双轴加载条件下红砂岩基本力学特性及破坏机制

Basic mechanical properties and failure mechanism of red sandstone under biaxial loading condition

为研究巷道开挖卸荷后岩体的变形破坏机理,开展了不同侧压条件下红砂岩双轴加载试验,分析侧压影响下双向应力状态红砂岩基本力学特性及声发射演化规律,揭示侧压影响下双向应力状态红砂岩破坏机制。结果表明:随着侧压增大,红砂岩峰值强度及弹性模量呈先增大后减小趋势,而峰值应变呈逐渐减小趋势,其破坏模式由劈裂破坏向剪切破坏转变;加载过程中声发射累计能量随侧压增大而逐渐减小,但试样破坏阶段声发射能量逐渐增大,表明双轴加载情况下剪切破坏释放能量大于劈裂破坏。研究结果可为巷道围岩控制及冲击地压灾害防治提供一定的理论支撑。

In order to study the deformation and failure mechanism of rock mass after excavation and unloading of roadway,biaxial loading tests of red sandstone under different lateral pressures were carried out.The basic mechanical properties and acoustic emission evolution law of red sandstone under bidirectional stress state under the influence of lateral pressure were analyzed and the failure mechanism of red sandstone under bidirectional stress state under the influence of lateral pressure was revealed.The results show that with the increase of lateral pressure,the peak strength and elastic modulus of red sandstone increase first and then decrease,while the peak strain decreases gradually and the failure mode changes from splitting failure to shear failure.The cumulative energy of acoustic emission decreases with the increase of lateral pressure during the loading process,but the energy of acoustic emission increases gradually during the failure stage,indicating that the released energy of shear failure is greater than that of splitting failure under biaxial loading.The results can provide theoretical reference for roadway support and rock burst mitigation.