RESEARCH ON LARGE SQUEEZING DEFORMATION AND ITS NONLINEAR RHEOLOGICAL MECHANICAL CHARACTERISTICS OF TUNNEL WITH WEAK SURROUNDING ROCKS

A complex mechanical behavior of large squeezing deformation of tunnel weak rocks is discussed under high ground stress condition.The large squeezing deformation can be belonged to the scope of a kind of large deformation rate with slow convergence.On the basis of rheological squeezing deformation's mechanism,a nonlinear 2D visco-elastoplastic constitutive model and a 3D elasto-viscoplastic constitutive model in case of large/small deformations are proposed respectively;and the corresponding secondary development special softwares are studied.The developed material subroutines are applied to analyzing the squeezing problem which occurred in rock excavation for the Wushaoling railway tunnel project.