On Solid Ground (Available only in the Geoenvironmental Special Issue)

by Gernot Ueblacker, P.E., (M.ASCE), Sr. Proj. Mgr.; Golder Associates Inc., Lakewood, CO,


Serial Information: Civil Engineering—ASCE, 1997, Vol. 67, Issue 2, Pg. 12A-16A


Document Type: Feature article

Abstract:

On four transportation projects in Portland, Ore., soil nails and micropiles are used as alternatives to conventional earth-retention and foundation systems. The use of soil nails and micropiles to meet the commuting challenges of modern urban sprawl is growing. Both technologies were introduced in the U.S. in the early 1970s and have gained regional acceptance at a steady pace, primarily along both coasts and in highly populated areas. Design load increment requirements of less than 0.5 in. of movement were met at both sites. Tension tests were performed first to verify the capacity of the reaction and test piles under lower loads. The reaction frame had been used to test MDCI's micropiles at John Day Dam on the Columbia River earlier in 1996 to maximum test loads of 1,300 kip. The test piles at PDX were loaded beyond 200% of the design load. At the south site, a reaction pile failed during the compression test at the 225% load increment. At the other site, the compression test failed by plunging at 250% of the design load. The installation of the production pile will include approximately 450 micropiles.

Subject Headings: Load tests | Pile tests | Micro piles | Load factors | Soil nailing | Compression tests | Load and resistance factor design

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