FIELD TEST OF GEOLOGICAL PREDICTION BY RADAR POSITIONING DETECTION IN KARST REGION

In order to test the actual effectiveness of karst scale and status detection by geological radar for tunnel engineering, American SIR-2000 radar is used in geological prediction study for Maoba syncline in Yuanliangshan tunnel of Yuhuai railway. The research results shown that there is obvious boundaries between grouting wall and bedrock in the front of main hole DK354+461; 4 meters away from the surface is water-bearing sand layer; there is significant stratification in 17 similar to 20 m deep. Under this mileage, a 4 similar to 6 m deep karst cave was developed 3 similar to 5 m back of tunnel face from the right wall of bottom heading; within 8m back of tunnel face of bottom heading, the walls both left and right sides and the rocks of arch parts are continuous; the surface surrounding rocks are broken with uneven density. The borehole results indicate that the karst conditions and rock thickness at this mileage are basically consistent with radar detection results.