Abstract:Based on the measured data in 101 meteorological stations over the Yellow River Basin, and the precipitation and temperature data dating from 1961 to 2099 of the six CMIP5 models under three scenarias, statistical downscale study is conducted by using equidistant cumulative distribution function matching method (EDCDFm). The accuracy of the downscaled data is evaluated by validating against the measured data dating from 1961 to 2005. After that, the meteorological drought around the Yellow River Basin is predicted by means of standard precipitation index (SPI). The results show that the accuracy of the raw models simulated temperature and precipitation has been significantly improved by using EDCDFm method, it is especially true with the modelling accuracy of their extreme values. The predicted results of the drought around the Yellow River Basin indicate that, the drought condition at the beginning of the 21st century has become more severe than that of the reference period under three scenarios, but is likely to be obviously mitigated at the end of this century. Notwithstanding, preventing drought around the Yellow River Basin is still a tough job in recent years.

Abstract:In this paper, a case study is performed on three small hill watersheds in Fuhe River Basin, where their storm flood process was simulated elaborately by using distributed Xin’anjiang model. The critical rainfall of each watershed is calculated by means of the verified Xin’anjiang model, so the different initial soil moisture of each watershed and the critical rainfall under different combinations of warning intervals can be determined. The calculated result of critical rainfall is demonstrated to be reasonable by comparing and validating with the measured storm flood data and storm design, which suggests that the distributed Xin’anjiang model can be used to determine the critical rainfall for early-warning of mountain flood in Fuhe River Basin. Besides, it provides a reference method for the early warning of mountain flood in Fuhe River Basin.

Abstract:Based on the monitoring data of water quality and quantity in major rivers around Taihu Lake and the monitoring data of the water quality in Taihu Lake timing from 2007 to 2017, four major pollutant indicators, including potassium permanganate, ammonia nitrogen, total nitrogen and total phosphorus are used to explore the pollutant load spatio-temporal distribution of different regions around Taihu lake, and further to evaluate the influences of the pollutant loads of the major rivers around the lake on spatio-temporal changes of the water quality in Taihu Lake. By analyzing the water quantity of the major rivers around Tahihu Lake and incorporating the long- term changes of the pollutant loads of the major rivers, the contribution of water quantity and quality in the major rivers to the pollutant loads of the Taihu Lake is investigated in a quantitive way so as to determine the impacts of the pollutant loads of the major rivers around the lake on the water quality in Taihu Lake. The results show that the major rivers around Taihu Lake have been effectively managed in recent years, indicating that controlling the pollutants of the rivers around Taihu Lake is an important approach to ease and control the input of pollution load into Taihu Lake, thus providing a reference for the formulation and implementation of the total discharge limit of the pollution load of the rivers into Taihu Lake.

Abstract:Due to the sediment deposition occurring in front inflows of the straight-edge forebay of large pumping station, where its water is taken from the river with high content of sand, the adjustment ability of the forebay is usually reduced and the operation efficiency of the pumping station becomes low. To solve this problem, a prototype 3D model of the forebay structure is established using the ICEM CFD software, with its flow regime being modelled and analyzed by using Standard k-εturbulence model in the FLUENT software. Moreover, two optimization measures are proposed for the bad flow regime by incorporating diversion pier or water pressure plate. The findings show that the computed results are consistent with those from site survey, the flow regime in the forebay is in disorder and the sand sedimentation is quite serious. The eight-shaped diversion pier can reduce to some extent the scope of the main re-circulation region, but only serves as allocating of the forebay flow without obvious improvement in its flow filed distribution. On the contrast, the 45°water pressure plate can effectively improve the mainstream effect in the forebay, and the back-flow region on both sides is obviously reduced. The sand sedimentation problem in the forbay is thus solved with the favorable inflow conditions being ensured for the water pump.

Abstract:To improve the calculation accuracy of the Duncan-Chang E-B model regarding the deformation of the rock-fill dam, the single factor analysis method based on finite element calculation nodes in the whole zone of the computational dam is proposed together with the orthogonal experimental method based on the double discriminant method in this study. The sensitivity of dam deformation due to the compacted density of dam and the model parameters is studied, so as to ascertain the main influencing parameters of the dam deformation. A case study indicates that the dam deformation is significantly influenced by five parameters i. e. φ₀, K_b, ρ, R_f and K, and their spatial differences deserve further research with emphasis. The methods proposed in this paper overcome the disadvantages of traditional single factor method, in which the samples are lack of representatives. With these methods, the significance level of parameters sensitivity can be determined in a quantitative way, thus improving the comprehensiveness and precision of the sensitivity analysis and providing some reference for the reasonable selection of model parameters that require spatial assignment in the refined analysis of rock-fill dam deformation.

