Study On Rock Creep Deformation Of Tunnel Based On The Creep Model

With the rapid development of our country highway engineering, highway tunnelconstruction in soft rock is more and more, the NATM of tunnel construction has greatadvantage in soft rock, it thought surrounding rock has a certain bearing capacity, canwork together with support structure, forming a common carrier, so surrounding rockallowed to exist certain deformation, the secondary lining reasonable supporting timingcan fully mobilize support system, is key to the success of the NATM. The stress andstrain of surrounding rock and supporting structure is relatively complex, and have a lotto do with time, have larger rheology, so we cannot just using elastic-plastic theory todescribe, when use the NATM to design and construction in soft rock areaBackground on FenShuiLing tunnel, quoting the displacement expression ofcomplex tunnel cross section on the basis of the theory of complex variable andconformal mapping, combined with field monitoring data inversion to divide the burgermodel parameters of the tunnel. Using FLAC3D finite difference software, consideringthe influence of creep of the rock in tunnel excavation, analysis the elastoplasticchanges, and the action of stress and strain change rule of surrounding rock andsupporting structure, assumed that applying the secondary lining in different time,analyzing the change of the tunnel structure, and combining with the specificationrequirements determine the optimal timing of the secondary lining of the FenShuiLingtunnel.In the model of burger, analysis the change of the creep of surrounding rock andthe secondary lining stress under the effect of creep in100years when the tunnel wasbuilt, to get the distribution regularity of stress field and displacement field around thetunnel. Increases with time tunnel surrounding rock gradually tend to behomogenization, but at arch foot of the cave appear stress concentration phenomenon,inside the secondary lining bending moment and axial force increases gradually atarch foot, so it is important to pay special attention to monitoring and reinforcement atarch foot.