Ahmad, Sohaib, Afridi, Noor Zada, Ahmad, Tufail, Shahzad, Muhammad Imran, and Awais, Muhammad (2023) Formation of stress relief discontinuities due to removal of normal load from foundation rocks, Tarbela Dam, Pakistan. Himalayan Geology, 44 (1). pp. 97-105.

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Abstract

The current paper presents a case study of the Tarbela Dam (Pakistan) based on highly deformed Precambrian schistose rocks. These rocks are exposed after removing the normal load from the foundation rocks. Stress relief discontinuities are induced by removing the normal load, which significantly influences the hydraulic conductivity of underlying rock mass. The ingression of water seepages through these discontinuities decreases the shear strength of foundation rock mass to a considerable extent. It subsequently enhances the potentialities of rock mass failure along planes of weak discontinuities. Water pressure tests were conducted during pre-and post-excavation stages to acquire the hydraulic conductivity at the same elevation of the foundation area. The hydraulic conductivity measured at the pre-excavation stage is less than its value at the post-excavation stage. It is indicating that stresses are released after removal of normal load from foundation rock mass with marked impact on dilation and enhanced amount of hydraulic conductivity (at post-excavation stage).

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