Abstract
In longwall mining of coal mines, the large deformation of small pillar retaining roadways creates difficulties for the safe and efficient retreating of the mining panel. Based on the engineering background of a small coal pillar retaining roadway in Wangzhuang coal mine, pressure relief technology for non-penetrating directional pre-splitting blasting with a deep hole ahead was proposed. The influence of the non-penetrating fracture length on the pre-splitting effect was studied by numerical simulation. The results showed that the vertical stress in the coal pillar center, the small pillar retaining roadway deformation, and the energy accumulation on the pillar decreased with an increase in the non-penetrating fracture length. The vertical stress at the working face end increased with an increase in the non-penetrating fracture length. The field application and monitoring results indicated that non-penetrating directional pre-splitting blasting could effectively control the deformation of small pillar retaining roadways. The roof-to-floor and rib-to-rib maximum convergences of the 6208 tail entry were reduced by 53.66% and 52.62%, respectively, compared to the results with no blasting. The roadway section met the demands of mining panel high-efficiency retreating, thereby demonstrating the rationality of the technical and numerical simulation results. The research results shed light on the improvement of small coal pillar retaining roadway maintenance theory and technology.
Highlights
The total length of the roadways on both sides of the mining panels in Chinese underground coal mines can be up to several million meters
Particle Hydrodynamics (SPH) and Finite Element Method (FEM) model to investigate the extent of stress, analyzed the crack propagation behavior related to slit charge blasting under high static stress damage zone and fracture patterns in rock due to blasting
Aiming at the characteristics of small coal pillar roadway protection, we propose pressure relief technology for non-penetrating directional presplitting blasting with a deep hole ahead
Summary
The total length of the roadways on both sides of the mining panels in Chinese underground coal mines can be up to several million meters. Particle Hydrodynamics (SPH) and Finite Element Method (FEM) model to investigate the extent of stress, analyzed the crack propagation behavior related to slit charge blasting under high static stress damage zone and fracture patterns in rock due to blasting. Research on blasting fractures is currently focused on fracture propagation, and distribution around a borehole under high static stress, analyzed the crack propagation behavior there are few studies on the control of blasting fractures propagation in the coal mines’ filed application. The use of non-penetrating directional pre-splitting blasting with a deep hole to protect the small coal pillar roadway is an important breakthrough in roadway maintenance, and will be conducive to the formation of a perfectly safe and efficient non-pillar mining theory and technical system
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