Abstract: In this study, a case study is conducted on the Chongqing-Kunming high-speed railway crossing underneath the Changshui airport, and the automatically monitored data in real-time of the airport surface displacement are used to analyze the lateral and longitudinal settlement patterns of the surface caused by the construction of the cantilever boring machine method. The results show the following: (1) The overall temporal evolution of surface settlement manifests in three distinct phases: gradual fluctuation, accelerated development, and stabilization. The rapid development of surface settlement concentrates in the interval after the upper bench passes through the monitoring point and before the lower bench passes through the monitoring point. (2) The modified Peck′s formula is more effective in characterizing the distribution of lateral surface settlement caused by the cantilever boring machine construction. The final settlement of the surface is 7.3 to 25.0 mm, the strata loss ratio is in the range of 0.16% to 1.01%, the lateral impact range is 4.0D to 5.3D (D is the span of the tunnel excavation), with the most unfavorable area concentrated in the range of 1.3D on either side of the tunnel, where requires particular monitoring. (3) The unfavorable conditions, including the diagonal intersection of the upper existing airport cargo access road, hidden cavities, and rock production, result in a shift in the distribution of surface settlement troughs in some sections to the right. (4) A notable discrepancy is observed in the extent of strata loss and surface settlement attributable to the various excavation phases, the strata loss rate associated with the excavation stages of upper and lower benches, as well as the invert arch, exhibits a descending order, with the respective proportions accounting for 81.3%, 17.0%, and 1.7% of the total settlement. (5) The longitudinal settlement pattern demonstrates that the longitudinal final settlement curve of the surface exhibits a pattern of increase initially and then decrease. The longitudinal influence of surface settlement resulting from tunnel excavation ranges from 3.2D to6.0D, with a corresponding variation of 1.3D to 2.3D ahead of the excavation and 1.4D to 3.9D behind.

Key words: high-speed railway tunnel, cantilever boring machine method, surface settlement, strata loss rate, influence scope