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三轴围压下煤冲击破坏特征及数值模拟

Coal impact failure characteristic and numerical simulation under triaxial confining pressure

  • 摘要: 为研究应变率、围压对煤样冲击破坏特征的影响,采用分离式霍普金森压杆装置,在应变率60~110 s-1、轴围压12、15、18 MPa条件下,开展15个煤样的动力学冲击实验,并结合实验结果探究冲击载荷下采空区破坏失稳模拟,进而根据数值模拟结果判断应变率—围压影响对于冲击地压类灾害数值模拟的适用性。研究结果表明:煤样冲击破坏呈显著的应变率效应,且煤样的动态抗压强度与应变率呈正向增长关系;12~18 MPa围压条件对煤体应变率效应和抗压强度有削弱作用,且相同冲击气压下,随着围压的增大,煤样破碎越显著;模拟结果与实验结果一致,因此,应变率效应和围压效应对冲击地压灾害数值模拟具有适用性。

     

    Abstract: In order to study the impact failure characteristics of strain rate and confining pressure on coal samples, the Split Hopkinson Bar experimental device was used to carry out the dynamic impact experiments of 15 groups of coal samples with strain rate of 60 s-1 to 110 s-1 and axial confining pressure of 12 MPa, 15 MPa, 18 MPa. Combined with the experimental results, the simulation of failure and instability of goaf under impact load was explored, and the applicability of the influence of strain rate-confining pressure on the numerical simulation of rock burst disasters was judged according to the numerical simulation results. The results show that the impact failure of coal samples shows a significant strain rate effect, and the dynamic compressive strength of coal samples is proportional to the loading strain rate. Confining pressure conditions from 12 MPa to 18 MPa have a weakening effect on the strain rate effect and compressive strength of coal, and under the same impact pressure, the coal sample crush becomes more significant with the increase of confining pressure. The simulation results are consistent with the experimental results, so the strain rate effect and confining pressure effect are applicable to the numerical simulation of rock burst disaster.

     

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