Abstract:  The monitoring results during construction indicate that the load on the supporting structure of deformable body at the right bank in front of Pubugou dam changes normally. The displacement of the slope is small, and the deformable body is stable until the first impoundment ． However, the first impoundment has brought negative effect on Pubugou hydraulic project ． According to the macroscopic deformation phenomena and monitoring results during impounding, and using the comparison mapping and eigenvalue statistics methods, detailed analysis is presented for the load change of supporting structure and the deformation of the deformable body. The comprehensive analysis indicates that the rock above strong unloading bottom border is influenced by the impoundment ， and the main deformation is creep deformation at superficial loose zone ． The displacement increases as the elevation increases, and the accumulative displacement on the ground surface reaches 10 to 20 mm ， with a maximum average displacement rate amounting 0.10 mm /d ． The anchor load below water level reduces obviously due to impounding ， with a maximum decrease of 70.0 kN ． The continuous monitoring data after the first impoundment indicates that the deformable body is still stable ．

Key words:  hydraulic engineering ,    first impoundment  ,   deformable body ,    safety monitoring  ,   stability