Analysis Of Anchorage Structure Characteristic Under Loosening Circle And Study Of Surrounding Rock Stability

In the supporting means such as bolt,not only support force is provided on the surface of roadway,but also anchorage structure is formed in a certain range of roadway.In the process of roadway stability control,the stability of surrounding rock is mainly controlled by support force and structural strength.In order to analyze the mechanism of interaction with surrounding rock in the process of further bolt support.On the basis of previous studies,this paper analyses the influencing factors of the relationship between bolt support system and surrounding rock,establishes the strength calculation model of anchorage structure,analyses the mechanical manifestations of anchorage structure under different surrounding rock conditions under different loosening circles,and puts forward the concepts of "anchorage limit thickness" and "support force amplification factor".The Elastoplastic Solution of surrounding rock considering anchorage structure is compared with the traditional elastoplstic solution of surrounding rock.Relevant research work and results are as follows:（1）Combing the formation of loosening circle and the mechanical performance of surrounding rock under different loosening circles,it is concluded that the rock mass within the loosening circle is the main factor affecting the convergence of roadway,and controlling the development of loosening circle is the key to maintain the stability of roadway.The current testing methods of loosening ring are summarized,and the factors affecting the range of loosening ring are obtained by numerical simulation.（2）The control of supporting structure on surrounding rock is affected by two factors,supporting force and structural strength,which include structural size and material parameters.On this basis,the mechanical calculation model of anchorage structure is put forward,and the strength expression of anchorage structure is obtained.According to the change of thickness of anchorage structure "b"and support force "p_i ",it is found that the structural strength plays a major role in the radial stress provided by surrounding rock,and the coordination between them can control the stability of roadway more effectively.（3）In the case of small,medium and large loosening zones,the support strength "p_ib "of plastic zone provided by the outer boundary of anchorage structure is discussed,and the corresponding support theory guidance is put forward according to the related problems in the supporting process of roadway.Through the analysis of the calculation process,the concepts of "anchorage limit thickness" and "support force amplification factor" are put forward for the first time in this paper,and the role of anchorage thickness "b"in roadway support system is further analyzed.（4）When considering the effect of anchorage structure,the stress distribution around the surrounding rock is re-solved.The peak stress shifts to the depth,and the change gradient is slower and the distribution is more uniform.The modified elastic-plastic solution of roadway can provide some reference for the supporting mechanism of roadway,and provide the corresponding theoretical basis for the design of supporting parameters of roadway.（5）In the research process of Luling Ⅲ811 machine roadway crossing goaf,combined with the theoretical basis of this paper,it provides guidance for the selection and optimization of field support parameters in the later stage.Figure 133 table 8 reference 77.