| Due to the increase of coal mining depth and the deterioration of resource conditions in China,the rockburst disaster induced by dynamic load is becoming more and more serious.At present,the relevant theoretical research of anti-impact support still lags behind the field engineering practice,especially the occurrence of roadway rock burst is closely related to static load stress,dynamic load stress,support conditions and pressure relief degree.The study of roadway rockbursting failure mechanism and related supporting theory considering multi-factors is rare.In this paper,theoretical analysis,numerical simulation,similar simulation test and other research methods are used to study the response characteristics and rockbursting effect of roadway surrounding rock under dynamic and static combined loading.First of all,the wave equation theory is used to analyze the physical and mechanical response characteristics of roadway surrounding rock under dynamic load.Through the discussion of P wave propagation potential function,the response characteristics of roadway surrounding rock under plane P wave of circular unsupported roadway and supporting roadway are compared,and the dynamic response model of circular supporting roadway under dynamic load is established to determine the stress concentration position.Based on the thin plate theory,the fracture-buckling mechanical model of roadway surrounding rock is established.According to the cusp catastrophe theory,the necessary and sufficient conditions for sudden instability of roadway surrounding rock system are determined,and the criterion for instability failure under dynamic load is proposed.Secondly,the influence of different factors on the dynamic response characteristics of roadway surrounding rock is studied by numerical simulation,and the stress and displacement evolution characteristics of roadway surrounding rock under different static loads are analyzed in detail.The mechanical response characteristics of stress,displacement and velocity in roadway surrounding rock under different strength,distance dynamic load and high ground stress are compared.The numerical simulation and response characteristics analysis of the impact failure process of roadway surrounding rock under static and dynamic combined superposition show that :(1)Under static load,there is a local stress concentration area in roadway surrounding rock,but there is no impact failure phenomenon;(2)There are significant differences in the disturbance effect of different strength dynamic load on surrounding rock of roadway.When the dynamic load strength reaches a certain limit value,the surrounding rock of roadway occurs sudden deformation and failure,and induces shock disasters;(3)The disturbance degree and influence range of a certain strength of dynamic load on surrounding rock of roadway decrease with the increase of distance.When the distance between dynamic load and roadway is small to a certain limit value,it is easy to cause instantaneous impact failure of roadway.(4)Under a certain strength of dynamic load,the surrounding rock of roadway under high ground stress occurs deformation and failure before normal stress,and the high level stress has a great influence on the stability of surrounding rock of roadway.Combined with numerical simulation and similar simulation,the influence of different support and pressure relief schemes on dynamic response characteristics and impact failure of roadway surrounding rock was explored.Under the action of small energy dynamic load,the surrounding rock of roadway has elastic vibration,and there is no impact failure on the macro level.The acceleration of surrounding rock and the displacement of floor have little change.When the superposition strength exceeds the bearing limit of surrounding rock,the deformation and failure of roadway surrounding rock occur,and the local deformation is obvious.When the dynamic load reaches a certain degree,the instantaneous impact failure of roadway is induced,and the acceleration of roadway surrounding rock and the displacement of floor are significantly changed.The conditions such as dynamic load strength and static load stress state are closely related to the deformation and failure of roadway surrounding rock.At the same time,pressure relief measures have a positive inhibitory effect on the impact damage degree of roadway surrounding rock under high strength dynamic load,which is beneficial to maintain the stability of roadway shape.Fourthly,from the perspective of static and dynamic combination,the mechanism of roadway induced impact under multi-factor coupling is analyzed.In view of the complex and changeable factors affecting the seismic and anti-impact ability of roadway,it is difficult to establish relevant mechanical models to accurately evaluate the seismic and anti-impact ability of roadway.The safety evaluation model of dynamic response characteristics of roadway surrounding rock is constructed by MATLAB neural network model.Considering the influence of dynamic load parameters,support and pressure relief measures on roadway induced impact,the PSO-BP method was used to predict and analyze the dynamic response characteristics of roadway surrounding rock.Taking the maximum floor displacement and maximum floor velocity as evaluation indexes,GA-SVM method is used to predict and analyze the failure of roadway surrounding rock.The prediction accuracy of roadway safety evaluation model based on PSO-BP and GA-SVM methods is high,and it has good effect on the dynamic response characteristics of roadway surrounding rock and the prediction of roadway surrounding rock failure.There are 78 pictures,18 tables and 99 references in this thesis. |
