Abstract
The mechanical properties and stress-strain relationship of cemented backfills with different stratified structure have a direct effect on the mining-filling cycle and the mining of adjacent pillars. To obtain the stress-strain evolution curves, the uniaxial compressive strength tests were performed on backfills with stratified numbers of 0, 1, 2 and 3. The deformation of stratified backfill under the compressive load is regarded as a compound of closed deformation of the macroscopic stratified structure and elastic deformation of material. The damage constitutive model of cemented backfills with different stratified structure are established by considering the influence of compacted section. Comparative analysis reveals that the calculated curve based on the established sectional damage constitutive model conforms well to the trial curve. The maximum closed strain of the structural plane has a more significant effect on the mechanical properties of backfill. In the Weibull distribution, with the increase of the parameter m, the peak strength of backfill gradually increases and then reaches to a certain value, and the stress-strain curve gradually becomes steeper, which shows that m is a reflection of the concentration level of micro-unit strength distribution in the backfill..
Highlights
Backfill mining has significant advantages in reducing tailings and controlling plane subsidence, it meets the requirements of environmental protection and has become the future development trend of mining [1,2,3,4]
Literature [11] based on the creep test of the backfill and introduced the damage variable into the Burgers model, established the creep statistical damage constitutive model of the backfill
Reference [12] considers the effect of initial temperature on the mechanical properties of the backfill, and combines the theoretical derivation to propose a temperature-time coupling damage constitutive model of the backfill
Summary
The dried tailings and Cementing material of a mine were used to do the laser particle size analysis and the particle size distribution curve of the graded tailings (Fig. 1). The mold for the backfill is made of transparent acrylic tube with a height of 100mm and an outer diameter of 50mm. The cement-sand ratio of all test pieces is set to 1: 6, and the paste concentration is 70%. 1.3 Backfill strength test Place all the finished specimens in a constant temperature (20 ± 5 °C) and constant humidity Each group of specimens was tested 5 times, and the larger discrete data was eliminated, the remaining data were averaged to obtain the stress-strain curve (see Fig. 3). In view of other scholars' research on cemented backfill, the average elastic modulus E50 is often used to characterize the backfill elastic modulus [12,13], so all the elastic modulus values in this paper are obtained by E50, which is 50% of the UCS divided by its corresponding strain value
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