Abstract
Studies on the seepage characteristics of water-sand cracks are of great significance to reveal the mechanisms of water and sand inrush. Using a self-made water-sand fracture seepage test instrument, a water-sand seepage test was carried out, and the permeability of water and sand in the fracture was determined. The hysteresis characteristics of water-sand flow in the fracture were obtained after the required permeability was attained. The results show that the hysteresis curve changes from type I to type IV with the increase in sand particle size and concentration. The hysteresis parameters are described by the maximum hysteresis Gp ∗ and the hysteresis area S, both of which show an increasing trend with the increase in sand particle size and concentration; however, this increase is not synchronous. The average velocity and turbulent kinetic energy distribution of the water-sand fluid on the fracture cross section are greatly affected by the particle size and concentration of the volume of sand. This study can provide a reference for further study of water inrush from a shallow coal seam. Through simulation, it is found that the particle size has a great influence on the seepage velocity, and the influence near the side wall surface is greater than that in the middle position.
Highlights
Experimental and theoretical research was done to obtain the mechanism of water and sand inrush [1–4]
Variation of Hysteresis Characteristics. e fracture aperture is 0.75 mm, and the ratio of the fracture aperture to average particle size was 2.7 : 1. Seepage tests are carried out step by step
Influence of Sand Concentration on Hysteresis Characteristics. e fracture aperture b 0.5 mm, sand particle size dS 0.230 mm∼0.276 mm, and sand mass concentration ps were selected as variables. e hysteresis curves of fracture seepage were studied by setting four different water-sand mixtures of 20 kg/m3, 40 kg/m3, 60 kg/ m3, and 80 kg/m3
Summary
Experimental and theoretical research was done to obtain the mechanism of water and sand inrush [1–4]. Du et al [25] obtained the law of water and sand flow in the broken rock, and Liu et al [26] obtained the permeability of water and sand in the fracture under different conditions. Liu et al [31] identified the phenomenon of hysteresis in the flow of water and sand, but the detailed characteristics were not discussed. E purpose of this work is to identify the water infiltration characteristics of sand as the research object, use indoor testing to determine the hysteresis change characteristics of the fracture seepage of water and sand, and use numerical simulation to study the influence factors of the water and sand seepage field. E purpose of this work is to identify the water infiltration characteristics of sand as the research object, use indoor testing to determine the hysteresis change characteristics of the fracture seepage of water and sand, and use numerical simulation to study the influence factors of the water and sand seepage field. is is of great significance to grasp the mechanism of water inrush and movement of sand
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