Abstract
Surface water, groundwater and sand can flow into mine goaf through the fractured rock, which often leads to water inrush and quicksand movement. It is important to study the mechanical properties of water and sand in excavations sites under different conditions and the influencing factors of the water and sand seepage system. The viscosity of water–sand mixtures under different particle sizes, different concentration was tested based on the relationship between the shear strain rate and the surface viscosity. Using the self-designed seepage circuit, we tested permeability of water and sand in fractured rock. The results showed that (1) effective fluidity is in 10−8–10−5 mn+2 s2−n/kg, while the non-Darcy coefficient ranges from 105 to 108 m−1 with the change of particle size of sand; (2) effective fluidity decreases as the particle size of sand increased; (3) the non-Darcy coefficient ranges from 105 to 108 m−1 depending on particle size and showed contrary results. Moreover, the relationship between effective fluidity and the particle size of sand is fitted by the exponential function. The relationship between the non-Darcy coefficient and the particle size of sand is also fitted by the exponential function.
Highlights
In China, water and sand inrush is very serious safety problem for coal mining in 20 years, there were many accidents which gave more damage to coal mining (Limin et al 2015, 2016)
The coal reserves are located at shallow depths and the thin bedrock and thick sand overburdens the strata layers, inducing connected cracks
The result of water and sand erupting, permeating fractured rock reflects the instability of the strata layers
Summary
In China, water and sand inrush is very serious safety problem for coal mining in 20 years, there were many accidents which gave more damage to coal mining (Limin et al 2015, 2016). The influence of mass concentration in water and particle size of sand on the seepage parameters are tested using specially designed instruments. It was deduced that the water–sand mixture was a pseudo-plastic fluid, whose viscous parameters changed with sand particle ds and mass concentration of sand ρs. Different consistencies were tested of coefficient C and power exponent n with the diameters of sand particle sizes 0.038–0.044, 0.061–0.080, 0.090–0.109 and 0.120– 0.180 mm; and sand 20, 40, 60 and 80 kg/m3 in the water. Consistency coefficient (N Sn/m) power exponent n increases along with the increase of mass concentration in water, and decreases along with the increase of sand particle. According to Eqs. 15 and 16, Ie and β were calculated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
