Advanced Materials Research Vols. 243-249

Abstract: Based on the normal H-K rheology model, a new rheological model containing fracture elements for concrete or rock cracked body is introduced. The method to ascertain rheology state is put forward. The new rheological model can change to Maxwell or Kelvin model to express the instantaneous failure, delayed failure state and the accelerating segment. The researching failure element method was used to study the crack propagation. Then the cracking elements were studied using rheology mechanics to solve the cracking time. At last a case study was given to validate the method is feasible.

Abstract: Differential evolution algorithm (differential evolution, DE) is a multi-objective evolutionary algorithm based on groups, which instructs optimization search by swarm intelligence produced by co-operation and competition among individuals within groups. While it can track the dynamics of the current search by the DE specific memory, in order to adjust their search strategy. The strong global convergence and robustness of the characteristics can solve the complex optimization problem which it hardly solves with the mathematical programming methods. This paper presents it to the research of short-term scheduling of hydro plant. Accord to the application of the hydro unit, the results shows that reasonable and effective.

Abstract: The failure process of hydrostructures concrete is a stochastic process relating to time and space. The durability failure mechanism, durability failure type and durability failure mode were presented. The relation of durability and resisting ability was studied. Based on credibility theory, the method for predicting service-life of hydrostructure concrete was put forward. Through a typical case analysis, the mend measures to improve durability were introduced. The design method for hydrostructure concrete should be controlled by both stress state and durability instead of traditional one.

Abstract: To study the seismic response of submerged floating tunnel, a numerical model of submerged floating tunnel is set up based on the potential fluid theory. According to the parameters of designed submerged floating tunnels at home and abroad, main factors that affect the dynamic response of submerged floating tunnel were analyzed by numerical method. The results show that, the investigated parameters, such as tether spacing, external diameter of tube, immersion depth of tube, water depth and tube concrete thickness, have strong influence on the global behavior of the submerged floating tunnel. Definitely, by the caring choice of such features, it is possible to optimize the submerged floating tunnel structural behavior.

Abstract: Spiral case with cushion layer is commonly given a significant consideration on hydroelectric power station design for vital practical reasons. In this paper, combined with an engineering project, non-linear constitutive equation suited to concrete material was selected according to the finite element theory. On the condition of structure weight and pressure of internal water, the combinations composed of jointly loaded spiral case structure including steel lining, different thickness of cushion layer and reinforce concrete structure around spiral case are calculated and analyzed. The relation between stress (concrete stress & spiral case stress) and thickness of cushion layer is proposed, which in turn provides design basis for the project.

Abstract: Non-depositing critical velocity is an important parameter in project design for low pressure pipe irrigation system in irrigation districts of sediment-laden water resource. The velocity used to be calculated through the critical velocity equation for solid particles delivery in pipeline system. However, the calculation error is relatively large due to the small sediment content and the large fine-textured particle content. This paper conducted different non-depositing critical velocity experiments under 6 sediment concentrations and 4 pipe diameters. The impacts of sediment concentration, pipe diameter, particle size and distribution on the non-depositing critical velocity of water delivery in pipeline system were analyzed based on the experimental results.

Abstract: Muddy river is the water source for most northern channel irrigation districts in China. Pipe clogging is the main problem to limit development of pipeline delivery irrigation technology in this area. The key to solve the problem is to determine the critical non-deposit flow velocity and the corresponding technologic measures. Based on part achievements of national “863” project, characteristic and operation of northern irrigation district , this paper analyzed the pipe clogging mechanism caused by muddy water and put forward a set of efficient pipe anti-clogging measures, which are confirmed to be practical through the application in a project.

Abstract: Based on the analyses of the traditional rockfill groins of spur dikes，the PHC pipe pile groin is presented.The functions of the riverwall protection function, anti-erosion performance, and structure design of the groin were analyzed. By the three-dimensional finite element numerical modeling, when the scour depth of spur dike is 20m, the safty coefficient of spur dike is 1.21 and the maximum deformation is 1.3 centimeter. The studies are shown that the PHC pipe pile have high strength, stability and anti-erosion performance; The deign of double-row pile is applied to the head of spur dike where the displacement is maximum and improves stress boundary condition of the spur dike and improves the whole stability effectively.

Abstract: Based on an actual slope in the Three Gorges reservoir, the 3D geological model was built as the foundation. The numerical simulation method of the slope instability process was put forward. Then, a series of dynamic parameters were computed, including stability factors, accelerations, velocities, displacements. And the hazards of surge and river-blocking were analyzed. It offers a new analytical approach to the reservoir slope instability.

Abstract: Based on Fick’s second law and the damage evolution due to sulfate attack, a new model is proposed to analyze the diffusion of sulfate ions in concrete. The relation between erosion damage and erosion time, as well as the concentration of sulfate ions is firstly investigated by virtue of the ultrasonic experimental results. Furthermore, the damage evolution is treated as the increase of porosity, and a new nonlinear differential equation on the diffusion of sulfate ions is established by substituting such an increasing porosity into Fick’s law. The nonlinear diffusion equation is then solved by numerical method. It is found that the erosion damage can significantly affect the diffusion of sulfate ions in concrete.