Application of Hydraulic Fracturing and Energy-Absorption Rockbolts to Improve the Stability of a Gob-Side Roadway in a 10-m-Thick Coal Seam: Case Study

Abstract

The full-height extraction of a 10-m-thick coal seam in one single lift caused severe squeezing deformation of Tailgate 14202 in Majialiang Coal Mine in Shuozhou, China. A combination method of hydraulic fracturing and snake-shaped energy-absorbing rockbolts was proposed to reduce the excessive deformation. Hydraulic fracturing was used to weaken the strength of the overlying strata to improve its caveability. Monitoring of the pressure changes of supports in the longwall working face showed that the supporting working pressure and the periodic weighting interval were reduced. Monitoring also indicated that tailgate deformation was decreased. The application of snake-shaped rockbolts in the field further reduced roadway deformation. Only a small number of rockbolts were found to have been damaged due to the large deformation. Hydraulic fracturing coupled with energy-absorbing rockbolts successfully reduced the large deformation of Tailgate 14202 and safeguarded the basic functions of the tailgate. This paper presents a case study of the improvement of the stability of underground roadways under the effects of the extraction of thick coal seams. The combination method might be helpful in reducing the excessive deformation of underground roadways subjected to large dynamic loads.