Delineation of Cavity in Downstream Surge Chamber at Punatsangchhu-II Hydroelectric Project, Bhutan

Authors

  • B.N.V. Siva Prasad Scientist, National Institute of Rock Mechanics, Bengaluru, India
  • A.P. Thapliyal Senior Geologist, Geological Survey of India, Dehradun, India
  • Rabi Bhusan Scientist, National Institute of Rock Mechanics, Bengaluru, India
  • Sripad R. Naik Scientist, National Institute of Rock Mechanics, Bengaluru, India

DOI:

https://doi.org/10.30564/jgr.v1i1.392

Abstract

On 3rd March, 2016, there occurred a massive roof fall incidence in one of the major caverns of Punatsangchhu-II Hydroelectric Project (PHEP-II), Bhutan which halted the operations in the major caverns and required additional strengthening measures. Prior to concluding anything on the treatment measures for the muck flown into the cavern and the cavity formed over the crown of Downstream Surge Chamber, there was a strong need to determine the extents of cavity. Even to understand the influence of cavity formation on adjacent caverns, the cavity needs to be delineated. Therefore, the management of PHEP-II adopted several techniques to decipher the shape and dimensions of the cavity like, surveying, geophysical, cross-hole seismic surveys, borehole scanning, and exploratory drilling. The tentative shape of the cavity could finally be established. The findings from each method are explained in this paper.

Keywords:

Cavity, Large caverns, Hydroelectric project, Tomography, Cavity monitoring system

References

[1] BNV Siva Prasad, SR Naik, K Sudhakar, R Bhusan, V Sekar and A Mishra, 2017,“Report on analysis of instrumentation data and assistance in installation & monitoring of instruments at C-3 Package of Punatsangchhu-II Hydroelectric Project, Bhutan”, NIRM Report No. NIRM/NM1701C.

[2] Geotechnical Report, 2011,“Document No. VII for Contract Package Number C3, P-II HEP,” by WAPCOS,

[3] S Rana, D Milani, R Aspesi and A Mishra, 2018, “Report on “Cavity detection by means of Seismic Tomography analysis of P waves between boreholes”, PARSAN Overseas Pvt. Limited Report No. S18SN06_Bhutan_PunatsangchhuII_tomography.

[4] Sajid Mukhtar, 2017, Project report on PHPA-II Measurement of cavity by using CMS V500”, APIPL.

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How to Cite

Siva Prasad, B., Thapliyal, A., Bhusan, R., & Naik, S. R. (2019). Delineation of Cavity in Downstream Surge Chamber at Punatsangchhu-II Hydroelectric Project, Bhutan. Journal of Geological Research, 1(1), 5–11. https://doi.org/10.30564/jgr.v1i1.392

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