Re-analyzing the in-situ stress field in the right bank of the Baihetan hydroelectric power plant using the borehole breakout data

Abstract

The Baihetan hydroelectric power plant, located on the Jinsha River in the Sichuan-Yunnan Block, Southwest China, is the second largest after the Three Gorges hydroelectric power plant. Crustal stress state is an important geological factor affecting underground engineering, and the stability analysis of underground chamber is of great significance. For the long-term safe operation of the Baihetan hydroelectric power plant, the ultrasonic borehole televiewer with high resolution is utilized to log 7 boreholes in the right bank. The data of borehole breakouts are used to calculate the present orientation of principal stress in engineering rock masses. The results show that the orientation of the maximum horizontal principal stress (SH) in the right bank is NNE-SSW, which is mainly influenced by tectonic stress, gravitational stress, river denudation and bank slope unloading, belonging to the local tectonic stress field.

Keywords

• baihetan hydroelectric power plant
• ultrasonic borehole televiewer
• borehole breakouts
• drilling-induced tensile fractures
• in-situ stress field
• orientation of the maximum horizontal principal stress