headwall
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English[edit]
Etymology[edit]
Noun[edit]
headwall (plural headwalls)
- (geography) The highest cliff of a glacial cirque.
- (geology) The steep cliff at the back of a cirque.
- (civil engineering) A retaining wall at the outlet of a drain, culvert or tunnel.
- 1950 September, “Central London Railway Jubilee”, in Railway Magazine, page 622:
- The platforms of all stations from Shepherds Bush to Liverpool Street have been lengthened from 325 ft. to 427 ft. between tunnel headwalls, to take longer trains.
- 2020 August 12, “Network News: HS2 tunnel portal readied for TBMs”, in Rail, page 10:
- HS2 Ltd has built a 17-metre-high headwall and reinforced the ground at what will become the south portal of the ten-mile Chiltern Tunnel, as part of preparations for the arrival next year of tunnel boring machines (TBMs).
References[edit]
- “headwall”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.