白鹤滩水电站是我国继三峡、溪洛渡之后又一座千万kW级的水电站。白鹤滩水电站挡水建筑物为双曲拱坝，坝基岩体主要为二迭系厚层玄武岩，其中第三层（P₂ β₃）微晶隐晶玄武岩柱状节理发育，坝基岩体的变形参数是大坝设计的重要依据。介绍了钻孔弹模计试验原理、方法和白鹤滩水电站坝址区柱状节理玄武岩弹模试验成果，以及钻孔弹模计与现场承压板法对照性试验成果。对照性试验表明，钻孔弹模计试验岩体的变形参数可以直接在工程上应用。

Baihetan hydropower station is another large hydropower station with a total installed capacity over 10 000 MW, following the Three Gorges and Xiluodu hydropower station. The water retaining structure of the station is a double-curvature arch dam, with the rock mass of dam foundation belongs mainly to Permian system thick bedded basalt and some microlite and crypto-crystal columnar jointed basalt. Deformation characteristics of the rock mass are important basis in dam design. We introduced the principle and method of borehole jack, and compared its measured results with in-situ bearing plate test results, and analyzed the deformation characteristics and variation regularity of columnar jointed basalt. Results showed that the deformation results measured by borehole jack well consists with that by in-situ bearing plate test, which indicates that the measured results are reliable. Moreover, the horizontal deformation modulus is evidently larger than vertical deformation modulus, and the deformation moduli in both banks are subject to influences of geological factors, geostress, and bank slope unloading. Deformation modulus of test holes near the bank slope is smaller than that far from the bank slope. The deformation parameters measured by borehole jack can be applied directly to engineering.