ABSTRACT
Hydraulic fracturing technique is an efficient technique for in-situ stress measurement at deep position. It was first introduced to China at the end of 1970’s by F. Li and J. Ding from Institute of Crustal Dynamics of the China Earthquake Administration. During 1983-1987, they cooperated with M. D. Zoback and B. C. Haimson from USA to conduct practical in-situ stress measurement with hydraulic fracturing technique for investigation of the tectonic stress field in westernYunnan Province (Li 1986). The measurement was completed at 4 boreholes, in which one borehole was 800 m deep and other three boreholes were 500 m deep. Since then, hydraulic fracturing technique gradually become a popular technique for in-situ stress measurement in rock engineering, especially in hydroelectrical and water conservancy engineering, highway and railway engineering, but less used in mining engineering before 2000 in China. (Gao & Ding 1990, Guo & An 2002)). However, in the recent few years it was already used in mining engineering for in-situ stress estimation at the early exploration stage of the mine and also in deep open-pit mines with high-steep slopes as the importance of in-situ stress state for such open-pit mines was recognized (Cai et al. 2010). It is clear that in the open-pit mine and in the early exploration stage of the underground mine, there is no any entrance to underground positions, compared with overcoring and other techniques, hydraulic fracturing technique is the only economical and reliable technique for detecting their underground stress state (Cai 1993, Ljunggren & Chang 2003).
