RESEARCH ON CHARACTERISTICS AND CONTROL TECHNIQUES OF ROCKBURST IN QINLING TUNNEL OF WATER DIVERSION PROJECT FROM HAN RIVER TO WEI RIVER

QinLing tunnel of the water diversion project from Han river to Wei river is a key water diversion project in Shaanxi province. Passing through the Qinling Mountain, complex geological structures, deeply buried, large in situ stress, and variable geological conditions are encountered. Geological information, design data, lab testing data and related literature are reviewed in this paper. Data on occurrence of rock burst in Qinling tunnel are recorded systematically; the characteristics of rock burst in the area are analyzed carefully. Engineering analogy method, theoretical analysis and FLAC3D numerical simulation method were applied in section K20+500 and K27+740 with depth 1170m and 750m respectively, the corresponding rock type is quartz schist and granite, drill and blasting method and TBM construction methods. Two section forms, horseshoe section and circular section were analyzed. With the increase of buried depth, the probability of rockburst increased, as well as the magnitude of rockburst. Stress concentration area mainly occurs in tunnel vault and bottom of arch. Secondary micro cracks in rock mass are roughly generated along tunnel tangential direction, when tangential stress exceeds dilation threshold stress. Prevention measures of rockburst and parameter selection for drilling and blasting method and TBM are proposed in the paper.