Study On Drawing Deformation And Failure Mechanism Of Wholly Grouted Anchoring System

Bolt support technology is a kind of reinforcement technology which uses anchor to reinforce rock mass and fully exert the stability of rock and soil. The anchoring effect of anchorage system is the result of the synergistic effect of the anchors, cemented materials and rock-soil, and the relative strength of three media will have a great influence on the tensile load of anchoring system. In this paper, the method of theoretical analysis, indoor test and numerical simulation is used to study the deformation and failure mechanism of wholly grouted anchoring system.(1) Based on the Mindlin solution of elastic mechanics and the existing load transfer model, the anchoring system is destroyed when the bolt-grout or grout-rock and soil interface begins to enter the plastic deformation stage as the assumption, and establishes the mechanics model and the deformation relation model. The stress distribution and deformation relationship between anchor, grout and rock-soil in drawing process are studied by using the model, and the correctness and rationality of the model are verified by the example.(2) The tensile performance test of wholly grouted anchoring system with different relative strength of three media is designed. The three main forms of failure of anchorage system are obtained through nine group test results, that is, the mortar-rock destruction, the anchor-mortar destruction and the failure of the anchor. The failure mechanism of anchoring system under different failure modes is analyzed through the P-S curve, and the failure mechanism of anchoring system is explained by the micro aspect,and the destruction mechanisms of anchoring system are the same in the homogeneous failure mode.(3) The deformation of the anchor, the grout and the rock-soil gradually increased from zero to the initial linearly synchronously, early.With the increase of the load, the deformation of the anchor increased gradually, and then the deformation of the grout increased obviously, and the deformation accompanied by the simultaneous increase of the deformation of the rock-soil at the same level. While, the load is transferred by the anchor, the grout and the rock-soil followed by pass,and accompanied by the coordination of the three deformations, and always maintain a linear relationship until the anchoring system is destroyed complete, the coordination deformation process is complete.(4) The deformation relations of three media under different destructive modes are analyzed and studied, find that the deformation relation fitting curves of the anchoring system are a linear equation at different stages. The failure mode is different, the linear relation is different. It is explained that the deformation of anchor, grout and rock-soil is coordinated by the force deformation of the anchoring system from the whole process is destroyed under drawing loads. And the deformation relationship is no longer coordinated when the linear relation is not fitting,that is, the anchoring system is completely destroyed. It also shows that anchoring effect is the result of mutual coordination between anchor, grout and rock-soil.(5) Using the finite element analysis software (ANSYS), adopting three-dimensional solid modeling, according to the different mechanical properties of anchor, grout and rock-soil material, the ideal elastic-plastic model, the Drucker-Prager constitutive model and the multi polyline constitutive model are respectively applied to simulate to study the changing regularity of displacement with load under pulling load and the deformation relationship between anchor, grout and rock-soil, and compare with the test results. The results show that the simulation results coincide well with the experimental results, and verify the correctness of the test conclusions.