The probabilistic on and off fault displacement hazard analysis for high-speed railways crossing the middle Xiaojiang fault zoneOA

Purpose-The rapid expansion of high-speed railway(HSR)networks in Western China has increased the exposure of linear infrastructure to active faults.This study establishes and applies a probabilistic fault displacement hazard analysis(PFDHA)framework to quantify both on-fault surface rupture and distributed offfault permanent ground deformation(PGD)hazards for HSR crossings of the Xiaojiang Fault Zone(XJFZ).Design/methodology/approach-A PFDHA framework is developed,integrating a Poissonian seismicity model with spatial rupture randomness.The methodology is applied to the XJFZ,which crosses the Nanning-Kunming(NK)and Shanghai-Kunming(SK)HSR.Permanent displacement hazards are evaluated for 2 probability levels:10% and 2%probability of exceedance in 50 years.Findings-Through the evaluation of displacement hazards for 50-year exceedance probabilities of 10% and 2%,this study finds that for the NK and SK HSR,permanent displacements at a 10% probability of exceedance range from 1.0 m to 2.9 m,peaking at fault intersections.Comparative analysis shows that traditional deterministic estimates(1.3-2.0 m)generally align with the probabilistic results but fail to capture the full range of risk.Originality/value-This work adapts PFDHA to linear infrastructure in a tectonically active region of China,explicitly considering both on-and off-fault displacement within engineering-relevant corridors.The integration of regional rupture scaling and segment-based constraints provides a reproducible basis for displacement hazard assessment in HSR planning and retrofit.