STUDY ON RELATIONSHIP BETWEEN CONVERGENCE LOSS AND LONGITUDINAL DEFORMATION CURVE IN TUNNEL EXCAVATION BY USING THREE-DIMENSIONAL FINITE ELEMENT ANALYSIS
Abstract：The objective of this study is that the application of convergence-confinement method and the 3D numerical analysis by using the finite element programming developed in laboratory are employed to analyze the interaction behaviors between rock mass and support system in tunnel excavation. The parametric studies of elastic rock mass，initial stress and tunnel radial displacement are taken account of the relationship between the convergence loss and the longitudinal deformation curve(LDC) with conditions of supported or unsupported tunnels. The analytical solutions of equations are compared with the results obtained by 3D numerical analysis to find out the influences of convergence loss. According to the obtained results，the comparison between numerical calculation and theoretical analysis shows that：(1) the convergence loss is particularly function of the LDC；(2) the influence of parameters considered can be eliminated by the process of normalization for the LDC；(3) the estimated preconvergence normalized by the maximum convergence value approximately equal from 25% to 36% at the advancing excavation face in elastic condition；and (4) the convergence loss from the proposed equations of LDC in two-dimensional condition can be probably used to not only describe the three-dimensional advancing effects，but also estimate the variation of stress-displacement of rock mass and support system in tunnel excavation.
