| The deformation of roadway surrounding rock is serious and common in the deep mine gob-side entry retaining retaining,especially during the peiod of roadway retaining.Using similar materials simulation,numerical simulation and theoretical analysis and other research methods,based on the evolution law of roadway surrounding rock deformation in deep mine gob-side entry retaining,large structure equation and small structure stability analysis model have been established,revealing the characteristic of roadway surrounding rock deformation in deep mine gob-side entry retaining,and the principle of stability control is proposed,the main research results are as follows:(1)During the excavation,the surrounding rock deformation distributes symmetrically,and during the advanced influenced period of first mining,the supporting point sink at the coalside near working face because of front abutment,meanwhile,the deformation of coalside is serious and the depth of rock failure and cracks increased development.In the period of roadway retaining,the empty roof spacing and deformation of the backfill cause the roof to further rotate and sink,high-strength backfill is embedded in the floor which leads to serious floor heave.The characteristic of asymmetric deformation is more obvious during the advance-impact period of the secondary mining.(2)The "easy stable arch structure" starting from the excavation along the large structural overlying strata and the overlying strata gradually evolves to the"conditionally stable arch structure" in the roadway retaining period.Eventually,the"difficult-stabilizing arch structure" in the advance-impact period of the secondary mining is formed.A large-structure mechanical analysis model for overburden rock is established.Large structural form equations are obtained.The effects of backfill width,working face length,coalside support resistance,and side pressure coefficient on large-scale structural shapes are analyzed The phenomenon that the difficulty of support is generally increased with the increase of depth is explained.(3)The anchorage of the roof is dominated by elastic deformation in the excavation period.In the first mining stage,the subsidence of the supporting point at the coalside near working face and the squeezed and subsidence during advance-impact period of the secondary mining are the main reasons of roof subsidence.The deformation analysis model in each stage is established,and the deformation expression is obtained.The deformation of the coalside is mainly because the shallow crushed zone and the cusp catastrophe model of the coalside is deduced,and the sufficient and necessary conditions for coalside mutation are obtained.The action mechanism of the backfill is analyzed and its working resistence is obtained.Based on the expressions of resistance and stress components,the effects of depth of mining,size of backfill,and direct roof thickness on the support resistance of backfill were studied.The floor was divided into a thick hard floor and a thin soft floor,and the deformation evolution characteristics under different types of floor were described.(4)The overall study of the surrounding rock system deformation found that:1)The deformation of roof and floor is related,but the strength of the rock itself is the most important factor to its deformation;2)Rock with the low strength is first deformed and destroyed;3)The damage mechanism of the system is the same as the failure mechanism of the weak part and the strength is closely related to other parts.(5)The control principals of surrounding rock stability in gob-side entry retaining in deep mines are proposed that "Step-by-Step Reinforcement Supporting Principles in Each Phase","Coordination Principle in Spatial Deformation","Strengthening Supporting Principle in Key Locations",and "Optimization Principles for Surrounding Rock Stress in Special Conditions".The above research results have been successfully verified in the tailentry of the 72207 working face of the Sanhejian Coal Mine of Xukuang Group. |
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