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THE EFFECT ON ROCK SWELLING DUE TO THE SALINITY DIFFERENCE BETWEEN ROCK PORE FLUID AND AMBIENT FLUID
Session: Rock Mechanics and Engineering Geology I / Mécanique des roches et ingénierie géologique I
Taesang Ahn, Ph.D., P.Eng. (Canada)
Silvana Micic, Ph.D., P.Eng. (Canada)
Kwan Yee Lo, Western University (Canada)
A consideration of swelling characteristics of shaley rock is essential for underground structures such as tunnels. The swelling characteristic known as time dependent deformation is mainly due to a mechanism of osmosis and diffusion between pore fluid in rock and ambient fluid. An extensive experimental program has been carried out to investigate the effect on rock swelling due to the salinity difference between rock pore fluid and ambient fluid having different salt concentrations. The test program includes free swell tests, semi-confined swell tests and null swell tests with measurements of salinity of rock pore fluid and calcite content on three rock formations including Georgian Bay, Queenston and Shaftesbury. It is observed that, for a given salinity difference between pore fluid of rock and the ambient fluid, a significant effect on swelling potentials exists both in vertical and horizontal directions during the free swell tests and semi-confined tests on Queenston, Georgian Bay and Shaftesbury shale samples.
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