Report No. : GEO Report No. 334

Report Title : Interim Review on Long-term Monitoring of Corrosion of Soil Nails (2018), 38p.

Author : F.W.Y. Ko

Abstract

In 1999, the Geotechnical Engineering Office (GEO) initiated a study of long-term durability of soil nails, with a view to developing an improved approach for designing and specifying corrosion protection for soil nails. In order to collect long-term data on the corrosion rates of soil nails, the GEO commenced in 2004 a long-term monitoring of the corrosion of sacrificial soil nails with different types of corrosion protection provisions. Soil nails, in the form of 1.5 m long, 32 mm diameter high-yield deformed steel bar, with different types of corrosion protection provisions were installed in the last quarter of 2004 at four different sites under the Landslip Preventive Measures Programme. The GEO has also collaborated with the Architectural Services Department to monitor the sacrificial soil nails installed at Slope No. 11SW-D/C2089 at the Hong Kong Stadium.

Exhumation of soil nails at the five monitoring sites was carried out between 2010 and 2013. In general, no significant corrosion was observed on all the exhumed soil nails with different corrosion protection provisions. Monitoring of corrosion of the sacrificial soil nails installed at the five sites will be continued according to the monitoring schedule.

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