Location

New York, New York

Session Start Date

4-13-2004

Session End Date

4-17-2004

Abstract

This paper summarizes a series of never-before reported axial compression load tests conducted on single micropiles that are embedded in or constructed on rock. These data are augmented by load tests on similar micropiles that have been reported by others. The observed displacements at the maximum test load (QMAX) and reported unfactored design load (QDL) are summarized. In addition, the small-strain load-displacement behavior of these foundations is evaluated by comparing the initial tangent slope (IS) to the theoretical elastic slope (ES), which is calculated by modeling the micropile as a free-standing column exhibiting fully -composite behavior. The data demonstrate that the ES/IS ratio has a strong dependence on the slenderness ratio D[depth]/B[diameter]. The observed results for micropiles in rock are discussed in the context of the micropile load test acceptance criteria proposed by the Deep Foundations Institute (DFI, 2001). In addition, recommendations are proposed for the maximum acceptable vertical displacement under the unfactored design load for such micropiles.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Fifth Conference

Publisher

University of Missouri--Rolla

Publication Date

4-13-2004

Document Version

Final Version

Rights

© 2004 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 13th, 12:00 AM Apr 17th, 12:00 AM

An Evaluation of the Load-Displacement Behavior and Load Test Interpretation of Micropiles in Rock

New York, New York

This paper summarizes a series of never-before reported axial compression load tests conducted on single micropiles that are embedded in or constructed on rock. These data are augmented by load tests on similar micropiles that have been reported by others. The observed displacements at the maximum test load (QMAX) and reported unfactored design load (QDL) are summarized. In addition, the small-strain load-displacement behavior of these foundations is evaluated by comparing the initial tangent slope (IS) to the theoretical elastic slope (ES), which is calculated by modeling the micropile as a free-standing column exhibiting fully -composite behavior. The data demonstrate that the ES/IS ratio has a strong dependence on the slenderness ratio D[depth]/B[diameter]. The observed results for micropiles in rock are discussed in the context of the micropile load test acceptance criteria proposed by the Deep Foundations Institute (DFI, 2001). In addition, recommendations are proposed for the maximum acceptable vertical displacement under the unfactored design load for such micropiles.