Creep behavior is one of the most important mechanical behaviors of coal. In the present study, we systematically carried out a series of creep experiments of briquette samples under triaxial compression and gas pressure. The experimental results showed that the creep deformation characteristics of coal were related to deviatoric stress and gas pressure. The accelerating creep stage initiated when the deviatoric stress reached or exceeded the yield stress until failure took place. In contrast, when the deviatoric stress was less than the yield strength, only transient and steady creep stage occurred. Besides, gas pressure played a positive role in the creep process of coal. The axial strain of coal slightly increased with gas pressure (range from 0.13 to 0.40 MPa) when the effective triaxial stress remained constant. For example, in the steady creep stage (σ₁ = 9 MPa, p = 0.13 MPa), the axial strain of sample S₁ is 2.710% and that of sample S₂ is 3.361%, that is, coal samples with high gas pressure have higher axial strain. Moreover, gas pressure has two main effects on the mechanical behavior of coal. One is that the coal adsorbs gas molecules resulting in swelling strain and swelling stress, and the other is that the gas pressure may compress the coal particles. Considering the swelling stress and gas pressure, we intensively studied the effective stress formula of coal containing gas. Then, the effective stress was taken into consideration in the nonlinear Nishihara creep model. Furthermore, the tertiary creep factor n was introduced in the nonlinear model to control the creep deformation evolution with time so that the nonlinear model could accurately describe the full creep stage of coal. In contrast, due to the lack of such a controlling parameter, the Nishihara model failed to reproduce the accelerating creep stage.

The construction of mine surface facilities shall be carried out according to the scope of mining rights and ease of use. The underground mining of Shirengou Iron Mine uses filling method mining, and the filling station needs to be built on the surface. According to the design, it is constructed near the open pit. Based on the protection of the filling station system, the stability analysis of the open slope is needed. The failure mode of iron ore open slope is circular arc sliding failure mode. The calculation model of the stability analysis is calculated by the residual thrust method. The maximum residual thrust of the I-I section is 128.9 tons/meter, and the maximum residual thrust of the II-II section is 75.39 tons/meter. According to the calculation results, the safety measures such as slope dressing and masonry retaining wall are carried out on the open slope, and the grouting prestressed anchor cable is selected to reinforce the slope. The anchor cables are connected by reinforced concrete frame and beam, and the concrete is used. The beam acts as an anchor pier. In order to effectively consolidate the slope stability, the grouting method is combined to effectively treat the slope. After a series of slope reinforcement measures, the stability of the open slope and the safety of the filling station can be guaranteed.

The adsorption of dodecyl trimethyl ammonium bromide (DTAB) on coal can affect the wettability of coal and change the water absorption of coal. After DTAB treatment, the change in the CH₄ adsorption capacity of coal is worth further study. To reveal the microscopic mechanism of the influence of DTAB on the CH₄ adsorption capacity of coal, we employed the density functional theory (DFT) with the 6-311 G (d, p) basis set. DFT-based computations interpreted the adsorption process of CH₄ and DTAB on coal molecules and determined the stable structure, adsorption distance, Mulliken overlapping populations, and adsorption energies of the two adsorption configurations. The results showed that the adsorption energies of CH₄ and DTAB on the molecular model of coal were 2.15 and 42.69 kJ/mol and the adsorption stability distances were 0.261 and 0.238 nm, respectively. The DTAB–coal configuration was more stable than the CH₄–coal configuration. When there was competitive adsorption between DTAB and CH₄ on coal, the coal molecules preferentially adsorb the DTAB. Infrared spectroscopy and adsorption experiments were also carried out, and the calculation results of quantum chemistry are consistent with the experimental results.