Abstract
The seepage action of underground water accelerates the deformation of roadway surrounding rock in deep mines. Therefore, the study of creep characteristics of surrounding rock under seepage action is the basis for the stability control of roadway surrounding rock in deep water-rich areas. In this paper, a seepage-creep coupling test system for complete rock samples was established. Combined with a scanning electron microscopy (SEM) test system, the seepage-creep law of coal measures sandstone and the damage mechanism were revealed. The study results showed that the maximum creep deformation of sandstone under natural and saturation state decreased gradually with the increase of confining pressure, and the maximum creep deformation under saturation state was greater than the corresponding value under natural state when the confining pressure was same. When the confining pressure was constant, the creep deformation, the constant creep deformation rate and the accelerated creep deformation rate of sandstone increased rapidly with the increase of infiltration pressure. With the change of time, the change of permeability parameters went through three cycles; each cycle was divided into two stages, slow change stage and rapid change stage, and the rate of variation increased with the increase of the seepage pressure. Based on the macroscopic and microscopic characteristics of sandstone rupture, the connection between macroscopic and microscopic mechanism on sandstone rupture was established. The results in this paper can provide a theoretical basis for stability control of roadway surrounding rock in water-rich areas.
Highlights
IntroductionMany coal mines in China have entered the stage of deep mining. Compared with shallow coal mines, deep rock masses have significant rheological properties [1,2,3,4,5,6,7]
At present, many coal mines in China have entered the stage of deep mining
Fan carried out the triaxial compression creep tests of oil-bearing mudstone under low confining pressure; the results showed that there was an initial stress threshold of creep and failure stress threshold of creep [14]
Summary
Many coal mines in China have entered the stage of deep mining. Compared with shallow coal mines, deep rock masses have significant rheological properties [1,2,3,4,5,6,7]. Some scholars [15,16,17] conducted researches on the creep characteristics of rock under different stress conditions. Li and Miao studied the seepage law and creep law of broken rock [32,33] He conducted creep-seepage coupling tests on coal samples to reveal the consistency of permeability changes and the creep damage of coal samples [34]. Based on the experimental results of rock stress-strain-permeability tests, Yang established a seepage-stress-damage coupling model with brittle characteristics from the microscopic view [39]. Some researchers [8,45] have used self-made test systems to conduct seepage-creep test studies on complete rock samples. This study provides a theoretical basis for the control of roadway surrounding rock in deep coal mines
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