| In recent years,with the large-scale development of the coal industry,the shallow energy has gradually dried up.In order to meet the energy demand of our country,the depth of coal mining has been deepened year by year,and it is faced with high ground stress and complex hydrogeological conditions,which is more prone to rock burst events.In this paper,aiming at the phenomenon of plastic zone expansion of shallow surrounding rock crushing deep surrounding rock in rock burst roadway,the grouting modification method of surrounding rock crushing zone is put forward.By grouting surrounding rock of roadway,the strength deterioration of surrounding rock crushing zone is delayed,the plastic zone expansion of surrounding rock is controlled,the deformation of surrounding rock is inhibited,and the impact resistance of surrounding rock support is improved.Theoretical analysis,experimental research,numerical simulation and field application methods were used to study the mechanical properties of surrounding rock before and after modification,and the impact resistance of surrounding rock support after modification.The main research results are as follows :(1)According to the actual situation of the site,the deformation and failure characteristics of the surrounding rock of the rock burst roadway are analyzed.Under the impact load,the shallow surrounding rock is seriously broken,the plastic zone of the deep surrounding rock expands,and the original supporting structure fails.In order to solve practical problems and improve the impact resistance of support.In this paper,the grouting modification method of surrounding rock in broken zone is proposed to prevent the strength deterioration of broken zone on the surface of surrounding rock and inhibit the expansion of plastic zone of surrounding rock.According to the actual situation of the site,the surrounding rock modification scheme is formulated,and the slurry injection head is designed.The displacement changes of the surrounding rock in the modified section and the unmodified section were measured by the ’ cross method ’.The results show that the displacement of the two sides and the roof and floor of the grouting section is reduced by 51 %and 49 % respectively under the same impact vibration.(2)The mechanical model of roadway surrounding rock is established,and the strain softening model and dilatancy model are introduced to derive the range of fracture zone and plastic zone.According to the actual situation,an example is used to analyze the changes of surrounding rock fracture zone and plastic zone under different influencing factors.The results show that the range of plastic zone of surrounding rock can be effectively reduced by controlling the residual strength of surrounding rock fracture zone.(3)Based on the theoretical calculation results,the numerical simulation method is used to study the influence of the strength deterioration of the surrounding rock fracture zone on the stress field and deformation field of the surrounding rock.The results show that with the strength deterioration of the surrounding rock in the fracture zone,the deformation of the surrounding rock is increased and the plastic zone of the surrounding rock is expanded.Controlling the strength deterioration of surrounding rock fracture zone can effectively control the deformation of surrounding rock and improve the impact resistance of surrounding rock.(4)Experimental study on the strengthening characteristics of surrounding rock with time after grouting modification in the broken zone of surrounding rock.The results show that with the increase of time,the mechanical properties of the broken zone of the surrounding rock gradually increase.The compressive strength and elastic modulus eventually reach 51.05 % and 63 % of the original coal sample,and the cohesion is 2.05 times higher than that of the original coal sample.The stability and integrity of the broken surrounding rock are greatly improved.(5)According to the test results,the grouting modification of surrounding rock improves the strength of surrounding rock broken zone,but there is still a certain gap compared with the strength of the original coal sample.The numerical simulation method is used to analyze the ability of surrounding rock support to resist deformation under impact load under three working conditions:no support,only bolt support and grouting modification after bolt support.The results show that after the grouting modification of the surrounding rock fracture zone,the deformation of the surrounding rock decreases under the impact dynamic load,the range of the plastic zone does not change significantly,the peak velocity of the surface particles is reduced,and there is a certain impact resistance.This paper has 70 figures,16 tables and 75 references. |
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