为研究环向控制速率对砂岩力学特性的影响,利用MTS刚性试验机开展了不同环向控制速率下砂岩的单轴压缩变形试验,分析了环向控制速率对砂岩应力-应变曲线、特征应力、脆性特征和破坏模式的影响,探讨了不同环向控制速率作用下岩石破坏过程中能量演化规律。试验结果表明:环向控制速率对峰前的变形规律和峰值强度影响较小,但在峰后出现应力和应变同时减小的变化特征,并且随着环向控制速率的减小,峰后的应力-应变曲线出现应力反复下降、升高的现象,体积应变在峰后也表现出同样的变化规律;环向控制速率对岩石的脆性基本没有影响,但随着环向控制速率的减小,岩石破坏所需的时间急剧增大;与轴向控制的结果相比较,环向控制下岩石破坏以剪切为主,峰前的总的耗散能比轴向控制的要小,但在峰后随着控制速率的减小,岩石变形中的耗散能逐渐增多,减弱了峰后破坏的剧烈程度,使得峰后破坏变得可控,为获取完整的应力-应变曲线提供有利条件,而轴向控制作用下岩石破坏以轴向劈裂为主,峰后侧向应变急剧增大,破坏速度快且剧烈。研究成果可作为岩石速率效应问题的有效补充,也可为脆性岩石在环向控制下的变形规律研究提供一定参考。

To investigate the influence of circumferential loading rates on the mechanical properties of sandstone, uniaxial compression tests were conducted on sandstone specimens at various circumferential control rates using an MTS rigid servo testing machine. The effects of circumferential control rate on stress-strain curves, failure modes, and energy evolution were analyzed. Results indicate that circumferential control rates have minimal impact on pre-peak deformation and peak strength, while reducing post-peak stress and strains. As circumferential control rate decreases, the post-peak axial stress-strain curves experience alternating stress decreases and increases. Post-peak volumetric strain exhibit the same trend. Although circumferential control rate does not significantly affect rock brittleness, the time required for rock failure increases sharply as the control rate decreases. Circumferential control yields predominantly shear failure, with lower total dissipated energy during pre-peak stage. As circumferential control rate decreases, dissipated energy gradually increases during post-peak stage, which weakens the post-peak failure and makes it controllable. On the contrary, under axial control mode, axial splitting is the dominant failure mode, with sharp increases in lateral strain post-peak and violent failure. These findings provide valuable insights for understanding the rock loading ratio effect and the brittle rock deformation characteristics under circumferential control conditions.