| 摘要 |
The tension head comprises essentially a sleeve with a threaded bore having opposed keyways extending therethrough. In those keyways is supported a U-shaped stop member. When the sleeve is turned up on the end of the bolt protruding from the hole until that end abuts the cross piece of the stop member, rotation of the sleeve rotates the bolt. When the inner end of the bolt is bonded to the rock, further rotation of the sleeve causes the stop member to break or deform. The lower end of the bolt pushes the deformed stop member or its fragments out through the bottom of the sleeve along the keyways.
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