The stability of tunnels has mainly been evaluated based on displacement. Because displacement due to the excavation process is\nsignificant, back analysis of the structure and ground can be performed easily. Recently, the length of a segment-lined tunnel\ndriven by the mechanized tunneling method is increasing. Because the internal displacement of a segment-lined tunnel is trivial, it\nis difficult to analyze the stability of segment-lined tunnels using the conventional method. This paper proposes a back analysis\nmethod using stress and displacement information for a segment-lined tunnel. A differential evolution algorithm was adopted for\ntunnel back analysis. Back analysis based on the differential evolution algorithm using stress and displacement was established and\nperformed using the finite difference code, FLAC3D, and built-in FISH language. Detailed flowcharts of back analysis based on\nDEA using both monitored displacement stresses were also suggested. As a preliminary study, the target variables of the back\nanalysis adopted in this study were the elastic modulus, cohesion, and friction angle of the ground. The back analysis based on the\nmonitored displacement is useful when the displacement is significant due to excavation. However, the conventional displacement-\nbased back analysis is unsuitable for a segment-lined tunnel after construction because of its trivial internal displacement\nsince the average error is greater than 32% and the evolutionary calculation is finalized due to the maximum iteration\ncriteria. The average error obtained from the proposed back analysis algorithm using both stress and displacement ranged within\napproximately 6â??8%. This also confirms that the proposed back analysis algorithm is suitable for a segment-lined tunnel.
Loading....