FEM ANALYSIS OF LONG-TERM SETTLEMENT OF SOFT SOIL CAUSED BY METRO LOADING

To investigate the subway induced long-term settlement of soft soils in Shanghai, a bounding surface constitutive model combined with the theory of elastoplastic dynamic consolidation is employed in this finite element analysis using ABAQUS software. A three dimensional track-tunnel-soil interaction model is established; and two kinds of tunnel layout are covered, that is single tunnel and double-tube parallel tunnel, respectively. The settlement regulations of subway tunnel under single and multiple train loads are studied. On this basis, three empirical calculation methods are applied to estimate the long-term settlement of the subgrade, the amplitude of dynamic stress and settlement caused by moving trainload under three different loading conditions are obtained as well. In addition, the settlement characteristics of single and double tube tunnels are compared, and the numerical solution is also compared with the measured values. The analysis shows that, the calculated result is consistent with the field test result. The subgrade settlement of the double tube tunnel is not merely a linear superstition of two single tube tunnel, amplification existed.