Research On Compatible Deformation Mechanism Between Backfill Body-Surrounding Rock And Gob-side Entry Retaining Technology

The length of mining roadway account for over60%of the length of allroadways in coal mining production. Using the gob-side entry retaining technologycan solve the problem about coal pillar loss, improve coal recovery and govern thegas ultralimit problem in workface production. Therefore, using the gob-side entryretaining technology with no coal pillars protection accords with developmentdirection of mining scientifically and greenly in our country. The stability of roadwaysupport backfill in the construction of gob-side entry retaining is one of the maininfluence factors which contribute to the success of gob-side entry retaining. Theroadway support backfill experiences a long period of sustainable roof activities, getsa high stress concentration degree and is under a serious dynamic pressure influence,thus there exists several uncertain factors which relate to the stability of backfill, thefailure and instability of backfill is one of the main causes which give rise to thefailure of gob-side entry retaining.In this paper, we utilize the method which combines theoretical analysis,stimulation calculation, laboratory experiment,industrial field test and many othermeans, study systematically the interaction mechanism of the roof of gob-side entryretaining roadway and the backfill, the coordinated deformation mechanism of thesurrounding rock and the backfill, the even stress distribution effect of the backfillwhich is used in roof–contacted filling with soft media and the stability of thebackfill roof-contacted with soft media and the caving gangue cementationsolidification backfill. We acquire very decent effect in the industrial field test. Theprincipal results are as follows:(1) We simplify the backfill, the roof-contacted soft media and the roof toequivalent spring with various rigidity coefficients (k=Eab-Δb). According to theinteraction mechanism of the backfill and the roof, the stress and deformationrelationship between the roof and the backfill and the demand for backfill to adapt toroof support, we implement the coordinated deformation between the main roof, theimmediate roof and the backfill through designing the strength parameters of thebackfill.(2) According to the law that caving gangue flows in inclined coal seam goaf, wemake full use of the caving gangue in goaf as main backfill material on gob-side entryretaining roadway and implement successfully gob-side entry retaining in incline coalseam through gunite and grouting solidification to improve the compressive strengthand the global stability of the backfill.(3) We break the requirement of the ratio of width and height of traditionalbackfill is not less than0.8and use the cementation material backfill with soft mediaroof-contacted which has a ratio of width and height accounting to0.23. It is a newexplores and practice for the mechanical properties of backfill and the stable factorsabout gob-side entry retaining system.(4) In the construction of the gob-side entry retaining with cementation materialbackfill, we adopt flexible material for roof-contaction to adapt to the given deformation from the main roof large structure and implement the even stressdistribution effect over the backfill, reduce the stress concentration, which caused by'rotation and subsidence' of the roof at the boundary of the backfill and transversedisplacement, on the backfill. We also improve the stability of the backfill.The above research results have been applied successfully in4working faces incomplex occurrence coal seam, whose dip angle is less than45°, in Panmei GroupCompany.