The Rock Mass Classification of Dam Foundation Rock Using the Knocking Ball Test

Abstract

In dam construction, the confirmation of dam foundation rock is important. So far, the evaluation of dam foundation rock is generally a “hammering test” and “visual confirmation of the crack state” by experts have been carried out, neither the criterion of evaluation item are qualitative, rock mass may differ by rater. The authors, in addition to the conventional process according to experts, was applied “The knocking ball test” can quantitatively and quickly measure the elastic modulus of the rock in situ. By “The knocking ball test”, it is possible to quantitatively evaluate the hardness classification. We were able to smoothly advance the dam foundation rock inspections conducted under the dam operators and technician attendance.