Study of the Stability Control of the Rock Surrounding Double-Key Strata Recovery Roadways in Shallow Seams

Abstract

Thestabilitycontroloftherocksurroundingrecoveryroadwaysguaranteesthesafetyoftheextractionofequipment.Rooffalling and support crushing are prone to occur in double-key strata (DKS) faces in shallow seams during the extraction of equipment. Therefore, this paper focuses on the stability control of the rock surrounding DKS recovery roadways by combining field observations, theoretical analysis, and numerical simulations. First, pressure relief technology, which can effectively release the accumulated rock pressure in the roof, is introduced according to the periodic weighting characteristics of DKS roofs. A reasonable applicationscopeandtheapplicable conditionsforpressurerelieftechnologyaregiven.Consideringtheinfluenceof the eroded area on the roof structure, two roof mechanics models of DKS are established. The calculation results show that the yield load of the support in the eroded area is low. A scheme for strengthening the support with individual hydraulic props is proposed,andthen,thesupportdesignoftherecoveryroadwayisimprovedbasedonthetimeeffectsoffracturedevelopment.The widthoftherecoveryroadwayandsupportingparametersisredesignedaccordingtoengineeringexperience.Finally,constitutive models of the support and compacted rock mass in the gob are developed with FLAC3D software to simulate the failure characteristics ofthesurroundingrockduringpressurerelief andequipmentextraction.Thesurroundingrockcontroleffects of two support designs and three extraction schemes are comprehensively evaluated. The results show that the surrounding rock control effect of Scheme 1, which combines improved support design and the bidirectional extraction of equipment, is the best. Engineering applicationresults show that Scheme 1 realizes the safe extractionof equipment. The research results can provide a reference and experience for use in the stability control of rock surrounding recovery roadways in shallow seams