Abstract Installing the anchor-root at the bottom of full-length bonded bolt in rock foundation could not only strengthen the anti-pullout capability of bolt anchorage system but also reduce the bolt length. A series of laboratory and in-situ tests are carried out to study the behavior of anchor-root. Two groups of bolts with different lengths are tested for comparing the curves of axis force along the depth,and one group of anchor-root bolts is installed for tests. The relationships between the installation location of anchor-root,the anchorage length,the bolt diameter,the shear stiffness between bolt and mortar are studied. The experiment results show that because the load transmits from the top to the bottom,the anchor-root plays the role when the small load is applied on short full-length bonded bolt. On the basis of curve characteristics of bolt axis force,an assumption that the anchor-root role is equivalent to anchorage length added is proposed,and the calculation model is established. Compared with measured data,this model can be used to predict the effect of anchor-root at the bottom of full-length bonded bolt.
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Received: 06 April 2010
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