Study On Stability Of Drift In Non-Pillar Sublevel Caving Method

The development and application of large structural parameters in non-pillar sublevel caving method have played a positive role in improving the production efficiency and reducing the production cost of the mining method.As an important project to realize the mining method,the stoping drift has a great influence on the application of trackless mining equipment and the improvement of mining effect.At present,the maximum drift width in the world has developed to 7m,and there is still an increasing trend.Under specific engineering conditions,there are many uncertainties in the stability of the mining drift,especially after the width of the drift increases,whether the stability during the mining period can be guaranteed is of great significance for the smooth progress of the mining work and the safety of the mining.Taking the-195 m horizontal stoping drift of underground stope in a mine as the research object,on the basis of studying the influence of drift width on ore drawing effect,in order to study the influence of structural parameter change of mining method on the stability of stoping drift,by means of numerical simulation mechanics analysis,using elastic-plastic rock mechanics,rock mechanics and other related theories and analysis methods,the influence of drift width,drift spacing and burden on the distribution characteristics and deformation law of surrounding rock stress field of stoping drift under vertical end wall condition is studied.The main research results are as follows:(1)The influence of different approach widths on the stress field,displacement field and plastic zone of surrounding rock is studied by numerical calculation method.The distribution characteristics of stress field and deformation law of surrounding rock are revealed.It is found that the increase of approach width will lead to the increase of principal stress at the side wall and the increase of roof subsidence.The maximum value is 42.47 mm,and the plastic zone will be further expanded.(2)By studying the displacement of surrounding rock and the change law of plastic zone under different approach spacing,it is found that the increase of approach spacing will not have a significant impact on the displacement of surrounding rock of mining approach,and the plastic zone is always distributed in the range of 2 m of surrounding rock of mining approach and will not be affected by the change of approach spacing.(3)By studying the influence of the change of approach spacing on the distribution law of surrounding rock stress field,it is found that the maximum value of principal stress is distributed on the side of the mining approach.With the increase of the approach spacing,the principal stress value decreases gradually,and the principal stress value at the roof is basically not affected by the change of the approach spacing.In general,the stability of the surrounding rock of the mining approach is the best when the approach spacing is 25 m.(4)The relationship between the caving step distance and the deformation law of surrounding rock and the relationship between the plastic zone expansion and the caving step distance are studied.The expansion law of the plastic zone range of the surrounding rock is obtained.It is found that with the increase of the caving step distance,the principal stress increases first and then decreases,and the displacement and the plastic zone of the surrounding rock increase gradually.