodynamic performances and the power output of turbine with duct is approximately 30％ more than that without duct under the same condition. Besides, the similar flow field data have been obtained from model tests. That is, the form resistance of constringent and dirergent sections is relatively small, so the enegy conversion effect is obvious for steady flow velocity in straight-line section. Therefore, the duct with fold line shape best matches this turbine scheme.

Abstract:Based on the river dynamics theory, we derived a mathematical expression of waterway depth variation before and after erosion of the channel at regulation stage. Then, the theoretical analysis of the expression showed that waterway depth could increase. Under the erosion of the release of clear water from the Three Gorges Reservoir, in order to make the release of clear water only erode vertically, it is necessary to take several measures, that is, protecting key movable bottomlands, controlling dredged channel(not broadening in both sides), and protecting low bottomlands from erosion in dredged channel. Thus, protective control works play a positive role in improving waterway condition. Taking Ouchikou and Taipingkou segments of the Jingjiang River at the middle reach of the Yangtze River as examples, we computed the variation of waterway depth in both segments after protecting key movable bottomlands. The model derived results are in accordance with the variation of waterway depth resultant from generalized measured profile, which further verifies the effect of protective control works on improving the waterway condition.

Abstract:This paper summarizes the research achievements on erosion-siltation balanced flow of Xinyanggang Sluice,and analyzes the erosion-siltation conditions and general laws of channel downstream sluice for 2012. Based on the data related to the erosion-siltation and water regime during the period from 2008 to 2012, the effects of discharging runoff on the erosion-siltation of the channel downstream the Xinyanggang Sluice are mainly analyzed with correlation analysis method. The results show that to keep the channel stable, the floodgate is not suitable to be closed for a long time and the ratio of undrained days accounting for total days should be less than 42％ in non-flood season. Runoff and tides interact on sediment transport capacity of flow, and the unbalanced sediment transportation at flood and ebb tides in channel can be improved by runoff conditions. Sediment can only be carried 7 to 9 km seaward by weaker ebb currents, so large discharges for long time will be useful for stability of the channel. When the channel reaches the equilibrium state of erosionsiltation, there is a relationship between daily average discharge(Q) and the average cross-section area(A) of the channel(i.e.,Q=0.13A). In the present channel regime, for proper functioning of the channel, the area is approximately 664m² and the daily average discharge is approximately 86m³／s.

Abstract:In order to analyze the shipping influence caused by Xiaonanhai Hydropower Station,in the article, the Saint-Venant partial differential equations are used together with Preissmann implicit difference for building a one-dimensional unsteady flow hydrodynamics model and the model was verified with the observed hydrological data. By simulating hydrodynamics for the daily regulation, the capacity of navigation in the lower reach are estimated. The simulating results show that the situation might deteriorate the flow condition in downstream in the case of daily regulation whose operating rules were formulating from the side of load, thereby impair the navigation during the low-flow phase. It is necessary to adjust the operating rules of power station or implement river regulation works for the lower reach after dam.

Abstract:According to the hydrogeological conditions and characteristics of groundwater movement of agricultural irrigation area in Fuyang City, China, this paper proposed a regional long-term combined regulation model of shallow grandwater. By regulating the groundwater exploitation, the depth to water table at the end could be restored to the beginning, achieving the long-term balance. Then, the safe exploiting coefficient and the safe exploitation quantity are obtained. The results based on a long series(1956-2010) show that the average total recharge of shallow groundwater is 17.856×10⁸m³, the safe exploiting coefficient is 0.469, and the safe exploitation quantity is 8.374×10⁸m³. Combining with the water using characteristics of agricultural irrigation area in Fuyang City, the method of equal proportion is applied to calculate the annual distribution of the safe exploitation quantity of shallow groundwater. Finally, it is determined the monthly safe exploiting processs of shallow groundwater within one year in Fuyang City.

Abstract:In order to improve the refinement degree of the quality control of slope excavation for hydropower stations and realize the informatization management, large amount of high precise point cloud data obtained by three-dimensional(3D) laser scanning was applied into the quality control of slope excavation. Based on the quality control theory of slope excavation and the comprehensive analysis of users’ demands, a quality control system of slope excavation for hydropower stations is designed and developed using the structure modular design method and software development technology. This system consists of five modules: data entering, data analysis of excavated surface, profile analysis of excavated surface, accident query, and statistical reports. The proposed system can provide real-time, dynamic, and interactive query of quality control information during the whole process of slope excavation. The results based on practical application show that this system can provide information for quality control and field management of slope excavation and assist engineers to take relevant quality control measures in time.

