Dynamic Mechanical Response Of Anchorage Retaining Structure Under Blasting Dynamic Load

In the field of geotechnical engineering,the stability of underground caverns or roadways is the key to safe production.As an economical and simple active support form,bolt support is widely used in engineering fields such as tunnels,slopes and mines to control the deformation and crack development of surrounding rock.In the actual support process,in addition to various static loads,the bolt support structure is often subjected to dynamic loads such as blasting or earthquake.Although domestic and foreign scholars have obtained a lot of research results in the dynamic response of the anchor under the dynamic load,the research on the theory of bolt support under the blasting dynamic load still lags behind the engineering application,which must be used for the blasting of the bolt.The mechanical response under dynamic loading is further studied to meet the needs of bolt support design.Firstly,based on the elastic wave theory,the vibration model of the rock mass in the elastic space is established.Based on the structural dynamics,the full-length anchor mortar anchor force analysis model is established.According to the iron ore support conditions of Jinshan And the blasting vibration monitoring data,the force characteristics of the full-length anchor bolt are analyzed.The results show that the axial stress and shear stress on the anchor rod body change dynamically with time,and the range of action is mainly concentrated in the anchoring section near the bolt hole;the axial stress and shear stress of the bolt increase with the explosion core distance.And the rapid decrease;the maximum axial stress of the anchor decreases with the increase of the elastic modulus of the surrounding rock,but the maximum value of the shear stress first increases gradually and then becomes gentle,with the decrease of the elastic modulus of the surrounding rock.The range of small shear stress on the anchor gradually increases and the maximum value gradually moves to the depth of the anchorage.Then,using FLAC^3D numerical calculation software,the force characteristics of the full-length anchor bolt under blasting dynamic load are analyzed.The results show that under the action of blasting dynamic load,the axial stress and shear stress of the bolts in different areas of the same section of the roadway have great differences along the distribution characteristics of the shaft.The maximum axial stress of the bolt at the bottom corner and the shoulder of the tunnel appears in the The position of the bolt hole is located,and the axial stress maximum position of the bolts at the two gangs and the vault shows an offset to the bottom of the bolt;the shear stress on the bolt body at the bottom corner mainly concentrates on the anchor near the hole Within the range of the section;the shear stress on the anchor body of the two gangs and the vault rapidly decreases after reaching the negative peak at the front end of the anchorage section,and rapidly rises to the positive peak in the rear section of the anchorage section.Rapid reduction;the shear stress of the anchor at the arched shoulder shows a"double peak"distribution along the length of the shaft.Finally,according to the above research results,it is proposed to use the support method of multiple support methods in the roadway which is greatly affected by the blasting dynamic load,select the type of explosive suitable for the type,select the appropriate single maximum explosive charge,and control the blasting.The scale,the selection of the detonation method in accordance with the supporting conditions and the improvement of the delay precision of the millisecond blasting are used to avoid the roadway damage.The research results provide a theoretical basis for the design and parameter optimization of roadway bolt support under blasting dynamic load,and further improve the theory of full-length anchor bolt support under blasting dynamic load.