| 摘要 |
Casings acting as circular-section revetments or coverings of cavities formed in the ground to resist the thrust of the ground; in said casing, a panel which adapts itself to the ground it must cover and which has an arcuate web bordered by inner flanges constituting a roughly rectangular frame, the web havong a meridian sectional shape having an outer bulge, the web being extended laterally by a frustoconical portion which is outwardly divergent and extends beyond the frame and defines a socket rabbet for assembly with a panel od an adjacent casing ring; the panel comprises, on one of the transverse flanges of its frame, at least one rib for assembly with an adjacent panel of the same casing panel and, in the transversely opposed flange, a support recess correspondint to and cooperating with said rib.
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