Experimental study on the mechanical properties of foam filling materials for the roof of ultra-high gob-side entry in thick coal seams
Sun Long
Liu Ruyuan
Liu Zhongyi
Liang Bo
Wei Jinping
Wei Sijiang
Abstract：Objectives To improve resource recovery rates and alleviate the tension in mining succession,the experimental study on the mechanical properties of foam filling materials for the roof of ultra-high gob-side entry in thick coal seams was conducted.Methods To verify the adaptability of the foam material,ex-perimental methods were employed to study the influence of factors such as height-to-width ratio and load-ing rate on its mechanical characteristics.Results The results indicate that,under a constant loading rate,the bearing capacity of the foam material gradually decreases as the height-to-width ratio increases.Con-versely,with a constant height-to-width ratio,the bearing capacity gradually increases with the loading rate.Based on the complete stress-strain curve,the loading process of the foam material can be divided into three stages:In the initial loading stage,the working resistance of the specimen increases sharply,representing a brief linear-elastic stage.As loading continues,stress increases slowly with strain,entering the plastic platform stage where the curve shows a clear linear characteristic.Stage III is the densification stage,where specimens with larger height-to-width ratios exhibit a significant reduction in bearing capac-ity,displaying characteristics of softening and structural failure.Graphite polystyrene foam material exhibits notable elastic aftereffect.After the initial loading,it rebounds by 50%to 80%,demonstrating strong deformation-yielding capacity and rebound-bearing performance.Conclusions Combining the engineering geological conditions of the ultra-high roadway in Yunding Coal Mine and based on the porous foam model and the theory of effective extension of anchor cables,it is concluded that foam material with a height-to-width ratio of 0.5 to 1.0 possesses strong bearing capacity and high compression modulus.It exhibits charac-teristics of strong initial deformation resistance and structural stability,enabling it to adapt to large defor-mations of the roadway roof and sides and meet the need to eliminate gas accumulation space.It is thus the preferred material for filling the roof of ultra-high roadways.
Keywords：ultra-high roadwaygraphite polystyrene foamheight-to-width ratiomechanical propertiesflexible backfilling
Publication Date：2026-03-31
Online Publishing Date：2026-03-04(First online date of this platform, not the publication date of the document)
Pages：8( 140-147 )