Report No. : GEO Report No. 175

Report Title : Soil Nail Head Review (2005), 106 p.

Author : Y.K. Shiu & G.W.K. Chang


Soil nails are extensively used for slope improvement works in Hong Kong. A study has been carried out to review the role and load transfer mechanism of soil nail heads.

This study comprises a review of the fundamental mechanism of soil nail heads, case histories of previous studies and technical guidance documents from France, Japan, UK and USA. In addition, numerical simulations have been carried out to examine analytically the functions of soil nail heads. Local stability of the soil between soil nail heads has also been examined.

From the results of the study, soil nail heads can enhance stability of slopes. This beneficial effect is attributed to the lateral confinement to the soil resulting from combined action of the nail heads and soil nails.

Three options of design methods including design charts derived from numerical analyses, lower-bound solution as proposed by HA 68/94, and prescriptive design approach are provided to assist engineers in determining the dimension of nail heads. Guidance on prevention of local instability of soil between nail heads is also given.

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