层理倾角对受载千枚岩能量演化及岩爆倾向性影响

Effect of bedding dip on energy evolution and rockburst tendency of loaded phyllite

  • 摘要: 选择5种不同层理倾角的千枚岩进行单轴一次加卸载试验,探讨层理倾角对千枚岩变形破坏过程中能量演化及岩爆倾向性影响.试验结果如下:各岩样应变能演化相似,在应力峰值前表现为能量积聚,峰值后为能量释放和耗散.但随着层理倾角的增大,其储能极限、残余弹性能和最大耗散能均呈U型变化,通过拟合在60°均取得最小值;随层理倾角增大,在峰前岩样的弹性能比例值呈倒U型变化,其中在60°取得最大值,表明峰前在60°处用于层理压密做的功最少.而且在峰前最大弹性能比例随层理倾角增加变化幅值较小,体现出峰前层理倾角对储能效率影响较小.在峰后弹性能比例下降幅度大小为60° > 30° > 45° > 90° > 0°,说明含0°层理岩样的峰后裂隙发育最不充分表现出的脆性最大;结合弹性变形能指数(Wet)和冲击能量指数(Wcf)的优点建立新判据储能性能和峰后继续破坏耗散能的比例(W),并计算各倾角岩样的W值,其从小到大为60°→45°→30°→90°→0°.

     

    Abstract: During the mining of deeply metal ore bodies, the accumulation and release of the strain energy of the surrounding rock is one of the causes of catastrophes. However, there are a large number of random distribution joints and fractures in a rock mass, which makes the evolution of strain energy more complicated and the catastrophe more difficult to predict. Therefore, five phyllites with different bedding dip angles were selected for uniaxial loading and unloading tests to investigate the effects of bedding dips on energy evolution and rock burst tendency during deformation and failure of phyllites. The strain energy evolutions of each rock sample are similar, showing energy accumulation before the peak stress and energy release and dissipation after the peak stress. However, with the increase of the bedding dip angle, the energy storage limit, residual elastic energy, and maximum dissipation energy show U-shape, and the minimum value is obtained at 60° by fitting. With the increase of the bedding dip angle, the ratio of the elastic energy of rock samples changes in an inverted U-shape before the peak, and the maximum value is obtained at 60°, indicating that the minimum work is done for bedding dip angle at 60° before peak. Moreover, the maximum elastic energy efficiency changes slightly with the increase of the bedding dip, which shows that the influence of bedding dip angle on the energy storage efficiency is small before the peak. After the peak, the decrease range of the elastic energy ratio is 60°→45°→ 30°→ 90°→0°, indicating that the post-peak fracture of the rock sample with 90° is the least developed and shows the greatest lithologic brittleness. A new criterion modified impact energy index (W) was established by combining the advantages of elastic deformation energy index (Wet) and impact energy index (Wcf). The W value of rock samples is calculated as 60°→45°→30°→90°→0° from small to large.

     

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