Aiming at the large deformation instability problem caused by the excavation unloading of a coal roadway in deep-buried slowly inclined jointed rock mass, the geomechanical parameters and deformation failure characteristics of an engineering geomechanical model were investigated. The in-situ stress state of the model was measured with the stress relief method. The geological and mechanical properties of roadway surrounding rock were described. The surrounding rock structure was revealed with the electron microscopy scanning method, micro-fractures and randomly distributed joints highly developed in roadway surrounding rock. Field investigation and monitoring indicated the cross-section of roadway surrounding rock shrank continuously and the deformation distribution was obviously asymmetric. Shotcrete spalling and cable broken failures frequently occurred in the middle and ride side of roof and right rib. Based on the geomechanical conditions of the coal roadway, a discrete element numerical model of coal roadway in gently inclined jointed rock mass was established. The parameters of rock mass in the numerical model were calibrated. The model ran in unsupported condition to restore the evolution process of stress, crack propagation and deformation in roadway surrounding rock due to gradual deviatoric stress release caused by excavation. On this basis, the space-time evolution characteristics and law of stress, crack propagation and deformation were obtained and then the asymmetric large fragmentation and dilatation deformation failure mechanism of roadway surrounding rock in deep-buried slowly inclined jointed rock mass was revealed. The failure reasons of the support structure were analyzed, and the relevant support principles were proposed. The research results can provide scientific references for the stability control of roadways excavated in jointed rock mass.

Deep rock mass mechanics is a professional course which is offered to undergraduate and postgraduate students in some mining universities. This course mainly includes the following topics: the geological structure of deep rock mass, the mechanical properties of deep rocks, the strength theory of deep rock masses, stability analysis and control of deep surrounding rock classification of engineering rock masses, and the application of deep rock mechanics in underground mining engineering The purpose of this course is to present students with a basic theoretical knowledge of deep rock mass engineering. Analyzing the limitations of traditional deep rock mass mechanics teaching methods, here, we propose integrating a combined FEM/DEM (Finite Element Method/Discrete Element Method) approach into the teaching of a course on deep rock mass mechanics. The mechanical behaviors and failure instability process of rock at laboratory and engineering scales were analyzed using ELFEN software (a finite/discrete element code). The results show that a combined FEM/DEM approach as a deep rock mass mechanics teaching method is completely feasible and reasonable; this approach has the advantages of strong intuition, high reliability, time and labor savings, and low cost, which can offset the shortcomings of traditional teaching methods. Moreover, the proposed approach can stimulate students’ interests in a mining course on deep rock mass mechanics, deepen students’ understanding of the course curriculum, and cultivate students’ innovative abilities and subjective initiatives.

In this paper, roof-cutting technology of directional energy-cumulative presplitting blasting is taken as the research object. Through the numerical simulation software Ansys/Ls-dyna3D, the process of energy-cumulative blasting and non-cumulative blasting is simulated and analyzed by using the ALE algorithm. Moreover, the evolution processes of tensile strain energy, detonation stress wave of explosives, stress state of rock mass, and rock crack damage cumulative are compared in two conditions. In the energy cumulative state, the detonation wave acts centrally on the hole wall in the energy cumulative direction to form an initial crack, and then under the action of the jet of energy cumulative, the crack continues to propagate until it runs through. In the non-energy cumulative state, the crack propagates uniformly around the hole wall, forming irregular short cracks. The simulation is verified by the field test, and the law of crack propagation is the same with the simulation. Therefore, directional energy-concentrated presplitting blasting has good practicability in a roof presplitting operation.

The difference in energy accumulation in coal and rock under the same stress level is analyzed, and it is found that the difference of energy accumulation of coal rock under the same stress level mainly depends on the elastic modulus of coal rock material. Based on the structural characteristics and mechanical properties of coal–rock, the mechanical model of combined coal–rock body was constructed and analyzed, and the calculation formula of partition energy storage of combined coal–rock body was deduced. The axial compression test of combined coal–rock body under different loading rates was designed and carried out. Finally, the differential energy instability model of the combined coal–rock body was constructed. An evaluation index of the impact tendency of the combined coal–rock body considering the elastic energy difference and the release time is proposed, which provides a multi-scale criterion for accurately evaluating the impact propensity of the combined body.

Strata structure is an important factor affecting floor heave of deep soft rock roadway, however, the mechanism of floor heave induced by the rock structure has not been fully understood, so it is still necessary to study the floor heave of deep-buried roadway under different rock structure conditions.Thus providing further theoretical basis and scientific basis for the control of surrounding rock in mine tunnels. In order to study the floor heave mechanism of soft rock roadway deep-buried roadway excavated in soft rock of gently inclined thin strata, a physical model experiment based on the engineering geological conditions of typical mine roadway was carried out. During the experiment, CCD camera and strain acquisition system were employed to collect image data and strain data. Based on the analysis of the experimental results, the following conclusions are drawn: (1) For the soft rock roadway located in deep-buried thin rock stratum, horizontal stress is an important factor affecting the floor heave of roadway; (2) When the floor heave occurs in the roadway, the strain distribution of floor of roadway is funnel-shaped, the max VME strain value of the floor is near 0.19, the affected range of floor strata is about half of the roadway width; (3) The surrounding rock within one time of the tunnel diameter is in the state of tensile stress after the process of roadway floor heave failure, and the areas of tensile stress and compressive stress in the surrounding rock alternates around the roadway; The failure mechanism of floor heave of the roadway is the fracture and uplift of the floor of roadway. Besides, a numerical model was conducted to verify the results of the physical model, the results of numerical simulation are in good agreement with those of physical model.

Xinzhuang Coal Mine in Huaneng Qingyang Mining Area has geological characteristics such as large buried depth, thick topsoil and hard overburden, which is a typical kilometer-deep rockburst mine.Currently, the mine remains in the fundamental construction phase. This provides a theoretical foundation for the mine’s subsequent production processes. , this paper studies the stress distribution law of surrounding rock in the stope of Xinzhuang Coal Mine. First of all, select the Panel 1 west wing of Coal 8 as a typical representative, and establish a large three-dimensional refined numerical model. Then, through numerical simulation research, the characteristics of surrounding rock abutment stress distribution zone in the mining process of the working face under complex conditions are obtained, which provides support for the regional design of rockburst prevention and control. The main research conclusions are as follows: (1) The research reveals the distribution characteristics of mining stress, elastic energy accumulation, and plastic zone at different widths of the first mining face, and determines the reasonable width of the working face. It is considered that the width of the working face can be greater than 175 m and less than 250 m, and the design width 200 m of the working face of Xinzhuang Coal Mine is reasonable. (2) The research reveals the evolution law and influence factors of mining stress, elastic energy accumulation and plastic zone distribution in the first mining face. The research results can not only provide theoretical support for the subsequent production of Xinzhuang Coal Mine, but also provide reference for the rockburst prevention and control work of mines with similar geological conditions.