Study And Engineering Application Of Self-screwed Slip Casting Tube Bolt In Soft-rock Tunnel Support

The traditional mortar anchor and the current hollow slip casting tube bolt used widely in soft-rock support have the problems that can't support immediately and grout fully. However, the self-screwed slip casting tube bolt solve the problem that the existing anchor bolt can't support immediately and the spin silk carve into the rock to form multi-point contact with friction anchoring force.It has the great theoretical significance and engineering practice value.Based on the structure characteristic and mechanism of action of the self-screwed slip casting tube bolt,the calculation of pullout resistance theory is discussed.Also,the calculation of pullout resistance theory of the hollow slip casting tube bolt is discussed also. Through the theoretical calculation and analysis,it deduces the theoretical formula of pullout resistance of the self-screwed slip casting tube bolt and the hollow slip casting tube bolt.Through field tests we get measured value of pullout resistance, grouting plumpness and settlement observations.With the engineering example, we deduce that the bending capacity of the self-screwed slip casting tube bolt, hollow slip casting tube bolt,the mortar anchor and the the bending capacity theoretical formula and value of them.In this paper, we simulate two cases that one advanced bolt can grout fully the have the initial anchoring force (self-screwed slip casting tube bolt) ,the other advanced bolt can't grout fully and don't have the initial anchoring force (hollow slip casting tube bolt).Finally, this paper compare the economic benefits of self-screwed slip casting tube bolt and hollow slip casting tube bolt.