DEFLECTIONS OF TIMBER-STRUTTED CORRUGATED-METAL-PIPE CULVERTS UNDER EARTH FILLS

AN ANALYSIS IS PRESENTED AND A FORMULA DEVELOPED FOR PREDICTING THE VERTICAL AND HORIZONTAL DEFLECTION OR CHANGE IN DIAMETER OF TIMBER-STRUTTED CORRUGATED-METAL-PIPE CULVERTS UNDER EARTH FILLS. IN THE ANALYSIS THE STRUTTED PIPE IS CONSIDERED TO BE A COMPOSITE ELASTIC STRUCTURE IN WHICH THE VERTICAL DEFLECTION OF THE PIPE IS THE SAME AS THE DEFORMATION OF THE TIMBER STRUT. THE DEFLECTION OF THE PIPE IS DETERMINED BY CURVED-BEAM THEORY AND EQUATED TO THE EXPRESSION FOR STRUT DEFORMATION. THE LOADING SYSTEM USED IN THE ANALYSIS CONSISTS OF A VERTICAL LOAD AND VERTICAL REACTION ON THE TOP AND BOTTOM OF THE PIPE AND HORIZONTAL PRESSURES AT THE SIDES. THESE HORIZONTAL PRESSURES ARE POSTULATED TO BE PASSIVE EARTH PRESSURES WHICH ARE MOBILIZED BY THE OUTWARD MOVEMENT OF THE SIDES OF THE PIPE AS IT DEFORMS. THE EXPRESSION FOR LATERAL PRESSURES INVOLVES A QUANTITY WHICH IS CALLED THE MODULUS OF PASSIVE RESISTANCE OF THE SIDE-FILL SOIL. RESULTS INDICATED BY THE DEVELOPED FORMULA ARE COMPARED WITH THE PERFORMANCE OF AN ACTUAL CULVERT INSTALLATION AT CULLMAN, ALABAMA. THIS CULVERT IS AN 84-INCH-DIAMETER 'IMPROVED MULTIPLATE' PIPE UNDER A HIGHWAY EMBANKMENT WHICH IS 137 FEET HIGH ABOVE THE TOP OF THE PIPE. EXTENSIVE OBSERVATIONS OF THE PERFORMANCE OF THIS STRUCTURE WERE MADE AND REPORTED BY THE ARMCO RESEARCH LABORATORIES. ALL OF THE FACTORS INVOLVED IN THE DERIVED EQUATION FOR DEFLECTION, EXCEPT THE MODULUS OF PASSIVE PRESSURE OF THE SIDE-FILL SOIL, ARE AVAILABLE IN THE REPORT OR CAN BE ESTIMATED FROM INFORMATION GIVEN. IT IS POSSIBLE, THEREFORE, TO COMPUTE THE VALUE OF THIS MODULUS. THE INDICATED VALUE IS 190 PSI. PER INCH, WHICH SEEMS TO BE VERY HIGH. HOWEVER, THE CHARACTER OF THE SOIL IS DESCRIBED AS A 'CRUMBLY SANDSTONE,' AND IT WAS COMPACTED TO 100 PERCENT AASHO DENSITY. SUCH A SOIL WOULD HAVE A VERY HIGH BEARING VALUE AND WOULD BE VERY RESISTANT TO DEFORMATION UNDER PRESSURE. IT IS THE AUTHORS' OPINION, THEREFORE, THAT THE CALCULATED VALUE MAY BE OF THE SAME ORDER OF MAGNITUDE AS THE ACTUAL VALUE. THE NEED FOR EXTENSIVE RESEARCH TO CLARIFY THE RELATIONSHIP BETWEEN MODULUS OF PASSIVE RESISTANCE AND SOIL TYPE AND DEGREE OF COMPACTION IS INDICATED BY THIS STUDY. /AUTHOR/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrbbulletin/102/102-002.pdf
• Supplemental Notes:
  • No 102, pp 12-18, 4 FIG, 4 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.
• Authors:
  • Spangler, M G
  • Phillips, Donald L
• Publication Date: 1955

Media Info

• Media Type: Digital/other
• Monograph Title: Tests on large culvert pipe
• Serial:
  • Highway Research Board Bulletin
  • Issue Number: 102
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Bearing capacity; Corrugated pipe culverts; Curved beams; Deflection; Earth pressure; Embankments; Fills; Loads; Mathematical analysis; Sandstones; Soils; Struts; Theory; Timbering
• Uncontrolled Terms: Passive resistance; Vertical loads
• Old TRIS Terms: Soil bearing capacity; Timbering (Supporting)
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00216761
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Apr 21 1994 12:00AM