APPLICATION OF HYDRO FRACTURE STRESS MEASUREMENT IN DEEP-BURIAL TUNNEL CONSTRUCTION WITH HIGH IN-SITU STRESS

The region of western China belongs to the north-east edge of Tibet Plateau. Due to the periods of tectonic movements and extrusion of current Tibet Plateau in the direction of NW-NNW,the region characterizes by intense horizontal squeezing, which generally shows a high-stress value. With the development of railway construction, it becomes more and more universal for deep-burial tunnel built in the west of China. As results of this stress condition, the problems induced by excavation of tunnel are exclusive, such as a constantly compressional deformation in lamellar soft rock. And they are chanlleging the tradational methods we uesd to deal with them. Thus, it is necessary for us to figure out current stress status of project area as well as to choose the appropriate axes of tunnel and take full advantage of self-bearing capacity of surrounding rock. In addition, a scientific support design is absolutely necessary. The hydrofracture stress measurement, which can be simply operated and measure deeply, is one of the most effective methods for in-situ stress measurement. We summarize a kind of high geo-stress evaluation derived from Hoek-Brown formula and Byerlee laws. It can appropriately evaluate whether the project zone of tunnel belongs to high geo-stress area by utilizing the result of in-situ stress test and quality of surrounding rock. By means of that, we can assure the construction of tunnel project safe and stabile.