Abstract
In order to study the seepage failure mechanism of roadway filling medium consisting of cohesive soil under complex hydrogeological conditions, a large-scale triaxial stress-seepage test system was utilized to investigate the influence of kaolin content and seepage loading rate on the seepage characteristics of filling medium. Through the analysis on the variation rules of sand loss and particle size distribution, the seepage characteristics and whole process of seepage instability of filling medium were explored in depth. It is concluded that (1) The seepage instability process of filling medium can be categorized into three stages: the initiation loss of fine clay, the accelerating loss of soil, and the stable status of soil loss. (2) The seepage failure process rate is proportional to the seepage loading rate and inversely proportional to the content of kaolin. (3) The kaolin and sand content of remaining mixture presented initial>bottom>middle>top status. The research results have guidance value for exploring the instability evolution mechanism of filling medium in deep roadway.
Highlights
Since the 21st century, especially with the implementation of the China Western Development and The Belt and Road Initiative, the focus of coal mining engineering or tunnel construction in China is gradually shifting to the western mountainous and karst areas with extremely complex terrain and geological conditions
(2) The seepage failure process rate is proportional to the seepage loading rate and inversely proportional to the content of kaolin
The key problem why mine water inrush disasters are difficult to forecast and control is that the geological conditions and catastrophic evolution process are extremely complex, which may cause that the catastrophic evolution mechanism of water inrush has not been systematically revealed
Summary
Since the 21st century, especially with the implementation of the China Western Development and The Belt and Road Initiative, the focus of coal mining engineering or tunnel construction in China is gradually shifting to the western mountainous and karst areas with extremely complex terrain and geological conditions. Previous studies on mine water inrush of deep roadway have focused on the water inrush mechanism and a large amount of research has been conducted through theoretical analysis, numerical simulation, and laboratory tests [17–20]. Su et al [27], Tomlinson and Vaid [28], and Fannin and Moffat [29] have successively adopted large-scale permeameters to carry out the internal seepage test and studied the influences of particle size distribution, permeability, and confining pressure on the seepage instability process of cohesionless soil. Meng et al [36] employed the three-dimensional model test system of mine water inrush to analyze the structural instability characteristics and seepage laws of karst conduit fillings with different permeability coefficients. From the perspective of mine water inrush disaster characteristics of filling structures in deep roadway, a large-scale triaxial stress-seepage test system was utilized to carry out seepage instability test on filling medium. The effects of kaolin content and loading rate on seepage characteristics and the evolution rules of grain size distribution before and after seepage are investigated, so as to reveal the variation rules of permeability characteristics and seepage instability mechanism in filling medium
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