Advanced Materials Research Vols. 163-167

Abstract: Tunnel Leakage has been a key issue of the Tunnel Engineering construction and maintenance because of the universality and serious harmfulness. Aiming at the status of tunnel Leakage in our country, this paper identifies the main factor from all kinds of factors. An evaluation indexes system is advanced which consists of 10 factors coming from following four grade indexes, including construction factors, Drainage and Waterproof Methods for Waterproof Tunnel, the situation of Surrounding Rock and groundwater and physical geography. In addition, an evaluation model based on the BP artificial network is designed. Combining with evaluation example, the calculation method is realized by software. The results show that the evaluation method is useful. The method provides a new way to increase the precision of tunnel leakage disease level evaluation.

Abstract: When the reliability analysis of in-service RC flexural member is carried on, an expert evaluation or AHP (analytical hierarchy process) for evaluation is commonly used, but human factors are big. This paper presents a comprehensive evaluation method of a existing RC flexural member’s reliability on the basis of attribute mathematics. According to the actual measured values of each index in the evaluation system, using a mathematical method to calculate weight, and build a comprehensive quantitative analysis model. Example analysis shows that this method can effectively identify and finely distinguish the reliability of in-service RC flexural members, which be much more objective and scientific compared with other previous methods.

Abstract: Based on finite element theory and finite element software ANSYS, this thesis establish three-dimensional pile-soil contact model pile to simulate the pile-soil interaction, analysis the bearing capacity particularity, analysis of different factors on the pile P-S curves. Using ANSYS optimization module Monte Carlo sampling method calculate pile capacity reliability, Simplify the cumbersome process of reliability analysis.

Abstract: Jacket Offshore Platform is a complex statically indeterminate structure, reliability of which is impacted by many factors, and the earthquake is a main factor. This paper simplify the significant failure mode of Jacket Offshore Platform by standard. Calculate the reliability of Jacket Offshore Platform under the effect of earthquake with the Monte Carlo method based on ANSYS. The result can provide evidence for safety assessment of Jacket Offshore Platform.

Abstract: Offshore Jacket Platform is a very important infrastructure in the offshore oil exploration and exploitation. In order to make it more economical, designers should do Structural Optimization to it. This paper do Structural Optimization to Offshore Jacket Platform, and provide reference for the using of ANSYS in the Structural Optimization of Offshore Jacket Platform.

Abstract: The structural reliability analysis with uncertainty-but-bounded parameters is considered in this paper. Each uncertain-but-bounded parameter is represented as an interval number or vector, an interval reliability index is defined and discussed. Due to the wide application of the Meshless method, it is used in structural stress and strain analysis. The target variable of requiring reliability analysis is estimated via Taylor expansion. Based on optimization theory and vertex solution theorem, the upper and lower bounds of the target variables are obtained, and also the interval reliability index. A typical elastostatics example is presented to illustrate the computational aspects of interval reliability analysis in comparison with the traditional probability method, it can be seen that the result calculated by the vertex solution theorem is consistent with that calculated by probability method.

Abstract: A detailed investigation has been carried out to clarify the effect of porosity on steel corrosion in cement-based materials. Corrosion behaviours of steel were studied by means of corrosion potential, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS), while the porosity of cover zone cement-based materials were investigated by evaporative water method (EWM) and mercury intrusion porosimetry (MIP). The results highlight that the corrosion parameters of steel are strongly related with porosity of cement-based materials. A linear relationship between porosity and corrosion rate of steel has been established which is in good agreement with the principle that the diffusion of chloride ions through porous cementitious materials may accelerate the anodic reaction of steel corrosion as well as oxygen diffusion for the cathodic reaction simultaneously.

Abstract: The effect of sulfate ions on the corrosion behavior of steel in ordinary Portland concrete (OPC) and high performance concrete (HPC) were investigated. Steel corrosion was evaluated by means of corrosion potential (E_corr), linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS) and cyclic polarization (CP). The electrochemical results indicated that, compared to the pure chloride solution, the presence of sulfate ions in the chloride solution both reduced the time to corrosion initiation and lead to an increase in corrosion rate of steel in OPC specimens; however, the sulfate ions had negligible effect in HPC specimens. Furthermore, the corrosion rate of steel exposed to chloride solution was higher that to the sulfate solution both in OPC and HPC specimens.

Abstract: Durability design of the concrete structure directly concerns structural durability, the current system of the structural durability design has not formed, merely limited to theoretical analysis condition of the environmental zoning, material preparation and structure life. This article has carried on the durability design factor analysis ,including the environment function, the durable condition monitoring design, the life design, the state control, the material design, repairable design and the mechanical design, based on this the establishment durability design method system is proposed, and the research method of establishing this system is discussed.

Abstract: X-ray computed tomography (XCT), a non-destructive test, was used to study three dimensional (3D) meso-defect volume distribution changes of cement paste due to carbonation. The 3D meso-defect volume from 0.02mm3 ~5mm3 before and after carbonation was analyzed through add-on modules of 3D defect analysis. The experimental results show that the meso-defect volume fraction before and after carbonation are 0.7685% and 2.44%, respectively. After carbonation, the smaller defect increased significantly than the bigger defect.