Experimental Study for the Effect of Fillings on Properties of Brittle Rock Containing Two Parallel Flaws

In the underground engineering, rock masses containing flaws are quite sensitive to the fillings, yet the studies on the mechanical properties of the flawed rock under different curing time of the filling slurry are rather limited. To study the effect of filling slurry on the mechanical properties of the flawed rock mass, uniaxial compression tests are conducted on the "backfill–rock" composite sample with different proportions of filling materials under different curing time. The results show that both compressive strength and elastic modulus of the flawed sample containing two parallel flaws with fillings present obvious improvement compared with those of the flawed sample without fillings, and the enhancement extent is 20.52% and 6.35% on average respectively. Both the peak strength and elastic modulus of the samples with fillings increase gradually with the increasing of curing time or the cement–sand ratio. The filling slurry enhances the ability of the flawed sample with fillings to absorb strain energy. Compared with the non-fillings sample, the flawed samples with fillings increase the total input energy and elastic strain energy by 54.52% and 63.45% on average, respectively. As the increasing of curing time or the cement sand ratio, the total input energy and elastic strain energy increases gradually. The filling slurry effectively improves the performance of flawed granite.