Abstract: In order to appraise the quality testing of grout curtain, digital borehole camera technology is applied to three boreholes of the grouting gallery No.3 in Xiaolangdi Water Control Project. This paper introduces the basic theory and analytical method of digital borehole camera technology, presents some typical borehole-wall images of joints, cracks, fracture zones and crack filler of mortar in the three boreholes and further analyzing. It is concluded that: ?The grout is impelled by grout pressure and seeped towards the rockmass around the boreholes mainly along fractures and cracks which have good connectivity and extension in the fracture network. The fractures are filled who open to the main seepage path cracks and those are neglected who not open to main seepage path or partly filled after flerried under grout pressure. As a result of our exploration, three different filling situations of all-filled, partly-filled and run-out mortar are observed in borehole wall. ? The filling of fractured zones depend on the size, property and connectivity with grout holes. These findings of the application have led the author to the conclusion that: the enhancement in rockmass integrity by grout curtain project in the grouting gallery No.3 of Xiaolangdi Water Control Project is obvious. The application of the digital borehole camera technology to quality test of grout curtain by boreholes exploration is feasible.

Key words: digital borehole camera, digital panoramic technology, grout curtain, quality test, Xiaolangdi, mortar filling