Coal Wall Spalling Mechanism and Grouting Reinforcement Technology of Large Mining Height Working Face

Abstract

To control the problem of coal wall spalling in large mining height working faces subject to mining, considering the Duanwang Mine 150505 fully mechanized working face, the mechanism of coal wall spalling in working faces was investigated by theoretical analysis, numerical simulation and field experiment. Based on analysis of coal wall spalling in the working face, a new grouting material was developed. The stress and plastic zone changes affecting the coal wall, before and after grouting in the working face, were analyzed using numerical simulation and surrounding rock grouting reinforcement technology was proposed for application around the new grouting material. The results showed that: (1) serious spalling of the 150505 working face was caused by the large mining height, fault influence and low roof strength, and (2) the new nano-composite low temperature polymer materials used have characteristics of rapid reaction, low polymerization temperature, adjustable setting time, high strength and environmental protection. Based on analysis of the working face coal wall spalling problem, grouting reinforcement technology based on new materials was proposed. Industrial tests were carried out on the working face. Field monitoring showed that the stability of the working face coal wall was significantly enhanced and that rib spalling was significantly improved after comprehensive anti-rib-spalling grouting measures were adopted. These results provide a basis for rib spalling control of working faces under similar conditions.

Control Effect Analysis and Engineering Application of Anchor Cable Beam‐Truss Structure on Large‐Deformation Roadway in Deep Coal Mine

“…To this end, scholars have proposed various types of active, passive, and combined supports through a variety of methods [3][4][5]. Overall, the roadway surrounding-rock control can be divided into fve basic support forms, namely, the basic support within the roadway [6,7] (wood bracket, metal bracket, and stone bracket), strengthening support in roadway [8,9] (permanent strengthening support and temporary strengthening support such as single hydraulic prop), roadway side support [10,11] (wood crib, dense pillar, gangue wall, concrete wall, and flling wall), grouting modifcation [12][13][14] (ordinary portland cement, Marysan, and new polymer organic and inorganic modifed materials), nonsingle support form [15][16][17] (above two and multiple combined support technologies). Te surroundingrock supporting theory of coal mine roadway mainly includes suspension theory, composite beam theory, composite arch theory, maximum horizontal stress theory, and surrounding rock strength strengthening theory [18].…”

Finite–Discrete Element Method Prediction of Advanced Fractures in Extra-Thick Coal Seams Based on a Constitutive Model of Rock Deformation–Fragmentation Failure Process

“…The results showed that under the disturbance of repeated mining the roof dynamic load is high, and the subsidence of the end face roof is large. In addition, Song et al [14] used the finite element method, Jiao et al [15] and Kong et al [16] used the discrete element method, and Wang et al [17] and Liu and Chen [18] used the finite difference method to numerically calculate the plastic zone or failure range of the coal rock mass in front of the coal wall of the working face. They summarized that the main controllable factors to roof fall and rib scattering follow the order of coal > support strength > mining height > distance to face > local force.…”