Influence of anchor length on grouted bolt behaviour

This paper describes the behaviour of two inclusions consisting of hollow fiberglass rods (40-60 mm of diameter) placed in boreholes and grouted with cement. These two bolts have a grouted length of 3 meters and 5 meters and are pulled out progressively. The analytical method developed by Bourdeau (1994) determines the frictional local law parameters (assumed constant along the rod) from the global relationship of the total load and the head displacement. An equivalent modulus of the rod-grout composite useful to describe the inclusion behaviour can also be deduced. This model can describe the complete mechanism of the friction along the anchor and works for "flexible" or "stiff" inclusions.