Abstract:In order to uncover the evolution process of Yellow River’s riverbed in frozen period, we studied the analytical method of three-dimensional visualization on riverbed under ice of the Yellow River in Inner Mongolia based on geographic information system(GIS). According to the results of field experiments, we analyzed the river terrain and plotted the riverbed contour maps, the vector topographic maps, and the typical cross sections of curved reach. In the process of visualization, we plotted the three-dimensional surface maps and shade relief maps, and made a quantitative calculation of riverbed’s scouring and silting changes in the frozen period and open period. Besides, we carried out a contrastive study of riverbed spatial under conditions of open channel flow and ice cover flow. The results showed that the GIS technology can be applied to the three-dimensional model-building of riverbed and the quantitative calculation of its scouring and silting changes at different times. It also can instantly reflect the change process of river channel, accurately calculate the scouring and silting volumes of riverbed, and explain the mechanism of interaction between sediment and flow movement in frozen period.

Abstract:In order to study the feasibility of the compound mineral additives composed of phosphorus slag powder and limestone powder(PL) for substituting fly ash(FA), basic characteristics of phosphorus slag powder(P), limestone powder(L) and FA were tested. Additionally, the micro structures of their cement paste were analyzed comparatively, and the performance of mechanical, durability, deformation of dam concrete with different mineral additives were tested. According to the comparison of characteristics of PL concrete and FA concrete, it is concluded that the performance of PL concrete is better than that of FA concrete on micro and macro scales, especially on the long-term compressive strength, and ultimate tensile strain scale. Besides, the PL mineral additive has lower cost as well as higher technical and social benefits. Thus, in Southwest China, where it is lacking high-quality FA, the substitution of PL additive for FA as mineral additive used in dam concrete is feasible alternative.

Abstract:In order to obtain the permeability of core wall mixed gravel under complex stress conditions, permeability tests on core wall mixed gravel are carried out by modified middle triaxial apparatus. Thereafter, the effects of different confining pressures, soil-rock ratios, and water head differences on the permeability coefficient of core wall mixed gravel are studied. The test results show that the larger confining pressure is, the smaller permeability coefficient of core wall mixed gravel is, that is, the relationship between them is shown as a negative exponential function. When the confining pressure increases to a certain value, the permeability coefficient almost keeps unchanged because the soil particles are difficult to be further compressed. In addition, the permeability coefficient has a negative correlation with the soil-rock ratio and it increases rapidly when the gravel content exceeds a certain value. Moreover, when the water head difference is small, it has little or no effect on the permeability coefficient.

Abstract:Based on the pile-soil interaction principle and mechanical equilibrium theory, we analyzed the pile-driven resistance and proposed two relevant measures to improve pile-body structure in order to improve portability and reduce energy consumption of anti-flood spiral pile. The first measure is to properly reduce outside diameter of hollow cylinder with invariable bottom outside diameter of cone, and the second measure is to properly reduce length of spiral blades. Thus, we obtained the contrast pile-driven torque curves by driving original pile and modified pile. The curves show that the maximum pile-driven torque is greatly reduced by 39.3％ and 16.5％, respectively, due to the two measures. It also shows that the piledriven torque of anti-flood spiral pile has an extreme value, and the modified pile increased the safety coefficient of pile section intensity when pile-driven. Moreover, the modified pile still meets the actual requirements although its lateral displacement would be larger than the original pile for lateral load.

Abstract:This paper presents a series of experimental studies about the influence of environmental waters on static strength of concrete, and analyzes the physical mechanism that static strength of wet concrete would decrease. Overall, it is pointed out that most of the present research is qualitative explanation, and quantitative research is rather less. Moreover, it is suggested that the impact of the interaction of several factors on static strength of concrete should be studied, and the finite element analysis method should be used to simulate the link coupling on each interface of wet concrete.

Abstract:This paper explains the necessity of the study on flow motion law in leaky aquifer system and reviewed its research status at home and abroad. Then, it discusses the research methods and model building in leaky aquifer systems, the existence and criterions of non-Darcy flow in low permeability media, and the related models and equations for non-Darcy flow in low permeability media. Finally, it points out that the coupling of the leakage and non-Darcy flow in low permeability media is one of the most important development directions of the study on flow motion law in leaky aquifer system in future. The influences of non-Darcy flow, consolidation, and elastic storage and release on flow in leaky aquifer system need to be studied from a spatio-temporal perspective.

Abstract:This paper reviews the current status of research on dynamic characteristics of gravel-mixed clay as well as analyzes the influence factors of dynamic shear modulus, damping ratio and dynamic strength. Additionally, it summarizes the numerical method and analytical theory of the materials mesostructure features, as well pointed out that they should be accounted in the research of dynamic characteristics of gravel-mixed clay. Finally, the areas for further research are suggested, i.e., the mesostructure features and influence factors of gravel-mixed clay, the influence mechanism of mesostructure for materials macroscopic dynamic performance, and the micromechanical model based on theory of particle reinforced composite.