| Roadway supporting of underground mining of mineral deposits is complex,the glass fiber reinforced plastic(GFRP)bolts easy to destroy and failure under the influence of ore and rock physical nature,mining technology,mining dynamic pressure,blasting shock and vibration etc,especially the greater impact of GFRP bolts is the blasting dynamic load,it is great influence for safety and reliability of the GFRP bolt in underground mining of metal mines.Therefore,it is great engineering significance for safety support of underground mines to study the mechanical response characteristics and cumulative damage effect of GFRP bolts under blasting load.Through the field investigation of the ore-rock existing condition and the supporting status of the eastern ore deposit in Jinshandian,and the tensile strength,shear strength and bending strength of GFRP bolts were tested by mechanical property experiment.According to the actual production situation of Jinshandian,blasting vibration monitoring test is designed,and the monitoring data are returned to the statistics,Obtained the site coefficient and attenuation index that can reflect the attenuation law of blasting seismic wave.The stress and strain of bonded segment of GFRP bolt are analyzed Based on the Kelvin’s solution;According to the crack propagation theory,the calculation model of the bolt damage is established,and the calculation of blasting cumulative damage of the GFRP bolt of the tunnel support in the east mountain area of Jinshandian is carried out.The results show that the GFRP bolt axial stress,shear stress,axial strain should be mainly concentrated in the front end of the bonded segment under blasting dynamic load;GFRP bolt produced some damage under many times blasting dynamic load,and the damage degree increases with the increase of the number of blasting.Through combining the dynamic analysis module of FLAC3 Dand the cable optional module of structural unit to establish the model of GFRP bolt support and study the dynamic response characteristics of GFRP bolts under single and multiple blasting load.The study shows that the mechanical response of the GFRP bolt with different installation angle is different under the blasting load,GFRP bolts would generate cumulative damage effect under multiple blasting load,the axial force of bolts would slowly superimposed increases along with the number of blasting load increases.Through the above research contents and results,the influence of blasting dynamic load on the GFRP bolt is analyzed,it can provide theoretical basis for optimization of GFRP bolt supporting design and blasting parameters,and to improving the effect of GFRP bolt.Similar problems in other mines also have a certain reference. |
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