Investigations on permeability of fractured, steep and deep rock slopes with high groundwater pressures

Efforts have been made in this study to determine fluid flow properties of the fractured rockmass, which greatly influence the construction/execution of any civil and mining engineering projects. In general, any engineering and mining activities brings fractures/discontinuities in the rockmass. Such fracture/discontinuity becomes a pathway for fluid flow. Further, presence of fluid in the fractured rockmass exerts pore water pressure on the rockmass. Increase or decrease in pore water pressure reduces or increases the effective stress respectively. As such, the strength of the rockmass depends on the behaviour of the effective stress. Consequently, an understanding of effective stress and pore water pressure becomes essential for the safe and economical execution of any civil or mining engineering projects. With this in view, a novel methodology to simulate flow of water through a fractured rockmass, by using an analogue material imbibing a single fracture, was developed. Further, fluid flow experiments were carried out on triaxial samples of granite, containing a ‘single rough walled fracture’, by employing high confining pressures (≈40 MPa) covers depth of upto 1000 m. Elevated fluid pressures (≈25 MPa) were applied and different fracture roughness created by selecting granite rock of different grain sizes, were considered in the present study. Furthermore, results obtained from the tests on analogue material and naturally occurring rockmass have been critically evaluated. This study demonstrates the usefulness of analogue material for easy and fast simulation of fluid flow properties through the fractured rockmass rather than resorting to the cumbersome and tedious process of sampling from the deep locations.Thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy of the Indian Institute of Technology, Bombay, India and Monash University, Australia