Experimental Tests Of Drawing On Expanded Head Bolt

The expanded head bolt is one kind of anti-floating artifacts which is more widely used in domestic in recent years. A large number of engineering practice indicates that, compared with anti-floating pile the expanded head bolt has lower costs, more environmental characteristics, higher bearing capacity, and more secure. While the expanded head bolt is used in engineering practices wider and wider, but so far the bearing characteristics of the expanded head bolt, pull-out failure mode, the expanded head bolt stress mechanism, the interaction between top resistance and side friction, and theory researches, which are few, and lack deep and overall knowledge. In this context, it is necessary to make a systematic research on the anchor of new type.In this dissertation, a systematic research on characteristics of the expanded head bolt, the axial force, side friction and top resistance of the expanded head bolt are applied with model test and theory researches. A mainly research is on the interaction between the play ratio of top resistance and side friction, and strengthen of side friction which is caused by top resistance. Finally a strengthen coefficient that top resistance effect on side friction when drawing load added on the expanded head bolt, is given through theory researches, based on the result of model test. The conclusion acquired in this paper are as below:(1) The side friction of the expanded head bolt increases first, while the top resistance is small, then the side friction decreases and tends to be stable, while the top resistance start to increases fast and tends to be stable.(2) The distribution feature of the pile side friction of the deep expanded head bolt is upper large and lower small. The distribution feature of the side friction of the shallow expanded head bolt is small in up and down, bigger in the middle when the top resistance is small, upper large and lower small when the top resistance is bigger.(3) Strengthen of the top resistance effect on the side friction is increases when the expanded head bolt is buried deeper and the diameter is bigger.(4) We introduce the strengthen coefficient into the bearing capacity calculation formula of the expanded head bolt, to correct the side friction of the expanded head bolt.