Abstract:In order to realize the dynamic and visual integration of multi-source construction information, including quality, schedule, and cost, and to meet the need for visually analyzing the whole construction process of a core rock-fill dam, a 4D construction information model for a core rock-fill dam(3D geometric model+time dimension+multi-source construction information)is proposed based on analysis of the multi-source characteristics of the construction information. The established method of the 4D construction model was studied, including techniques for the establishment of a 3D model of the core rock-fill dam, the integration of the multi-source construction information, and the 4D visualization method in the construction process of the rock-fill dam. Practical engineering applications show that the integration and interactive analysis of multi-source information and 4D visualization of the construction process are realized based on 3DGIS, which can provide theoretical and technical support for site control and management of the rock-fill dam.

Abstract:In consideration of the fact that the interaction between different monitoring points is seldom considered in traditional displacement monitoring, the application of the spatial autoregressive model in the prediction of high slope deformation was examined based on the basic theory of spatial econometrics. Using a high slope as an example, the results of displacement prediction based on the monitoring data of exterior deformation were compared with those from the traditional autoregressive integrated moving average model. The results show that, with a significant spatial autocorrelation coefficient, the spatial autoregressive model is more accurate than the traditional model in prediction of slope deformation, and that, compared with the traditional model, the spatial autoregressive model has more concise parameters, considers the factors more comprehensively, and can perform displacement prediction at different monitoring points at the same time.

Abstract:In order to remove humic acid(HA)in source water, magnetic-modified sepiolite(MSEP)was made and its physicochemical characteristics were investigated. The adsorption and desorption behaviors of MSEP for humic acid in source water were studied. The results showed that the specific surface area and specific saturation magnetization of the MSEP were 25. 354 m²/g and 32. 36 A·m²/kg, respectively. The adsorption isotherm of MSEP to HA could be fitted with the Langmuir equation, and the adsorption kinetics could be described with the pseudo-second-order kinetics equation.

Abstract:A novel floating photocatalyst based on polyurethane foams modified with TiO₂/graphene-montmorillonite was synthesized. The characteristics of the photocatalyst were investigated with a scanning electron microscope, transmission electron microscope, energy-dispersive X-ray spectrometer, X-ray diffractometer, and UV-visible diffuse reflectance spectroscope. The results showed that TiO₂ nanoparticles dispersed on graphene sheets, and photocatalytic active components uniformly and stably dispersed in the matrix and on the surface of the polyurethane foams. The density and specific surface area of the photocatalyst were 0. 26 g/cm³and 17 m²/g, respectively, assuring the floating property of the photocatalyst and good adsorption capacity of pollutants. The adsorption capacity of 1 g photocatalyst to 2 mg/L 17α-ethinylestradiol(EE2)reached 73%, and the maximum EE2 degradation efficiency was found to be 76% over a period of 4 h. Moreover, no obvious decrease of the degradation efficiency was observed after five cyclic operations. This demonstrated the strong stability and reusability of the photocatalyst for the restoration of polluted water bodies.

Abstract:The research on the contents of neonicotinoid residues in water and their direct and indirect effects on aquatic organisms are reviewed. The acute and chronic toxicity of neonicotinoids to aquatic vertebrates(fish and amphibians)and invertebrates(mayfly and Daphnia magna)is described, as well as the indirect effects on fish through the variations of biotic communities and food chains. It is concluded that the acute toxicity of neonicotinoids to aquatic vertebrates is significantly lower than the toxicity to invertebrates. Chronic toxicity and long-term effects on aquatic organisms exist at low concentrations of neonicotinoids. The indirect effects of neonicotinoids in risk assessment are discussed. It is pointed out that neonicotinoids significantly affect the community and population of non-target organisms through the accumulation and transfer functions of food chains.

