JOURNAL OF ROCK MECHANICS

JOURNAL OF ROCK MECHANICS

Determining the Optimal Direction of Grout Injection Holes in the Cut Off Curtain of Safarood Dam Using Combination of Hydraulic Conductivity Tensor and Lugeon Test

Document Type : Original Article

Authors
1 University of Zanjan,
2 Hamedan University of Technology, mining engineeing Dep.
3 University of Zanjan, University Blvd., Zanjan, I. R. Iran
Abstract
Cracks are known as the main water passes in rock masses. Determination of the leakage path within the cracks and the quantity of hydraulic conductivity is essential for controlling the water escape path, economic issues and stability of dams. After determining the water escape paths, direction of injection boreholes will be specified. Hydraulic conductivity tensor method can provide a relatively reasonable orientation of the main pathways of water flow through discontinuities, but one of the most important parameters -the aperture of the joints- cannot be easily determined. Hence, according to the cube law this method cannot be used independently. On the other hand, the most common method to determine the hydraulic conductivity factor of jointed rocks is Lugeon test. This test directly determines the permeability of the rock around the boreholes, but cannot determine the orientation of leakage tensor. Therefore, the in-situ hydraulic experiments and hydraulic conductivity tensor methods should be combined to correct the leakage tensor in broken rocks. The main directions of water leakage in rock and implementation of versus ruling leakage joints is determined in the DIPS software and the optimized direction of the injection boreholes in the rock mass is studied. Then the capability of injection holes' direction in fault zones has been studied and, in the zones, where the decreasing of capability was observed, the direction of the optimal hole was determined. The principal values of hydraulic conductivity tensor were corrected using Lugeon test results as well. Based on the results of the Lugeon tests and the correction of the hydraulic conductivity tensor, the maximum and minimum permeabilities were observed in the left abutment and in the foundation bed of the site, respectively. In addition, the optimal orientation for more effective grouting is drilling boreholes along the (K0) direction, which is perpendicular to the K1 and K2 directions and to the K1-K2 plane.
Keywords
Subjects

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