Applied Mechanics and Materials Vols. 90-93

Abstract: The 3-D numerical model of bifurcation embedded in anchor block concrete of a diversion type power station is built. And FEM is adopted to analyze the pipe stresses and displacement. The influence of initial gap along the penstock outside, concrete’s crack status of anchor block and deformation modulus of the bed rock is discussed. Some conclusions can be achieved as follows. Safe factor is enough when the exposed-penstock design scheme is adopted. But enough rebar is required to guarantee the integrity of anchor block. The initial gap, concrete’s crack and the deformation modulus of bed rock has marked influence on the stresses of penstock. According to the design criteria of reinforced concrete penstocks, combined bearing ability of bifurcation steel and anchor block concrete is advised to reduce the thickness of penstock. As a result, the difficulty of construction is reduced and the investment is more economized than before.

Abstract: Chloride ions are the main factors of concrete building in irrigated area. Through the analysis of the failure mechanism which chlorine ion to the building in irrigation return water, the mathematical mode is established to forecast the service life of buildings in high salinity groundwater erosion environment.

Abstract: Geocell protection of slope was influenced by environment and climates largely. Many of them came to failure when subjected to rainfall infiltration. Aiming at the general shear failure mode of the geocell-protection-system (GPS), its stability analysis model during rainfall was established by the limit equilibrium method. A new approach of evaluating stability of the GPS was proposed.

Abstract: This paper studys on how the high degree mineral groundwater erodes the concrete building of great high lifts irrigation project in JingDian (GanSu province) and GuHai (NingXia province), and analyzes the break reasons for erosion and investigate the repair technique. In the idea of reducing the erosion medium and enhancing the concrete anti-erosion quality, the authors suggest a popularized repair technique and protection measure about the break reasons for erosion of the concrete building of high lifts water irrigation project in loess plateau regions.

Abstract: Apart from traditional optimization techniques, modern heuristic optimization techniques, like genetic algorithms (GA), particle swarm optimization algorithm (PSO) have been widely used to solve optimization problems. This paper deals with comparative analysis of GA and PSO and their applications in a reservoir operation problem. Extensive component analysis, parameter sensitivity analysis of GA and PSO show that both GA and PSO can be used for optimal reservoir operation, but they display different features. GA can obtain very high approximate global optimal solutions of the problem with a high stability and a high computing efficiency, but it can’t obtain the problem’s accurate global optimal solutions. For GA, population size and mutation rate are two main parameters affect its solution qualities. Comparative to GA, PSO can obtain the accurate global optimal solutions of the problem with a higher computing efficiency, but with a less stability. For PSO, population size and velocity parameter are two main parameters affect its solution qualities.

Abstract: Non-dominated sorting genetic algorithms II (NSGAII) has been widely used for multi- objective optimizations. To overcome its premature shortcoming, an improved NSGAII with a new distribution was proposed in this paper. Comparative to NSGAII, improved NSGAII uses an elitist control strategy to protect its lateral diversity among current non-dominated fronts. To implement elitist control strategy, a new distribution (called dogmatic distribution) was proposed. For ordinary multi-objective optimization problem (MOP), an ordinary exploration ability of improved NSGAII should be maintained by using a larger shape parameter r; while for larger-scale complex MOP, a larger exploration ability of improved NSGAII should be maintained by using a less shape parameter r. The application of improved NSGAII in multi-objective operation of Wohu reservoir shows that improved NSGAII has advantages over NSGAII to get better Pareto front especially for large-scale complex multi-objective reservoir operation problems.

Abstract: Several optimized designs of trajectory bucket pattern for spillway tunnel outlet are compared in the experiment of Sanliping hydropower project integer physical model and the results show that energy dissipation of outflow nappe is sufficient after optimization and no scouring occur near the riverbank either at high water level or at low water level, which ensure the security of spillway structure. And these experimental results can provide a scientific foundation for the design of Sanliping project.

Abstract: In the optimal design of large prestressed aqueduct structure, the optimal design results need to be automatically drawn. In this paper, the parametric drawing method is proposed by combining high-level programming language FORTRAN and Auto LISP, and developed a designing system of mixed programming using FORTRAN and Auto LISP. The programming system is applied to the optimal design process of large prestressed aqueduct with rectangle and U-shaped cross-section. The optimal design result is automatically transformed into visual graphics (documents), therefore realized the automatic drawing. In this way, designers’ graphics labor intensity and repeated, complicated calculation can be reduced and the design cycle can shorten. Data files (*.DAT) and graphics files (*.LISP) can be generated not only by FORTRAN, but also by other high-level programming languages such as C⁺⁺, VC etc.

Abstract: The Lombardi slenderness coefficient is usually used to assess cracking potential of an arch dam. In consideration of the fact that the Lombardi fractural curve former presented do not rely on any safety indexes and shape index of the dam and is only related to the dam height, the modification to the Lombardi fractural curve is carried out and the new Lombardi fractural curve is put forward related to the tensile strength of the dam concrete, the dam height and the width of dam site valley in the paper. In the end the new Lombardi fractural curve put forward in the paper verified through some examples of arch dam projects home and abroad has better adaptability and better rationality to assess cracking of an arch dam.

Abstract: based on the situation of port security and risk at present, the analytic hierarchy process AHP was adopted in this article, thus an analysis model was established for the security and risk of port from view of the system engineering. In addition, subjection function of factors sets was determined based on fuzzy mathematics, then comparison matrix was also gained. Through fuzzy evaluation, complex evaluation point was obtained respectively for the security and risk of port. The result shows that this method is scientific and rational in port security and risk judgment, and it can offer a decision.