LARGE-SCALE TRIAXIAL TESTS TO STUDY EFFECTS OF COMPACTION ENERGY AND LARGE CYCLIC LOADING HISTORY ON SHEAR BEHAVIOR OF GRAVEL

摘要

This study examines the effects of compaction on peak strength and small strain stiffness of large prismatic specimens of gravel by conducting monotonic and large cyclic loading triaxial compression tests. The specimens were prepared using an automatic compaction system while measuring quantitatively the compaction energy. For the evaluation of small strain stiffness, a static technique using small cyclic vertical loading with local strain measurement and a dynamic technique using P-wave measurement were employed. It was revealed that the peak strength of compacted gravel increased in a non-linear manner with the increase in the compaction energy. On the other hand, the difference between statically and dynamically measured small strain Young's moduli was reduced as a result of increase in the compaction energy. The peak strengths of three almost equally dense specimens were found similar to each other irrespective of the difference in the loading histories with/without large cyclic loading. However, the values of the axial strain at the peak stress state were different among the three specimens, affected by the different loading histories.