Study On Service Life And Durability Enhancement Techniques Of Anti-slide Pile

Slides are a kind of harmful natural calamities which usually occur in the mountain areas, especially in Southwest China. Every year, slides cause great losses, and they cost the nation and region lots of human and material resources to treat them. Chongqing locates in the geological calamity porosity area, according to incomplete statistics; there are over 20,000 various big or small cause-hazard bodies only in Three Gorges Reservoir in which deformable slides make up over 50 percents. Anti-slide piles are one of the most widely used constructions in treating slides and reservoir banks. Their durability and service life have contact with the safety and function of support engineering directly. Ensuring pile durability and farther geological hazard body's stability has economic, technique and social benefits. On the basis of collecting materials extensively, combining actual investigation and model test, this thesis screen out factors that influence anti-slide pile durability and their corrosion mechanism. On these bases, this paper establishes a durability prediction model of anti-slide pile, and puts forward the durability design principle. Main innovations are got as follows:First, steel-bar corrosion test that steel-bar were buried in acid soil were carried out. It can be obtained that the steel-bar corrosion velocity buried in Chongqing Jurassic acid soil is 4. 48g/dm~2·a.Second, durability model test for cantilevered and prestressed anchor anti-slide pile are took up, all model piles are affected under acid-stress coupling. The experimental results indicate that concrete deteriorate continuously with time, mainly presented as that there is a linear relationship between concrete neutralization and square of time. For cantilevered anti-slide pile, displacement of pile increase continuously with time, the topper displacement is max. The failure envelope is nearby design failure surface when load achieve extreme. And for prestressed anchor anti-slide pile, the topper displacement and anchor strain increase continuously with time also, but to compare with cantilevered anti-slide pile, the degree of topper displacement and concrete deterioration are obviously lower.Third, according to field data of concrete neutralization of model pile, a model to predict the pile concrete neutralization is conducted. The thesis also gives some discussions about parameter values in this predication model. By analysis, a calculation method of the initial time and allowable time for steel-bar corrosion is built. Then a mathematic model for anti-slide pile service life is established.Forth, take some factors such as material selection, concrete admixtures, mineral admixture and mix proportion into account, some enhancement techniques have been put forward. By analyzing influence including supplementary structure, constructional measure, and constructive quality and so on, this thesis composes some constructional measures for anti-slide pile's durability life.