To explore the effects of water-cement ratio and sand-cement ratio on micro-pore structure characteristics and macroscopic mechanical properties and thus improve the understanding of rock-like materials, the mechanical test and detection of micro-pore structure combining NMR and SEM were carried out. The effects of WCR and SCR on different porosity parameters and mechanical properties were discussed. The correlation and internal relationship between mechanical properties and parameters of different porosities and fractal dimensions were analyzed. Experimental results showed that the different porosity parameters and fractal dimensions increased with the increase in WCR. 1.0 (SCR) was the turning point of different porosity parameters and fractal dimensions. When the SCR was less than 1.0, the porosity parameters and fractal dimension gradually decreased, while when the SCR was greater than 1.0, the porosity parameters and fractal dimension gradually increased. Microscopic porosity parameters and fractal dimension played an important role in the influence of experimental factors on mechanical properties. Different porosity parameters and fractal dimensions were negatively correlated with mechanical properties. Compressive strength and different porosity parameters conformed to a good exponential relationship, while the fitting relationship between tensile strength and mechanical properties was not obvious. This study can provide a reference for the follow-up study of rock-like materials.

As an important energy material, mineral resources have an important role in the rapid growth of the national economy. In recent years, with the enhancement of mining strength and the improvement of mechanized production level, the depth of mining has also increased year by year. Therefore, the number of heat hazards in deep mine mining has increased year by year, and the problem of heat loss in deep mines has become increasingly prominent, which has seriously affected the safe and efficient production of mines. In this paper, the application of nanoporous super insulation materials in the prevention of thermal damage in deep mining of metal mines is studied, and the related theories of nanoporous super insulation materials and the prevention of thermal damage in deep mining of metal mines are understood on the basis of literature data. Nanoporous thermal insulation materials refer to thermal insulation materials with pore diameters in the nanometer range. This material can effectively prevent the collision of gas molecules and prevent the heat conduction of the gas. Then, the application experiment of nanoporous super thermal insulation materials in the prevention and control of heat damage in deep mining of metal mines is carried out. Through experiments, it is concluded that the room temperature thermal conductivity of the experimental material decreases with the increase of the addition of SiO₂ aerogel, and the downward trend is linear, and when the heat source temperature is 200°C, the coating surface temperature of the thermal insulation material (excluding aerogel) is 100°C, and the thermal insulation temperature difference is 100°C, while when the coating surface temperature of the aerogel thermal insulation coating is only 60°C, the thermal insulation temperature difference is 140°C. From these data, it can be seen that the thermal insulation performance of nanoporous super thermal insulation materials is better, which verifies the feasibility of its application in the prevention of heat damage in metal mine mining.

The repeated cyclic freeze-thaw effect in low-temperature environments causes irreversible damage and deterioration to the microscopic pore structure and macroscopic mechanical properties of a rock. To study the effects of the freeze-thaw cycle on the porosity and mechanical properties, the indoor freeze-thaw cycle test and mechanical tests of sandstone-like materials were conducted. Based on nuclear magnetic resonance, the influence of the freeze-thaw cycle on microscopic pores was analyzed, and the intrinsic relationship between porosity and mechanical strength was discussed. Meanwhile, the energy change in the uniaxial compression test was recorded using the discrete element software (PFC2D). The influence of freeze-thaw cycles on different types of energy was analyzed, and the internal relationship between different energies and freeze-thaw cycles was discussed. The results showed that the microscopic pore structure is dominated by micropores, followed by mesopores and the smallest macropores. With an increase in the freeze-thaw cycle, both micropores and mesopores showed an increasing trend. The porosity showed an exponentially increasing trend with the increase in freeze-thaw cycles. The peak strength and elastic modulus decreased exponentially with the increase in freeze-thaw times, while the peak strain showed an exponentially increasing trend. The strain energy and bond strain energy showed a trend of increasing and decreasing in the front and back stages of the peak strength, respectively. However, the frictional energy always showed an increasing trend. The total energy, strain energy, bond strain energy, and friction energy all showed exponential increases with the increase in the number of freeze-thaw cycles.

