挠曲核部破碎带岩石力学特性的试验研究

立煤湾膝状挠曲核部破碎带横穿向家坝水电站大坝坝基,破碎带的岩石由于完整性差,孔隙率大,含水率较高,会对坝基的变形和稳定性产生影响。通过研究破碎带岩石的物理和力学特性,发现破碎带岩石的碎裂岩、碎屑岩在三轴压缩条件下呈现非线性的应力应变关系,强度低、变形大,且没有明显的强度峰值,最终因变形过大而破坏;试验过程中,还发现随着岩石的屈服和变形的发展,出现明显的体积膨胀。并且通过破碎带岩石的流变力学试验,发现岩石流变特征明显,偏应力对流变速率有较大影响。最后根据常规三轴试验的应力应变关系建立了基于双曲线模型的改进Burgers模型,并对其参数进行辨识。

Experimental Investigations on the Mechanical Properties of Rock in the Fractured Zone of Deflection Core

The Limeiwan knee-shaped fractured zone passes through the dam foundation of Xiangjiaba Hydropower Station. Due to its poor integrity, large porosity and high water content, the soft rock in the fractured zone may have a significant impact on the deformation and stability of the dam. An experimental investigation has been conducted on the physical and mechanical properties of the soft rock in the fractured zone. In the tri-axial compression condition, the behaviors of the soft rocks are characterized by a non-linear stress-strain relationship, low strength, large deformation without obvious strength peaks and failure due to excessive deformation. Obvious volumetric dilation was also observed in the process of rock failure and plastic deformation. Furthermore, through the creep test, we found that the rocks had large creep deformation and the deviatoric stress had a great impact on the creep rate. Finally, a modified Burgers model is proposed using a hyperbolic model based on the results of tri-axial tests.