Rapid In-Situ Stress Measurement in Vertical Borehole Based on Borehole Diametrical Deformation Analysis

In-situ stress measurement is an important prerequisite for underground engineering excavation design and surrounding rock stability analysis. However, it is still a difficult problem to complete in-situ stress measurement quickly and accurately, especially in deep vertical borehole with more complex environment. Aiming at the existing problems, a new in-situ stress measurement method is proposed in this study. The principle of in-situ stress calculation based on the borehole diametrical deformation analysis is established, and a borehole diametrical deformation measurement equipment which can realize the directional measurement of multi-directional borehole wall displacement is developed according to this principle. The traditional single action double-tube drilling tool is optimized, and the corresponding in-situ stress measurement process is formulated, forming a rapid in-situ stress measurement method with the cooperation of drilling tools. The measurement method has been applied to the in-situ stress measurement at − 410 m and − 500 m levels in Zhangfushan deposit of Jinshandian Iron Mine, and effective diametrical deformation data of 6 measuring points were obtained. The measurement results show that the optimized single action double-tube drilling tool has the ability of accurate drilling and complete coring, and can assist in the rapid measurement of in-situ stress. The principal stress at the 6 measuring points basically increases with the increase of depth, and the direction of the maximum horizontal principal stress is about SN, which is basically consistent with the existing in-situ stress data. The results show that the method proposed in this paper can realize the rapid and accurate measurement of in-situ stress in vertical borehole.