Research on the whole process and nonlinear law for coupling evolution of new and old overlapped tunnel systems is still in exploring stage. Based on the coupling mechanism analysis of the overlapped tunnel systems in undercrossing and after construction

the whole change processes of stress state and displacement state are quantitatively analyzed in its coupling. According to the nonlinear analysis of tunnel stability

the nonlinear law for coupling evolution is studied from viscoelasto-plasticity

dynamics and energy dissipation. The coupling standard and evolution function are established. On this basis

the general characteristics of coupling evolution are systematically summarized. The expansibility in space and furtherance in time of the coupling mechanism are also pointed out. Such kind of study is able to provide valuable theoretical guidance for stability quantitative analysis and control of overlapped tunnels.