Abstract:Up to now, few studies have been performed to evaluate the safety of underground cavern group under earthquake, and most of the researches are limited in a single factor such as stress or displacement. Based on the integrating strength reduction method, particle swarm optimization method, projection pursuit method and set pair analysis model with Vague set, an seismic safety evaluation model with multiple parameters is proposed for huge underground cavern group. In this model, several dynamic response parameters such as vertical displacement, horizontal displacement, acceleration, and compressive stress are taken as the key factors to evaluate the seismic safety of underground caverns. A multi-index seismic safety assessment method system is hence proposed for large underground cavern group in this paper. A case study is performed to evaluate the seismic safety of the underground cavern groups of a huge hydro-power project, the results show that the selected three sections of the underground caverns are all in a safe and steady rating, which in turn demonstrate the effectiveness of the proposed model.

Abstract:In view of the lack of quantitative analysis method in the layout planning of the port-centered industries, an industrial spatial layout model based on multi-objective planning and systematic layout design is established in this paper, which is then analyzed and solved to address two problems: scale and spatial layout of the port-centered industries. Finally, a case study for the port-centered industry zone of the Binhai Port of Yancheng City is performed, in which a spatial layout model for port-centered industries is established and solved by means of LINGO solver and simulated annealing algorithm. The optimal layout program for the port-centered industries of the Binhai Port is obtained, which demonstrates the feasibility and accuracy of the model.

Abstract:Based on acoustic survey, an integrated method for inspecting the unburied status of submarine pipeline is proposed. A Multi-Beam Bathymetric System(MBS)with dual-sonar sensors and a side-scan sonar system is employed in this method, and analyzing and optimizing of system parameters are implemented for efficient and accurate inspection of the unburied status of submarine pipeline at Shengli Oil Field in Shandong Province. The analysis of inspection results shows that the MBS with dual sonar sensors is able to obtain high-density point cloud data of submarine pipeline, which greatly improves the stability and reliability of the inspecting data. The well inspecting effect of a side-scan sonar system is dependant on the optimum value of its acoustic grazing angle. With the help of the optimized system parameters, the detection efficiency of the integrated system is significantly improved so that the actual status of submarine pipe can be determined more precisely.

Abstract:To summarize the occurrence regularity and characteristics of sudden siltation during typhoon period in the deepwater navigation channel of Yangtze Estuary, the meteorological conditions and corresponding wave conditions during sudden siltation are analyzed. The results show that the wave energy correlates well with the siltation in NPJ station. The analysis of typhoon paths suggests that the sudden siltation in the navigation channel is significantly influenced by the taphoon passing through the east part of Yangtze Estuary. In this study, three typical typhoon paths are selected with reference to the historic typhoon paths in Yangtze Estuary, and the typhoon field was replicated by combing the empirical circular(Fujita and Takahashi)wind field and CFSR(climate forecast system reanalysis)wind field. SWAN model is then used to simulate the wave conditions under different typhoons paths. Finally, the effects of different typhoon paths on the sudden siltation are analyzed by taking the shallow water wave energy in NPJ station as the discriminant parameter. The study indicates that the typhoon passing through the east area of the Yangtze Estuary is found to be a typical typhoon path, which can readily induce relatively large wave energy and subsequent sudden siltation. And such analysis result agrees well with that of measured typhoon path causing sudden siltation since 2010.

