Abstract:

The problem of surrounding rock support of soft rock roadway in deep coal mining, especially the stability of surrounding rock of soft rock intersection roadway, has been concerned for a long time. From the analysis of the internal causes of the deformation and failure of the intersection, it is concluded that the roof and the rock pillar support system in the triangle area are the weak points of the instability and failure of the intersection. Based on the concept of ‘equivalent span’ and catastrophe theory, a cusp catastrophe model of the roof rock-column system at the intersection is established and the cusp catastrophe equation at the intersection and the necessary and sufficient judgment conditions for the instability and failure of the system are obtained. The effects of engineering geological factors (buried depth H and elastic modulus of rock column E), structural parameters of roadway intersection (intersection angle q and roadway height h) and support design parameters a on the stability of intersection are analyzed. It is concluded that the non-linear relationship between q, E, a and the control parameter v has a curvature change inflection point. When q <35º and E<16 GPa, the sensitivity order of control parameters to various factors is: q >E>a>h>H, that is, when the rock column is weak, the stability of the intersection is strongly affected by the strength of the rock column, and the design angle of the intersection should not be less than 35º. When q≥35º and E≥16 GPa, the order of sensitivity is: h>H>q >a>E, that is, when the strength of surrounding rock is high, the stability of intersection is significantly affected by structural parameters. Combined with the example of deep well soft rock engineering in Dingji mine, theoretical analysis is used to guide the optimization of design parameters of intersection. The ground pressure monitoring data show that the optimized support design effectively controls the surrounding rock deformation at the intersection of the west third track back link roadway, and verifies the correctness of the theoretical derivation.

Key words: deep roadway engineering, intersection point, cusp catastrophe model, sensitivity analysis, engineering application