Abstract
The stability of underground goaf in filling mining is dominated by the interaction mechanism of the backfill-surrounding rock combination. In order to investigate the interaction mechanism and failure characteristics of the backfill-surrounding rock combination, backfill-red sandstone combinations with three different cement–sand ratios were prepared for uniaxial compression tests. The deformation and failure characteristics of the specimens were analyzed. It was found that at the cement–sand ratio of 1:4, the backfill and red sandstone interacted with and restricted each other, and the through cracks appeared in the whole specimens, which indicated that the backfill and red sandstone can jointly resist external loads and play a role in common bearing. However, with the decrease of the cement–sand ratio, the stress mainly acts on the backfill, and the deformation observed in the backfill is large while there is no obvious rupture in the rock. Based on the failure characteristics and the stress–strain curves of the specimens, the damage constitutive relationship that can describe the failure process and deformation characteristics is proposed. Correlated with the experiment results, the damage constitutive equation is established in three stages including compaction pre-synergy stage, quasi-elastic synergy deformation stage and rupture deformation stage. The failure characteristics observed in each stage are analyzed. The research results are of great significance to accurately understanding the interaction between backfill and surrounding rock, which can be used to design and select the mixture ratio of the filling materials.
Highlights
Deep mining is one of the major technical issues faced by the mining industry
The red line represents the stress–strain curve drawn by the data collected from is obvious, the stress–strain is approximately linear, and the stress increases continthe strain gauges affixed tocurve the red sandstone during loading, while the blue line is the uously with the increase of strain
For the backfill-red sandstone combinations with the cement–sand ratio of 1:4, the loading damage can be equivalent to the coupling of two damage states of backfill and red loading damage can be equivalent to the coupling of two damage states of backfill and sandstone
Summary
Deep mining is one of the major technical issues faced by the mining industry. With the increase of mining depth, the ground pressure and roadway offset increase resulting in frequent occurrence of rock burst, which significantly increases the difficulties in maintaining the stability of roadway and stope. The above research on the combined action of surrounding rock and backfill mainly involved their mechanical action mechanism and only studied the failure law, without considering the synergistic effect, and the damage constitutive model was established [29,30,31,32]. The uniaxial comIn this study, the backfill-red sandstone combination is prepared by red sandstone and pression tests are carried out, and the deformation and failure characteristics of the comfull tailings cemented backfill with different cement–sand ratios. The damage constitutive model of the describe the damage evolution law of the synergistic action between the surrounding rock backfill-red sandstone combination is established which is able to describe the damage and backfill.
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