Papers by Author: Jun Zhi Zhang

Abstract: The flood in the mountainous area is characterized by remarkable outburst, low foreseeability, sudden rise and sudden fall and large destruction and is one of the natural disasters in rural area. In order to reduce the loss from mountain flood, this Thesis, taking the section of Siwu Village on the upstream of Miaoyuanxi Stream as the study object, conducts the calculation of the design flood for the small watershed of Miaoyuanxi Stream. The small watershed is short of the data of actually measured rainfall, especially runoff; therefore, based on the geographic information system (GIS), with irregular triangle net and spatial analysis function, we have realized the interpolation of the hydrologic characteristic value isoline of the research area; with frequency analysis, we have calculated the design rainfall of different time at different frequency and further calculated the design peak with the rational formula; in addition, with the hydraulic method, we have calculated the corresponding water depth of the three control sections of Siwu Village. The result shows that, the combination of small watershed design flood calculation and the GIS can make the hydrologic calculation more accurate and convenient. The research result may be the reference for the establishment of the flood prevention and avoidance guarantee system for the rural area.

Abstract: According to a series experiment for bending resistance of hydraulic concrete and RC element of mixing short-chopped basalt fiber, the reinforcing effect of bending strength and flexural elastic modulus of short-chopped basalt fiber concrete are analyzed, and increased cracking-resistance loads of short-chopped basalt fiber RC beams is also researched. Experimental results show that bending resistances of short-chopped basalt fiber concrete are increased, short-chopped basalt fiber in concrete is useful to reinforce the bending strength of concrete and cracking loads of RC beams.

Abstract: According to risk analysis theory, a model of analysis for failure risk of upstream revetment of existing levees is proposed in this paper. Based on the model, the load effect and generalized resistance for the failure risk of upstream revetment of existing levees are analyzed, and then the influencing factors of the failure risk of upstream revetment are studied. The calculation results show that the proposed model is workable and effective for analysis of the failure risk of upstream revetment of existing levees, and the main factors influencing failure risk of existing upstream revetment are the randomness of the existing effective thickness of upstream revetment and ratio mean of upstream slope of the existing levees.

Abstract: According to a test for chloride ion erosion in concrete under designed manual climate environment, distributions of chlorine ion concentration in pure bending concrete of short-chopped basalt fiber RC beam and check RC beam without fiber with different flexural loads are analyzed in this paper, and diffusion coefficients of compression and tensile concrete are fitted on the basis of Fick’s second law. Analysis results show that erosion-resisting properties for chloride ion of the basalt fiber compression and tensile concrete in the pure flexural region are increased

Abstract: The permeability of chloride ion in concrete can be studied using the accelerated aging method in a short period, but the influence of loading characteristic on chloride ion permeability and diffusion coefficients is not considered generally. Three RC beam (120 mm×240 mm×2400 mm) specimens with different flexural loading state are exposed in an artificial corrosion container filled with salt-fog of 5.0 % sodium chloride for 40 days, the chloride ion concentration in different depths of compressive and tensile region are measured, diffusion coefficients of different region concrete are fitted on the basis of Fick’s second law, the effect of flexural loading on chloride ion concentration and diffusion coefficients of concrete are analyzed. The results show that the effect of the flexural load influences permeability of chloride ion and diffusion coefficients of concrete, content of chloride and diffusion coefficients of concrete are controlled by loading level, and the bending load is one of the important factors that can not be ignored in the study of concrete durability.