Research on Strength Prediction Model and Microscopic Analysis of Mechanical Characteristics of Cemented Tailings Backfill under Fractal Theory

Abstract

In order to further study the internal relationship between the microscopic pore characteristics and macroscopic mechanical properties of cemented tailings backfill (CTB), in this study, mine tailings and ordinary Portland cement (PC32.5) were selected as aggregate and cementing materials, respectively, and different additives (anionic polyacrylamide (APAM), lime and fly ash) were added to backfill samples with mass concentration of 74% and cement–sand ratios of 1:4, 1:6 and 1:8. After 28 days of curing, based on the uniaxial compressive strength test, nuclear magnetic resonance (NMR) porosity test and the fractal characteristics of pore structure, the relationships of the compressive strength with the proportion and fractal dimension of pores with different radii were analyzed. The uniaxial compressive strength prediction model of the CTB with the proportion of harmless pores and the fractal dimension of harmful pores as independent variables was established. The results show that the internal pores of the material are mainly the harmless and less harmful pores, and the sum of the average proportions of the two reaches 73.45%. Some characterization parameters of pore structure have a high correlation with the compressive strength. Among them, the correlation coefficients of compressive strength with the proportion of harmless pores and fractal dimension of harmful pores are 0.9219 and 0.9049, respectively. The regression results of the strength prediction model are significant, and the correlation coefficient is 0.9524. The predicted strength value is close to the actual strength value, and the predicted results are accurate and reliable.

Study on Acoustic Emission and Coda Wave Characteristics of Layered Cemented Tailings Backfill under Uniaxial Compression

“…However, there is a lack of research results on the use of acoustic emission and ultrasonic signal characteristics to monitor and warn about the deformation damage of LCTB. Therefore, this paper performs uniaxial compression acoustic emission tests and ultrasonic tests on LCTB based on previous studies on the mechanical properties of LCTB [18][19][20][21] and the acoustic emission and ultrasonic characteristics of intact cemented tailings backfill [22][23][24][25]. Two factors-different filling times and filling interval time-are considered to analyze the changes in acoustic emission and ultrasonic signals during the deformation and damage of LCTB.…”

Correlation Analysis between Microscopic Pore Parameters and Macroscopic Mechanical Properties of Rock-like Materials from the Perspective of Water-Cement Ratio and Sand-Cement Ratio

“…In recent years, many scholars have carried out a series of studies on the internal relationship between micro-pore structure and mechanical properties. Many researchers [ 16 , 17 , 18 ] have used different detection methods to explore the micro-pore structure. Zhang [ 19 ], Deng [ 20 ], Li [ 21 , 22 , 23 , 24 ] discussed the evolution of the micro-pore structure of sandstone and granite samples under freeze-thaw cycles through NMR, establishing the relationship between porosity and mechanical properties.…”

Association Study on the Pore Structure and Mechanical Characteristics of Coarse-Grained Soil under Freeze–Thaw Cycles

“…With the deepening of research, it has been found that the nature of the decrease in mechanical properties of freezing-thawing porous materials is that the freezing-thawing action changes their internal microstructure [25][26][27][28][29][30][31][32][33][34]. Tang, LY [35] used nuclear magnetic resonance (NMR) to analyze the effect of freeze-thaw cycles on the internal pore structure of the soil-rock mixture.…”