Finite Characteristic Ratio Theory Model Analysis for the Thin Rock Pillar of a Twin Tunnel

The machnical response of the thin rock (and/or soil) pillar of a twin tunnel with super-large-span and small-spacing is described upon a model of finite characteristic ratio constitutive theory (FCRT). The analysis result is compared with the results from in situ monitoring and the D-P model of the classic plastic constitutive theory; it shows that the deformation characteristics of the middle pillar during tunnel excavation process can be reasonably described by the FCRT model, and the method of parameter determined of the FCRT model is relatively simple than the classic plastic model due to the model has a clear physical background and with little randomness.