ABSTRACT Understanding soil arching and failure modes of ground subsidence above buried pipelines is crucial for developing effective mitigation strategies to reduce sinkhole hazards. Although previous studies have examined soil arching using discrete or continuum methods, the soil–pipeline interaction under localized subsidence remains insufficiently quantified. To address this gap, the present study employs a discrete–continuum coupled (DEM–FEM) trapdoor model, which was quantitatively validated against previous trapdoor tests. Using this validated framework, the influence of pipeline diameter ( D ) on the evolution of soil arching was systematically analyzed for five D / B ratios ranging from 0.5 to 1.5. The results reveal that increasing the pipeline diameter broadens the disturbed zone and induces three distinct soil‐arching evolution patterns: closure type, parallel open‐ended type, and divergent open‐ended type. A critical transition occurs at D / B = 1.0, corresponding to the minimum soil‐arching ratio, beyond which arching efficiency improves. Larger trapdoor displacements reduce the magnitude and spatial extent of high‐pressure zones, while varying D / B produces staged pressure redistribution and anisotropic stress transfer above the pipeline. Moreover, both the coordination number and fabric anisotropy analyses highlight microstructural degradation and directional instability with increasing pipeline diameter, revealing multiscale mechanisms governing stress redistribution and soil–structure interaction that have not been previously reported in trapdoor studies.
Zhang et al. (Mon,) studied this question.