1、英文原文Surrounding rock deformation and its controlling technology gob-side entry at isolated island coal faceAbstract:Based on voussoir beam structure theory of the overlying strata,deformation mechanism of surrounding rock of gob-side entry at isolated island coal face was analyzed,principles for def
2、ormation controlling of surrounding rock were established.According to engineering geological conditions in return airway of 1251(3) Pansan colliery,and distribution of advance abutment pressure,roadways supporting scheme during the tunneling and zoning advance reinforcement plans for roadways befor
3、e mining.Field practice shows that supporting scheme is feasible for stability of surrounding rock.Keywords:isolated island coal face;gob-side entry;surrounding rock deformation;ground strata controlI.IntroductionIsolated island coal face appears stress concentration,its strata behaviors are obvious
4、,surrounding rock occur and larger deformation and severe damage;Roof-to-floor and sides convergence are larger,floor heave in roadways is strong,coal seams are prone to spontaneous fire,these cause hidden troubles for safety mining,therefore,it was found that how to control surrounding rock deforma
5、tion effectively and understanding of strata behaviors deeply was key factors to quick mining and isolated island coal face safety.II.Deformation mechanism of surrounding rock of gob-side entry at isolated island coal faceDuring the mining,voussoir beam structure produces sliding instability or rota
6、tion instability because superposition action of abutment pressure results from working face and gob,narrow coal pillars will lose the protection from voussoir beam structure.When narrow coal pillars suffered from damage,main roof produces toppling rotation,subsidence.Main roof near the coal wall al
7、so produces toppling rotation and subsidence.This changes voussoir beam structure stability of the overlying strata in gob-side entry to cause stress in surrounding rock to increase sharply.In Fig.1,balance state of voussoir beam structure in the overlying strata was strongly influenced during the m
8、ining are summarized as follow:1)When the face is mining,main roof in the gob produces new fracture,the new rock block C and B connects with the original key rock block B.2)After the main roof rupture,the block C subside toward the face and key block B in the action of rotary moment and ,thereby und
9、ermining the original balance of the voussoir beam structure in overlying strata,articulated rock block C and key block B are in motion and instability state,which causes some subsidence of block B or higher abutment pressure occurs in the front of face.3)voussoir beam structure of overlying strata
10、is under higher abutment pressure,rock block C and key block B will produce rotary subsidence.Instability of voussoir beam structure results in stress redistribution and concentration of surrounding rock of gob-side entry again,its impact is much larger than that of the tunneling.4)when face mining,
11、the surrounding rock of gob-side entry occur high stress concentration,coupled with the soft surrounding rock,so gob-side entry produces deformation;at the same time,voussoir beam structure results in heterogeneous stress redistribution of surrounding rock,this shows that there is a big difference t
12、he deformation and its mode of roof,floor,sides of solid coal and coal pillar in the roadway.5)loads on overlying strata of voussoir beam structure in the mining increase continuously,but because the supporting conditions between blocks does not change,it will remain random balance,the difference is
13、 between the block loading situation has changed.Therefore,before the face is advanced,the voussoir beam structure stability will not have fundamental changes,so long as the roadway supporting is reasonable,bolts and surrounding rock form stable structures,roadway damage is small;steady equilibrium
14、state of voussoir beam structure in overlying strata is destroyed only after the working face is advanced, then instability occurs,resulting in the complete failure of roadway.The above analysis shows that the overlying strata of gob-side entry will remain in the random equilibrium in the process of
15、 extraction,this steady state change will lead to continuous increase of surrounding rock deformation.III.Controlling principles of surrounding rock deformation for gob-side entry in isolated island coal face1）advance reinforcement principleFrom the roadway supporting practice,it is found that most
16、of the support bolt,bolt-mesh supporting can maintain roadway stability during the excavation,but in the period of mining,there was a severe convergence occur in roadway and had to expand the sides.This not only requires a lot of manpower and resources,and interrupt the continuity of coal production,influence high yield and efficiency of the coal mine,the concepts of advance reinforcement principles are proposed.2）Self-supporting properties of surrounding
