Abstract:

Geological radar is one kind of the electromagnetic wave technologies with high frequency, which is widely used in geological exploration. According to the Zijingshan karst tunnel engineering during the Daguangnan Highway construction in Hubei, a continuous mode was adopted to collect signals by geological radar in order to detect an  adverse geological body. Signals collected were processed by gain control and filtering processing. Combining with the typical examples of fissure, karstcave and water-bearing rock mass, the specific characteristics of their radar reflection were analyzed, such as unorganized events in reflection of joint fissure, zonal distribution in reflection of karst fissure, hyperbola in reflection of karst caves, the decrease of frequency and energy in reflection of water-bearing rock mass. These characters are helpful for estimating the concrete position and scale of an adverse geological body and can provide a basis to protect the safety of tunnel construction.

Key words: geological radar; geological forecast; karst tunnel