THE APPLICATION OF CROSSHOLE SEISMIC CT METHOD TO THE ADVANCED GEOLOGICAL PREDICTION OF SHIELD TUNNEL

Using the seismic crosshole CT method for high precise detection of metro shield zone, Acquiring the information of formation and the distribution of adverse geological between test hole were acquired, so as to achieve the purpose of the shield advance geological prediction in tunnel construction. By introducing the size error and location error, the detection effect of location and size, which was detected by cross-hole seismic CT tomographic, were further compared and analyzed. And base on erroranalysis, the difference between each effects detected in different detecting target or different detecting area were analyzed. The results of error analysis show that the detection effect of the target location is superior to effect of the size, and, the detection accuracy for different object is mainly determined by the difference of the seismic wave velocity between object itsself and the surrounding. In addition, through the contrast of detection effect for different location on test section, can also be concluded that detection accuracy of areas in the middle of the test hole is higher than the areas adjacent test hole. According to the analysis result and the conclusions, the geological prediction method for shield tunnel which based on cross-hole seismic CT was formed.