STRESS FIELD AND POTENTIAL UNDERGROUND GEOHAZARDS IN EASTERN MARGIN OF QINGHAI-TIBET PLATEAU

A series of deep and large active fault zones are widely developed in the eastern margin of the Qinghai-Tibet Plateau,which strongly controls the regional stress field. Here we determine the in-situ stress field under the influence of active faults in the eastern margin of the Qinghai-Tibet Plateau by numerical simulation inversion of an extensive collection of 1181 groups of in-situ stress data collected from 178 points. The result show that an obvious non-uniformity is the most significant characteristic in the Qinghai-Tibet Plateau. The stress value decreases gradually from west to east. The potential of rock burst and large deformation at the depth of 100~2000 m in the eastern margin of the Qinghai-Tibet Plateau is also analyzed by ArcGIS. Rock burst is concentrated within the secondary plate while the large deformation mainly occurs at the boundary. The area of rock burst does not change with depth basically,however,large deformation gradually increases and develops to the interior of the secondary plate. The potential of rock burst and deformation changes regularly with the buried depth. Finally,two engineering cases of Erlang Mountain tunnel and Shuangjiangkou Hydropower station are presented to discussed the applicability of the prediction of rock burst and large deformation potential. The results indicate that the underground geohzards potential in the eastern margin of Qinghai-Tibet Plateau predicted in this study is basically consistent with the rock burst tendency based on the strength-stress ratio and the rock burst phenomenon in the two cases.