LARGE-SCALE PLANE STRAIN COMPRESSION TESTS ON COMPACTED GRAVEL WITH ACTIVE AND PASSIVE CONTROLS

摘要

Large-scale plane strain compression tests were performed to study the effect of compaction on strength and deformation properties of gravel. The specimen is rectangular prismatic with dimensions of 50 cm in height and 22 cm times 25 cm in cross-section. By employing well-graded crushed sandstone called as Chiba gravel, five sets of plane strain compression tests were conducted on partially saturated specimens having dry densities in the range of 1.80-2.15 g/cm~3 that were prepared using manual or automatic compaction techniques. For each set of tests, one specimen was tested by following the conventional approach called as "passive control" of ε_2, while the second specimen was tested by following a new approach called as "active control" in which one of the two confining plates was allowed to move forward and backward for keeping the locally measured value of ε_2 almost zero. As a result, no significant effect of the active control was found on the stress-strain behavior as compared to the passive control, except for the beginning of shearing. The maximum deviator stresses in the two kinds of plane strain compression tests were about 20% larger than those in the relevant triaxial compression tests under the employed range of the compaction levels.