Location
Chicago, Illinois
Date
01 May 2013, 2:00 pm - 4:00 pm
Abstract
Punatsangchhu Hydroelectric Project stage-I was conceptualized in Wangdue- Phodrang district of Bhutan for harnessing the hydro-power potentiality of Punatsangchhu River. Regionally the project area is located within a part of a gneissic terrain of Tethyan Belt of Bhutan Himalayas. The project envisages construction of 195m high concrete gravity dam across the river Punatsangchhu. For Desilting chamber and Powerhouse, it is always desirable to carry out in-situ stress measurement in such huge underground openings for designing of the support types. The stability of the underground cavern gets enhanced if the long axis of the cavern is oriented along or sub-parallel to that of maximum principal stress. National Institute of Rock Mechanics, a premier Research Institute under Ministry of Mines, Government of India, carried out stress measurements at RD 100m and RD 150m inside an exploratory drift approaching towards desilting chamber with a rock cover of 100m. This test was required to freeze the orientation of desilting chamber vis. a vis. orientation of maximum compression (σH) which was found to be N 150°. As it was only 100 to 150 m away from the portal, a topography effect on the orientation of (σH) was not completely ruled out. So when the adit to Desilting chamber reached at RD 360m with a rock cover of 410m, it is necessary to carry out stress measurement at RD 360m to confirm the results of earlier tests at RD100m and RD 150m to find out the influence of topography on which the present paper is based was primarily for determination of in-situ stress measurements. The stress orientation as evaluated at RD 360m reconfirms the orientations revealed from earlier stress measurements at RD 100 and RD 150m.Thus it is recommended to freeze the direction of Desilting chamber along N 150°. It also confirms that the earlier stress measurement results do not suffer from topography related influence.
Department(s)
Civil, Architectural and Environmental Engineering
Meeting Name
7th Conference of the International Conference on Case Histories in Geotechnical Engineering
Publisher
Missouri University of Science and Technology
Document Version
Final Version
Rights
© 2013 Missouri University of Science and Technology, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Document Type
Article - Conference proceedings
File Type
text
Language
English
Recommended Citation
Subrahmanyam, D. S.; Sengupta, S.; Sinha, R. K.; and Shyam, G., "Determination of In-Situ Stress at Desilting Chamber of Punatsangchhu Hydroelectric Project (Bhutan), to Reconfirm Its Orientation Influenced by Topography — A Case Study" (2013). International Conference on Case Histories in Geotechnical Engineering. 18.
https://scholarsmine.mst.edu/icchge/7icchge/session01/18
Determination of In-Situ Stress at Desilting Chamber of Punatsangchhu Hydroelectric Project (Bhutan), to Reconfirm Its Orientation Influenced by Topography — A Case Study
Chicago, Illinois
Punatsangchhu Hydroelectric Project stage-I was conceptualized in Wangdue- Phodrang district of Bhutan for harnessing the hydro-power potentiality of Punatsangchhu River. Regionally the project area is located within a part of a gneissic terrain of Tethyan Belt of Bhutan Himalayas. The project envisages construction of 195m high concrete gravity dam across the river Punatsangchhu. For Desilting chamber and Powerhouse, it is always desirable to carry out in-situ stress measurement in such huge underground openings for designing of the support types. The stability of the underground cavern gets enhanced if the long axis of the cavern is oriented along or sub-parallel to that of maximum principal stress. National Institute of Rock Mechanics, a premier Research Institute under Ministry of Mines, Government of India, carried out stress measurements at RD 100m and RD 150m inside an exploratory drift approaching towards desilting chamber with a rock cover of 100m. This test was required to freeze the orientation of desilting chamber vis. a vis. orientation of maximum compression (σH) which was found to be N 150°. As it was only 100 to 150 m away from the portal, a topography effect on the orientation of (σH) was not completely ruled out. So when the adit to Desilting chamber reached at RD 360m with a rock cover of 410m, it is necessary to carry out stress measurement at RD 360m to confirm the results of earlier tests at RD100m and RD 150m to find out the influence of topography on which the present paper is based was primarily for determination of in-situ stress measurements. The stress orientation as evaluated at RD 360m reconfirms the orientations revealed from earlier stress measurements at RD 100 and RD 150m.Thus it is recommended to freeze the direction of Desilting chamber along N 150°. It also confirms that the earlier stress measurement results do not suffer from topography related influence.
