THE USE OF AN IMPACT ROLLER IN COMPACTING A COLLASPING SAND SUBGRADE FOR A FREEWAY

THE PROBLEM OF DIFFERENTIAL SETTLEMENT ON ROADS IN SOUTHERN AFRICA HAS OCCURRED ON CERTAIN SILTY SANDS WITH HIGH VOID RATIOS, DUE TO THE "COLLAPSE" OF THE SOIL STRUCTURE. IN COMPARATIVE FIELD TRIALS OF POSSIBLE SOLUTIONS TO THIS PROBLEM, A FLAT-SIDED IMPACT ROLLER WAS FOUND TO CAUSE CONSOLIDATION TO GREATER DEPTH THAN VIBRATING OR PNEUMATIC ROLLERS. THIS IMPACT ROLLER WAS LATER USED FOR THE COMPACTION OF A SILTY SAND SUBGRDE UNDER A NEW FREEWAY NEAR WITBANK. THREE DEEP PROFILES WERE THEN STUDIED: UNDER THE FREEWAY WHERE THE IMPACT ROLLER HAD BEEN USED, UNDER AN OLD EXISTING ASPHALT ROAD, AND IN THE UNDISTURBED NATURAL CONDITION. THE VARIATIONS WITH DEPTH OF DENSITY, MOISTURE CONTENT, AND PENETRATION RESISTANCE WERE DETERMINED. DOUBLE OEDOMETER TESTS WERE CARRIED OUT IN THE LABORATORY ON UNDISTURBED SAMPLES, MAKING POSSIBLE THE PREDICTION OF COLLAPSE SETTLEMENT ON INUNDATION UNDER VARIOUS LOADS. IT WAS FOUND THAT THE STATE OF COMPACTION ACHIEVED BY THE IMPACT ROLLER WAS SUFFICIENT TO PREVENT ANY LATER COLLAPSE SETTLEMENT WITH NORMAL TRAFFIC LOADS UNDER CONDITIONS OF INUNDATION. FURTHER, IT WAS CONCLUDED THAT SPECIAL MEASURES SHOULD BE TAKEN TO COMPACT SUCH SUBGRADES TO A DEPTH OF 1.4 METERS (4 FT 6 IN.), IN ORDER TO PREVENT COLLAPSE SETTLEMENT UNDER HEAVY TRAFFIC. /AUTHOR/

Media Info

  • Media Type: Print
  • Features: Figures; References;
  • Pagination: pp 21-28
  • Monograph Title: Soil: compaction, classification and laterites
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00215495
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: May 16 1972 12:00AM