A STUDY OF INTERACTIONS OF SELECTED COMBINATIONS OF SUBGRADE AND BASE COURSE SUBJECTED TO REPEATED LOADING

THIS PAPER REPORTS THE RESULTS OF A LABORATORY STUDY TO INVESTIGATE THE EFFECTS OF REPETITIVE LOADING ON SELECTED COMBINATIONS OF SUBGRADES AND BASE COURSES. TWO SUBGRADES WERE STUDIED; A HIGHLY PLASTIC CLAY, AND A CLAY OF MEDIUM PLASTICITY. TWO GRADATIONS OF BASE COURSE WERE STUDIED, BOTH OF WHICH WERE WELL-GRADED MIXTURES OF GLACIAL GRAVEL. THE FIRST OF THESE WAS "OPEN-GRADED," THE SECOND, "DENSE-GRADED." TWO TYPES OF LOADING WERE UTILIZED: "SINGLE-ACTING," AND "DOUBLE-ACTING," IN WHICH THE LOADING PISTON HAD A LENGTH OF STROKE WHICH INCREASED AS THE DEFLECTION IN THE BASE COURSE-SUBGRADE SYSTEM INCREASED. A TOTAL OF 40,000 LOAD REPETITIONS WAS APPLIED TO STATICALLY COMPACTED SPECIMENS AT INTERVALS OF 4 SEC., WITH EACH LOAD SUSTAINED FOR 0.3 SEC. THE LABORATORY STUDY WAS DESIGNED AS A COMPLETE FACTORIAL EXPERIMENT AT TWO LEVELS. OPEN-GRADED BASE COURSES WERE FOUND GENERALLY SUPERIOR TO DENSE-GRADED BASES, INASMUCH AS TESTS WITH THE MORE PERMEBLE BASE COURSE RESULTED IN SMALLER TOTAL DEFLECTION AND A LESSER WEIGHT OF PUMPED MATERIAL. SIMILARLY, COMBINATIONS WITH THE MORE PLASTIC FREDERICK SUBGRADES WERE FOUND TO PERFORM SLIGHTLY BETTER THAN THOSE WITH THE LESS PLASTIC CROSBY SUBGRADES. INCREASING THE COMPACTION OF THE SUBGRADE WAS FOUND DECIDEDLY BENEFICIAL FOR ALL SAMPLES, ALTHOUGH AN INCREASE IN THE BASE COURSE COMPACTION APPEARED TO HAVE LITTLE EFFECT. AN INCREASE IN PRESSURE ACCELERATED THE ONSET OF PUMPING AND INCREASED ITS SEVERITY. /AUTHOR/

  • Supplemental Notes:
    • Vol 36, pp 443-478, 10 FIG, 7 TAB, 30 REF
  • Authors:
    • Havers, J A
    • Yoder, E J
  • Publication Date: 1957

Media Info

  • Monograph Title: Proceedings of the Thirty-Sixth Annual Meeting of the Highway Research Board, Washington, D.C., January 7-11, 1957
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00233144
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: May 22 1972 12:00AM