Abstract:To further identify the effects of four typical typhoon parameters,namely, central atmospheric pressure, distance from typhoon center to Yangtze Estuary, maximum wind radius and moving wind velocity on the sudden siltation of navigation channel in Yangzi Estuary, the orthogonal experimental design (OED) method is used to design 64 groups of typical working conditions. The wind filed is established with the empirical formula of Fujita- Takahashi circular wind filed, and SWAN model is used to simulate the wave conditions under different typhoon working conditions, by which the wave energy at NPJ station is calculated. The sensitivity sequence of the four parameters is then deduced according to the RA (Range Analysis) and VA (variance analysis) of wave energy. The study shows that in the typhoon passing through Yangtze Estuary, the distance is the most sensitive parameter and maximum wind radius is less sensitive. In this case, the two major sensitive parameters(distance and central pressure) are taken as representative parameters, while moving wind speed and maximum wind radius are generalized. A typical envelope line is proposed based on a reasonable selection of the critical wave energy which is likely to cause sudden siltation, hence providing a novel reference to predict the sudden siltation.

Abstract:In this paper, physical modelling tests are performed to study the safe operation of the ship lock running as an open channel, in which the flow regime, flow velocity and hoist force at different tide levels of the upstream and downstream are modelled for the lock chamber and approach channel region. Based on the test results, the relationship between tide level difference and the maximum longitudinal velocity is established. Moreover, a method is proposed to determine the safe operation conditions of the open ship lock, in which the tide level difference between the upstream and downstream is taken as the control condition, and the flow regime, the maximum transverse flow velocity, the maximum longitudinal flow velocity and the maximum hoist force are taken as judging indexes. The tide level difference is thus determined for the safe operation of the ship lock by combining all these judging indexes. The case study for the Jiaogang ship lock shows that, a tide level difference of -0. 37 m to 0. 39 m between upstream and downstream is requested to ensure its safe operation.

Abstract:To study soil permeability of soil element within the high earth-rock dam under complex stress state, medium-sized triaxial tests are carried out on the medium-sized triaxial apparatus for three kinds of soils with different gradations from the same material site, which incorporates five levels of confining pressure(100 kPa、400 kPa、800 kPa、1 200 kPa and 2 000 kPa), with each being consisted of four stress levels(0、0. 2、0. 4 and 0. 8). The permeability coefficient of soil sample is determined by using constant-head test method when the sample deformation is basically stable in the initial stress state. The test results show that, the coefficient of permeability is largely influenced by soil grading. Under the same stress state condition, the coefficient of permeability appears to decrease with the increase of silt and clay contents. Moreover, this coefficient of permeability is gradually reduced by the increased confining pressure and stress level, the effects of confining pressures on the coefficient are remarkably intensified by a lower contents of silt and clay and higher content of soil with large particle. For soil samples with different gradations and the same compactness, the effects of stress levels on the coefficient of permeability are basically the same. Based on the analysis results of the coefficient of permeability varying with the confining pressures and the stress levels, an empirical formula is finally established to describe the the permeability coefficient of soil under complex stress state.

Abstract:For the purpose of making a more accurate study on the interface mechanical properties of the frozen soil from more perspectives, improvements on the original multi-function direct shear apparatus for frozen soil are conducted, which involve improvements on temperature collecting and recording device, displacement measuring device, and loading and unloading device for frozen soil box. These improvements will allow the direct shear apparatus to better meet testing requirements on the interface mechanical properties of frozen soil. Based on the original direct shear apparatus, modules related to the adfreezing strength test on the interface of frozen soil and the mechanical property test on the interface layer of frozen soil are integrated, meeting the multi-function testing requirements. The new functions are developed by means of modular design, in which the compatibility and convenience of switching between different functional modules are emphasized. The experimental results have shown that the improved direct shear apparatus is able to meet the multi-function experiment requirements for the frozen soil, such as the research on the adfreezing strength and mechanical properties of interface layer, and the testing data is demonstrated to be stable and reliable.

Abstract:Based on the Mohr-Coulomb failure criterion and the hypothesis of the rock micro-unit strength subject to Weibull random distribution, a new statistical damage constitutive model is established by introducing the pore water pressure by means of the effective stress theory. The new model can consider the influences of both pore volume change and damage threshold. In addition, a novel micro-unit strength calculation method for the rock is proposed. In order to make the model parameters have definite physical meaning, the model parameters m and F₀ are determined by using the peak point strength in the stress strain curve. In this study, the conventional triaxial compression tests for sandstone are conducted to verify the rationality of the model, by which the damage evolution and porosity variation of the rock under different confining pressures are analyzed, and the effects of confining pressures on the model parameters are explored. The findings show that the model can well reflect the relationship between triaxial stress and strain of the rock.