Numerical Simulation Study of the Contact Relationship Between the External Supporting Arch and the Surrounding Rock in a Soft Rock Roadway

To develop an effective research tool for special contact behaviors observed in the field measurements of large deformation roadway to simulate the radial separation and circumferential friction sliding contact between the supporting arch and the surrounding rock, especially in the process of arch yielding. In view of the fact that the traditional method unable to achieve both the yield of the arch and the contact behavior with the surrounding rock, as well as the practicality of the engineering. The improved numerical simulation approach is constructed through additional development of FLAC3D. The yield criterion of the supporting arch was embedded in the modified Liner element via the FISH language programming, and the separable arch-rock interaction module is realized. Taking an actual mining roadway tunnel as the simulation object, three simulation schemes adopting the newly improved approach and the original methods were carried out respectively, and verified by the field measured data. The results show that: (1) the bending moment and axial force at the yielding moment of the supporting arch change from independent to related after modification, and the computed deviation of the arch model caused by the shortcomings of the original Liner element were effectively suppressed; (2) the surrounding rock controlling and the supporting arch stress results in the modified model scheme are closer to the actual; and (3) the modified Liner element is proved effective to simulate the supporting arch by the responses of supporting forces curves and relative displacement of the supporting arch and surrounding rock. The analysis shows that the improved numerical simulation approach is much more reliable to simulate the contact relationship between the supporting arch and the surrounding rock.