Micropile Design and Construction – Part II

Course Outline

Worldwide use of micropiles has grown since their original development in the 1950s, and in particular since the mid-1980s. In general, micropiles are applicable when there are problems with using conventional deep foundation systems like driven piles, drilled shafts, or augercast piling.  Mircopiles are primarily used as elements for foundation support to resist static and dynamic loading conditions, and less frequently as in-situ reinforcements for slope and excavation stability.  Micropile can be designed as soil frictional piles or rock socketed piles either under tension or compression. The advantages of micropiles are that their installation procedure causes minimal vibration and noise, they can be installed in difficult ground conditions, and they can be used in areas with low headroom and restrictive access. This makes micropiles the preferred choice of foundation system for retrofitting existing structures in challenging areas.  This course is entirely based on US Department of Transportation Publication No. FHWA NHI-05-039, Micropile Design and Construction. This two-part series discusses micropile classifications, design concepts, problems associated with the common installation methods, specifications, construction control and performance of this pile system.  This is part two of the series that covers the following Chapters:

Chapter 5 Design of Micropiles for Structure Foundations
Chapter 6 Design of Micropiles for Soil Slope Stabilization

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of course materials.

Learning Objectives

At the conclusion of this series, the student will learn:

• Definitions;
• Historic background;
• Classifications;
• Applications;
• Construction types;
• Feasibility;
• Advantages and disadvantages;
• Micropile for structural support;
• Micropile for slope stabilization;
• Design approach;
• Structural design;
• Reinforcement;
• Lateral resistance;
• Buckling;
• Geotechincal capacity evaluation;
• Settlement;
• Details;
• Corrosion protection;
• Seismic considerations;
• Soil slope stabilization application;
• Earth retentions;
• Construction Methods;
• Grouting procedures;
• Drilling techniques;
• In-situ reinforcement;
• Load testing; and
• Cost estimate.

Intended Audience

This course is intended for geotechnical engineers, civil engineers, structural engineers, construction professionals and contractors.

Benefit to Attendees

The attendees will gain a general knowledge of the design, construction and performance of micropile foundation system.

Course Introduction

A micropile is a small diameter (typically 5" – 12"), drilled and grouted pile with reinforcement.  Micropiles are commonly made up of high strength steel casing and rebar, but can also be installed in some soil conditions using pressure grouted all-thread self-drilling hollow bar systems.  Designed to carry compressive or tensile loads, micropiles are high-performance piles that can achieve working loads over 200 tons and extend to depths of 200 feet.  The load is mainly accepted by the steel casing and transferred via the grout to the surrounding rock or soil by high values of interfacial friction with minimal end bearing components, as in the case for ground anchors and soil nails.  The drilling equipment and installation methods allow micropiles to be drilled through natural and artificial ground condition with minimal vibration, disturbance and noise and at any angle below horizontal. 

Course Content

The course content is entirely based on US Department of Transportation Publication No. FHWA NHI-05-039, Micropile Design and Construction.  For this course, you are required to study Chapters 5 and 6 of the following document.

USDOT Publication No. FHWA NHI-05-039, Micropile Design and Construction (27 MB PDF Document)

Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right-clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader from your computer.

Course Summary

This course presents the general guidelines on micropile selection, application, benefit, design, construction, cost and testing of micropile foundations.

Once you finish studying the above course content you need to take a quiz to obtain the PDH credits.

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DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDHonline.org or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered professional engineer. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.

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