Effect of strain rate in cohesionless soil

Cohesionless specimens composed of coral sand are tested over a wide range of strain rates, varying from traditional static rates to approximately 1100 %/sec measured globally. Due to the high loading rates associated with transient testing, drained triaxial compression tests using evacuated axisymmetric specimens are performed. High-speed film photography coupled with digital image an lysis techniques are used to capture specimen deformations and piezoelectric load cells measure the load for transient tests. A traditional style load cell and loading frame is used for static testing. A custom designed loading apparatus and triaxial cell are used to perform the transient testing. Photographic images are presented that illustrate changes in specimen deformation patterns for high strain rate tests. Preliminary results suggest granular materials experience measurable strain rate effects. Two separate series of tests under medium and loose configurations are presented.