Experimental study on triaxial disturbance and failure characteristics of rock-like specimens
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国家科技期刊平台
NETL
NSTL
维普
万方数据
为研究高应力围岩扰动破坏机制,开展了不同围压下类岩石试件的三轴常规压缩和三轴循环扰动试验,得到了试件的扰动应力-应变规律和变形破坏特征,并对试件开展了核磁共振(Nuclear Magnetic Resonance)成像试验,从微观角度进一步阐明了试件扰动破坏机理.研究结果表明:(1)试件在不同围压下均存在一个阈值强度,轴向荷载超过阈值强度后,轴向变形对扰动变得敏感,再次施加扰动会引起试件显著变形,当轴向荷载低于阈值强度时,变形对扰动不敏感.阈值强度与极限强度的比值可以反映试件的抗扰动能力,随着围压增大,该比值呈现逐步递减的规律,说明高围压下试件抗扰动能力下降,对扰动作用更敏感.(2)扰动作用下类岩石试件存在弱化效应,如常规三轴10 MPa围压下试件表现出腰鼓破坏,而受扰动作用后,试件呈现斜切脆性破坏,与常规三轴5 MPa围压下破坏形态相近.(3)岩石试件在高应力作用下进入塑性流动状态,内部颗粒重新排列,内部小孔隙与大孔隙的占比减少,而中孔隙的占比显著增多,试件内部孔隙率整体降低.
To investigate the disturbance and failure mechanisms within high-stress surrounding rocks,this study conducted triaxial conventional compression and cyclic disturbance tests on rock-like specimens under various confining pressures,elucidating the specimens'disturbance stress-strain behavior and deformation failure charac-teristics.Additionally,Nuclear Magnetic Resonance(NMR)imaging tests were performed to delve deeper into these mechanisms from a microscopic standpoint.The findings reveal:(1)Under varying confining pressures,each specimen exhibited a threshold strength,beyond which axial deformation became markedly sensitive to dis-turbances,leading to significant specimen deformation upon reapplication of disturbances.Below this threshold,deformation showed insensitivity to disturbances.The ratio of threshold to ultimate strength reflects the speci-men's resistance to disturbances,which decreases with increasing confining pressure,indicating heightened sensi-tivity to disturbances under high-pressure conditions.(2)A weakening effect was observed in rock-like specimens under disturbance;for instance,specimens exhibited barrel failure under a conventional triaxial confining pressure of 10 MPa,while displaying oblique brittle failure akin to that observed under 5 MPa after disturbance,highlight-ing the transformative impact of disturbances on failure modes.(3)High-stress conditions prompted rock speci-mens to enter a plastic flow state,characterized by internal particle rearrangement and a significant shift in pore size distribution,with a notable decrease in both small and large pores in favor of medium-sized pores,overall reducing the specimen's porosity.These insights advance our understanding of the behavior of high-stress sur-rounding rocks under disturbances,offering valuable perspectives for engineering and geological applications.
rock-like specimentriaxial disturbancethreshold intensitydestruction patternnuclear magnetic resonance
国家科技期刊平台
NSTL
维普
万方数据
