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Title: STRUCTURAL FAILURE OF WESTERN HIGHWAYS CAUSED BY PIPING
Accession Number: 00233937
Record Type: Component
Abstract: HIGHWAY FILLS, EMBANKMENTS, BRIDGES, AND DRAINAGE STRUCTURES CONSTRUCTED FROM AND BUILT UPON LOCAL GEOLOGIC MATERIALS, PARTICULARLY VALLEY-FILL ALLUVIUM IN THE DRYLANDS WEST, ARE PIPED TO AN ALARMING DEGREE IN MANY PLACES. PIPING AND RELATED COLLAPSE STRUCTURE WERE OBSERVED AT NUMEROUS SITES. VALLEY ALLUVIUM AND MUCH OF THE BEDROCK IN THE MORE ARID PARTS OF THE WEST GENERALLY ARE HIGHLY MONTMORILLONITIC AND HAVE A HIGH CONTENT OF EXCHANGEABLE NA. ALSO, MUCH OF THE VALLEY FILL ALLUVIUM HAS A VERY LOW FIELD-MOISTURE CONTENT WITH LOOSELY COMPACTED COMPONENTS, CHIEFLY IN THE CLAY-SILT-SAND SIZE RANGE. COMMONLY THE SILT AND SAND-SIZE GRAINS ARE OF HARDER MATERIALS SUCH AS CRYSTALLINE-ROCK FRAGMENTS. WEAK CLAY OR SILT CEMENT BINDS, WHEN DRY, THE LOOSELY PACKED AGGREGATES INTO FIRM, STABLE MATERIALS. BUT WHEN THESE BECOME SATURATED WHERE WATER IS CONCENTRATED AND SEEP DOWNWARD THROUGH THE SOIL, THE CLAY AND SILT CEMENT MELT AWAY, COLLAPSE FOLLOWS, PRODUCING A VERTICAL HOLE OR DEPRESSION. THESE SINKS FURTHER CONCENTRATE DRAINAGE, AND IF A NEARBY GULLY OR DITCH OFFERS A SHORT, STEEP-GRADIENT PATH FOR THE INFILTRATING WATER TO ESCAPE TO, THE WATER WILL FLOW UNDERGROUND TO SUCH DISCHARGE POINTS AND IN DOING SO PRODUCE LATERAL DRAINAGE TUBES, THE PIPES. MOST PIPING AND RELATED COLLAPSE AFFECTING HIGHWAYS APPEAR TO BE INITIATED BY DRAINABLE DESSICATION CRACK SYSTEMS. STORM OR SNOW-MELT WATER FLOWING TO DISCHARGE POINTS THROUGH THE CRACKS RAPIDLY ENLARGES THEM BOTH BY PHYSICAL MEANS AND CHEMICAL DISAGGREGATION. THE POROUS, MONTMORILLONITIC ALLUVIAL CRUMBS SORB WATER RAPIDLY AS IT FLOWS THROUGH THE DESSICATION CRACKS. PIPING AND ASSOCIATED COLLAPSE ALSO IS COMMONLY INITIATED IN SITUATIONS WHERE INFILTRATING WATER PENETRATES AND SATURATES A LAYER HAVING HIGHER PERMEABILITY THAN OTHER LAYERS IN THE ALLUVIUM. BRIDGE ABUTMENTS, WING WALLS, PIERS AND CULVERTS ARE MOST COMMONLY IMPERILED BY PIPING. TO MINIMIZE MAINTENANCE COSTS AND POSSIBLE LOSSES OF LIFE RELATED TO HIGHWAYS OR BRIDGE FAILURES DUE TO PIPING AND COLLAPSE STRUCTURE, PRE-CONSTRUCTION SURVEYS SHOULD ASCERTAIN IF LOCAL ROAD-BUILDING MATERIALS AND ROUTE LOCATIONS ARE SUBJECT TO PIPING. CATCHMENT BLEED-OFF DRAINS UNDER BRIDGE DECK-ROADWAY JUNCTION LINES WOULD BE MOST USEFUL IN PREVENTING PIPING BENEATH ABUTMENTS AND ADJACENT BRIDGE APPROACHES. CULVERT DISCHARGE SHOULD NEVER BE CONCENTRATED NEAR THE HIGHWAY BUT SHOULD BE CARRIED OVERLAND TO DISCHARGE INTO THE MAIN FULLY. THE MAIN RULES TO FOLLOW ARE; /1/ AVOID PIPING SITES AND MATERIALS WHENEVER POSSIBLE AND /2/ AVOID ALLOWING CONCENTRATION OF WATER WHERE PIPING MAY UNDERMINE ROADWAYS, BRIDGES, OR DRAINAGE STRUCTURES.
Supplemental Notes: Paper sponsored by Committee on Sub-Surface Drainage and presented at the 46th Annual Meeting.
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
Monograph Title: Monograph Accession #: 01410153
Authors: Parker, Gerald GJenne, E APagination: pp 57-76
Publication Date: 1967
Serial: Media Type: Print
Features: Figures
(23)
; References
(26)
TRT Terms: Old TRIS Terms: Subject Areas: Geotechnology; Highways; Hydraulics and Hydrology; Safety and Human Factors; Security and Emergencies
Files: TRIS, TRB
Created Date: Feb 2 1994 12:00AM
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