Laboratory Tests to Refine the Maximum Density Procedure for Cohesionless Soils Using a Vibratory Table

摘要

To improve the test procedure for determining the maximum laboratory dry density of cohesionless soils, time of vibration, initial dry density, amplitude and frequency of vibration, and the moisture condition of the material were investigated. Changes in the gradation during vibration increased both the minimum and maximum dry densities of a weakly-cemented dune sand. The increase in density was insignificant for times of vibration greater than 6 minutes except for the weakly-cemented material. The initial density of the soil prior to vibration did not have a significant effect on the final density. No conclusions could be drawn as to the effect of the amplitude and frequency of vibration on the dry density from the results using two electromagnetic vibrators and one eccentric weight vibrator. The difference between the densities obtained using ovendried soil and initially saturated soil was not significant for the two soils tested: a poorly graded sand and gravel, 3-inch maximum-size, and a poorly graded fine sand. The results did not suggest any revisions which would improve the Bureau's current method for determining the maximum laboratory density of cohesionless soils. (Author)