Effect of Rock Fracturing on the Modulus, as Determined by Borehole Dilation Tests.
Proc 2D Internat Cong Internat Soc Rock Mechanics Belgrade Yugoslavia Sept 21-26 1970 :5 pages
In situ dilation tests were made in small boreholes to determine the apparent modulus of rigidity of fractured rock, using the Bureau of Mines cylindrical pressure cell. A steady decrease of modulus occurred with decreasing fracture spacing. Application of the law of similitude leads to an interpretation of this result as a size effect. This interpretation seems capable of rationalizing the results of all types of static tests to determine rock modulus. A good estimate of the apparent modulus for any size of structure, such as a dam foundation or a tunnel, can be derived from a testing program that takes proper account of rock fracturing.
Proc. 2D Internat. Cong., Internat. Soc. Rock Mechanics, Belgrade, Yugoslavia, Sept. 21-26 1970