Durability Experiment And Evaluation Theory Of Grouting Concretion Stone

With the rapid development of underground engineering and the wide use of grouting materials, research on the durability of grouting materials and evaluation theory become the hot spot and core research in this area. Improving the durability of grouting materials and strengthening the reinforcement and anti-seepage are of not only important social and economic significance, but also great realistic engineering value. Durable grouting curtain provided for the underground engineering structure will not only ensure the safety of operation, but also extend its service life.Supported by the National High Technology Research and Development Program863and engineering project of the Qingdao Jiaozhou Bay subsea tunnel, the paper widely collects and analyzes research achievements at home and abroad. Moreover, the paper analyzes and summarizes the grouting material erosion factors and failure mechanism by researching on consolidation principle of cement grouting materials and influence factors of grouting stone strength. On the basis of durability test on grouting materials, the paper predicts and evaluates their service life, and then makes a special design for subsea tunnel grouting of the Qingdao Jiaozhou Bay. The main works are as followed:(1)Hydrition and consolidation theories of cement grouting materials such as cement slurry, cement water glass grout, cement clay grout and clay solidified slurry are elaborated. Composition and structure of cement grout stone is analysed and factors effecting cement grout stone pore distribution is obtained. Through summarizing the pore structure and strength theory of cement base grouting material, approaches to improve the hardened slurry microcosmic structure and pore structure are obtained. So the purpose of high-performance grout is also obtained.(2) Erosion and damage mechanism of grouting materials in all kinds of corrosive environments is summarized, such as ground water dissolution, Alkali aggregate reaction, freeze-thaw cycle, carbonic acid erosion, general acid erosion, sulfate erosion, magnesium salt erosion and seawater erosion. (3) Through the laboratory test of grouting material, the influence of various slurry compositions on slurry stone strength is researched and the best strength formulation solution in every periods is obtained by using orthogonal test theory and probability and statistics methods in the paper. Through the specimen soaking test respectively in fresh and sea water, the difference of sample strength development situation in both cases is compared and the corrosion rule of seawater on the sample is obtained.(4) The basic principle of service life assessment of grouting materials with pH value test method is clarified and the macro life prediction model is founded. The service life assessment procedures and evaluation standard of slurry calculi body are established in this paper. Grouting material's deteriorating law of mechanics properties on normal acid rain conditions are obtained by accelerating corrosion test on cement base grouting material in low pH value acidic environment. Through using the basic principle of pH value testing, the paper is able to forecast the service life of cement grouting materials.(5)Taking ordinary cement, the superfine cement and sulfur aluminum acid salt cement grouting materials as the research object, experimental research on the durability of the anti-seawater erosion is done. Choosing grouting material resistance to erosion and seawater resistance sulphate penetration, anti-chloride ion erosion and volume stability as influencing factors, the paper determines the weights of various factors by using analytic hierarchy process and evaluates the grouting material performance with multiple factors fuzzy comprehensive evaluation theory.(6)The relationship between unconfined compressive strength and water-cement ratio of materials, ages, seawater concentration, silicon powder content, fly ash content, slag content under sea erodes environment by using grey system theory is analysed and service life of different grouting materials is predicted.