Experimental Investigation on the Law of Grout Diffusion in Fractured Porous Rock Mass and Its Application

Abstract

Because of the limitation of mining techniques and economic conditions, large amounts of residual coal resources have been left in underground coal mines around the world. Currently, with mining technology gradually developing, residual coal can possibly be remined. However, when residual coal is remined, caving areas might form, which can seriously affect the safety of coal mining. Hence, grouting technology is put forward as one of the most effective technologies to solve this problem. To study the grouting diffusion in fractured rock mass, this paper developed a visualization platform of grouting diffusion and a three-dimensional grouting experimental system that can monitor the grout diffusion range, diffusion time and grout pressure; then, a grouting experiment is conducted based on this system. After that, the pattern of the grouting pressure variation, grout flow and grout diffusion surface are analyzed. The relationship among some factors, such as the grouting diffusion radius, compressive strength of the grouted gravel, porosity, water-cement ratio, grouting pressure, grouting time, permeability coefficient and level of grout, is quantitatively analyzed by using MATLAB. The study results show that the flow pattern of the grout in fractured porous rock mass has a parabolic shape from the grouting hole to the bottom. The lower the level is, the larger the diffusion range of the grout is. The grouting pressure has the greatest influence on the grouting diffusion radius, followed by the grouting horizon and water-cement ratio. The grouting permeability coefficient has the least influence on the grouting diffusion radius. The grout water-cement ratio has the greatest influence on the strength of the grouted gravel, followed by the grouting permeability. The grouting pressure coefficient has the least amount of influence on the grouting diffusion radius. According to the results, the grouting parameters are designed, and a layered progressive grouting method is proposed. Finally, borehole observation and a core mechanical property test are conducted to verify the application effect. This grouting technology can contribute to the redevelopment and efficient utilization of wasted underground coal resources.

Performance Research of Materials and Engineering Application of Overburden Strata Separation-Zone Grouting Technology

“…is requires that the filling slurry material has efficient bonding properties and self-solidification properties. At the same time, the overburden strata separation-zone grouting (OSSG) technology is generally constructed from the ground surface to the underground strata through a long-distance grouting borehole, which puts forward higher requirements on the fluidity, concentration, and precipitation speed of the slurry [14,15].…”

Macro and micro grouting process and the influence mechanism of cracks in soft coal seam

“…On the one hand, cracks in the coal seam can serve as slurry flow channels to reduce slurry diffusion resistance. On the other hand, because of the weakening effect of cracks on the strength of coal, the coal is more likely to split under grouting pressure, which is conducive to slurry diffusion (Gothall and Stille 2009;Jin et al 2019;Jiang et al 2018;Deng et al 2018;Xiao et al 2017). Therefore, cracks in the coal seam and their distribution characteristics have an important influence on the grouting effect.…”

Modeling of Grouting Penetration in Porous Medium with Influence of Grain Distribution and Grout–Water Interaction

“…A large number of laboratory and field studies have been conducted to estimate the permeability of porous media [7][8][9][10]. Among these established models, The Kozeny-Carman (KC) equation is the most well-known semi-empirical equation, which is widely accepted and used extensively for permeability estimation.…”

“…For decades, many researches have studied the penetrability of grout suspension both in the laboratory [10][11][12][13][14][15] and in the field [16,17]. Grouting with micro-fine cement has also been studied.…”