Mechanism of anomalously low friction phenomenon in deep block rock mass

The anomalously low friction phenomenon is one of the typical dynamic phenomena in the deep block rock mass,reflecting the inconsistent and inconsecutive dynamic characteristics of deep block rock mass.Based on the anomalously low friction test carried by Russian academician Kurlenya M V,a one-dimensional dynamic model was established,and the analytical solution of transverse displacement of working block was obtained.It was demonstrated that the analytical results based on the one-dimensional dynamic model agreed well with the experimental data.The geo-mechanical condition for the occurrence of the anomalously low friction phenomenon lied in the canonical coordination of delay intervals between the vertical and horizontal pulse impact on the block system and the working block respectively,and its formation mechanism rested on the redistribution of vertical force and variation of dynamic friction factors between blocks under the powerful impact,and the discrete periods of anomalously low friction phenomenon were closely related with the spectrums of low-frequency low-speed reversal pendulum-type wave.