Implementation of bolt axial force losses in FLAC3D under blasting and application

For the problem that FLAC3D original models can not achieve axial force loss of CABLE structural elements under dynamic loads,based on the maximum shear stress criterion and the criterion of strain energy density,proposed the damage criterion of CABLE unit under blasting vibration,and the distribution rules of the anchorage structure dam- age quantity along the path of seismic wave propagation. Based on the above results,a modified model of bolt axial force loss was established. Based FISH language platform,developed computing program of correction model,which could achieve the function of bolt axial force loss due to CABLE structural unit dynamic damage in FLAC3D dynamic a- nalysis,and apply the functions on the analysis of single row anchor bolt axial force loss and reduced quality compari- son of all bolt support roadway under blasting vibration,the results show that:① Bolt axial force evolution of modified model under blasting included three stages:steady,descent and steady,and the loss rate of bolt axis force was expo- nential decay with the increase of the distance to the source,which achieved to the desired effect of bolt axial force quantitative losses;② Through the modified model,the main damage scope and extent of the roadway support were obtain. Specifically,under the 6 kg and 8 kg dose blasting,the peak value of stress loss rate were 35% and 76% respec- tively,and the bolt axial force loss rate of the distance to the source of 0 to 4 m and 0 to 12 m was more than 25% re- spectively. In addition,The modified model can correct the deformation of surrounding rock and the volume of plastic zone in the dynamic analysis. The peak values of deformation correction coefficient of 6 kg and 8 kg were 70% and 37. 5% respectively,while the plastic zone volume correction coefficients were 22. 2% and 9. 9% respectively,which showed that the correction effect of less blasting charge was more significant ③ The results of modified model numeri- cal simulation were in good agreement with the in-situ monitoring results.