Advanced Materials Research Vols. 838-841

Abstract: Taking the concrete face cock-fill dam upper reservoir of Tianchi as an example, the stress and deformation characteristics of concrete face rock-fill dam are studied in-depth in this paper. The article builds a fine three-dimensional finite element model of Tianchi upper reservoir by a nonlinear elastic model of the finite element software ADINA. The stress and deformation of the two conditions under completion and storage for the dam are calculated ,which will be analyzed to obtain stress - strain distribution of the dam in two conditions, comparing dam stress and deformation before and after impoundment to get impact of the water pressure on the dam stress and deformation: comparing after impoundment and completion , the dam water level displacement of upstream side from role of horizontal water pressure will increase , the dam upstream offsets to downstream , but the offset is little ; Due to dam is affected by vertical hydrostatic pressure and uplift pressure after impoundment , the dam settlement is slightly less than the completion in storage. KEY WORDS: Tianchi upper reservoir, The concrete face cock-fill dam, Three-dimensional finite element, Nonlinear elastic model, Analysis of stress and deformation

Abstract: Based on the theory of membership degree and comprehensive evaluation in the Fuzzy mathematics, 15 groundwater samples form SuoLuoShu water resource were collected and assessed. Through the analysis of water quality and the local pollution characteristics, chloride, sulfate, nitrate nitrogen, total dissolved solids, total hardness were selected to be the evaluation index system. And the value of the corresponding indexes of 5 grades in the national water quality standard was the comprehensive evaluation level in this study. On this basis, the membership degrees of the groundwater samples in the 5 grades were calculated and by using the maximum membership principle, the groundwater grade of each samples were determined. The results show that the groundwater quality in this area is better generally. 80% of the samples measure up the standard of grade III and the three samples beyond it were all caused by the nitrate nitrogen pollution which was brought by human activities.

Abstract: The North China Approach to assess karst groundwater vulnerability was proposed based on European Model, modifying C and P factors to adapt the specificity of karst regions specificity in North China. It was firstly applied to the Fangshan karst regions in Beijing and the vulnerability maps indicate high vulnerability nearby karst caves and the areas lacking overlying soil.

Abstract: This paper demonstrates the application of fuzzy inference system (FIS) employed by mapping meteorological data between known inputs (wind speed, relative humidity, temperature, and sunshine radiation) and output (evapotranspiration). The results after training show that the FIS is able to capture the nonlinear feature for evapotranspiration. Moreover, the trained FIS is integrated into geographical statistical technology for the estimation of the regional evapotranspiration, forest and farmland in Dan-Shui Basin as an example. It is found that FIS simulation effectively reduces the amounts of formula parameters, computation time, and diverse procedure, which it can be another efficient mathematical tool to deal with the study of evapotranspiration estimation.

Abstract: This paper makes a detailed analysis on the natural conditions, flood disasters and watercourse conditions and evolution in Yibin, and conducts an analytical study on the flood control in Yibin Reach based on the needs of social and economic development in Yibin City. Based on hydrologic and hydraulic calculations as well as the layout of the project, it puts forward the recommendations for urban flood control in Yibin Reach, which is of great importance to improve the regional ecological environment and promote the development of regional economy in Yibin, and can bring considerable social benefits and economic benefits.

Abstract: As a problematic material, fine grained tailings have many particular engineering characteristics and seriously affect the safety and stability of the tailing dam body. These engineering properties are closely related to moisture migration and soil suction under different water content. This article chose fine grained tailings of Li Tie Lan Ting tailings dam in Zhejiang province as an example, and measured the soil water characteristic curve (SWCC) of fine grained tailings with different partical size composition and dry density using vapour equilibrium technique. Efforts have also been made to demonstrate the influences of soil type, dry density on water retention. The study result shows that particle-size composition has a significant impact on SWCCs of the tailings. Finer grained samples have lower water loss rate and higher water-holding capacity than coarse grained samples in the same suction state. Contrary with low suction stage, dry density has negligible influence on the soil suction, and parameters effect SWCCs at high suction stage. The research results may provide a theoretical support and a beneficial reference for further research of fine grained tailingss engineering properties.

Abstract: Through artificial seawater simulation test this paper analyzed erosion mechanism of concrete corroded by the ions in seawater. High performance marine concrete was successful developed because of mineral admixture and corrosion-resistance additive double adding. The paper researched the durability of concrete containing freeze-thaw cycles and chloride ions diffusion. Modern testing technologies were used such as scanning electron microscopy and differential thermal analysis in the experiment. Research founded that the amount of unstable or metastable matter reduced such as calcium hydroxide and high alkaline calcium aluminates in the marine concrete. There were more compact hydration products created which made the structure stabler and denser. Those were the reasons that the marine concrete had excellent performances in terms of erosion-resistance and durability.

Abstract: Seepage is important influence factors of degradation and instability to the water or under water concrete structure, it is also the difficult point in geotechnical engineering research.Through the concrete seepage experiment，combined with the Seep/W module of GeoStudio software，simulation of unsteady seepage of concrete，it was obtained that the seepage field under the action of a variable water head in 24 hr,And the results were compared with laboratory data，For further research on concrete permeability structure in practical engineering, foundation stability and durability.

Abstract: Influence of aggregate types on the impermeability and frost-resistance of concrete with different water/cement ratios were investigated, as well as the pore structure and hydrates of the ITZ. The results show that, concrete prepared with a high water/cement ratio and using granite aggregate, presents the highest values of chloride diffusion coefficient and the lowest numbers of freeze-thaw cycles. Whereas concrete prepared with a low water/cement ratio and using limestone aggregate, obtains the similar durability results. The limestone aggregate with a rough surface and higher water absorption, has a tight bonding with the cement paste. However, the granite and basalt aggregate that formed by magma eruption, have higher activity. The XRD results demonstrate that more clinkers participate in the hydration of cement, therefore, resulting in a denser ITZ. In order to improve the concrete durability, the basalt aggregate both with higher activity and rough surface is consider optimal.

Abstract: With the reduction of natural river sand, the application of sea sand is on the increase. When sea sand is directly applied in engineering, steel bar will be eroded and thus has an impact on the durability of concrete. Adopting perfect desalinization method and carrying out strict management measures can help to promote the use of sea sand.