Migration mechanism of grouting slurry and permeability reduction in mining fractured rock mass

Abstract

In order to solve the water and gas discharge hazard caused by gob water and harmful gases (such as CO), the method of grouting overburden fractures is adopted to achieve the purpose of safe and efficient mining production in coal mines. This paper carries out the experimental research on the permeability reduction effect of grouting in fractured rock mass, expounds the relationship between gas flow rate and pressure gradient, seepage pressure and permeability, confining pressure and permeability, and analyzes the permeability change law of fractured rock mass before and after grouting. Besides, the grouting migration and permeability reduction model of fractured fine-grained sandstone is constructed by combining grouting test and numerical simulation, which reveals the dynamic evolution law of rock mass permeability in the grouting process. The results show that the permeability of the grouting rock sample decreases from 700–13,000 to 15–300 mD than that of the ungrouting rock sample, and the decrease is more than 95%, which indicates that the sealing performance of grouting slurry is better. Besides, numerical simulations show that the initial permeability of rock samples is 971.9 mD, and the permeability decreases to 45.79 mD after 1800s, and the permeability decreases to 95.3%, which is basically consistent with the experimental results after grouting. The greater the grouting pressure is, the better the grouting effect is. With the increase of the grouting pressure, the increase of the grouting effect is no longer obvious.

Research on overburden structural characteristics and support adaptability in cooperative mining of sectional coal pillar and bottom coal seam

“…The existing results provide a reference for the safe mining of the working face, but there are few studies on different mining techniques for different mining heights in the same working face 28 . Therefore, theoretical calculation, numerical simulation and field industrial test are used to comprehensively analyze the movement law of overlying strata and the adaptability of support in working face, and the feasibility of hydraulic support is studied.…”

Experimental study on the fracture surface morphological characteristics and permeability characteristics of sandstones with different particle sizes

“…2,3 The presence of joints affects the mechanical properties of the rock mass and the way the energy source propagates within it, and changes the damage mode of rock mass, affecting the strength and stability of rock mass, and the three-dimensional visualization and quantitative analysis of damage section morphology under different stressing methods and water-filled conditions. [4][5][6][7][8][9][10][11] Anisotropic characterization of structural faces formed under cleavage and shear was carried out and their influence on shear mechanical properties was studied. [12][13][14][15] Han et al systematically analyzed the changes in the mechanical behavior of natural rough rock joints during shear under cyclic loading conditions.…”

Study of wellbore instability in shale formation considering the effect of hydration on strength weakening

“…Previous research has improved the understanding of the physicochemical properties of shale and characteristics of borehole instability, achieving good application effects (Ma, 2015;Wen, 2015;Zhang et al, 2017;Meng et al, 2019;Gao and Zhang, 2022;Zhengzheng et al, 2024a;Zhengzheng et al, 2024b;Zhang et al, 2024;Zhang et al, 2024). However, the problem of borehole instability in shale formations has not been completely solved, especially the evident delayed effect and stable time window of borehole instability in shale formations (Wang F. et al, 2023).…”