TRENCH COMPACTION-PRACTICES AND PROBLEMS

RESEARCH IS REPORTED ON TRENCH COMPACTION AND TRENCH BACKFILL. A SURVEY OF SPECIFICATIONS CURRENTLY EMPLOYED BY 45 AGENCIES YIELD THE FOLLOWING STATISTICS: (1) 89% HAD A BACKFILL SPECIFICATION, (2) 60% HAD A SPECIFICATION, THE REQUIREMENTS OF WHICH VARIED WITH LOCATION AND DEPTH, (3) 70% HAD A MATERIAL QUALITY REQUIREMENT IN THE BACKFILL SPECIFICATION, (4) 95% HAD A COMPACTION REQUIREMENT, (5) 93% REFERRED TO JETTING FOR DENSIFYING TRENCH BACKFILL, (6) 91% HAD A MINIMUM COMPACTION REQUIREMENT WITH JETTING, AND (7) 55% GAVE GENERAL INSTRUCTIONS FOR JETTING AND 12% GAVE PRECISE REQUIREMENTS FOR JETTING. COST STUDIES SHOW THAT COMPACTION BY JETTING WAS ABOUT THE SAME WHETHER THE NATIVE MATERIAL WAS REUSED OR REPLACED BY A FREE-DRAINING GRANULAR MATERIAL. A TRENCH BACKFILL SHOULD BE DESIGNED FOR THE PARTICULAR SITUATION UNDER THREE DIFFERENT LAYERS: BEDDING INTERMEDIATE, AND TOP LAYER. THE TOP LAYER IS THE MOST IMPORTANT TO BE CONSIDERED IN TRENCH BACKFILL. JETTING IS EFFECTIVE ONLY IN FREE-DRAINING, GRANULAR MATERIAL OR WHERE COMPACTION IS NOT CRITICAL. SAND IS A POOR BACKFILL MATERIAL IN CONGESTED TRENCH AREAS SINCE FUTURE TRENCHING WILL REMOVE THE SUPPORT AND CAUSE CAVING. LOOSE BACKFILL IS USUALLY QUITE ERODIBLE. THE DEVELOPMENT OF BETTER TRENCHING AND BACKFILL EQUIPMENT IS RECOMMENDED AS WELL AS CUTTING THE COSTS FOR LIME TREATMENT OF NATIVE BACKFILL.

  • Corporate Authors:

    Itte, University of California, Berkeley

    Abstracts of 19th California Street & Highway Conference
    ,   USA 
  • Authors:
    • Lundgren, R
  • Publication Date: 1967-2

Subject/Index Terms

Filing Info

  • Accession Number: 00214833
  • Record Type: Publication
  • Report/Paper Numbers: pp 37-38
  • Files: TRIS
  • Created Date: Jun 18 1994 12:00AM