Abstract：The pressure-bearing plate test is a kind of field test method which is extensively used to determine deformation parameters of rock mass. According to the field deformation test information of large-scale rigid pressure-bearing plate of Dagangshan dam zone，the loading and unloading deformation relation curves of test rock mass are described in detail. The deformation parameters such as elastic modulus，deformation modulus and equivalent deformation modulus of test rock mass are calculated by the deduced compressive deformation formula of deep rock mass. The empirical regression equations and high significance fitting curves of sound wave velocity and deformation modulus for test rock mass are got by regression analysis method. The analytical results of field pressure-bearing plate test indicate that the deformation parameters of diabase dike at dam zone are smaller，the compressive deformation of rock mass mainly concentrates in soft diabase dike interlayer and the deformation parameters of rock mass at right dam zone are smaller than that of left dam zone. These test analysis results provide important basis for revealing changing laws of mechanical parameters of dam zone rock mass.
