A Gyratory Compactor for Molding Large Diameter Triaxial Specimens of Granular Materials

摘要

A mechanical gyratory compactor is described which was developed for fabricating 6-inch diameter by 12-inch high triaxial test specimens of granular materials. The apparatus was constructed after a review of existing laboratory compaction techniques and equipment which indicated that suitable, economical methods for this purpose were not available. A detailed description of the compactor is presented as well as a detailed discussion of the compactor operation. Fabrication drawings of the compactor are not included, but they are available upon request. In principle, the compactor is a mechanical modification of the manual gyratory compactor developed in the early 1940's by the Texas Highway Department for molding asphaltic concrete specimens. The excessive forces required to gyrate and then level large specimens of granular materials necessitated a unique gyratory model, but the components used in the compactor are, for the most part, stock items which are readily available. Operation is semiautomatic and requires no manual effort on the part of the operator. An important feature of the compactor is the wide latitude in the applied compactive effort; it can be varied by changing the magnitude of the vertical pressure, the angle of gyration, the speed of gyration, and the number of gyrations. Electronic equipment for obtaining a meausre of the compactive effort is included on the compactor. It is necessary to develop special compaction molds--one being of ceramic-lined steel which represents a new and potentially valuable concept in compaction molds. A subsequent publication will study the ability of the compactor to perform its design objectives. At this time, however, cross-sections of compacted specimens show no particle segregation, and densities of replicate specimens are virtually identical. (Author)