Advanced Materials Research Vols. 706-708

Abstract: In order to validate the interface concrete self-stressing method of the homemade stress box can achieve the accuracy of the traditional test methods of the strain gauge pasted on the outer wall of steel tube and make up for its shortcomings, in this article, the self-stressing of expansion concrete filled steel tubular short columns with different expansive agent dosages are tested from homemade stress boxes, and the interface concrete stresses are converted from the measured strain by the strain gauge pasted on the outer wall of steel tube. The calculation stresses are smaller than the conversion stresses because of the surface friction of rebar by comparison, but the changing trends are the same, such arrangement and test method is proved to be feasible.

Abstract: Mechanical properties of steel fiber concrete under dynamic load had been obtained through dynamic loading experiments of steel fiber concrete in different volume ratios. The experimental results indicate that the dynamic load strength of steel fiber concrete is obviously more than the static load strength, the dynamic load strength increases with the increasing of the steel fiber volume ratio; and the effect of variable strain rate is obvious. When the strain is at 0 ~ 0.01 or smaller, the toughness index of plain concrete is slightly more than steel fiber concrete; the strain exceeded 0.01, the toughness of steel fiber concrete has improved greatly with the increase of the strain. When the strain rate is smaller, the elastic modulus changes little, and once the strain rate is more than 60 per second, the elastic modulus there is the more amplitude with the increase of strain rate.

Abstract: In order to achieve the optimal interface composite properties between the inner wall of steel tube and the core concrete as well as evaluate the expansion properties of concrete filled steel tubular rationally, the mechanical properties of 5 CFST specimens were tested in this paper with different dosage of expanding agent measured from zero to 28d curing age. Besides, this research also examined the validity and accuracy of homemade concrete stress box. The result proved that the test results coincide with the calculated value of theoretical analysis perfectly, which provided experimental and theoretical basis for the expansion mechanism of self-stressing concrete in steel tube constraint and the designing goals of expansion properties in concrete filled steel tubular.

Abstract: In this study, a strain of cellulolytic bacterium named N-6 was isolated from lake Huguang Maar. Phylogenetic analysis based on a partial 16s rDNA sequence showed that the strain was Bacillus cereus. Extracellular cellulase produced by the strain Bacillus.cereus N-6 exhibits optimum activity around pH 8.0 at 50°C and has good pH tolerance in the range of 6-9.

Abstract: Using gray theory established entropy weight and gray association model in analyzing the mostly infection factors of coal and gas outburst, entropy theory was used to calculate the weights of contamination. Analysis of sample data, in accordance with the order of gray correlative degree, it is found out the closest relations with the outstanding master factors to identify the most likely sensitive indicators to improve the accuracy of coal and gas outburst forecast prominently.

Abstract: In this paper, the interval analysis method is introduced and an uncertainty inverse analysis method is presented. The intervals of unknown parameters can be obtained by the input of measured data. Even for few measured data, the analysis results can be also obtained by the inverse analysis method. And the analysis results can be applied to appraise the uncertainty in interval. Based on parameter perturbation, the reversible inverse analysis model is proposed for linear-elastic problems. A numerical example is given to illustrate the validity of the present method. The influence is illustrated about different measured precisions and different numbers of analyzing parameters on the inverse analysis results. And the conditions of existence or convergence of the solution are given.

Abstract: Soft rock is frequently encountered in underground excavation process. It is difficult to excavate and support in soft rock mass which has low strength, large deformation and needs much time to be out of shape but little time to be self-stabilized. Based on a large underground power station, finite element model analysis was carried out to simulate the excavation process and the results of displacement, stress and plasticity area were compared between supported and unsupported conditions to evaluate the stability of the rock mass.

Abstract: This paper used the FLUENT software to analyze a flow field of the advection type air-float pool, the simulation analysis is applied to study of partition plates, water retaining plate and floatation pool length depth ratio and other key parameters which influence the flotation pool flotation effect .The research results provide the basis for the structure design of improving the flotation pool. It has a certain reference value for the same type of flotation pool design.

Abstract: Abstract：In this paper,HCI solution in the chemical corrosion tests carried out in room temperature,measured mass loss of CFRP tendons. After extraction and analysis, preliminary search the FRP reinforcement corrosion mechanism under acid erosion. The tensile test is done at 60d and 120d,respectively. Determination of the tensile strength of CFRP tendons. The experimental analysis of the data collected, identify the law of CFRP reinforcement corrosion. Fiber reinforced composite material (Fiber Reinforced Polymer, of FRP ) is a continuous non-metallic fibers and fabric reinforced thermosetting or thermoplastic resin matrix composite made of a new material . Fibers and resin matrix composed of FRP bars under normal circumstances is not easy to rust, but in recent years, the study found that acid salt , moisture , UV , temperature and other environmental conditions on the long-term performance of FRP bars have a certain impact[3-5]. By CFRP tendons under acidic corrosion durability test study reveals CFRP tendons under the corrosive effect of the variation of the quality and strength . Can provide a theoretical basis for CFRP tendons durability design , to provide theoretical guidance to improve the efficiency of the FRP bars in harsh conditions .

Abstract: The relationship between the SBS modifier types and asphalt components on the effect of modified asphalt properties was discussed in this paper. Higher block ratio, higher molecular weight and star-like structure of SBS can improve modified asphalt high temperature properties. Colloid content decrease leading the processing easier, result stability decline. Our research group invented a chemical titration combined with fluorescence microscopic analysis detection method monitoring SBS modifier dosage. This method applied in highway construction site, the effect is significant.