Abstract: In view of limitations of the sleeve fracturing method for deep in-situ stress testing, a sleeve expansion pipe was improved for ground stress measurement. Synthesizing the characteristics of single-hole sleeve fracturing method and control fracturing method, a more operable ground stress measurement technology of parallel boreholes sleeve fracturing method was provided in this paper. Additionally, the formulas for the single-hole sleeve fracturing and the control fracturing were modified reasonably through the testing. The results show that the correction coefficients obtained for single-hole sleeve fracturing method was 0.78, while that for control fracturing method was 0.83. In-situ test was carried out for main track roadway buried in 965 m underground located at Zhuji east coal mine. The test results show that the maximum principal stress is 23.16 MPa in the west-east direction, the intermediate principal stress is 21.04 MPa in the vertical direction, and the minimum principal stress is 13.01 MPa in the north-south direction.

Key words: sleeve fracturing method, in-situ stress, parallel boreholes, model experiment, in-situ test