Determination of some engineering properties of weak rocks

It is difficult to make specimens of regular shape of weak rocks as they disintegrate and fail along planes weakness while coring or cutting. Various rock indices based on testing irregular lumps provide a valuable means of predicting the strength. Strength of weak rocks determined by testing specimens of irregular shapes have also been found to be close to the strengths determined by testing specimens of regular shapes. The paper deals with the various techniques of determining rock indices and gives the results obtained in the rock mechanics laboratory of the Bañaras Hindu University.