Based on the complex deep foundation pit group process of the Huimin Avenue Comprehensive Reconstruction Project in Nanjing, the finite element numerical simulation method is used to analyze the deformation characteristics of the retaining structure and the coupling effect between foundation pits during the whole process of excavation and support construction of the complex foundation pit group. Meanwhile, the differences in the deformation characteristics and coupling effects of the retaining structure under different construction time sequence schemes of the foundation pit group are studied. Finally, some suggestions are put forward for the monitoring and construction in this project, which provides a reference case for the design and construction of similar foundation pit groups.

Cemented soil offers advantages over conventional concrete, including reduced carbon emissions, cost-effectiveness, and recyclability, making it suitable for foundation reinforcement and excavation support. However, reliable health monitoring of cemented soil structures remains challenging. This study introduces multi-walled carbon nanotubes (MWCNTs) and nano-magnetite (NM) as conductive fillers to develop self-sensing cemented soil composites for real-time monitoring of pile foundations. The electrical conductivity, piezoresistive response, and dynamic sensing behavior of composites prepared with different doping strategies were systematically evaluated through model pile loading tests and microstructural analyses. Results indicate that MWCNTs enhance electro-mechanical coupling by forming conductive networks, while NM primarily improves early mechanical properties and densifies the matrix. Combined doping mitigates nanotube agglomeration, optimizes conductive pathways, and enhances microstructural integrity. Under cyclic compression, composites achieved a maximum fractional change in resistivity (–35%) with strong linear correlation to strain ( R ² > 0.90), maintaining stable responses across repeated loading cycles. Single-pile horizontal loading tests further demonstrated effective signal output across monitoring depths, synchronized with strain fluctuations, and preserved even in deeply buried regions, indicating robust signal penetration and multi-layer sensing capacity. Moreover, the conductive network remained stable under large deformations and micro-crack evolution, confirming high adaptability and fault tolerance. These findings provide strong evidence that co-doped MWCNTs and NM cemented soil composites are reliable and scalable materials for real-time health monitoring of pile structures under practical engineering conditions.