Abstract: Elastic parameters of engineering rock masses are key indexes for calculation of rock mass quality classification, elastic resistance coefficient of surrounding rock, rock mass strength parameters, etc. In practice, pressure-bearing rigid plate test (PRPT) and acoustic wave test (AWT) are two major methods for testing elastic modulus, deformation modulus, and wave celerity of a rock mass. Due to the differences in test principles, test results obtained by applying various methods to different lithology or different directions may be quite scattered. This paper sorts out some of the test results of basalt rock mass elastic parameters obtained in the pre-feasibility and feasibility study stages of the Baihetan dam, the largest hydropower project under construction in the world － including a 156-point PRPT, a 665-borehole deformation test (200 rigid and 465 flexible), a 58-adit test of rock mass seismic wave, a 143-adit-borehole AWT (58 adits and 85 boreholes). By examining the correlation between measured elastic modulus, deformation modulus and wave celerity, we determine and suggest better test schemes and work out an empirical formula for the conversion of wave celerity into rock mass modulus. The PRPT results are poorly correlated to seismic wave tests, so the conversion of seismic wave celerity to rock mass elastic parameters is not recommended. The PRPT and borehole modulus are exponentially related to acoustic wave speed. We recommend the PRPT method as a basis for the static modulus tests of rock masses and AWT as a basis for the dynamic modulus tests. The results would enrich the basic data for hydropower construction and help its survey and design.

Key words: elastic parameters of rock mass, wave velocity test, pressure-bearing rigid plate test, Baihetan basalt