Channel Tunnel, Texas Style

Ivor-Smith, Douglas; Nandagiri, Showri; ,

Channel Tunnel, Texas Style

by Douglas Ivor-Smith, (M.ASCE), General Mgr.; Civil Engineering Div., Brown and Root, Houston, TX,
Showri Nandagiri, Manager; Dept. of Public Works, Water Engrg. Branch, Houston, TX,

Serial Information: Civil Engineering—ASCE, 1989, Vol. 59, Issue 12, Pg. 40-43

Document Type: Feature article

Abstract:

Two water supply pipelines under the Houston Ship Channel and Greens Bayou are an example of deep tunneling in soft ground. The navigable waters and the water-bearing silty soils in the Houston area posed design and construction challenges. The pipelines traverse almost nine miles and in some sections, descend as deep as 100 ft below the channel beds. When completed in 1990, they will convey 320 mgd of raw water to a treatment plant. Both bodies of water are navigable and will be dredged to 50 ft in the future. Geotechnical data indicated easier tunneling in deeper ground, hence the great depth. The channel tunnel is 1,800 ft long and the Greens Bayou tunnel is 8,860 ft. A contractor's value engineering proposal saved $500,000 on the latter tunnel by changing the alignment to make better use of his equipment and to enable the use of conventional lagging. Three deep permanent shafts were built for the project, two for tunneling operations. A bolted segmental steel liner was used. Both closed form and finite element analyses were used to simulate ground and lining behavior at the site. Monitoring during construction showed that liner deflection stayed within acceptable limits.

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