Providing support for deep soft rock roadways under dynamic pressure is a major technical challenge. In this study, the distribution characteristics of surrounding rock-bearing structure of such roadways were systematically examined using theoretical analysis and numerical simulation. Based on the control effect of different support methods on the surrounding rock-bearing structure; a reinforcement scheme for deep dynamic soft rock roadway was proposed and applied. The results indicate that: (1) by increasing the supporting strength of the internal bearing structure, cohesion, and internal friction angle of the surrounding rock, and by reducing the influence of mining, making the external bearing structure close to the roadway and reducing the thickness of the bearing structure, can improve the bearing capacity of the shallow surrounding rock in the roadway; (2) under the conditions of dynamic load and creep of the surrounding rock; the deformation of the rock increases significantly; external bearing structure is far away from the roadway, and thickness of the bearing structure increases; anchor cable support and floor pressure relief effect better control over the roof and the roadside deformation and floor heave, respectively; and the thickness of the corresponding external bearing structure is reduced by 30.84% and 41.50%, respectively; and (3) based on the application, the zonal reinforcement scheme of “fix cable to shed, floor pressure relief, deep-shallow composite grouting” is proposed and put into practice, with good results. The results of this study can provide theoretical support and reference for the determination of supporting parameters in deep roadways.

The borehole television approach is an effective way of detecting mining-induced fractures in overburden strata as it can visualize fractures to facilitate a quantitative analysis of size, quantity, length, and other features. In this article, the borehole television approach is applied on panel 20105 of the Wangjialing Coal Mine in China to investigate the overburden movement and spatiotemporal evolution law of mining-induced fractures from the coal seam to ground surface. The results revealed that the overburden strata experienced the phases of roof caving, generation of fracture, bed separation, dislocations, fracture propagation, surface subsidence, and closing of fractures. The process can be divided into the initiation stage, the active stage, and the degradation stage along the mining direction. For exploited working faces, the caved zone height is 2.9–4.11 times the mining height, and the height of the fractured zone is 19.35–22.19 times the mining height. The height range of the three parts in the fractured zone is 24–26, 40–45, and 30–35 m. Significant fractures were observed in the bending zone. Step subsidence and cracks, which indicate severe damages, were observed on the ground surface above the goaf.

This paper systematically examines the feasibility of using ultrasonic vibration excitation for rock breakage and fragmentation; it focuses on the failure mechanisms of rock mass under the impact of ultrasonic waves, and the development of ultrasonic technology. Laboratory testing using a self-designed system was conducted in this paper to further validate the efficiency and reliability of rock breakage using ultrasonics. The results show that: (i) under the effects of both the high speed impact of ultrasonic vibration excitation and induced rock vibration excitation, a fracture is initiated and propagates rapidly within and outside of the rock. Under ultrasonic vibration excitation for 140 s, the compressive strength decreased by 45.6%; (ii) under the excitation of ultrasonics, the rock specimens failed completely in a short time from inside to outside, and there are distinct fissures in the internal nucleation of the rock. It is suggested that ultrasonic excitation provides a novel and promising option for rock fragmentation and breakage, which optimises the efficiency of underground hard rock engineering.

Critical mining under buildings, railways, and water bodies (BRW) brings the contradiction between high recovery rate and minor environmental hazards. To lessen this contradiction, an innovative mining method referred to as “wide strip backfill mining” (WSBM) was proposed in this study. A Winkler beam model is applied to the primary key strata (PKS), and the study revealed a surface subsidence control mechanism and designed the technical parameters of the method. The respective numerical simulations suggested the feasibility of the proposed method and the main influencing factors on surface subsidence can be ranked in descending order as wide filling strip width (WFSW), filling ratio, and pillar width. Meanwhile, a drop in the WFSW from 96 m to 72 m brought out the surface subsidence reduction by 44.5%. By using the super-high water content filling material, the proposed method was applied in the Taoyi coal mine under critical mining conditions. The resulting surface subsidence and deformations met the safety requirements for building protection level 1, and the recovery rate reached 75.9%. Moreover, the application of the method achieved significant technical and economic benefits. The research can provide a theoretical and experimental substantiation for critical mining under BRW.