Study On The Anchorage Properties Of Flexible Pressurized Anchor

Flexible pressurized anchor is a kind of new anchor which has new structure and unique anchoring mechanism. It can actively adapt for the motion of adjacent rock, facilitate the detection of anchor inner cavity pressure and monitor the change of mine pressure through the change of inner cavity pressure,the weight of anchor is light and it is easy to achieve recycling reuse of anchor. But its mechanism of action including the role of law and the methods of theoretical analysis is not clear and defined. Therefore, it has important theoretical significance and practical value to study the subject.The author has researched and explored anchorage properties of the new type of flexible pressurized anchor by the methods of theoretical analysis,numerical simulation,laboratory simulation analysis and field measurement analysis and has made some meaningful research results and conclusions.The material is simplified as linear elastic material body, applied elasticity theory, given the analytic solutions of stress field and displacement field for the flexible pressurized anchor rod and adjacent rock. And applied strength theory on this basis, assumed that blind-side rock bolt has sufficient resistant pullout force in case that the anchor bolt can be pulled out of anchor bolt hole, Given the maximum allowable pullout load of anchor which is determined by the strength of steel wire,the strength of rod polymer material and the interfacial shear strength between steel wire and rod polymer material.Ignore effects of Interfacial anchor,simplify analysis of contact anchor bolt body with rock to two-dimensional plane strain problem. Establish finite element model for two-dimensional contact problem, study the regulation of the main parameters of anchor bolt anchorage system for bolt anchoring effect. Give the optimum condition of anchorage system of Flexible pressurized anchor: there is a reasonable value of anchor wall; a reasonable choice of wire number and cross-section of the wire; some structural parameters of anchor bolt and its scope of application of rock material and so on. Thereby, provide the basis for the design, manufacture and application of the new anchor. Establish three-dimensional finite element model for anchor anchorage system, carry out numerical simulation for contact stress distribution of anchor anchorage section. Anti-friction stress curve of anchor anchorage section can be obtained by setting a certain displacement value on the head-end of anchor anchorage section, which is a secondary loading way. And the vertical curve is divided into three stages: Stress wave segment, stress plateau segment and stress downhill section.Assess and verify many aspects of flexible pressurized anchor through ground test and under shaft field test, such as experimental installation,testing program,anchor structure and anti-pullout anchor load and so on, and obtain satisfactory results. Compare the values of experimental pullout load with theoretical results and numerical analysis and come to the result that the line of theoretical values and line of the values of numerical calculation are two approximate parallel straight lines. And the result certifies the accuracy of theoretical calculation and numerical calculation in a certain degree; that coefficient of friction is considered as a constant and simplified as linear elastic material lead to a certain deviation caused by experimental values, theoretical and numerical values.The analysis and discussion on the characteristics of flexible pressurized anchor group and the anchoring effect of the flexible pressurized anchor group of flat tunnel roof show that : the horizontal effect of each anchor of anchor bolt groups is partial; the layout of anchor group has a obvious vertical effect ;the change of the vertical displacement of roof to the level stress is not enough sensitive while to the change in stress of the overlying strata is very sensitive.