Abstract:For the scientific and objective evaluation of regional water use efficiency, a projection pursuit(PP)model based on the soccer league competition(SLC)algorithm was established. The evaluation of water use efficiency in Wenshan Prefecture during the period from 2006 to 2015 was used as an example. The SLC algorithm was validated using six typical high-dimensional functions, and the simulation results were compared with the optimization results of the teaching-learning-based optimization(TLBO)algorithm, gray wolf optimization(GWO)algorithm, differential evolution(DE)algorithm, shuffled frog-leaping algorithm(SFLA), particle swarm optimization(PSO)algorithm, and imperial competitive algorithm(ICA). From five types of water use, including comprehensive water use, industrial water use, agricultural water use, domestic water use, and ecological environmental water use, 23 indices were selected to build an index system for the evaluation of water use efficiency. A water use efficiency evaluation standard with five grades(low level, relatively low level, medium level, relatively high level, and high level)were constructed based on the mean and standard deviation values of the projection series. Based on this standard, the SLC-PP model was used to analyze the trend of water use efficiency in the study area over the past ten years. The results showed the following: First, whether for the optimization of unimodal or multimodal functions, the SLC algorithm performs better than the TLBO and GWO algorithms, and much better than the DE, SFLA, PSO, and ICA algorithms. The SLC algorithm has the advantages of high optimization accuracy, fast convergence, high capability in seeking extreme values, excellent stability, and high reliability. Second, the evaluation results of water use efficiency in the study area using the SLC-PP model show that the water use efficiency grades were at a low level in the period from 2006 to 2007, a medium level from 2008 to 2012, and a relatively high level from 2013 to 2015. The water use efficiency shows a significant increasing trend over time.

Abstract:Based on the Penman-Monteith equation, the sensitivities of potential evapotranspiration to the maximum and minimum temperatures, relative humidity, wind speed, and sunshine duration were analyzed using the global sensitivity method at 12 meteorological stations in four climatic regions of China. The results indicate that(a)ranks of the sensitivity of the potential evapotranspiration to meteorological factors were different in various climatic regions and seasons. Sunshine duration had the greatest influence on potential evapotranspiration in summer, while the maximum temperature, relative humidity, and wind speed were sensitive in winter, and the minimum temperature was insensitive throughout the year. (b)From the middle temperate and semi-humid area to the plateau temperate semi-arid area, north subtropical humid area, and south subtropical humid area, the impact of sunshine duration on potential evapotranspiration presented an increasing tendency, and the impact of wind speed on potential evapotranspiration decreased. (c)The results were significantly different with use of the global and local sensitivity methods, and the ranking of the sensitivity of potential evapotranspiration to meteorological factors with use of the local method was related to the selected values of the meteorological factors.

Abstract:In order to obtain the reasonable design parameter range of a partially earth-anchored PC cable-stayed bridge with a single pylon, the formulas for the total bridge cost and the cost per unit length of the bridge were obtained through computation of the material dosage and cost of cables, the main pylon, the anchor, and the girder. According to these formulas, the reasonable ratio of the self-anchored length of the side span to the length of the main span, the ratio of the anchor length to the main span length, the side-to-main span ratio, and the ratio of the pylon height to the main span length of the partially earth-anchored PC cable-stayed bridge with a single pylon were studied, and they were compared with those of other cable-stayed bridges. The results show that, considering the spanning capacity of the whole bridge, larger values in the range of 0. 336 to 0. 487 should be used as the ratio of the self-anchored length of the side span to the length of the main span, and lower values in the range of 0. 487 to 0. 544 should be used as the side-to-main span ratio. Considering the spanning capacity of the single span, the opposite is the case. Values to some extent lower than those mentioned above are allowed when the main span is smaller, and vice versa. The ratio of the pylon height to the main span length should have a value of about 0. 372, and the corresponding main span side-cable inclination is about 20. 4°. Larger values can be used when the span is lower, as with other types of cable-stayed bridges. The partially earth-anchored PC cable-stayed bridge with a single pylon performs better economically than a common cable-stayed bridge with a single pylon only when the self-anchored space of the side span is limited by terrain conditions. It has no advantage in common terrain conditions.

