Notice of RetractionRisk analysis of shield tunnel segment failure based on Fuzzy Fault Tree method
Through analyzing and summarizing the types of shield tunnel segment failure and the relevant causes of the accident, Fuzzy Fault Tree Analysis (FTA) was employed to study the failure risk of segment and the Fuzzy Fault Tree system model of segment and segment-related systems were established. The potential failure modes of risk accidents and their influencing factors were discussed through qualitative and quantitative analysis. With its application on practical project, some effective control measures were proposed. This research could be valuable reference for the design, construction and control of shield tunnel segments.
The Study on the Methods of Fuzzy Signficance Analysis
After expounding the methods for significance analysis in FTA from the exact to the fuzzy,the paper presents a new method for studying fuzzy significance analysis-named the median method. For those new type systems with complicated structures,this method is an important component part of reliability and storage reliability study using the technology of fuzzy fault tree analysis. At last,the paper gives an example to compare the above two kinds methods of fuzzy significance analysis.
Weathering of the Oporto granite: geotechnical and physical properties
Abstract This paper characterizes the weathering products of the two-mica Oporto granite in terms of its mineralogical, chemical, geotechnical and physical properties. This information is used to identify a physical property that can be used as an index of the degree of weathering and to estimate other properties. In outcrop, the Oporto granite is always weathered and weathering profiles frequently exceed 20 m. Within these profiles, granitic saprolites are composed of quartz, feldspars and some mica with kaolinite and gibbsite as final weathering products. The average percentage of secondary minerals determined by bulk X-ray diffraction (XRD) is low in both weathered rock (2.4%) and saprolite (8.7%). Geotechnically, the saprolites exhibit no or low plasticity (plasticity index, PI≤12%). The skeleton character of the saprolites is reflected in the significant proportion of fines (29.5%