不同应力水平下大理石蠕变损伤声发射特性

为研究不同应力水平下岩石的蠕变损伤与破坏规律,保持大理石分别在裂纹压密阶段、弹性变形阶段、裂纹的稳定扩展和扩容阶段与裂纹的非稳定拓展至破坏阶段处于蠕变应力作用,之后卸载重新加载至破坏,同时采集试验过程岩石的声发射数据。试验结果表明:前两个阶段应力持续作用下岩体承载能力增强,声发射AE数较少,以微裂纹闭合为主,之后加载破坏时AE数明显增多,产生时间也有所提前,b值下降时间更早;而后两个阶段应力持续作用下大理石发生蠕变破坏,裂纹的稳定扩展阶段和扩容阶段大理石发生突发式破坏失稳,只在破坏突然产生较大的AE数和能量释放率,最终破坏为主裂纹贯通破坏;裂纹的非稳定拓展至破坏阶段大理石发生渐进式失稳破坏,AE数持续产生,破坏前AE数和和能量释放率增加不明显,最终破坏为多条裂纹贯通破坏。

Marble creep damage and acoustic emission characteristics under different stress levels

In order to research the effects of rock creep damage under different constant stress，keep marble suffering stable stress during the stage of fissure pressureair tightness，the elastic deformation，crack’s stable propagation、crack’s nonstable propagation，then unload and load to failure，collecting the figure of acoustic emission.The experimental results show that the AE events of strengthing marble reduce suffering stress in the first two stages，while loading to failure then，the AE events of marble significantly increase and the b values decline in earlier time.The creep failure of marble occurs during suffering the latest two stage，crack’s nonstable propagation stage.The marble have a sudden unstable failure with the main crack，lager AE events and energy release at the moment of failure while suffering the constant stress in rack’s stable propagation stage.The marble have a graduate failure with several cracks，small variation of AE events and energy at the moment of failure while suffering crack’s nonstable propagation stage.