Analytical And Experimental Study On Pull-out Load Transfer Mechanism Of Anchor

Anchor is one of the effective methods to improve the stability of geotechnical engineering and solve the complex geotechnical engineering problems. It is widely used in slope, tunnel, mining, foundation ditch and so on. On-site pull-out tests is one of the important methods to detect the quality of anchor. Proper evaluation on the status of bolting system is greatly significant for anchor design in projects domain. Based on elastic-plastic theoretical analysis and pull-out tests ,the load transfer and failure process of anchor bolt and the parameters of anchoring layer interface was discussed in the paper. Get some significant results:The failure mode and anchorage mechanism of bolt anchor and mechanism has been analyzed. The failure mode and reason under the drawing load were elaborated. In the process of load transfer, the bond mechanism and mechanical behavior of two interfaces were analyzed.The existing shear slip model between the anchorage and the rock mass has been summarized. Based on the shear slip model of pore wall which built by B.Benmokrane, taking the load transfer function method, a elastic-plastic model was set up for the theoretical solution of the shearing stress distribution law along the length direction. Research shows that anchor solid rock interface can be divided into the residual shear stage, plastic softening stage and elastic deformation stage, and the different position of interface has different shear stress distribution. And the factors which influence the anchoring effect were analyzed exactly.By the field experiment of bolt in loess, the stress distribution along the anchorage was measured. The test results are in good agreement with the theory analysis results. For the bolt of supporting in Ningtiaota Coal Mine, the pull-out test has been taken in the roadway. By the test, we get the whole load-displacement curve of the bolt with the resin in the coal. Based on the characteristic pull out curve, the failure process of interface is analyzed and the process is divided into: elastic deformation stage, sliding deformation stage and debonding appearance and development stage and completely debonding stage.The formula between the limit shear strength parameter and the bolt P-S curve was derived. By the data of field anchor tests, the shear strength parameters between the resin and coal were calculated. Based on the stress distribution of bolt in loess, the shear strength parameter between the loess and mortar was calculated. They provide a feasible way to get the shear strength parameters and give a reference for following design.