ABSTRACT
There is a growing number of immersed tunnel that used concrete-type structure and gravel bed. However, the friction coefficient between tunnel element and gravel bed, which is an important parameter for the appropriate design and preparation of construction, was missing. In this paper, the author reported extensively on the data of friction coefficient between concrete slab and gravel layer. The data were observed from site work of installing the thirty-three immersed tunnel elements on Hong Kong-Zhuhai-Macao Bridge Project, i.e. pulling connection and re-alignment of tunnel element, and from small-scale physical model tests. In the tests, the influential factors of the friction coefficient were studied such as contact pressure, geometrical character of foundation layer, sediments, and nominal diameter of gravel. Further, an observation of a special case during the work of closure joint were discussed to reflect the overall friction coefficient of tunnel elements after backfilling.
