Numerical Simulation And Analysis Of The Coupled Temporal Effects Of Shallow Tunnel Excavations And Ground Materials

With the development of urban construction, the tunnel and underground space will be vigorously developed and utilized. Excavation will change the stress in the vicinity of the stratum and generate movement, thus affect the normal use of road, the facilities, buildings, and even security. Therefore, it is necessary to take reasonable control measures and prediction to the ground movement along with the time variation.In this paper, the numerical simulation method is used to analyze the influence of time effect on stratum settlement during the process of tunnel construction from three aspects:(1) Analysis of the temporal effects of shallow tunnel excavations. Using the temporal effects in the process of tunnel construction, we can calculate stratum settlement induced by tunnel construction for full-face excavation, benching tunneling method and CRD excavation method. With tunnel working face moving, we can obtain the displacement curve changing with time at surface observation point, we can see from the curve:when the working face get through the observation point, we can get the maximum displacement at the observation point; After the working face get through the observation point, within a period of time, it still affect the displacement, but the scope is limited. When exceeding the scope, the displacement will tend to be stable.(2) Analysis of the coupled temporal effects of shallow tunnel excavations and ground materials. We should calculate the temporal effects of ground materials In the simulation of full-face excavation, benching tunneling method and CRD excavation method, namely, after the end of the excavation, we need to calculate creep effect; characteristic time of creeping material is related to specific viscosity model and it is a relatively long time generally; displacement of observation points increases due to the temporal effects of ground materials.(3) Compare and analysis the influence of surface settlement for full-face excavation, benching tunneling method and CRD excavation method in two cases, which is the temporal effects of excavations and the coupled temporal effects of excavations and ground materials. The results shows that CRD excavation method is superior to benching tunneling method, benching tunneling method is better than full-face excavation on the surface settlement controlling.