Study On Durability Of Diaphragm Wall Of Subway Station

The reinforced concrete durability of substructures has long been neglected, and there is few people touching upon the durability research of diaphragm wall until now. Currently, the durability design of diaphragm wall is mainly based on that of the superstructure, and sometimes even omitted. But experiences show that the diaphragm wall does not have the "durability" that people used to imagine, and there are accidents from time to time for the shortage of durability. So it is necessary to study the rule of reinforced concrete durability of diaphragm wall in order to guide the durability design and life-expectancy analysis.The subway station diaphragm wall also suffers the erosion of stray current except the factors of common diaphragm wall such as carbonation, erosion of harmful ion and construction factors etc. The dissertation will study the durability of subway station diaphragm wall based on the influence of carbonation and stray current.The dissertation makes detail summarization and analysis of durability influencing factors of diaphragm wall, and compares them with those of superstructures;based on the data from indoor accelerated carbonation test and natural conditions , the dissertation establishes carbonation depth model relating to the density of carbon dioxide, stress state, and relative compression strength separately;considering the coupling effects of stress state, carbon dioxide density and time, the dissertation also establishes corresponding comprehensive carbonation depth model;the dissertation discusses the common used life-time criterions of concrete structures, and presents calculation methods of corresponding key points;the dissertation discusses the production mechanism of stray current and its influence on diaphragm wall durability;considering the influences of carbonation and stray current, the dissertation establishes calculation model of failure probability and reliability index based on the life-time criterion of covering layer cracking for reinforced steel corrosion.