Abstract:A new method for boundary treatment of the smoothed particle hydrodynamics(SPH)method is presented through introduction of the long-range force in peridynamics(PD)to the solid boundary treatment of SPH. The reliability of the method is verified by four numerical simulation examples, including a liquid column break, Poiseuille flow, water casting filling, and soil collapse. The results show that the method can solve the problem of non-physical particle penetration boundary and objectively reflect actual boundary action, and is effective for dynamic problems with complex geometric boundies and material strength.

Abstract:A finite element model of non-uniform corrosion-expansion-induced cracking of a concrete cover was built using the extended finite element method(XFEM)and interference fit assembly. The calculated results show that a cracking band including several microcracks occurred across a range of 10° to 30°, adjacent to steel bars on their left and right sides, and developed symmetrically in the backward direction away from the medial axis of the steel bars. With increasing degree of corrosion, a diagonal main crack occurred in the crack band, resulting in wedge-shaped destruction of the concrete cover. By means of the secondary development of ABAQUS, the length of corrosion-expansion-induced cracks was obtained, and an exponential relationship between the crack length and the corrosion ratio of steel bars was deduced. The cracking development can be divided into three stages, corresponding to the occurrence of the embryonic zone, extending zone, and gradual development zone of cracks, and the corrosion ratio of steel bars, when cracks enter the gradual development zone, can be used to evaluate the durability of structures. The accuracy of the calculated results was verified by comparison with damage of bridges on the Guanghui Expressway induced by concrete cover desquamation.

Abstract:The governing equations, discretization method, and grid configuration of non-hydrostatic models are summarized based on review of the development of non-hydrostatic models. As the main limitation of non-hydrostatic models is the low computational efficiency, three kinds of approaches to improving the models efficiency are analyzed. Moreover, the main differences in the governing equations and numerical method between the non-hydrostatic and hydrostatic models are examined. The applications of non-hydrostatic models in coastal wave transformation and estuarine baroclinic problem are shown. The performances of non-hydrostatic models in these cases show that the models have advantages in simulating wave transformation, wave-structure interactions, and fresh water-salt water mixing in estuarial areas. Nevertheless, there are still many problems in the computational efficiency, boundary conditions, sallow-water nonlinearity, wave breaking, and practical applications of non-hydrostatic models. Finally, based on these problems, future directions for non-hydrostatic models are presented.

Abstract:In order to explore the health patterns of engineering systems from the point of view of maintenance information, a life cycle reliability analysis model for waterway locks was developed and verified based on maintenance event data. With the engineering system breakdown structure used for technical support and in combination with maintenance event information during the waterway lock life process, the maintenance interval was used to measure the system life cycle reliability by means of the complex system reliability theory. The overhaul interval, medium maintenance interval, breakdown repair time, and failure frequency were defined as waterway lock reliability parameters. Referring to the ideas of reliability analysis in the product development stage in the manufacturing industry, a reliability analysis model for waterway locks was proposed based on maintenance event data, and its practicability was examined using historical maintenance records of 17 waterway locks on the Grand Canal in the north of Jiangsu Province of China.

Abstract:In order to expand ideas for improving the insufficient capacity of many crude oil import terminals in China, this study examined the capacity improvements of a crude oil import terminal consisting of a navigation subsystem and a terminal subsystem. As the navigation subsystem featured a one-way navigation channel, we focused on the scenario of adding berths for unloading and building a ship-passing anchorage(SPAC)as a buffer zone. The terminal capacity and the tanker average delay time under different scenarios were obtained through simulation with the software Arena. A case study of the Shihua Terminal of the Rizhao Port shows that the marginal increase in the capacity of the crude oil import terminal decreases with the mere increase of the unloading berths; that the percentage increase in the capacity, as a result of building a SPAC, increases with the added unloading berths; and that adding unloading berths and building an extra anchorage area concurrently reduce the average delay time of tankers at the port significantly.