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Title: FACTORS AFFECTING VERTICAL LOADS ON UNDERGROUND DUCTS DUE TO ARCHING
Accession Number: 00235365
Record Type: Component
Abstract: A THEORETICAL AND MATHEMATICAL ANALYSIS IS PRESENTED ON THE THEORY OF EARTH PRESSURE ON UNDERGROUND CONDUITS. NO DIFFERENTIATION IS MADE BETWEEN RIGID OR FLEXIBLE CONDUITS BECAUSE THE SHAPE OF THE CONDUIT IS NOT CONSIDERED A VARIABLE. THE MATHEMATICAL TREATMENT DEALS WITH THE PRESSURES ACTING IN THE PLANE PERPENDICULAR TO THE LONGITUDINAL AXIS OF THE CONDUIT. IT IS SHOWN THAT THE PRESSURE ON TOP OF BOTH COVERED-UP AND MINED-IN CONDUITS IS GOVERNED BY THE SAME MATHEMATICAL RELATIONS. HOWEVER, THE VALUES OF THE PHYSICAL FACTORS APPEARING IN THE THEORETICAL EXPRESSIONS DEPEND UPON THE GEOMETRY AND NATURE OF INSTALLATION, THE PHYSICAL PROPERTIES, AND THE INITIAL STATE OF THE MATERIALS, AS WELL AS ON THE CONSTRUCTION METHODS AND WORKMANSHIP EMPLOYED. A GOOD SOIL EXPLORATION OF THE SITE WHERE THE CONDUIT IS TO BE INSTALLED IS IMPERATIVE BECAUSE KNOWLEDGE OF THE PHYSICAL PROPERTIES OF THE SOILS INVOLVED IS NECESSARY. THE LOAD ON COVERED-UP CONDUITS BECOMES A MINIMUM IF THE CONDUIT SIDE SUPPORTING MATERIAL IS THOROUGHLY COMPACTED, THE DITCH DIRECTLY ABOVE THE CONDUIT IS MADE AS HIGH AS ECONOMICALLY FEASIBLE, AND THE DITCH IS FILLED WITH A COMPRESSIBLE, LOOSE MATERIAL. SINCE AN UNDERGROUND CONDUIT HAS THE TENDENCY TO SETTLE MORE IN THE MIDDLE THAN AT ITS ENDS, THE EARTH MASS WHICH IS ABOVE ITS MIDDLE PORTION, WILL TEND TO BRACE ITSELF AGAINST THE END MASSES THEREBY INCREASING THE NORMAL PRESSURE AND THE LONGITUDINAL STRAINS AT THE ENDS AND DECREASING THE PRESSURE AT THE MIDDLE. THE AFFECTS OF SUCH ARCHING ACTION ARE CONSIDERED TO BE ESPECIALLY SIGNIFICANT IN THE CASE OF LONG CONDUITS INSTALLED UNDER HIGH FILLS.
Supplemental Notes: No 125, pp 12-57, 13 FIG, 4 TAB, 59 REF, 1 APP 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 #: 01410526
Authors: Costes, Nicholas CPublication Date: 1956
Serial: TRT Terms: Old TRIS Terms: Subject Areas: Bridges and other structures; Construction; Geotechnology; Highways
Files: TRIS, TRB
Created Date: Sep 16 1994 12:00AM
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