Published: Građevinar 78 (2026) 8
Paper type: Original scientific paper
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Mechanical characteristics and parameter optimisation for extra-large deep foundation excavation at cross-transfer subway stations

Strict control of ground settlement and internal forces within the support structure represents a key technical challenge in the excavation of extra-large deep-foundation pits for cross-transfer metro stations. Based on the field monitoring results of the research section and fundamental geotechnical parameters of the rock mass, two-stage excavation schemes, BZL1 and BZL2, are proposed. The model was validated against the monitoring data. The evolution patterns of the ground settlement and internal forces within the support system for the two excavation schemes were analysed, and the optimal excavation scheme was selected. The results showed that the maximum error between the numerical simulation and field monitoring data of the ground settlement under the BZL1 excavation scheme was 13.84 %, indicating that the established model was reliable. When the BZL2 scheme for excavating foundation pits was employed, the peak cumulative surface settlement could be reduced by up to 56.7 %, whereas the peak axial force in the cross braces could be reduced by up to 48.14 %. The BZL2 scheme is the preferred option for excavating ultradeep large-scale foundation pits, offering superior safety and economic viability. These findings may serve as a reference for the construction of extra-large deep excavations at cross-transfer underground railway stations.

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