Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-4-2013

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

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Seventh Conference

Publisher

Missouri University of Science and Technology

Publication Date

4-29-2013

Document Version

Final Version

Rights

© 2013 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 29th, 12:00 AM May 4th, 12:00 AM

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.