Abstract: According to the in-situ stress measurement results with the method of hydraulic fracturing measurement at three nuclear power stations in Guangdong province, the distribution characteristics of current in-situ stress state at each nuclear power station are obtained. The results show that the horizontal stresses are dominant at each nuclear power station; and that horizontal principal stresses increases linearity with the depth at Dayawan and Yangjiang nuclear power station, while the phenomenon is not obvious at Taishan nuclear power station; and that the direction of maximum horizontal principal stress is NW-NWW at Dayawan and Yangjiang; however, is NNW at Taishan. Based on the data of stress and the interrelated theories as well as criterions, it is concluded that major axis orientation of tunnels at Dayawan goes against the stabilities of the tunnels; while these are beneficial to tunnels’ stability at Taishan and Yangjiang; and that the favorite shapes of all tunnels’ cross-section are ellipses with horizontal long axis, vertical short axis and long to short axis ration as lateral pressure coefficient; and that the rock burst is not happened during tunnels excavation at different buried depth. Finally, based on the sliding friction criteria of fault, the stabilities of the active faults are discussed.

Key words: hydraulic fracturing technique, nuclear power station, in-situ stress field, stabilities of tunnels, sliding friction criteria of fault