ABSTRACT
Prediction of water flow into underground structures is a challenging issue due to uncertainties on the rock mass parameters. Seepage estimation into tunnels and caverns is vital and a major task during construction and operation period. The data required for seepage estimation include geology information such as lithology and stratigraphy, and considering the geometric, mechanic and hydraulic characteristics of discontinuities.
In this paper the results of the measurements of water inflow into the powerhouse cavern and drainage tunnel of the Rudbar hydroelectric project are compared to the estimations. These structures are located in limestone and dolomitic limestone with medium thickness. The cavern and drainage tunnel are distant about 250 m from the reservoir of Rudbar main dam and about 110 m below the normal reservoir water level. This makes these structures susceptible of inrush of water during construction and operation period. The seepage into powerhouse cavern and drainage tunnel has been estimated with analytical and numerical methods. The main flow paths are the rock discontinuities, faults and fractures. Their characteristics such as the hydraulic aperture, orientation, connectivity are flawed by uncertainties that affect seepage estimation. So, the estimated seepage with analytic and numerical methods differs from the measured seepage.
