FLAC3D中爆破震动下锚杆轴力损失的修正及应用

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

  • 摘要: 针对FLAC3D现有模型无法实现由于CABLE结构单元在动载下出现损伤而导致支护轴力损失的问题,基于最大剪应力准则和应变能密度准则,提出了爆破震动下CABLE单元破坏损伤判据,以及锚固结构损伤量沿震波传播路径的分布规则,由此建立了锚杆轴力动力损失修正模型。基于FISH语言平台开发修正模型的计算程序,使得FLAC3D具备由于CABLE结构单元动力损伤而导致轴力损失的功能,并应用该功能进行了爆破震动下单排锚杆轴力损失与全锚杆巷道支护质量减弱的对比分析,结果表明:1修正模型锚杆轴力在爆破下,经历平稳→下降→平稳3个阶段,锚杆轴力损失率随至震源距离的增大呈指数衰减,达到了锚杆轴力定量损失的预期效果。2通过修正模型得到了爆破对巷道支护的主要损伤范围和程度,其中6和8 kg药量爆破下锚杆轴力损失率峰值分别为35%和76%,并且至震源0~4和0~12 m内锚杆轴力损失率超过25%,支护损伤较大。同时,修正模型能较大幅度修正动力分析中的围岩变形量以及塑性区体积,其中6和8 kg药量爆破下变形修正系数峰值分别为70%和37.5%,而塑性区体积修正系数分别为22.2%和9.9%,说明爆破药量越小修正效果越显著。3修正模型计算结果与现场实测结果具有较好的一致性。

     

    Abstract: 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.

     

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