Dingxiao Tunnel is located at the karsts area in Guizhou province; in which the geological structure is very complicated and full of crushing rocks. All these bring high risk in tunnel excavation; and its tunnel geological prediction work faces great difficulty. Currently there are several tunnel geological prediction techniques

but most of them have three major issues. First

they did not differentiate the echo seismic waves from individual directions; it assumes all the seismic waves come from the front tunnel face. Second

they can not calculate the rock velocity in the front tunnel face. Third

they cannot separate p wave and s wave correctly. So the result cannot be accurate and reliability. For safety and efficiency

a new tunnel geological prediction technique

the tunnel seismic tomography(TST) is adopted in Dingxiao tunnel. TST utilizes spatial observation

F-K filtering and velocity scan techniques which solved all the issues indicated above. The function of spatial observation and velocity scan in TST gives precise velocity analyzing and enabled accurate geological structure locating. The F-K filtering function of TST gets rid of the surface wave and sidewise echo wave

only uses the wave coming back from front.