Abstract:Laboratory tests are commonly used to investigate seismic compression of sands. Research status and recent advances in laboratory tests of seismic compression of sands are reviewed. After a brief introduction to principles of seismic compression of sands, the applicable scope and characteristic of instruments are sketched in detail. And the advantages and disadvantages of each experimental method are discussed and compared. Furthermore, this paper analyzes the effects of internal factors(soil properties)and external factors(load characteristics)on seismic compression. Finally, the shortcomings of recent research are proposed, including compression prediction of field, multidimensional loads, directionality of loads and soil properties, which provides reference for further issues.

Abstract:Noble gases dissolved in groundwater have been used as an ideal medium for reconstructing the records of paleo-temperature and paleo-humidity when the groundwater is recharged. This paper briefly introduced the principle of a noble gas thermometer and three interpretative models used for noble gases in groundwater. The advances and major disadvantages of paleoclimate research(on temperature and humidity)of noble gases in China and abroad were addressed in detail, including the necessity of improvement of calibrating models and groundwater dating in the future.

Abstract:In order to improve accuracy of rivers runoff forecast, a new method combining the rescaled range(R/S)analysis with the grey theory(GM)was proposed, based on that the R/S analysis provides scientific and effective non-linear prediction and rivers runoff has a grey character. This new method using the R/S-GM(1, 1)model can overcome the defects of low prediction accuracy when there is a larger fluctuation in data. Then it was applied in the runoff forecast of the Yingluoxia and the Zhengyixia stations in the Heihe River, with the use of six series of the annual runoff, flood season and non-flood season runoff. It is validated that the prediction accuracy of annual runoff and flood season runoff series are about 90%, and those of non-flood season runoff series are more than 80%, and the forecast results of the runoff series are consistent with the Mann-Kendall trend test results. Hence, the predication result is reliable, providing a new approach for accurate runoff forecast.

Abstract:The traditional fractional Brownian motion(FBM)model and the improved FBMINC model were analyzed. Based on these two models and the particle tracking model, an accelerated fractional Brownian motion(AFBM)particle tracking model was developed and used to simulate the diffusion of floating pollutants in oceans. The simulation results show that, compared with the traditional model, the AFBM particle tracking model is more reliable and has a wider scope of application, due to the wider range of the Hurst exponent.

Abstract:An evaluation method of structural connectivity for rivers and lakes in a basin or an area is provided based on the theory of fractal geometry. This study used the simple fractal model to check and evaluate the structural connectivity of rivers and lakes in the main district of Changzhou City by calculating river and lake coverage, fractal dimension and branching dimension. The results are compared with those from the West Taihu Basin. The results show that the fractal dimension and river and lake coverage in the main district of Changzhou City are greater than in West Taihu Basin, while the branching dimension is 1. 50 in both basins, which means that the structural connectivity of rivers and lakes in the main district of Changzhou City is greater than in West Taihu Basin. Both of the basins are at the mature stage of erosion development.

Abstract:With consideration of three principles, ecological functional perfection, ecological environmental protection, and ecological energy saving, an assessment index system including ten indices was established to evaluate the effects of ecological construction of the Nanjing Waterfront. Based on the projection pursuit evaluation model(PPE), which uses the genetic algorithm(GA)to optimize the projection direction, the values of the optimal projection function were adopted for grade assessment. The results show that, during the first construction period of the Nanjing Waterfront, the Hexi area falls into grade Ⅰ, with a perfect ecological effect, and the Xiaguan District, Jiangpu District, and Pukou New District fall into grade Ⅱ, and the following indices should be improved: the wetland coverage ratio, the percentage of discharged wastewater reaching the standard, the green coverage ratio, the percentage of water reaching the water quality standard, and the renewable energy utilization rate.

Abstract:Large free-surface vortex with air-core easily occurs in front of gate at the side crest outlets. A series of physical model tests were conducted to observe the flow patterns, analyze the cause of vortex formation, study the influences of operating head, gate opening, distance from side pier to the reservoir bank and the operation conditions of crest outlet adjacent to side crest outlet on vortex, and discuss the effect of vortex on pressure of crest outlet surface. The results demonstrate that, the large vortex with air-core is mainly generated by flow around side pier, which is a special hydraulic phenomenon occurring at the side crest outlets. The air-core diameter of vortex decreases with the increase of gate opening, and increases with increasing operating head and distance from side pier to the reservoir bank; moreover, the vortex is larger when the gate of crest outlet adjacent to side crest outlet in fully opening than in partially opening conditions; the vortex leads to the occurrence of sub-pressure at the sidewall and even cavitation damage, so it should be controlled for practical engineering.

