Towards the Understanding of Damage Mechanism of Cemented Tailings Backfill

Haijun Wang

doi:10.1155/2021/4117209

Abstract

Recent studies have shown that the damage characteristics of cemented tailings backfill (CTB) are influenced significantly by the variation of cement-tailings ratio, while the effects of other influencing factors remain unanswered. The CTB damage constitutive model, which takes the corrected coefficient of damage variable into consideration, and peak toughness are introduced to investigate the effects of fine tailings contents, curing ages, curing temperatures, and water-to-cement ratios ( w / c ) on the damage evolution laws, damage ( D P ), and specific energy ( G P ) at peak stress point of CTB. The results show that appropriate content of fine tailings could improve the compressive strength of CTB and reduce its damage evolution speed and D P . The damage growth rate of CTB decreases with curing age in early curing period and increases with higher curing temperature and w / c . D P of CTB takes on a descending trend with higher w / c and fine tailings content but shows an increase with curing age. There exists no significant relationship between D P and curing temperature. G P of CTB increases with curing age and higher curing temperature with a quadratic function but is on a decline with increases of fine tailings content and w / c with logarithmic and exponential function, respectively. The results obtained from our study have important application to the successful design of backfill structures in underground mines.

Highlights

Damage Constitutive Models for Cemented Tailings BackfillIt has been well recognized that the cemented tailings backfill (CTB) contains random distribution of microcracks before failure and belongs to a kind of heterogeneous continuous medium
Those studies have shed light on the damage evolution and characteristics of cemented tailings backfill (CTB). They mainly concentrated on the influence of the c/t ratio, and the effects of other factors, e.g., w/c ratio, curing age, and fine tailings content, on the damage characteristics of CTB are rarely reported. us, this study introduces a modified damage constitutive model to characterize the uniaxial compression stress-strain curves of CTB with various curing ages, curing temperatures, fine tailings contents, and c/t ratios based on reported data and analyse these factors’ effects on the damage evolution behaviour. e peak toughness concept was introduced to compare the damage value and specific energy at peak stress point
(2) e damage growth rate of CTB increases with fine tailings content when the fine tailings content is more than 50% but decreases when the content of fine tailings is less than 50%

Summary

Damage Constitutive Models for Cemented Tailings Backfill

It has been well recognized that the CTB contains random distribution of microcracks before failure and belongs to a kind of heterogeneous continuous medium. In the failure stage of CTB, the stress prediction value of the Mazars damage model is closer to the test result because of the consideration of residual strain, but the failure rate is higher than the test curve. E residual strength of cemented backfill is susceptible to the damage correction coefficient α, while the curve changes slightly in the prepeak stage The three damage constitutive models can reflect the stress-strain behaviour and damage failure process of the filling body under uniaxial compression reasonably, but an effective damage correction coefficient should be selected for the modified Weibull damage model. The model proposed in [20] is more consistent with the experimental results, the postpeak damage rate is significantly higher than the experimental curve. e residual strain value of the filling body under uniaxial compression is not easy to determine. erefore, in the third part of the paper, the modified Weibull damage model is selected to study the influence of different factors on the damage characteristics of the filling body. e determination method of the correction coefficient of the reasonable damage variable is shown in [26]

Damage Characteristics of Cemented Tailings Backfill

Findings

Conclusions