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Abstract The assessment of deflection and voiding resulting from shield tunnelling on overlying pipelines is critical for safeguarding their structural integrity. A method for calculating such deflection and voiding during shield tunnel excavation，taking into account variations in stiffness between the pipeline?s overlying and underlying subgrades，was developed using a double-layer Winkler foundation model. Model tests verified its applicability. Conventional subgrade bearing theories for pipelines buried in sand were refined based on plate load tests，providing recommendations for stiffness and ultimate bearing capacity relevant to soil-pipeline interaction during shield tunnelling. Parameter analysis revealed that void width increases with pipeline flexural stiffness and tunneling ground loss，albeit at a decreasing rate. Significantly，under conditions of high ground loss or pipeline flexural stiffness，both the soil-pipeline elastic interaction theory and the single-layer foundation method，considering interface voiding，tend to overestimate pipeline deflection and bending moments. In contrast，the double-layer Winkler foundation method，incorporating interface voiding，delivers a more precise prediction of pipeline deflections.
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