基于鞭梢效应的煤岩组合体超低摩擦效应研究OA

To further reveal the influence mechanism of the size proportion of coal-rock assemblages on ultra-low friction rockbursts,a theoretical benchmark model of the ultra-low friction effect was established based on blocky rock masses.Starting from structural characteristics,the experimental model of blocky rock masses was linked with the"whiplash effect".A sandstone-coal-sandstone block structure was adopted to simulate the actual roof-coal seam-floor conditions encountered in underground coal mining.Combin-ing a self-developed ultra-low friction test device with FLAC3D numerical simulation,the influence of the height-width ratio of the"working block"on the stability of the block structural system model under the same stress environment was analyzed.The hori-zontal displacement and horizontal acceleration of the"working block"were used as indicators to characterize the intensity of the ultra-low friction effect.The correlation between the susceptibility of generating the ultra-low friction effect in the system and the ab-rupt change characteristics of the horizontal displacement of the"working block"was analyzed.The results show that the size pro-portion of the"working block"has a significant influence on the triggering threshold of the ultra-low friction effect.As the height-width ratio of the"working block"increases within a certain range,its horizontal displacement exhibits a nonlinear response of first decreasing and then increasing,while the stability first increases and then decreases.Significant instability characteristics are ob-served in the typical case"h-100 mm"(i.e.,the height of the"working block"is 100 mm,with a height-width ratio of 1:1):the x-direction acceleration time-history curve shows sustained asymmetric oscillation deviating from zero,producing persistent and irre-versible effects;the z-direction acceleration is amplified in phase,triggering instability sliding induced by the ultra-low friction ef-fect until severe slip instability of the system occurs.