Abstract:In order to simulate wave propagation accurately, a two-dimensional numerical wave flume was constructed based on the smoothed particle hydrodynamics and arbitrary Lagrange Euler(SPH-ALE)method. An approximate Riemann solver was introduced to replace the artificial viscosity in the standard SPH model. The repulsive force boundary condition was used at the solid wall to prevent fluid particles from penetrating the solid boundary. The exponential damping function was used in the sponge layer to eliminate wave reflection at the end of the flume. The regular wave propagation was simulated in the constructed wave flume. The results show that, in comparison with the standard SPH method using artificial viscosity, the SPH-ALE method can simulate the wave propagation without attenuation and effectively reduce the pressure fluctuations near the solid boundaries.

Abstract:In order to thoroughly discuss the interannual change regulations of the precipitation and reference evapotranspiration in Xinjiang area, the Mann-Kendall trend analysis and BG segmentation algorithm were applied to study the trend and mutation characteristics of the annual precipitation and reference evapotranspiration of 52 meteorological stations in Xinjiang area, calculated with the FAO-56 Penman-Monteith formula. Results show that, over the last 60 years, the annual precipitation is increasing and the annual reference evapotranspiration is decreasing in general; furthermore, the mutation of annual reference evapotranspiration is more frequent and complicated comparing with annual precipitation. The natural supply and demand condition of water resources for agriculture in Xinjiang area is inclined to improve, which is beneficial to agriculture development.

Abstract:The coincidence risk of the non-stationary flood peak between the Yellow River and Qingshui River was analyzed. The variability of flood peak time series was detected using the comprehensive diagnosis method. The mixed Von Mises distribution and mixed P-Ⅲ distribution were used to fit the flood occurrence dates and peak magnitudes, respectively. The asymmetric partially nested Archimedean Copula function was selected to establish the joint distribution of flood peaks of the two rivers, and the occurrence dates and corresponding magnitudes between the two rivers were studied. Diagrams of coincidence risk of floods with different combinations of frequencies of the two rivers were provided. The results indicate that the flood time series in both rivers had changed; the coincidence risk of the flood peak occurrence dates of the two rivers peaked on July 31 and August 31, with values of 3. 36×10^-4 and 1. 15×10^-4, respectively; and the peak coincidence risks of flood peaks with difference frequencies were obtained in two periods, from July 26 to August 2 and from August 31 to September 5.

Abstract:According to measured hydrological and suspended sediment data from spring tides in Bohe Bay, the suspended sediment transport flux was divided into several dynamic items using the mechanism decomposition method, and the mechanism of suspended sediment transport was analyzed in terms of the advection sediment transport, tidal pumping effect, and vertical circulation transport. The results show that the Lagrangian residual current basically moves in the direction of the flood tide and its value increases with the distance from the shore. The Euler residual current has a value similar to the Lagrangian residual current, while the value of the Stokes residual current is close to zero. The advection is the leading factor affecting the suspended sediment transport and the transport effect of the Euler residual current is correlated with preferential flow in the tidal process. The tidal pumping effect in Bohe Bay does not have a strong influence on the suspended sediment transport, and it is induced by the asymmetry of the tidal current and suspended sediment concentration. The vertical residual circulation has a weak effect on the suspended sediment transport and is related to the vertical distributions of the Lagrange residual current and suspended sediment concentration.

Abstract:In order to demonstrate the superiority of using MgO-mixed concrete in dam construction, autoclave tests of cement-fly ash-stone dust mixed paste specimens were conducted according to the autoclave principle, and the mixing ratio of MgO in the specimens was increased to 6. 5%. This technology was applied to the concrete arch dam of a grade IV small-scale(type 1)hydropower station. The results show that concrete with a high content of MgO can improve the anti-cracking performance of the dam concrete and simplify temperature control measurements of mass concrete, allowing for an improved concrete dam construction method, in which few induced joints are needed, longitudinal joints can be cancelled, and entire concrete blocks of the dam body can be poured.

