Comprehensive geophysical prediction and treatment measures of karst caves in deep buried tunnel

• Engineering geological and hydrogeological conditions of the tunnel were investigated.
• GPR method was integrated with Geological Drilling for karst cave prediction.
• TSP method was also applied and the result agrees well with the field investigation.
• Beam–Slab and Backfill methods were carried out for the treatment of the karst caves.

While tunneling in karst terrains, engineers may encounter hazardous geotechnical structures such as faults, karst caves and collapse columns which may induce geohazards and seriously endanger the construction safety. Geological processes significantly affect the varieties and characteristics of karst caves, and therefore engineering geological and hydrogeological conditions of Shangjiawan Tunnel were analyzed firstly. In order to accurately predict the geometric characteristics of karst caves and their spatial relationship with the tunnel, the Ground Penetrating Radar (GPR) and Geological Drilling (Geo-D) were applied comprehensively in the present study. The Tunnel Seismic Prediction (TSP) system was also applied to forecast whether any karst cave existed in front of the tunnel face and the detection results generally agree well with the field investigation. Furthermore, the Beam–Slab method was carried out for the treatment of the karst cave which situated under the tunnel floor, while the Backfill method was applied for the karst cave which was exposed during the construction.