Abstract: Hydraulic fracturing as a technique of geostress measurement has been widely applied at home and abroad due to its many outstanding merits. But this measuring method is only used to the two－dimensional stress in a plane normal to the borehole axis in former time．Recently，the method of by hydraulic fracturing measurement of three－dimensional geostresses is prevalent and has been used successfully in many projects. In Shenzheng Pumped Storage Power Station，the three－dimensional geostresses have been measured by hydraulic fracturing technique to adopt two different measuring methods including in three boreholes with different directions method and in one borehole method, and the measured results are very satisfactory. The latter measuring method was applied in two boreholes that one is in vertical direction and the other one is in approximately horizontal direction. The three－dimensional geostress measured results not only checked the two－dimensional geostress measured stress states in the corresponding borehole’s cross-section and preexisting fissure planes, but also the measured results of the two different measuring methods in the same place confirmed each other; and the measured results confirmed by the results obtained overcoring stress refief method in the same borehole. At the same time, the measured results of the two type methods are very consistent (one borehole measuring methods including non-vertical borehole and vertical borehole), and it can represent the geostess state in the measured area.

Key words: hydraulic fracturing technique, three-dimensional geostress measurement, three boreholes with different directions measuring method, one borehole measuring method, Shenzheng Pumped Storage Power Station