SOME CHARACTERISTICS OF THE MODULUS OF PASSIVE RESISTANCE OF SOIL: A STUDY IN SIMILITUDE
APPROXIMATELY 20 YEARS AGO THE IOWA ENGINEERING EXPERIMENT STATION, IN COOPERATION WITH THE BUREAU OF PUBLIC ROADS, CONDUCTED RESEARCH DIRECTED TOWARD THE RATIONAL DESIGN OF FLEXIBLE PIPE CULVERTS UNDER EARTH FILLS. COMBINED ANALYTICAL AND EXPERIMENTAL STUDIES OF THIS PROBLEM RESULTED IN THE DEVELOPMENT OF THE IOWA FORMULA FOR PREDICTING THE DEFLECTION OF A STRUCTURE OF THIS KIND. FULL-SCALE PIPELINES RANGING IN DIAMETER FROM 36 TO 60 IN. UNDER FILLS OF SEVERAL KINDS OF SOIL IN SEVERAL DIFFERENT STATES OF COMPACTION WERE USED IN THE EARLY EXPERIMENTS. FROM THESE STUDIES, THE MODULUS OF PASSIVE RESISTANCE APPEARED TO BE A FUNCTION OF THE TYPE OF SOIL AND ITS DENSITY OR STATE OF COMPACTION. THEY DID NOT REVEAL ANY INFLUENCE OF OTHER COMPONENTS OF THE PIPE-FILL SYSTEM, SUCH AS DIAMETER OF PIPE, HEIGHT OF FILL, AND STIFFNESS OF THE PIPE WALL. IT WAS THEREFORE ASSUMED THAT THIS MODULUS WAS A FUNCTION OF SOIL PROPERTIES ALONE. SUBSEQUENT ATTEMPTS TO APPLY THE IOWA FORMULA TO ACTUAL FLEXIBLE PIPE INSTALLATIONS HAVE LED TO CONFUSING RESULTS, WHICH APPEAR TO BE DUE IN LARGE MEASURE TO A LACK OF UNDERSTANDING OF THE TRUE CHARACTER OF THE MODULUS OF PASSIVE RESISTANCE OF SOIL. AGAINST THIS BACKGROUND OF RESEARCH AND EXPERIENCE, AN ATTEMPT HAS BEEN MADE TO DELVE DEEPER INTO THE NATURE OF THE MODULUS, EMPLOYING THE PRINCIPLES OF ENGINEERING SIMILITUDE AND THE BUCKINGHAM PI- THEOREM IN A STUDY OF THE PROBLEM. ONE RESULT OF THIS STUDY IS THE QUALITATIVE SHOWING THAT THE MODULUS OF PASSIVE RESISTANCE IS NOT A FUNCTION OF THE SOIL ALONE, BUT IS MATERIALLY INFLUENCED BY THE DIAMETER OF THE PIPE. SPECIFICALLY IT IS SHOWN THAT THE MODULUS E IS NOT A CONSTANT FOR A GIVEN TYPE OF SOIL, BUT RATHER THAT THE PRODUCT E R IS CONSTANT, WHERE R EQUALS THE RADIUS OF THE PIPE. THIS OPENS UP A WHOLE NEW AVENUE OF APPROACH TO THE PROBLEM OF RATIONAL DESIGN OF FLEXIBLE PIPE CULVERTS AND GIVES PROMISE OF AIDING IN THE CLARIFICATION OF SOME UNCERTAINTIES WHICH HAVE PERSISTED SINCE THE IOWA FORMULA WAS FIRST PUBLISHED. /AUTHOR/
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Supplemental Notes:
- Vol 37, pp 576-583, 1 FIG, 1 TAB, 13 REF. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
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Authors:
- Watkins, R K
- Spangler, M G
- Publication Date: 1958
Media Info
- Media Type: Digital/other
- Monograph Title: Proceedings of the Thirty-Seventh Annual Meeting of the Highway Research Board, Washington, D.C., January 6-10, 1958
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Serial:
- Highway Research Board Proceedings
- Volume: 37
- Publisher: Highway Research Board
Subject/Index Terms
- TRT Terms: Conduits; Diameter; Failure; Flexible structures; Modulus; Pipe culverts; Soils
- Uncontrolled Terms: Passive resistance
- Old TRIS Terms: Flexible conduits
- Subject Areas: Geotechnology; Highways; Hydraulics and Hydrology;
Filing Info
- Accession Number: 00204372
- Record Type: Publication
- Files: TRIS, TRB
- Created Date: Sep 27 1971 12:00AM