层状板岩拉伸行为及爆破非均匀损伤特征研究

Tensile behavior of laminated slate and non−uniform damage characteristics of blasting

  • 摘要: 矿山、隧道等工程中,普遍会遇到层状岩层,特别是对于一些爆破工作,层理结构的存在会显著影响爆破裂纹的扩展。因此,准确认识层状岩层的力学行为及爆破荷载下塑形区演化规律对于工程施工至关重要。本文通过巴西劈裂圆盘实验和声波测试,得到了层状板岩的抗拉强度,总结了纵波波速、波形、频谱等声学各向异性特性,并探讨了纵波波速与层状板岩抗拉强度的内在关联。采用数值模拟验证并研究了不同层理角度下层状岩体预裂爆破损伤情况,探讨了预裂爆破下层状岩体损伤特性。实验结果表明:层理角度对岩石抗拉强度和纵波波速、波形频谱特征有很大影响,抗拉强度随层理角度的增加呈对数关系减小,随纵波波速的增加呈指数关系增大,声波入射角越大,纵波速度越大,波形越光滑平稳,岩石完整性越好。层理角度对爆破损伤区大小有影响,炮孔连心线与层理夹角越大,损伤区越大。本文研究结果可为层状岩层稳定性控制及爆破作业参数优化提供重要的理论借鉴。

     

    Abstract: In mining, tunneling and other engineering projects, stratified rock formations are commonly encountered. Particularly in blasting operations, the presence of bedding structures significantly influences crack propagation during rock fracturing. Therefore, accurate understanding of the mechanical behavior of stratified rocks and the evolution patterns of plastic zones under blasting loads is crucial for engineering construction. This study employed Brazilian splitting disc tests and acoustic wave measurements to determine the tensile strength of layered slate, summarized acoustic anisotropic characteristics including P−wave velocity, waveform, and frequency spectrum, and explored the intrinsic relationship between P−wave velocity and tensile strength of layered slate. Numerical simulations were conducted to verify and investigate damage patterns in bedded rock masses under pre−splitting blasting at different bedding angles, with particular focus on damage characteristics. Experimental results show that: 1) Bedding angles significantly affect rock tensile strength and P−wave velocity characteristics − tensile strength decreases logarithmically with increasing bedding angle while increasing exponentially with P−wave velocity; 2) Larger acoustic wave incidence angles correspond to higher P−wave velocities, smoother waveforms, and better rock integrity; 3) Bedding angles influence blast−induced damage zones, with larger angles between borehole connecting lines and bedding planes resulting in more extensive damage areas. These findings provide important theoretical guidance for stability control of stratified rock masses and optimization of blasting parameters in engineering practice.

     

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