The response characteristics of the mesostructure and macro-characteristics of the soil–rock mixture under repeated freeze–thaw action have an important influence on the safety and stability of the dump slope in low-temperature environments. In order to further understand the multi-scale response behavior of a soil–rock mixture under freeze–thaw cycles, this paper carried out indoor freeze–thaw cycles, uniaxial compression, and electrochemical impedance spectroscopy tests on a soil–rock mixture taken from a graphite mine dump in Jixi City, Heilongjiang Province, China. Combined with the simulation calculation of discrete element numerical software (PFC2D 7.0), the effects of freeze–thaw cycling on electrochemical impedance spectrometry (EIS) mesoscopic parameters, uniaxial compressive strength, and crack propagation of soil–rock mixtures were analyzed. The intrinsic relationship between mesoparameters and macroscopic mechanical properties was established. The results showed that as the number of freeze–thaw cycles increases from 0 to 15, the mesopores inside the soil–rock mixture gradually increase, and the angular similarity of distribution characteristics increases by 5.25%. The uniaxial compressive strength and the peak secant modulus increase exponentially with the increase in the number of freeze–thaw cycles, the uniaxial compressive strength decreases by 47.62%, and the peak secant modulus decreases by 75.87%. The peak strain and pore compaction stage showed an exponential increase and an increasing trend, respectively, and the peak strain increased from 2.115% to 4.608%. The failure mode was basically similar in different cycles; the failure cracks extended from the corners to the middle and lower parts before the failure finally occurred. The types of failure cracks were mainly tensile cracks, followed by tensile shear cracks and the fewest compression shear cracks. The similarity and uniaxial compressive strength conformed to a good linear relationship with the number of freeze–thaw cycles, with the uniaxial compressive strength decreasing linearly with the increase in similarity.

The experiment of rock-like material plays an important role in the simulation of engineering fractured rock mass. To further understand the influence of raw materials on rock-like materials, this paper carried out the indoor mechanical properties test and the micro-pore structure detection combining NMR and SEM. The effects of micron-silica fume (SF) on microporous structure parameters and macroscopic mechanical properties under different conditions of water–cement ratio (WCR) and sand–cement ratio (SCR) were discussed. The intrinsic relationship between parameters of different scales was analyzed. The experimental results showed that the porosity parameters of different radii gradually decreased with the increase in SF. The reduction rate of macroporous porosity was the greatest, and the decreasing rate of microporous porosity was the smallest. With the increase in SF, the microscopic characteristics of the internal surface changed from more pores, complex morphological distribution, rough surface to fewer pores, regular morphological distribution and flat and uniform surface. The box fractal dimension also showed a decreasing trend. Micro-pore structure makes a valuable contribution to the influence of SF on mechanical properties. The compressive strength and tensile strength increased with the increase in SF. The box fractal dimension and porosity of different radii were negatively correlated with mechanical strength. Different porosity parameters conformed to a good exponential relationship with mechanical properties. The research results can provide reference value and research space for subsequent rock-like material research.

In order to ensure the safe mining of kilometer mining working surface threatened by impact ground pressure, a metal mine ground pressure monitoring and early warning based on deep learning data analysis are proposed. This paper expounds the theoretical basis of rock burst, analyzes the inducing factors of deep well rock burst, analyzes and introduces the classification of rock burst, focuses on the progressive failure process of rock burst and standard of rock fracture depth of deep ore and rock in a metal mine, carries out triaxial stress-strain test on the core in the laboratory, and evaluates the tendency of rock burst for deep ore and rock through elastic strain generation, strength brittleness coefficient method, and deformation brittleness coefficient method. The real-time monitoring and early warning system of rock burst can monitor the dynamic change of advance stress in the working face in real time and give real-time early warning to the dangerous area and degree of rock burst. The experimental results show that the working face enters the fault affected area when it advances 170 m in front of the fault. When the working face advances to 100 m in front of the fault, it enters the high stress area formed by the superposition of fault tectonic stress and mining stress. When the working face advances to 40 m in front of the fault, the stress reaches the maximum. Therefore, the system can accurately predict the impact risk area and its risk degree and realize the safe mining of high impact risk face.