COMPACTION AND CYCLIC SHEAR STRENGTH OF GRANULAR BACKFILL

A compacted granular coarse to fine sand with varying gravel content is to be used as structural backfill below and around major structures for an important industrial facility being constructed in southern New Jersey. It is of paramount importance that the backfill for the major structures perform well under the design earthquake loading. This paper summarizes the index properties as well as the cyclic shear strength of laboratory compacted samples of the granular backfill material. In addition, it discusses the criteria utilized in selecting this material as a suitable structural backfill. Index properties investigated included grain size distribution, specific gravity, maximum and minimum densities, as well as moisture density relationships based on Modified Proctor compaction tests. The effect of "scalping" on the results of the compaction tests and cyclic strength tests is also discussed. The degree of compaction of the tested soils was based on percent compaction rather than on relative density. The rationale behind this approach is also outlined in the paper. Compacted samples for dynamic testing were prepared using wet tamping and the concept of under compaction. Samples were compacted to 95 and 98 percent of the maximum dry density based on Modified Proctor compaction test results. A series of cyclic triaxial liquefaction tests was performed at different shear stress ratios, confining pressures, and principal stress ratios during consolidation. The results are presented in this paper in the form of a cyclic shear stress ratio versus the number of cycles to failure. The cyclic shear strength of the samples compacted to 98 percent of the maximum dry density, based on the Modified Proctor tests, was significantly higher than those compacted to 95 percent of the maximum dry density. /Author/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 1042-55

Subject/Index Terms

Filing Info

  • Accession Number: 00179796
  • Record Type: Publication
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Oct 12 1978 12:00AM