Report No. : GEO Report No. 165

Report Title : Prescriptive Soil Nail Design for Concrete and Masonry Retaining Walls (2005), 78 p.

Author : B.L.S. Lui & Y.K. Shiu

Abstract

A study has been carried out to develop prescriptive measures for upgrading of concrete retaining walls and masonry retaining walls using soil nails. As part of the study, past design cases involving analytical design of soil nails for upgrading about 80 cut slopes with a toe wall, and concrete or masonry retaining walls have been reviewed for deriving the prescriptive design guidelines.

This report documents the findings of the study. It is shown that the prescriptive design approach and the standard layout of soil nails for soil cut slopes as recommended in the second edition of GEO Report No. 56 can be applied to cut slopes with a toe wall, but an additional length of soil nail is required for accommodating the nail length passing through the retaining wall and fill material. Similar prescriptive soil nail design guidelines have been developed for concrete and masonry retaining walls. The guidelines may be used for upgrading works or preventive maintenance works. A chart has also been devised to assist designers in determining whether a concrete or masonry retaining wall is substandard or not.

Typical details of soil nail heads and wall facing for use in conjunction with the prescriptive soil nails are given in the report. Areas of soil nail detailing and construction requiring special attention were also discussed.

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