Abstract:The aseismic safety of high earth rockfill dams is one of the key problems in hydropower development in western China, where strong earthquakes often occur. Based on a summary of advantages and disadvantages of previous aseismic measures for high earth rockfill dams, a composite reinforcement aseismic measure(CRAM)and the related construction method were developed. The CRAM also takes advantage of the strong aseismic performances of the flexible material(geogrid)and rigid material(steel bars). The development background, structural form, and technical features of the CRAM are introduced. The effectiveness and reliability of the CRAM were validated through comparative model tests using a large-scale shaking table. The results show that the CRAM can effectively decrease the earthquake-induced permanent deformation and inhibit the loosening of rockfill at the crest, and has certain effects on shock absorption and isolation. Finally, an engineering application of the CRAM in the aseismic design of the Lianghekou Earth Rockfill Dam, 295m in height, is introduced.

Abstract:To improve the performance of a clay liner in blocking the volatile organic contaminants(VOCs)at the bottom of a landfill, a mathematical model intended to study the migration of VOCs through the clay liner with bubbles was established based on the convection-diffusion-adsorption mechanism. Other mechanisms, including consolidation deformation of the clay liner with disconnected bubbles, intrinsic biodegradation of VOCs, and transferring of VOCs between the liquid and solid phases, were integrated in the newly proposed model. Using an actual project as an example, the mathematical model was solved with a finite element software for multiple physical fields, and the transfer and transformation of representative VOCs through the clay liner were investigated. The results show that the retardation effect of vapor formed by the trapped bubbles can impede the break of typical VOCs through the clay liner to some extent. In particular, when the gas in the bubbles is oxygen, significant intrinsic biodegradation of VOCs due to the presence of oxygen can efficiently block the VOCs, and the bubble wall layer is relatively thin under common concentration conditions of pollutants in landfills.

Abstract:In this study, numerical wind tunnel simulation technology was used, the incompressible Navier-Stokes equations for viscous fluids were employed to describe the motion of the wind, and appropriate boundary conditions for the computational domain were established. In this way, a new method for wind resistance analysis for a tower structure of a high-rise ship lift was developed based on the ADINA software for finite element analysis. The correctness and validity of this method were verified with an example. Combined with a project case, the wind-induced response of the ship lift tower structure was analyzed, and the wind-load shape coefficient of the ship lift tower structure was obtained, the expression of the downwind vibration coefficient of the ship lift tower structure was derived, and the calculated wind-load shape coefficient and downwind vibration coefficient were compared with the results obtained from the specification. Numerical simulation results show that the downwind maximum displacement of the high-rise ship lift tower structure occurs near the top of its windward side. The wind-load shape coefficient of the ship lift tower structure obtained from the numerical wind tunnel simulation technology is greater than the result obtained from the specification. The downwind vibration coefficient obtained from the specification is lower than that obtained from the numerical wind tunnel simulation for the whole region, except in the region below the elevation of the structure of 90 m.

Abstract:In order to analyze the vibration characteristics and causes of structural vibration of the Third Huaian Pumping Station, a three-dimensional finite element model was established, using the finite element-based dynamic analysis method, according to the structural characteristics of the bulb tubular pumping station. The finite element model was used to analyze the self-vibration characteristics, dynamic responses, and causes of vibration; measures for vibration resistance and reduction were also studied. The results show that the main cause of vibration of the Third Huaian Pumping Station is the resonance vibration induced by the substructure and fluctuating pressures of water flow. Under fluctuating pressures of water flow, the structures of the Third Huaian Pumping Station show large dynamic displacements, approaching the maximum allowable displacement of architectural structures. Corresponding measures for resisting and reducing vibration were developed by increasing the floor thickness and beam section size of the pumping station.

Abstract:In order to explore the optimal design parameter and layout scheme of a hydraulic flashboard permeable spur dike with the minimum scour depth at the jetty head, single factor experiments were carried out by changing the discharge, the jet angle, the water permeable rate, and the length of the spur dike. The regression equations between each single factor and the scour depth at the jetty head were obtained. The best test level in each group of single factor test results was chosen and an orthogonal experiment with four factors and three levels was designed using the L9(34)orthogonal experiment design table. The experimental results show that the four single factors influence the scour depth at the jetty head of the hydraulic flashboard permeable spur dike in the following descending order: the water permeable rate of the spur dike, the discharge, the length of the spur dike, and the jet angle of the spur dike. With a certain discharge, the design parameters of the optimal layout scheme of a hydraulic flashboard permeable spur dike are as follows: the water permeable rate of the spur dike is 30%, the length of the spur dike is 30 cm, and the jet angle of the spur dike is 60°.