Differential Evolution-Based Universal Segment Preliminary Layout Method for Shield Tunneling

The shield tunneling method is currently the most widely used underground construction technique, where the formed tunnel is composed of many sequentially arranged segments. Before construction, a preliminary layout of the design tunnel axis (DTA) is required to assess the segments' ability to fit the DTA and determine the number of segments needed. Existing preliminary layout methods only consider the axis fitting deviation of the next ring of segments to select the assembly point, which can lead to significantly increased axis deviations for subsequent segments, potentially exceeding allowable limits. This results in incorrect assessments of the segments' fitting ability, particularly for DTAs with small curvature radius. To address this issue, this paper proposes a segment preliminary layout method that considers the maximum fitting deviation of the next multiple rings of segments. The method uses a differential evolution algorithm to optimize the assembly point combinations of the next multiple segment rings. It employs a segment pose transfer algorithm to calculate the poses of the next multiple rings, and then computes the corresponding axis fitting deviations for these rings. The assembly point combinations with the minimum maximum axis fitting deviation is selected as the optimal solution, and the first assembly point is selected to assembly next segment. This method was applied to a 900m radius circular arc DTA using 28-point large diameter segments with a calculation of five segment rings. The maximum axis fitting deviation across the entire DTA was 9.3 mm, significantly lower than the 52.8 mm deviation obtained using existing layout methods.