Fusion of numerical simulation and on-site monitoring for full-life-cycle stability regulation and reinforcement optimization of karst region large-span aqueduct slopes: a case study of the Longchang Aqueduct in the Qianzhong Water Hub, China

This study establishes a full-lifecycle stability control framework for ultra-large-span aqueduct slopes in karst terrain, integrating numerical simulation and field monitoring. Using the Longchang Aqueduct slope of Guizhou’s Qianzhong Water Control Project as a representative case, we addressed geological challenges including intense weathering, karst development in limestone/marly limestone, and heterogeneous slope structures. Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D) simulations evaluated slope stability under natural conditions, construction loads (anchor-cable tensioning), and operational impacts (aqueduct seepage and groundwater infiltration). Key innovations include: (1) a karst-adapted modelling protocol that dynamically adjusts rockmass parameters based on RMR classification and real-time monitoring; (2) reinforcement optimisation combining grouting (15 m radius) and 211 prestressed anchors, decreasing maximum foundation displacement from 65.4 mm to 6.4 mm (>90% improvement); and (3) verified operational resilience under seepage, maintaining displacement below 9.1 mm (confirmed via extensometers with ≤1% error). Field monitoring showed stability throughout construction (max. 10.93 mm displacement) and operation, within the ≤12 mm safety threshold. This framework offers a validated methodology for lifecycle stability management of mega-infrastructure in high-risk karst environments.