Study On Mechanical Mechanism Of Anchorage System Based On Coupling Of Steel Particles

The effectiveness of bolt support in rock strata control has been widely studied,mainly for resin bonded anchorage system.In order to further improve the mechanical properties and economy of bolt-surrounding rock anchorage system,it is still necessary to study other anchorage materials.In this thesis,a new type of anchorage system with steel particles as coupling materials is proposed.In order to study the mechanical mechanism and effectiveness of the new steel particle coupling anchorage system,the steel tube-bolt pull-out test was carried out with the assistance of digital image correlation(DIC)technology,infrared thermal imaging(IRT),acoustic emission(AE)technology and microscopic observation technology.The applicability of the anchorage system was evaluated by concrete-bolt pull-out test and engineering field pull-out test.The main conclusions are as follows :(1)The design optimization of the relevant parameters of the steel particle coupling anchorage system is proposed.It is considered that the 20 mm diameter bolt has better mechanical properties under the matching of 1.4 mm steel particles and 28 mm borehole inner diameter.The difference between the steel particle coupling anchorage system and the traditional bond anchorage system is analyzed.Based on the force chain structure,the action forms of steel particles of different sizes in the annular space are obtained,and the extrusion force formula of steel particles in the anchorage system is obtained according to the theoretical calculation.(2)The steel particles and resin anchoring agent can produce mechanical strengthening effect after mixing,thus providing higher anchoring performance.The pull-out tests based on different strength concrete specimens show that the steel particle coupling anchorage system has insufficient support efficiency for soft rock,but it can be used as an alternative support scheme for jointed hard rock.The pull-out tests carried out in Gubei Coal Mine and Qingdong Coal Mine also give similar conclusions.(3)A series of techniques such as DIC,IRT,AE and microscopic observation were used to analyze the pullout failure mechanism of steel particle coupling anchorage system.The mechanical mechanism of steel particle coupling anchorage system was revealed,and the relevant model was established.It is pointed out that the deformation degree of steel particles in different regions is highly correlated with the shear force distribution of anchorage system.(4)From the three aspects of theoretical research,laboratory and engineering field pull-out test,this study deepens the understanding of the mechanism of discontinuous anchoring medium,and also provides ideas for solving the film coating problem of resin anchoring.Under the condition of mature construction machinery,it can provide rapid support for surrounding rock in specific areas.There are 46 figures,8 tables and 85 references in this thesis.