The Study On Shear Creep Model Of Wall Rock Of Long, Great And Deep Buried Tunnel

Rheological mechanical characteristics is one of the most important mechanical characteristics of rock. It's related closely with long-time stability of rock engineerings. Engineering practice and studies indicate that destabilizing failures of rock mass is related closely with time. The Jinping hydraulic power plant curve cut-off the Yalong rive great river bend with 150km long and huge natural drop to excavate tunnel to generate electricity. The tunnel is very long, great and deep buried. Otherwise, the area where the tunnel in is an area of high terrestrial stress and high external water pressure. The rheological mechanical characteristics of rock mass arround the tunnel will effect the long-time stability of Jinping hydraulic power plant. So it's important to study on rock samples from the area of excavation with direct shear creep experiment for understanding rheological mechanical characteristics of rock and the long-time stability of Jinping hydraulic power plant deeply.The rock mechnics researchers has studied on rock rheology and built many rheology constitutive models. But most of these studies did't take time-dependence of rheology parameters into account. The Burgers rheology model is a rheology model with four elements. It refects the instant elastic strain of rock and the rheological characteristics of rock of the first and second creep phase. Through fitting with constant parameters or parameters time-dependent with data of direct shear creep experiments on marble, we conclude that:1. The results of fitting with constant parameters with data of samples which have no creep phase of acceleration are good. But the error is big, especially when the creep rate during stable creep phase. So it's necessary to introduce a time-dependent parameter to minish fitting error and advance fitting effect. So introduce a time-dependent parameter G_K.2. Introducing expression of time-dependent parameter G_K, fit with data of creep experiments. The fitting results indicate that the parameter G_M is very approximate to the theoretical value calculating with instant elastic strain.3. The accuracy is advanced by large degrees and the error is minished by fitting with time-dependent parameters, expecially the samples with very small creep rate during the second creep phase.