Study On Stability Of Surrounding Rock Of Roof In Cross Section Of Large Section Roadway

In order to construct a complete underground coal transportation,drainage,ventilation and other systems,to achieve safe and efficient operation of coal mines,various roadways will form a crossover point when connected to each other.Therefore,roadway intersections are widely existed in coal mines.At the same time,the intersection point is more complicated than the general single roadway.Due to the influence of two or more intersecting roadways,the stress state of the surrounding rock is complicated,and the top surface of the top of the crossing point is large,which makes the stability problem of the roof of the crossing point more prominent..Therefore,it is imperative to comprehensively study the stability of the top of the intersection and how to achieve the stability of the top of the intersection.Based on the previous studies,the thesis analyzes the stress distribution and failure modes of the surrounding rock at the intersection,the beam-type mechanical structure of the roof and the equivalent span on the stability of the surrounding rock of the large-section intersection.The stress boundary method(S-B method)generates initial stress,and Flac3 D is used to focus on the influence of different section size,intersection angle and section shape on the stability of the top of the crossing point;combined with the roof supporting principle of the crossing point,the large section of the Qipanjing coal mine Supporting the defects,verifying the rationality of the support scheme through numerical simulation and on-site monitoring.The research shows that the cross-section size and cross-angle of the roadway affect the stability of the top of the cross-section by changing the equivalent span of the top of the cross-section,but the way to change the equivalent span is different.The width of the roadway will directly change the maximum equivalent span of the roof of the crossing point.The increase of the height of the roadway will increase the range of the limit balance area of the two roadways.The limit balance area of the main and branch roads will overlap at the end of the triangle,and the depth of the surrounding rock will increase.Therefore,the support effect on the top plate is weakened,and the maximum equivalent span of the top plate of the intersection point is increased.The smaller the cross angle,the greater the depth of damage at the end of the intersection of the intersection point,and the weakening of the support of the top plate,thus changing the size and position of the maximum equivalent span,resulting in the phenomenon that the maximum displacement of the top plate is offset to the acute side.The difference in the shape of the roadway section will make the surrounding rock stress distribution different.The arched roof can transmit the pressure of the roof to the two surrounding rocks.For the T-shaped intersection,the arched roof section shows better than the rectangular section stability.Finally,based on the engineering background of Qipanjing coal mine roadway,it is proposed to use the composite anchor cable to strengthen the roof of the crossover point on the basis of the original support.The verification results show that the combination of the anchor cable can suspend the roof in the deep part.Surrounding rock,alleviate the pressure relief of the roof of the crossing point,reduce the anchor cable load at the intersection,and improve the reliability of the supporting structure.The combination of the anchor cable to strengthen the roof can improve the stability of the surrounding rock of the roof of the intersection.