Mechanical Properties and Damage Constitutive Model of High Water Material at Different Loading Rates

High water material is a new kind of chemical cementing material, that is, an important filling material in underground coal mines. To study the influence of loading rates on the mechanical properties of high water material, uniaxial compression tests at different loading rates are carried out in this work on specimens with different water to cement ratios. The results show that the peak strength, elastic modulus, and mass loss rate of the high water material have an obvious loading rate effect. The peak strength and elastic modulus increase with the loading speed, whereas the mass loss rate decreases with the increase of loading rate. For different loading rates, the failure modes of the high water material are different, and the fractal dimensions of the broken block distribution can describe the degree of crushing for high water material subjected to different loading rates. Based on the Weibull distribution function, the parameters m and F that describe the micro-unit strength of high water material are introduced. Finally, using the uniaxial stress-strain data, a damage constitutive model for high water material with different water to cement ratios subjected to different loading rates is established and the physical meanings of m and F are clarified.