FLAC Analysis of Mechanical Response of Surrounding Rock Mass in Deep Tunnel

The deep tunnel has strong dynamic disturbance characteristics.A series of numerical simulation tests have been carried out using a finite difference code FLAC(Fast Lagrangian Analysis of Continua)to study mechanical responses of tunnel surrounding rock mass under the action of dynamic disturbance.A 60m×60m plane strain model containing a single 4m×4m centrally located tunnel is built and the dynamic disturbance is simulated by adding a sinusoid wave at the bottom of the model.The results show that after the action of dynamic disturbance,the magnitude of the highest horizontal stress both in the roof and floor of the tunnel will increase.And the distances from the roof line and floor line to the location of the highest horizontal stress will also increase.Significant downward roof movement increasing and plastic yield fields increasing can also be observed.The higher the in situ stress,the more significant dynamic disturbance influences on stress fields,displacement fields and plastic yield fields.Especially for the high-stress deep tunnel,dynamic disturbance may lead the highest horizontal stress increasing to a very high status in company of a large plastic yield fields and a critical status of rock crump.