Experimental Study on the Properties of Simulation Materials for an Aquifuge for a Fluid–Solid Coupling Physical Similarity Model Test

Abstract

In order to meet the special requirements of physical and mechanical strength and high water resistance of similar material in aquifuge (aquitard) strata for the testing of the fluid–solid coupling physical similarity model for a mine water inrush. Based on the similarity theory of solid–fluid coupling in equivalent homogeneous continuous media, a new type of aquifuge simulation material was developed, which used river sand as the skeleton of the material, gypsum and calcium carbonate powder as the auxiliary cementing agent, and paraffin wax and petroleum jelly as the waterproof cementing agent. Similar materials of aquifuge (aquitard) strata are created according to a specific proportion of the components and an established technological process. Through orthogonal tests and systematic analysis, the influence mechanism of the different proportions of the raw materials on the variation of the physical–mechanical strength and hydraulic parameters is studied in this paper. The experimental results demonstrate when the mass ratio of solid material to liquid material is 8:1 and 9:1, the mass ratios of river sand, calcium carbonate, and gypsum is 30:3:7, 30:3:7, and 50:3:7, and the mass ratios of paraffin wax to petroleum jelly are 1:2, 1:1, and 2:1, respectively. The controlled ranges of uniaxial compressive strength, softening coefficient, and permeability coefficient of the similar materials are 16.99–426.47 kPa, 0.660–0.805, and 1.01 × 10−7–8.34 × 10−7 cm/s, respectively. The above data show that the materials have the characteristics of low strength, controllable water absorption, and low permeability.

Experimental study and application of similar materials in thick coal seam mining

“…When the mass ratio of aggregate to cementing agents was constant, an increase in gypsum content led to an increase trend in the compressive strength of similar materials, which is due to gypsum content determining the strength of similar materials, with calcium carbonate showing no significant enhancement in compressive strength. However, when the gypsum content was excessively high, similar materials exhibited noticeable brittleness, and the addition of calcium carbonate can improve the properties of similar materials (Shen et al, 2023;Sun et al, 2023).…”