Of C80 High Strength Concrete Dynamic Load Injury Test And Vibratory Hammer Pile Driving Parameters

PHC piles (abbreviation of pre-stressed high strength concrete piles) have been used more and more widely in China in recent years as one kind of foundation piles. But when applying hydraulic vibration hammer to PHC pile driving, the existing pile driving parameter regulation theory regards the piles as absolutely rigid body and no damage brought by the excessive stress was considered. As a result, practical applications often didn't meet the design requirements for piles'damage. Targeted at this problem, this paper carried out the following researches based on relative theories:First, the development, the structure and the production of PHC piles and the status of research on damage of high strength concrete were studied and reviewed. The short of current pile driving parameter regulation theory was pointed out. Then the research ideas and contents based on experiment were proposed.The feasibility of fractal theory applied to analysis damage evolution of high-strength concrete was studied. And an algorithm program in Matlab based on digital image dimension theory that could solve the fraction dimension in crack evolution process of high-strength concrete was designed.The C80 high-strength concrete specimens were prepared according to the production process of PHC piles. The material testing machine was applied to test their quasi-static compression. And the split Hopkinson pressure bar (SHPB) test equipment was applied to test their strain rate strengthening under impact loading and dynamic damage evolution. Then the results were studied in detail using the fractal theory. The quantitative relation between strain rate and ultimate dynamic compressive strength and the relation between dimension value and maximum stress were got.Finally, the specific contents of existing parameter of pile driving were studied in details. A mechanical model of pile vibration system was created and the critical portable conditions were got. Then the experimental results were imported into this model. A parameter regulation theory of hydraulic vibration hammer based on damage studies of PHC piles was established. Also a maneuverable mathematical table was made.The parameter regulation theory established in this paper based on high strength concrete dynamic damage of PHC piles was a complement to the existing parameter regulation theory. It has some significance to prevent damage of PHC piles when driving in theory guiding and practical application.