Directional drilling in karst areas frequently encounters adverse geological phenomena such as drill sticking and water inrush, significantly impacting construction progress and increasing investment risks. This study investigated a water conveyance project for a newly constructed reservoir in Zhejiang Province, employing integrated geophysical methods including parallel electrical resistivity, transient electromagnetic method, and ground-penetrating radar for systematic route surveying. The findings reveal that: (1) The resistivity distribution along the top of the directional drilling route is discontinuous, with significant interruptions in high-resistivity zones;three-dimensional resistivity imaging identifies extensive low-resistivity anomalies extending into deeper strata; (2) transient electromagnetic data indicating multiple overlying low-resistivity closed anomalies, more extensively distributed in water-inrush sections; (3) ground-penetrating radar profiles showing strong-amplitude diffraction-scattered reflections within 0-110m laterally and 30m vertically. Comprehensive analysis confirmed water inrush primarily resulted from intersecting karst zones or water-conducting faults, prompting route adjustment recommendations.Subsequent highway collapse incidents validated the reliability of the geophysical results, providing crucial technical support for construction optimization and risk mitigation.
 

Directional Drilling ；,Integrated Geophysical Methods,ground-penetrating radar,parallel electrical resistivity,transient electromagnetic method