(1. Institute of Geomechanics，Chinese Academy of Geological Sciences，Beijing 100081，China；2. Key Laboratory of Neotectonic Movement and Geohazard，Ministry of Land and Resources，Institute of Geomechanics，Chinese Academy of Geological Sciences，Beijing 100081，China；3. Beijing Research Institute of Uranium Geology，Beijing 100029，China)
Abstract：In order to know the geostress characteristics of a candidate repository，in-situ stress measurement of hydraulic fracturing using a single loop system was carried out in four boreholes in granite rock. The data of geostress and the orientation of the maximum horizontal principal stress at depths ranging from 0 to 700 m below the ground surface were obtained successfully based on the information of borehole log. The geostress state and the fault activity in the candidate repository were analyzed according to the measured data，Byerlee law and Coulomb criterion for fault friction. Three principal stresses have the good linear relationships with depth. Within the range of tested depth，the horizontal stresses are generally higher than vertical stresses and the regional stress field is dominated by the tectonic horizontal stresses，which attenuate gradually with depths. The horizontal force in rock mass in the north is greater than that in the middle and south and it is the lowest in the south. The orientations of the maximum horizontal stress are dominantly in the NEE direction，which is in accordance with the direction of regional tectonic stress field. From the interior and the edge of the Tibetan plateau to the eastern Tianshan mountain，the maximum horizontal stress orientations show the variation of the NE to NEE. The geostress values do not reach the limit state of fault friction sliding and the fault activity is weak.
2017, Vol. 36 
