Experimental Study on Influence of Loading Rate on Brittleness Indexes of Marble

Experiments on dried and saturated marble samples were conducted at different loading rates to investigate the influences of loading rate and saturated water on the deformation, strength and brittleness indexes of marble. Strength and deformation, the applicability and variation of different brittleness indexes, and the relationship between elastic strain energy limit and brittleness indexes were analyzed comprehensively under different loading rates. The results show that the strength of marble increases with an increase in loading rate, while elastic modulus decreases and peak strain increases. The influence of loading rate on brittleness was analyzed for seven values of the latter. The results indicate that some of the indexes of brittleness cannot reflect the influence of loading rate. Meanwhile, there are two indexes that can accurately express the variation law of rock brittleness with an increase in loading rate. Moreover, these brittleness indexes increase linearly with an increase in loading rate and exhibit a quadratic function relationship with elastic strain energy limit. A new brittleness index that can comprehensively consider strength and energy is proposed to fully express the effects of loading rate and saturation on rock brittleness. In accordance with the macroscopic failure characteristics of marble, the conclusion that a brittleness index increases with an increase in loading rate was proven correct.