Backfilling is commonly used in underground mines to improve the stability of overlying strata. The performance of the backfill and its interaction with surrounding rock are the key issues in backfill mining research. In this paper, the displacement and stress field evolution characteristics of the overlying strata in backfill mining were analyzed by a physical model, as well as the interaction between the backfill and surrounding rock. The research results show that when backfill mining is employed, the backfill mass and the unexcavated rock mass jointly bear the loads of the overlying strata. The loads of the overlying strata are transferred to the dense backfill mass and the surrounding rock. The stress in the near-field area of the surrounding rock increases and stabilizes gradually. The backfill mass improves the stress distribution state and reduces the stress concentration of the surrounding rock, which is conducive to preventing the progressive damage of the overlying strata. In addition, the backfill mass excavation has a significant influence on the stability of the overlying strata and the surrounding rock stress field. The backfill mass is a passive force-bearing structure that can effectively manage the deformation of the overlying strata and the phenomenon of underground pressure.

Due to the impacts on the ecological environment, production safety and the economic benefits of large open-pit water deposits, there is no longer a single drainage method within the pit that can be used to meet the need for further deep mining. Therefore, curtain grouting technology is proposed for use in the prevention and control of mine water. The flow control equation of slurry in vertical fissures under the influence of self-weight stress was derived, and a three-dimensional visualized laminated jointed rock grouting model was developed independently to study the slurry transport mechanism, diffusion pattern, and sealing mechanism, which verified the correctness of the control equation. Field trials of industrial curtain grouting were also carried out at the mines, and the effectiveness of curtain water blockage was tested using visual analysis, inspection hole detection, and geophysical exploration methods. The results showed that after grouting the curtain, water-conducting cracks in the formation can be filled well and sealed, and the curtain has a good water-blocking effect. A complete set of diversified value-taking grouting systems is obtained, which can ensure the development of a green, safe and sustainable mine in the future.

To grasp the phase change characteristics of the filling slurry from fluid to solid state in time, conducted a study on the setting characteristics of the filling slurry with different aggregate combinations, and analyzed the law of the initial and final setting time with the change of the amount of cementation powder, filling plant tailings, tailing pond tailings, and water. The results show that the initial and final setting time of the filling slurry prepared from the tailings of the filling plant is proportional to the concentration, and is positively correlated with the slope decline of the sand-cement ratio. The filling slurry prepared from the tailings of the tailing pond shows roughly the same change trend as the above slurry, but the change law is not obvious, which cannot be expressed by one kind of functional model, and the initial setting time and final setting time are less than the above slurry, which is because the tailings of the tailing pond contain more fine particles, which play a role in delaying setting in the slurry. For example, for five kinds of filling materials with different aggregates of 4:1, 6:1, 8:1, 12:1, and 20:1 sand-to-ash ratios and concentrations of 66%–72%, the initial setting times of filling slurry prepared from tailings of filling plant and tailings of tailing pond were 75.3 h–112.3 h, 77.6 h–122.2 h, and the final setting times were 82.8 h–123.4 h, 85.5 h–133.9 h. Therefore, it shows that the use of filling plant tailings containing fewer fine particles to prepare filling slurry can obtain a better treatment effect of the mining area, and the shortening of the solidification and hardening process of filling slurry can accelerate the mining cycle operation, and increase the amount of solid waste disposal per unit time, thus creating the necessary technical conditions for the enterprise to improve production efficiency and sustainable development.

In order to investigate the microscopic response mechanism of limestone deterioration under alternating water-rock action in the acidic environment, the porosity, water absorption, mass loss characteristic, and microcrack propagation characteristic were analyzed by laboratory wetting-drying cyclic tests. The results show that, with increasing the number of cycles, the porosity, water absorption, and mass deterioration of the limestone specimens showed an overall increasing trend; moreover, at the beginning of the cycles, the physical deterioration of the specimen was significantly affected by the wetting-drying cycles, and at the end of the cycles, the physical deterioration of the specimen tended to be stable. The porosity deterioration degree reached 30.324% at the beginning of the cycles; there is a slight fluctuation in 20 cycles and then decreases as the number of cycles increases. The growth rate of water absorption increases slowly in 5~15 cycles and reaches the peak value in 20 cycles, and the growth rate decreases rapidly in the latter stages of the cycles. The increase rate of mass deterioration degree decreases with the increase of cycle number, the maximum average value can reach 61.887% at the beginning of cycles and is relatively stable at 20~25 cycles, and the average value at the end of cycle is obviously reduced by 3.167%. The nuclear magnetic resonance (NMR) test shows that the number and size of pores in the rock gradually increase with the increase of the number of wetting-drying cycles, and the wetting-drying cycles aggravate the internal damage of the rock. The number of shear cracks and fragmentation of the specimens increase as the increase of the number of cycles, and the failure of the specimens is mainly in the form of shear damage in the uniaxial compression test.

In order to reveal the compaction and deformation mechanism of the crushed rock body in the collapse zone of the hollow area and the rule of slurry diffusion, the rock body in the collapse zone of the 10806 integrated mining face was taken as the object of the study, and indoor physical simulation and ANSYS Fluent numerical simulation were combined to carry out the study. Firstly, a multi-axial loading platform was used to carry out the compaction test of the broken rock body, and the rock body was graded according to the grain sizes of 0–2, 2–4, 4–6, 6–8 and 8-10cm to analyze the compression deformation and void evolution characteristics; then a visual grouting system was used to study the flow pattern of the slurry; finally, models with different porosities (0.4, 0.6) were constructed to investigate the effect of grouting pressure (10 kPa-1 MPa) on the diffusion of the slurry. Finally, different porosity (0.4, 0.6) models were constructed to investigate the effect of grouting pressure (10kPa ~ 1MPa) on slurry diffusion. The results show that: the compression of fractured rock body is divided into two stages: rapid (74%-85.7% of total deformation) and slowing down, and the rapid compression stage is the optimal time for filling; the smaller the porosity is, the slower the flow rate of the slurry, and the lower the filling efficiency is; the positive correlation between grouting pressure and slurry diffusion area and flow rate, and the best filling effect is achieved when 1MPa is used, and the compacted area needs higher pressure and encrypted grouting holes. The study can provide theoretical basis for the optimization of filling parameters in the collapse zone of the hollow zone.