Abstract
Pore abundance and deformation characteristics of saturated fragmentized coals during creep process are of significant meaning to the study on ground sediment in the mined‐out area. The law of porosity variation of saturated fragmentized coals during creep process and its creep constitutive model were studied by using the self‐developed multiphase coupling creep test device. And, results have indicated that the porosity logarithm of fragmentized coal during creep process shows a linear negative correlation with the time ln(n−a) = −ct + lnb, and the porosity decrease is evidently divided into three phases. In addition, when the stress level is relatively low, the porosity decreases slowly; when the stress level rises up, the porosity decreases quickly; when the stress level remains stable finally, the porosity is smaller. Under the equal stress, as the grain size of fragmentized coals decreases, the porosity tends to decrease, and as the grain size of fragmentized coal tends to be stable, the porosity tends to increase; the creep constitutive equation of fragmentized coals with different grain sizes was established by using the Kelvin–Voigt model, and the correlation analysis shows that the Kelvin–Voigt creep model of fragmentized coals is reasonable.
Highlights
Coal is an inhomogeneous and porous media [1], and compaction and bearing problems of fragmentized coals are quite common during coal mining
With the impact of external forces, coals are constantly crushed, densified, and compacted; some relevant physical and mechanical properties of fragmentized coals are changed, which can cause some engineering problems such as overburden movement, ground sediment [2–5], and side slope instability in the mined-out area. e study on the law of porosity variation of fragmentized coals during creep process [6–11] and its creep constitutive equation lays a theoretical foundation for resolving engineering problems such as the evaluation of deformation of ground sediment in the minedout area
Phase III: the porosity changes more slowly than the first two phases, and gradually tends to be stable; due to the attrition crushing in Phase II, a larger gap exists between coal particles and is filled with fine coal particles after fragmentized
Summary
Coal is an inhomogeneous and porous media [1], and compaction and bearing problems of fragmentized coals are quite common during coal mining. With the impact of external forces, coals are constantly crushed, densified, and compacted; some relevant physical and mechanical properties of fragmentized coals are changed, which can cause some engineering problems such as overburden movement, ground sediment [2–5], and side slope instability in the mined-out area. E study on the law of porosity variation of fragmentized coals during creep process [6–11] and its creep constitutive equation lays a theoretical foundation for resolving engineering problems such as the evaluation of deformation of ground sediment in the minedout area. Among current analyses of fragmentized rocks [12–14], few can systematically analyze the porosity variation law of fragmentized rocks during creep in terms of different stress and different grain sizes; in the description of creep deformation law, regression analysis means, such as logarithm fitting and fit exponential decay, are usually adopted, but its constitutive relation is not analyzed, and its creep deformation mechanism is explained from the perspective of the material prosperity of fragmentized rocks
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
