Study On Shear Stress Distribution Characteristics Of Surrounding Rock In Contact Zone Roadway Based On Photoelastic Test

The surrounding rock of contact zone roadway is prone to incompatible deformation,which leads to extensive shear failure in engineering.Quantitative analysis of shear stress distribution characteristics in surrounding rock of roadway in contact zone is an objective requirement to control the stability of surrounding rock.Based on the three-dimensional photoelastic test,the distribution of shear stress in the surrounding rock of the contact zone roadway was visually represented,and the distribution law of shear stress in the surrounding rock of the contact zone roadway with the change of contact angle and distance from the contact zone was quantitatively analyzed.The research results have certain guiding significance for the layout and stability control of engineering roadway.Taking the iron ore-limestone contact zone as the research object,a photoelastic test model was constructed according to the principle of mechanical similarity.Based on the stress freezing test,the photoelastic stress fringes obtained visually showed the shear stress field of the surrounding rock of the contact zone roadway,and the shear stress value of the whole field was quantitatively calculated by using the ten-step phase shift method.The variation of shear stress of radial and axial surrounding rock with contact angle and distance was analyzed,and the distribution characteristics of shear stress of surrounding rock in contact zone were obtained.The distribution characteristics of shear stress in radial surrounding rock of roadway were as follows: the distribution of shear stress on both sides of contact zone was inconsistent;when the contact angle changes in the range of 15 ~75,the shear stress along radial direction of roadway decreased first,then increased and then decreased;with the increase of contact angle,the shear stress of radial surrounding rock of roadway decreased first and then increased.The distribution characteristics of shear stress in the roadway axial surrounding rock showed that the shear stress on both sides of the contact zone was incompatible;the maximum shear stress on the top of the roadway in the contact zone increased with the increase of the contact angle;and the difference between before and after shear stress mutation decreased with the increase of the distance from the roadway axis R~3R roadway top surrounding rock.Based on the physical and mechanical parameters of iron ore and limestone,numerical calculation models for surrounding rock of roadway in contact zone were established based on the actual size of the project.The shear stress distribution characteristics of radial and axial surrounding rock of roadway in 15 degree contact angle contact zone were analyzed.The calculated results were consistent with the photoelastic test results.The numerical simulation analysis was extended to the shear stress distribution characteristics of surrounding rock of roadway in other contact angle contact zone.The calculated results were the same as those of other contact angle contact zone roadways of the photoelastic test results,which confirmed the correctness of the photoelastic test results.