Analysis of Vibratory Compaction Process in Fresh Concrete
Manabu CHOSA and Masayasu OHTSU
Abstract:In the case of vibratory compaction of fresh concrete, it is not easy to assess the effects of insert depth, compaction time, and spacing of the vibrator. So far, compaction behavior inside fresh concrete is not theoretically elucidated yet. A vibratory compaction test by using an internal vibrator was conducted in a laboratory, and the pore-water pressures were measured. Near the surface of fresh concrete, the decrease in the pore water pressure was observed due to over-vibration. A falling-head permeability test was conducted to determine a coefficient of permeability. Comparing with the slump values, a reasonable relation between a coefficient of permeability and a slump value was observed. Applying Biotfs two-phase theory, the pore-water pressure and the effective stress were theoretically analyzed by the element method (BEM).It is found that the pore-water pressures numerically determined are in reasonable agreement with those of the experiment. Thus the validity of the BEM analysis is demonstrated. The effective stress was analyzed on the basis of Drucker-Pragerfs equivalent stress, and stress distribution due to the internal vibrator is clarified. Key Words:Fresh concrete, Consistency, Boundary element method(BEM), Pore water-pressure, Vibratory compaction, Bios two-phase theory