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For investigating the stiffness changes on reinforced concrete beam at different level of corrosion after fatigue, a group of RC beams were designed with different corrosion ratio, and fatigue test was carried on these specimens. The deflection, strain and crack of these specimens were analyzed in fatigue loading. The results indicate that the effect of corrosion ratio on fatigue performance of RC beams is very obviously.

The concrete which take coral fragments as aggregate can solve the shortage of building materials in the ocean reef island effectively, The coral concrete shall be classified as light weight aggregate concrete from the angle of the apparent density of building materials, its basic mechanical properties are similar to ordinary light weight aggregate, but there are also significantly different. The different between coral concrete and pumecrete、haydite concrete and the basic mechanics characteristics of coral concrete were study in this paper. The intensity、development of intensity with age、stress-strain relations、failure mode under load were discussed.

In this paper, concrete was analyzed as a composite consisting of coarse aggregate, mortar matrix and interfacial transition zone (ITZ). Because permeability of each phase are not the same, ITZ will affect the concrete permeability. Effect of ITZ on the concrete permeability was studied by laboratory test and numerical analysis.The diffusion coefficient of ITZ, mortar,and concrete can be caculated by laboratory test. The results indicate that the diffusion coefficient of ITZ is far greater than mortar，which is about 40 times of mortar. The chloride ions diffusion ignoring ITZ and considering ITZ were simulated, the results show that the diffusion coefficient of concrete was bigger when the ITZ was considered, which was closer to the experimental results.

Considering the co-action of micro-pile and soil nailing, the state equation of limit equilibrium and the performance function of inner global stability of foundation pit supported by the micro-pile composite soil nailing is set up with the slope limit equilibrium theory and the circular sliding slice method. The calculating model of sliding surface for inner global stability of foundation pit is established with the geometry controlling method and the optimization searching of the most dangerous sliding surface is achieved. Then with the shear strength indexes of soil as random variables, the partial derivatives of the performance function to all random variables is deduced and the reliability index of inner global stability of foundation pit supported by micro-pile composite soil nailing is calculated with the design checking point method. Finally, the effects of coefficients of variability of the random variables on reliability index are analyzed.

The study presented herein has been carried out in order to investigate the chloride diffusivity of recycled aggregate concrete (RAC). Meanwhile, the effect of the binder type, involving cement replacement materials such as, fly ash, slag and silica fume on the chloride diffusivity has also been investigated. For this purpose, RAC and concrete containing the different type of binders with w/b ratios of 0.35, 0.40, 0.45, 0.50, 0.55, and 0.60 were used. As a result, the chloride diffusion coefficient of RAC is higher than that of natural concrete and the partial replacement of cement with fly ash, slag and silica fume is effective in decrease in the chloride diffusion coefficient, measured by a rapid chloride conductivity test.

Based on the limit equilibrium theory and the circular slip surface method, the state equation of limit equilibrium and the calculation model of the most dangerous sliding surface for inner global stability of foundation pit supported by the prestressed anchor composite soil nailing is established with the disturbing force method. And the searching and solving method of the most dangerous sliding surface is optimized with the SLP optimization method and the simplex optimization method. Then with the mechanical parameters of soil as random variables, the reliability index of inner global stability of foundation pit is calculated with the design checking point method. Finally, a practical project is used to analyze the sensitivity of the reliability index to the coefficients of variability of all random variables.

Consideration of influence of the groundwater seepage and supporting measures to deep-foundation pit,the deformation characteristics of surrounding soil of the foundation pit are given. Seepage and deformation characteristics of surrounding soil are simulated to predict deformation of the deep foundation in ha er bing and stability of deep-foundation pit is analyzed base on the influence of the seepage. The analysis results are compared with observed data and it is showed that the calculated results with the model considering coupling response of permeability coefficient are closer to observed value than those results with the other model. So, the model considering fully coupling response of permeability coefficient is reliable and applicable.

Based on BAYES data processing theory, a new method of fuzzy probability is proposed for the parameter reliability of small sample. Prior distribution of fuzzy parameter is obtained by stochastic weighted method, then posterior distribution of fuzzy parameter is got by the method of conjugate distribution. In the end, the formula of fuzzy membership function is constructed, and probability of fuzzy events is solved.The study of this paper aims at the membership function which is deduced in the condition that mean is known and deviation is unknown in normal population distribution. At the same time using information of small sample of actual experiment, the study fully utilizes prior information, so, it is convincing to evaluate reliability of fuzzy parameter. It is obviously economical.