Study On The Propagation Characteristics Of Stress Wave In Roadway Surrounding Rock Of Dynamic Pressure

Coal mine dynamic pressure is a dynamic phenomenon of energy release caused by the sudden failure of rock mass under high stress state.This is a major problem that coal mines must face after deep mining.While the roadway surrounding rock is subjected to high static load,it is also affected by dynamic load such as mining disturbance,blasting vibration and roof fracture.The dynamic pressure acts on the surrounding rock in the form of stress wave,induces the deformation and failure.Taking the coal mine of Yingsheng as engineering background,this paper comprehensively uses the methods of laboratory test,numerical simulation and theoretical analysis to research stress wave propagation characteristics and failure law of dynamic pressure roadway surrounding rock.The main research contents and results are as follows:Yingsheng coal industry is obviously affected by the dynamic pressure of working face mining.Through the static mechanical test,the basic physical and mechanical parameters of roadway surrounding rock are obtained.The analysis shows that the uniaxial compressive strength of roof is greater.Through the rock mass quality evaluation,it is concluded that the roof rock belongs to hard rock with great brittleness.The overlying hard roof is easy to fracture and collapse,resulting in strong dynamic pressure,which affects the stability of roadway surrounding rock.The dynamic mechanical properties and stress wave propagation characteristics of Ying Sheng No.15 coal hard roof under impact load were studied by SHPB test system.The dynamic stress-strain curve characteristics,dynamic mechanical properties,failure mode and stress wave propagation characteristics are analyzed.The relationship between impact load and dynamic mechanical properties,stress wave amplitude and failure mode are obtained.And the relationship between wave impedance and stress wave transmittance is obtained.That is,the stress wave acts on the roadway surrounding rock repeatedly,which intensifies its fatigue damage and eventually leads to deformation and failure.The tensile wave reflected at the free interface or crack has the greatest damage effect on the roadway surrounding rock.Based on established the mechanical model of stress wave propagating through the rock stratum interface,the attenuation law of stress wave at the interface between two rock strata and roadway surface are studied.And the effects of incident angle,wave impedance,rock wave velocity and density on the attenuation of stress wave are revealed.Based on the sine wave function,the propagation equation of stress wave at the roadway interface is deduced.The failure mechanism of stress wave on roadway surrounding rock is revealed.That is,the stress wave acts on the roadway surrounding rock repeatedly,which intensifies the fatigue damage of the roadway surrounding rock,and finally leads to deformation and failure.The tensile wave reflected at the free interface or crack has the greatest destructive effect on the roadway surrounding rock.The numerical model of roadway surrounding rock under the stress wave is established through PLAXIS software.The roadway surrounding rock dynamic response characteristics under different amplitude stress wave are studied,such as stress,displacement and plastic failure zone.The deformation and failure characteristics of roadway under the condition of different roof lithology combination are analyzed,and the failure law of roadway surrounding rock under the stress wave is revealed.The protective measures of surrounding rock of dynamic pressure roadway under stress wave disturbance are put forward,and it is concluded that the buffer protective belt has obvious protective effect on roadway.The above results have certain guiding significance for promoting the research of roadway surrounding rock protection technology under the action of stress wave.