Abstract
The knocking ball test is the in-situ handy test developed by the authors to measure deformation characteristics of rock materials and rock masses quickly. The principle of this test is based on the Hertz theory which is the classical contact mechanics but still the suitable solution for non-adhesive contact problems of two elastic bodies. First, this paper shows the correlation between the elastic moduli (E50) obtained by uniaxial compression tests and the elastic moduli acquired by the knocking ball tests (Ekb). As a result, it is found that multiplying Ekb by the correlation coefficient of 1.65 gives the E50. Second, a deformation modulus, a tangential and secant elastic modulus, which are gained by uniaxial cyclic compression tests, are compared with Ekb so as to corroborate the strain level of Ekb. Consequently, it is confirmed that the strain level of the test is roughly similar to the one of laboratory tests. Finally, the knocking ball tests are applied to determine the rock mass classification and to evaluate aggregate quality. The result of the former shows that E50,kb has a possibility to be a property which helps determine the rock mass classification promptly on site. And the latter suggests that the knocking ball test is more useful and appropriate than the Schmidt rock hammer to obtain reliable elastic moduli of aggregates.
