One-dimensional Static And Dynamic Loads Under The Rock Mechanical Properties Of The Pilot Study

The theories and experimental study of uniaxil static loading and dynamic loading on rocks for the last decades were firstly summarized, in which Dr. Li XiBing and their study group's theories on rock impact dynamics were especially reviewed. Then a new method for dynamic loading with intermediate strain rate was developed in experiments, in which a low cycle fatigue loading is adopted to obtain qusi-dynamic loading using servo-controlled Instron material testing system. Through the above method, large numbers of experimentations were carryed out on red sandstone, and experimental results obtained from sandstone revealed that the static load is of great influence on both the failure energy G and dynamic response of rock. It was found that both the failure energy G and the maximum failure load Pb, decrease with the increasing of static load. The maximum failure stress ob in the present loading case is found to be larger than that in the static loading case but less than that in the dynamic loading case only. Stress vs. strain curves become nonlinear in the whole static-dynamic loading process as the static stress increases to one third of static strength of sandstone, which may be considered as a transition point of this rock. Young' s modulus E decreases while Poisson's ratio v increases with the increasing of static load, which shows a kind of soften tendency under a higher staticload.Based on these experiments on sandstone, the conclusion that rock may be broken easier under a combinatory static-dynamic loading than under a dynamic loading only is acquired. The combinatory loading method is useful for the investigation of constitutive relationship and failure behavior of rock,Finally, the practical meaning and engineering applications were simply discussed, and some potential applications were illustrated.