Geotechnical Behavior of Underreams in Pleistocene Clay

by Michael W. O'Neill, Univ of Houston, Houston, TX, USA,
Shamim A. Sheikh, Univ of Houston, Houston, TX, USA,

Document Type: Proceeding Paper

Part of: Drilled Piers and Caissons II


Enlarged bases are often constructed in cylindrical drilled-and-cast-in-situ foundation elements (footings, bored piles) to increase their capacity. Enlarged bases that are cut mechanically into the soil in the shape of a truncated cone are called underreams or 'bells. ' The use of underreams is especially popular in stiff to hard clays where they can be excavated and concreted in the dry. Despite the wide use of underreams, relatively few comprehensive studies have been conducted to investigate their bearing capacity and settlement characteristics. This paper describes load tests on two full-sized underreams at two separate test sites in the Pleistocene clays of southeast Texas. The objectives of the study were to develop reliable methods of computing bearing capacity and of estimating settlement of underreams in heavily overconsolidated clays.

Subject Headings: Load tests | Soil properties | Clays | Bored piles | Soil tests | Soil pressure | Soil settlement | Foundation settlement | Texas | United States

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